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In recent decades astronomers have suspected that the center of our galaxy has an elongated stellar structure, or bar, that is hidden by dust and gas. Many spiral galaxies in the universe exhibit such a bar through the center bulge, while other spiral galaxies are simple spirals. Astronomers ask, why? In a recent paper Dr. Andrea Kunder, of Cerro Tololo Inter-American Observatory (CTIO) in northern Chile, and a team of colleagues have presented data that demonstrates how this bar is rotating.
Over a period of 4 years almost 10,000 spectra were acquired with the CTIO Blanco 4-meter telescope, located in the Chilean Atacama desert, resulting in the largest homogeneous sample of radial velocities with which to study the core of the Milky Way.
Analyzing the stellar motions confirmed that the bulge in the center of our galaxy appears to consist of a massive bar, with one end pointed almost in the direction of the sun, which is rotating like a solid object. Although our galaxy rotates much like a pinwheel, with the stars in the arms of the galaxy orbiting the center, the BRAVA study found that the rotation of the inner bar is cylindrical, like a toilet roll holder. This result is a large step forward in explaining the formation of the complicated central region of the Milky Way.
The full set of 10,000 spectra were compared with a computer simulation of how the bar formed from a pre-existing disk of stars. Dr. Juntai Shen of the Shanghai Observatory developed the model. The data fits the model extremely well, and suggests that before our bar existed, there was a massive disk of stars.
This is in contrast to the standard picture in which our galaxy’s central region formed from the chaotic merger of gas clouds, very early in the history of the Universe. The implication is that gas played a role, but appears to have largely organized into a massive rotating disk, that then turned into a bar due to the gravitational interactions of the stars.
The stellar spectra also allow the team to analyze the chemical composition of the stars. While all stars are composed primarily of hydrogen, with some helium, it is the trace of all the other elements in the periodic table, called “metals” by astronomers, that allow us to say something about the conditions under which the star formed.
The BRAVA team found that stars closest to the plane of the Galaxy have a lower ratio of metals than stars further from the plane. While this trend confirms standard views, the BRAVA data cover a significant area of the bulge that can be chemically fingerprinted. By mapping how the metal content of stars varies throughout the Milky Way, star formation and evolution is deciphered, just as mapping carbon dioxide concentrations in different layers of Antarctic ice reveal ancient weather patterns.
The international team of astronomy on this project has made all of their data available to other astronomers so that additional analysis will be possible. They note that in the future it will be possible to measure more precise motions of these stars so that they can determine the true motion in space, not just the motion along our line of sight.
The Daily Galaxy via National Optical Astronomy Observatory
Image credit: ESO | 0.855186 | 4.141365 |
Back in February, physicists set the world on fire (not literally) with the announcement of the first direct evidence of the gravitational waves that Einstein predicted more than 100 years ago.
It was a massive achievement - one that you’d definitely get tattooed on your arm if you were in any way involved - but now scientists want to take things a whole lot further. They want to spend around US$1.3 billion to get a new space-based observatory into orbit by 2029, so we can detect gravitational waves a whole lot closer to the source.
Why is it worth such an astronomical (sorry) amount of money to study gravitational waves from out in space, rather than on Earth?
Well, the twin LIGO (Laser Interferometer Gravitational-wave Observatory) detectors, located in Louisiana and Washington, did a great job at detecting the first-ever direct evidence of gravitational waves, but with one big limitation - they’re not powerful enough to probe anywhere near the actual source.
"Currently, gravitational wave observatories possess relatively blurry vision," NASA explains, adding that LIGO scientists were only able to trace the source of the gravitational waves detected on 14 September 2015 to an arc of sky spanning an area of about 600 square degrees - about the angular area on Earth occupied by the entire United States.
That area has since been narrowed down by new data coming from NASA’s space-based Fermi Gamma-ray Space Telescope, and that’s exactly the point - if we want to get to know gravitational waves properly, we need to go to where they live.
And according to a new report, the European Space Agency’s (ESA) proposed mission to get a new gravitational waves observatory into space is not just technically feasible - it’s also really freaking compelling.
As Jonathan Amos reports for BBC News, the ESA recently asked a panel of experts called to perform a "sanity check" on the project, which is expected to cost well over 1 billion euros (US$1.3 billion).
Called the Gravitational Observatory Advisory Team (or Goat), the expert panel announced that it sees no major hurdles in the proposed plan, and even went so far as to recommend that the launch date be brought forward from 2034 to 2029.
It’s a pretty good day when the people you request a sanity check from tell you you’re being too cautious.
"[A]fter submitting our report, ESA came back to us and asked what we thought might be technically possible, putting aside the money," Goat chairman Michael Perryman told the BBC. "We are in the process of finalising a note on that, which will suggest the third quarter of 2029. So, 13 years from now."
Amos reports that the ESA is now expected to issue a call to the scientific community to submit a detailed proposal in the coming weeks.
So what would this space-based observatory actually do to detect the ripples in space-time caused by gravitational waves? The Goat scientists advise that it should take the same approach as LIGO did here on Earth, called laser interferometry.
"The LIGO laboratory works by bouncing lasers back and forth in two 4-km-long pipes, allowing physicists to measure incredibly small changes in spacetime," Fiona MacDonald explained for us back in February. "[T]his light is bounced back and forth by a set of mirrors. Any tiny ripples in spacetime will cause slight timing changes in this laser light, and the LIGO detectors are able to pick that up."
Essentially, the ESA would use the same technique for the new observatory, but this time, we’d be firing the lasers out in space.
One thing that makes ESA's whole mission that much more feasible is the fact that it already has a satellite out in orbit that's doing 'practice runs' of the kinds of experiments that a larger space-based observatory would need to conduct.
Launched on 3 December 2015, the LISA Pathfinder will not directly search for gravitational waves, but will test several new technologies that will be useful for such a mission.
"The agency is currently doing experiments in orbit that will prove some of the equipment needed on a future gravitational wave observatory," Amos reports for the BBC. "But the Goat also identifies critical additional developments that must now be prioritised to take the laser approach into space."
Only time will tell if the ESA will manage to gather together all the funds in time, but we sure hope it does. Because it's not every day that a big, crazy, moonshot idea like putting an entire observatory out in space in just over a decade gets the "Hell yeah, it's practical!" stamp of approval. Let's not waste it. | 0.822267 | 3.61889 |
The observation of solar eclipses may bring significant risks for eyesight. During partial or annular eclipses (see the two drawings on the left on the illustration below), it is mandatory to wear eye protection to prevent eye damage, particularly for children.
Ophthalmic risks are real, particularly during the hours closest to solar noon, at which time the short wavelength visible radiation and ultraviolet light from the Sun are least absorbed by the atmosphere.
Ophthalmic risks linked to a direct observation of the Sun, are of two kinds:
- corneal lesions of the keratitis type, related primarily to ultraviolet light, painful but usually reversible within days,
- retinal lesions or burns related to the thermal effect of solar radiation and to a photochemical effect on retinal cells that are particularly vulnerable. This effect can be irreversible and ultimately lead to impaired eyesight, or even blindness.
To observe such event with good eye safety, it is mandatory to use special protective goggles that are completely opaque to visible light. These eclipse glasses are personal equipment and should comply with the provisions of European directive 89/686/EEC on personal protective equipment, and carry the CE mark of conformity. Eclipses glasses should also meet the more recent ISO 12312-2:2015 standard.
The filtering part is made from either polyester film coated with a thin layer of aluminum foil or black tinted polymer film (the latter is much less fragile and more stable over time). These films are usually embedded in cardboard mounts. The cardboard-framed glasses should be considered disposable. The optical quality of the filter can deteriorate if the glasses are stored in poor conditions.
It is also possible to use welding glasses, either held directly by hand or mounted on cardboard for protection. This glass must be of shade #14, of good optical characteristics under the European standard EN 169/1992. Such filters can be reused and will not deteriorate or change over time; it is currently the best protection if properly used.
People should be warned against using other means of protection, such as smoked glasses, X-ray films, CD/DVD disks or just sunglasses whose faculty of protection is very low.
In no event shall the Sun be observed with optical instruments (binoculars, cameras, ...) without using suitable filters placed at the opening (extremity pointing towards the Sun). Similarly, eye protection at the rear of an instrument should be avoided in all circumstances because they are not designed to absorb such an amplification of solar radiation; the appropriate filters can be purchased at astronomy stores.
It is also advisable to limit the continuous observation time starring at the Sun and make a pause between two observations in order to let the eyes rest.
Parents should take special care to protect their children.
The illustration below gives you an indication of when you should wear the eclipse glasses. | 0.808032 | 3.069314 |
Just when you thought images of Pluto returned by the New Horizons spacecraft could get any more awe-inspiring, NASA / JHU APL release a set of raw images that are utterly stunning.
The images come from the wide-angle Ralph/Multispectral Visual Imaging Camera (MVIC) on the space craft and were captured just 15 minutes after the vehicle reached is point of closest approach to the little world, and thus from a distance of just 18,000 km (11,000 miles) from Pluto.
The stunning vistas presented in the image show the ice plains of “Sputnik Planum” bordered to the left and from below by Pluto’s huge mountain ranges, informally named Hillary and Norgay, Montes after the first partnership to successful reach the summit of Mt. Everest here on Earth. All of this is dramatically backlit by sunlight reflected through Pluto’s hazy atmosphere to create a wonderful scene said to be reminiscent of views of the Antarctic viewed from space or very high altitude.
However, the images aren’t just notable for the panoramic beauty; they actually reveal a lot about what is happening in the Plutoian atmosphere. Because of the back lighting from the Sun, the high-resolution MVIC has revealed just how complex Pluto’s atmosphere is, comprising multiple layers of nitrogen and other gases rising to around 100 km (60 mi) above Pluto’s surface (and visible as a banding in the images above).
“In addition to being visually stunning, these low-lying hazes hint at the weather changing from day-to-day on Pluto, just like it does here on Earth,” said Will Grundy, lead of the New Horizons Composition team from Lowell Observatory, Flagstaff, Arizona.
What is also exciting the science team is evidence within the images for Pluto having a complex “hydrological” cycle which seems to be comparable in some ways to that found on Earth – only on Pluto, it involves nitrogen ice, rather than water ice.
When compared with images captured as New Horizons approached Pluto, the MVIC images further suggest that the regions eastward of “Sputnik Planum” appear to have been encroached over time by ices and material possibly evaporated from the surface of “Sputnik Planum” to be deposited on the higher lands as a new ice blanket, which in turn appears to have formed glacial formations flowing back into “Sputnik Planum”.
“We did not expect to find hints of a nitrogen-based glacial cycle on Pluto operating in the frigid conditions of the outer solar system,” said Alan Howard, a member of the mission’s Geology, Geophysics and Imaging team from the University of Virginia, Charlottesville. “Driven by dim sunlight, this would be directly comparable to the hydrological cycle that feeds ice caps on Earth, where water is evaporated from the oceans, falls as snow, and returns to the seas through glacial flow.”
To Scale: The Solar System
We’re all familiar with the idea that the solar system is so vast, that it is almost impossible to show the Sun and the major planets proportional to one another and at a scale where all the later are both visible and have orbits which can be adequately encompassed in an easily viewable space.
Obviously, some models do exist; the Lowell Observatory in Arizona, USA, for example, has a walk that allows visitors to travel from the sun and by each of the planets, but it’s not always easy to clearly grasp the sheer scale of things. The same goes for digital models (and a few have been built within virtual worlds like Second Life).
With this issue of scale and proportion in mind, Wylie Overstreet and Alex Gorosh set out to produce a scale model of the solar system that might help people understand just how vast our planetary back yard is when looked at on a human scale.
They started with a blue marble to represent the Earth, echoing the famous photograph taken on December 7, 1972, by the crew of Apollo 17 en route to the Moon and which NASA dubbed the Blue Marble.
Taking the marble’s diameter as a basis meant that the Sun would be around 1.5 metres (2.4 ft) across, which immediately brought up a problem: to build a correctly scaled model of just the eight major planets of the solar system, they’d need a flat area of land 11.2 km (7 miles) across.
Cue a dry lake bed in Nevada, and a remarkable film which also celebrates the era of Apollo.
And in case you’re wondering what this means for the size of our galaxy, consider two comments by “Walter Boxhead” following the video:
- At the same scale, the Voyager 1 space craft, the furthest human-made vehicle from Earth, would be 23 km (14.4 miles) away from the balloon representing the Sun.
- Also at this scale, the Sun’s nearest stellar neighbour would be around 47,000km (29,375 miles) away – just over that at which the iconic Blue Marble photo was taken in 1972.
On Display: the Soviet Space Programme
Those of us in the UK into space exploration can enjoy a unique insight into Russia’s Soviet-era space endeavours including a glimpse of the work of the “grandfather of rocketry”, Konstantin Eduardovich Tsiolkovsky, via a new exhibition being hosted by London’s Science Museum.
Cosmonauts: Birth of the Space Age, which opened on Friday, September 18th and runs through until March 13th, 2016, features 150 Soviet-era spacecraft, spacesuits and other artifacts, together with original drawings dating from 1933 by Tsiolkovsky depicting living and working in a microgravity environment when orbiting the Earth.
In particular, the exhibit includes the most complete example of a Soviet crewed lunar lander in existence, and the capsule which carried the first woman into space, Valentina Tereshkova and returned her safely to Earth.
Tereshkova, who was also technically the first civilian to fly in space, her position and rank in the Soviet Air force being purely honorary, was present at the opening of the exhibition, as was the world’s first space-walker, Alexey Leonov.
“Cosmonaut is a once-in-a-lifetime exhibition that has taken years of dedication and skill to make a reality,” Ian Blatchford, the director of the Science Museum said during the opening of the exhibition. “The Russian space programme is one of the great intellectual, scientific and engineering successes of the 20th century, and I am thrilled that we have been able to bring together such an outstanding collection of Russian space artifacts to celebrate these achievements.”
Cosmonauts: Birth of the Space Age is the culmination of partnership spanning several years between the Science Museum in South Kensington, London, the Russian State Museum and Exhibition Centre Rosizo in Moscow, and Russia’s Federal Space Agency Roscosmos.
First Crewed flight for NASA’s Orion My Slip
NASA has indicated that the first crewed flight of the Orion space vehicle may not take place until 2023.
The announcement was made as the Orion’s development programme achieved a milestone known as Key Decision Point C (KDP-C) on September 16th, 2015. This review, one of several which have taken place / will occur during both the vehicle’s development and that of its associated Space launch System (SLS) rocket launcher, found that there is a 70-percent chance Orion will be ready for its first crewed mission, Exploration Mission 2 (EM-2), no later than April 2023.
The findings do not indicate there are any issues with the development programme for the vehicle, which is designed to fly crews well beyond Earth’s orbit, such as back to the Moon and, as part of a large spacecraft, to Mars. Rather, it reflects concern that there may yet be “unknowns” which might arise in the future which serve to delay the flight.
Nevertheless, despite the potential of an 18-month delay when compared with the original target launch period of August 2021, the Orion development team are still pushing forward with an “aggressive” programme to get the vehicle ready for its first crewed mission in 2021 even while acknowledging the chances of hitting the target are low. The potential slippage in no way impacts on the next planned launch of Orion, designated EM-1, which will see an uncrewed version of the vehicle launched atop the new SLS rocket in the autumn of 2018.
SHEE: The Self-building Habitat
A team of engineers and designers from five European countries have spent the last few years working on unique approach to building living space on Mars and / or the Moon, and which could have major implications for things like disaster relief here on Earth.
The Self-deployable Habitat for Extreme Environments (SHEE) project is researching the means to provide habitat spaces which literally “build themselves” and could provide expanding living accommodation on a Lunar or Mars mission without the need for “on-site” construction or the bulky addition of having to fly the modules in a “pre-built” state.
The basic idea behind SHEE came out of a research idea initiated by architect Ondrej Doule, who saw the construction of any large-scale habitat elements suitable for support long-stay crews on either the Moon or Mars as potentially one of the most risk-intensive elements in trying to establish a long-term presence in either location. Some €2.3 million ( US $2.6 million) has been awarded in funding for the project to date, which has been used to finance a 36-month initial programme to develop and prototype SHEE modules through until December 2015.
The habitat is a hybrid structure composed of inflatable, rigid and robotic components. It is divided into five functional areas, which in the default unit comprise entrance ports, work areas, private crew quarters, a kitchen and a toilet. However, individual units could be equipped to accommodate specific tasks and activities, allowing a number of the units to be interconnected to produce a small base camp.
The prototype system utilises a rigid structure comprising a rectangular core element together with six semi-circular sections, some of which are pre-furnished and which are stored within the core element during flight / pre-deployment, and then which rotate out from the core to form the two circular bulges on either side, as shown in this SHEE video.
Currently, the prototype is undergoing testing at COMEX, France. However, there are plans to move it to the International Space University in Strasbourg, France. Once there, it will undergo a series of intensive tests without humans “in the loop”, to verify whether the unit can function as expected for up to 14 days in an extreme environment. A deployment to a Mars analogue region around the Rio Tinto river in Andalucia, Spain, where it will be used in human / robotic interaction tests.
A more Earthly use for the system might be in disaster relief, where its compact size and easy deployment could be used to quickly present those suffering under a natural or other disaster with shelter and accommodation. In addition, the units could be used for a range of research opportunities in hard-to-access locations on Earth and with minimal ecological impact. | 0.893858 | 3.778694 |
When wind blows over sand on Earth, it can produce two types of patterns: small ripples or large dunes. On Mars, there also appears to be a unique category in the middle: large ripples, with crests separated by a meter or more (seen here in this Curiosity rover "selfie"). Researchers discovered the pattern when the NASA rover stopped at a set of dunes in Gale crater in late 2015 and early 2016, and they first reported the discovery in March at the Lunar and Planetary Science Conference in The Woodlands, Texas. In a paper published online today in Science, they say the formations are fluid drag ripples, similar to those seen underwater in streambeds on Earth, and that their size is controlled by the thickness of the martian atmosphere. That means that the ripples, if preserved as patterns after the sand turns to stone, could be a "paleobarometer". The scientists found ripple patterns in ancient rocks that are slightly smaller than the ones found across the planet today. That, they say, suggests that the ancient atmosphere was slightly thicker. | 0.820659 | 3.446727 |
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Mars Global Surveyor spotted a sand dune.
NASA has announced its fifth Centennial Challenges prize competition: the Regolith Excavation Challenge. Teams will compete head to head in 2006 or 2007 to see whose digging machine can excavate the most lunar soil, or regolith, in 30 minutes and deliver it to a collector. Any future Moon base will require large quantities of regolith to be moved around by robotic diggers, so NASA is hoping to see innovative ideas now to base future technologies around.
Mars is a more dramatically changing place than scientists had ever imagined. Thanks to its long lifetime, the Mars Global Surveyor has spotted a gully coming down the side of a sand dune that didn't exist just three years ago. The gully could have formed when frozen carbon dioxide was suddenly warmed up enough that it evaporated, releasing gas that flowed downhill like a liquid. Mars Global Surveyor is still very healthy, and could be making observations 5-10 years from now.
Newborn stars hide in a shroud of dust and gas, so they're difficult to photograph. Astronomers have used the Infrared UKIRT telescope on Mauna Kea, Hawaii to peer through one of these envelopes to see a pair of newborn stars - probably only 100,000 years old. The stars are quite large; however, they weigh 10 times the mass of the Sun together. The surrounding disk of material probably has enough left over to create 100 Jupiter-mass planets.
Astronomers have known about a strange blue light coming from the heart of the Andromeda Galaxy (M31) for many years, but they were never sure exactly what it was. Thanks to new observations from Hubble, they now know it's a ring of young hot stars which are whipping around the supermassive black hole in the middle of M31. The 400 stars are packed into a disk only 1 light-year across, which is nestled inside a larger ring of older, redder stars. Our own Milky Way might have a similar phenomenon, which means this could be the situation in most galaxies.
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A channel in an ancient Martian "riverbed" wasn't carved by liquid water but was built by molten lava, according to a new study of surface features on Mars.
Pictures of the red planet have long revealed features such as valleys and alluvial fans reminiscent of those seen around water bodies on Earth. (Related: "Huge Mars Region Shaped by Water, Rover Mission Finds.")
Water is a prerequisite for life as we know it, so these formerly wet landscapes have been touted as some of the best places on Mars to look for traces of past life.
But new high-resolution images of a peculiar 168-mile-long (270-kilometer-long) channel near the Ascraeus Mons volcano aren't likely to have been made by water after all.
"We started seeing that, instead of this [liquid] cutting into an existing surface, it was building a surface—it built a ridge up to 40 meters [130 feet] high" millions of years ago, said study co-author Jacob Bleacher of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
The channel is also roofed over in some areas and lined with vents—features most often associated with lava tubes. On Earth, lava tubes form during sustained volcanic eruptions, when lava flowing through previously solidified masses leaves behind empty channels in the rock. (Related: "Mars Has Cave Networks, New Photos Suggest.")
"You don't see this on Earth in [river] settings," Bleacher said. "But you see it all the time in volcanic settings. So that's kind of our smoking gun."
That's not to say liquid water never flowed on Mars, said Bleacher, who presented his work last week at the 41st Lunar and Planetary Science Conference.
But the findings do mean that researchers might need to reevaluate when and where they think water might have existed on the red planet. (Related: "Mars Had Liquid Water in Recent Past, Rover Finds.")
Solving a Martian Puzzle
The results are also exciting because they add new layers to Mars's volcanic history, said Laszlo Kestay, a planetary geologist on the NASA team that produced the new images of the channel.
"I think there are some very clearly water-formed features on Mars, but there are other things that are more puzzling. Jake and colleagues make a very compelling case that at least this one is volcanic," said Kestay, with the U.S. Geological Survey's Astrogeology Science Center.
And there's a good chance other channels in the Ascraeus Mons area will turn out to be lava-made as well, Kestay said.
In general, the latest find is among the myriad new details about Martian lava flows being uncovered by high-resolution imaging of the Martian surface, Kestay said.
The new image data, he said, are "revealing not just these channels but a whole suite of smaller volcanic features and showing that volcanism is more widespread spatially than people thought."
NASA Grants a "HiWish"
In addition, the new study highlights a pioneering program that allows people anywhere in the world to get behind the lens of the Mars-orbiting camera used in Bleacher's work: NASA's High Resolution Imaging Science Experiment.
HiRISE started sending back color pictures of the Martian surface in 2007, with the primary goal of finding a suitable landing site for the upcoming Mars rover Curiosity, slated to launch in 2011.
Now that the options have been narrowed down to four possible landing sites, NASA has launched HiWish, a Web site where the public can suggest new targets for the high-resolution camera.
Bleacher's research is based on images taken after he had submitted a request to a beta version of HiWish made available to scientists.
In previous pictures of the Ascraeus Mons region of Mars, "the big hindrance has been that you can see [only] the big features," Bleacher said. "But you really need the details to see how things evolved."
HiRISE offers "a more detailed glimpse into what's going on with these volcanoes. Now, as we're able to look at these things in their entirety, we really need to readdress our thoughts on how they formed." | 0.839157 | 3.837653 |
Measuring the Universe: The Historical Quest to Quantify Space
a thrilling & available mixture of background & state of the art technology, this ebook chronicles man's makes an attempt to thrust back the frontiers of knowing. From a librarian in historical Alexandria understanding the circumference of the earth via learning the way in which the daylight fell right into a desolate tract good, via Newton's estimates of the gap to the closest stars, to the newest advancements in theories as to what's past the borders of the observable universe, clever minds have requested questions on our universe, & our position in it. this is often the tale in their look for solutions. The queries variety from the mechanical to the metaphysical, yet all are rooted in centuries-old interest. An event tale that whisks us via three millennia of clinical ingenuity & highbrow historical past.
Numbers. almost immediately sooner than Freedman made her findings public in October 1994 there have been different experiences whose effects implied that present estimates of the universe’s growth price and age can be headed for one more revision. A group led via Robert Kirschner of the Harvard-Smithsonian heart for Astrophysics, utilizing the Cerro Tololo Inter-American Observatory in Chile, measured the increasing particles from 5 supernovae and judged the universe may be from nine to fourteen billion years outdated. yet Freedman’s.
A dating among the luminosity and spectral line widths of galaxies to estimate their distances. twenty-one centimeter line width: Hydrogen atoms, of which many of the interstellar topic unfold all through a spiral galaxy is composed, emit radio noise on the wavelength of twenty-one centimeters. How a lot that spectral line is blurred through the rotation of the galaxy is without delay with regards to the rate at which the galaxy rotates, and that velocity is said to the galaxyʼs absolute importance.
Them out, the particular measurements frequently look dry as airborne dirt and dust: The solar is 149.5 million kilometres away (mean distance). the closest big name is 4.3 mild years. The ‘Local team’ of galaxies covers a space approximately three million mild years in diameter. the space to the sting of the observable universe is 13.7 billion mild years. We shake our heads at how huge those numbers are or admit their largeness makes them meaningless, consider them for an afternoon or perhaps lengthy sufficient for a college examination . . . after which.
in comparison to the hoop of far away stars that Mars, X and Y could be considered all being, primarily, on the centre of the megastar ring. The parallax shift of Mars as seen from ends of any final analysis attainable in the world isn't anyplace close to as huge as 30°. it's going to be transparent now why Cassini’s undertaking required having observers in greatly separated destinations at the face of the Earth. There were obscure plans for the Observatory to ship an day trip to the tropics for different astronomical.
Century for the 1st time. not just did such legislation exist, yet human minds may become aware of them and comprehend them. the concept that used to be now not a whole novelty to scientists, even though to work out it confirmed as fantastically because it used to be in Newton’s Principia was once a novelty. To the non-scientific public Newton’s revelation used to be sensational, striking. the celebrity of his publication unfold fast all through Europe, and his principles have been popularized in lots of varieties. there has been a e-book known as Newton for girls in France. | 0.865287 | 3.563822 |
Astronomers have discovered a lonely planet that's floating by itself in deep space without orbiting a star.
The powerful Pan-STARRS 1 (PS1) telescope at the summit of Maui's Haleakala volcano in Hawaii first detected the solitary alien world through a faint heat signature 80 light-years from Earth while it was searching for brown dwarfs.
Dubbed PSO J318.5-22, the exoplanet is relatively young at 12 million years old, researchers say. With a mass about six times that of Jupiter, the planet resembles gas giants that orbit young stars, follow-up observations with other telescopes showed. But the one thing it appears to be missing is a parent star.
"We have never before seen an object free-floating in space that that looks like this. It has all the characteristics of young planets found around other stars, but it is drifting out there all alone," study researcher Michael Liu, of the Institute for Astronomy at the University of Hawaii at Manoa, said in a statement. "I had often wondered if such solitary objects exist, and now we know they do."
The absence of a bright star could be a boon for scientists trying to understand the nature of planets outside our solar system, only a handful of which have been observed through direct imaging. Researchers typically study these alien worlds through indirect means, such as watching for the dips in starlight that occur when an exoplanet crosses in front of its star.
"Planets found by direct imaging are incredibly hard to study, since they are right next to their much brighter host stars," Niall Deacon, of the Max Planck Institute for Astronomy in Germany, explained in a statement. "PSO J318.5-22 is not orbiting a star so it will be much easier for us to study. It is going to provide a wonderful view into the inner workings of gas-giant planets like Jupiter shortly after their birth."
The number of known exoplanets has exploded over the past 10 years. Astronomers have confirmed more than 800, but some estimates suggest there are likely be tens of billions of exoplanets in the universe.
PSO J318.5-22 was inadvertently discovered during a survey of brown dwarfs, starlike cosmic objects sometimes called "failed stars" because they are bigger than planets but too cold to flare up into a veritable star.
In their search for the dim red signals of brown dwarfs, astronomers chose to use PanSTARRS 1 (PS1), short for Panoramic Survey Telescope and Rapid Response System, which takes the equivalent of 60,000 iPhone photos each night.
"We often describe looking for rare celestial objects as akin to searching for a needle in a haystack," Eugene Magnier, of the Institute for Astronomy, said in a statement. "So we decided to search the biggest haystack that exists in astronomy, the dataset from PS1."
In their survey, they spotted PSO J318.5-22, an object redder than even the reddest known brown dwarfs. The researchers watched the planet for two years and concluded that it lies in a collection of 12-million-year-old stars called the Beta Pictoris moving group.
Observations with other telescopes found signatures in the cosmic body's infrared light that are best explained by it being young and low-mass. In fact, PSO J318.5-22 is one of the lowest-mass free-floating objects known, the researchers say.
The discovery will be detailed in Astrophysical Journal Letters, but the study is available online now on the preprint service Arxiv.
Image: MPIA/V. Ch. Quetz
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- Space Lung Tissue Experiment Returns to Earth
This article originally published at Space.com here | 0.91035 | 3.738199 |
15 Sep 10 — A layer of trillions of nanosize diamonds discovered in the Greenland ice sheet “adds credence to the hypothesis that fragments of a comet struck across North America and Europe about 12,900 years ago,” says this article in Science Daily.
“There is a layer in the ice with a great abundance of diamonds,” said James Kennett, professor emeritus in the Department of Earth Science at UC Santa Barbara. “The diamonds are so tiny that they can only be observed with special, highly magnifying microscopes. They number in the trillions.”
I don’t agree with Kennett’s assessment. I think the Greenland nanodiamonds lend credence to my hypothesis that giant explosions in the sky during the Gothenburg magnetic reversal created vast amounts of carbon – including the nanodiamonds – which then rained onto our planet. (See Magnetic Reversals and Evolutionary Leaps.)
This discovery supports earlier published evidence for a cosmic impact event about 12,900 years ago, Kennett explained.
Previously, Kennett and his son, Douglas J. Kennett, of the University of Oregon, had reported the discovery of nanosize diamonds in a layer of sediment found on Santa Rosa Island, off the coast of Santa Barbara, Calif.
The Santa Rosa layer corresponds with the disappearance of the Clovis culture, and with the extinction of many large animals across North America, including mammoths, camels, horses, and the saber tooth cat.
There is also evidence of widespread wildfires at that time, said Kennett.
The “evidence of widespread wildfires” comes from a layer of carbon found at many areas around the world, in some cases a foot thick. As I said above, I think that carbon was created in the sky right above the mammoth’s heads.
It rains carbon on Saturn’s moon Triton. Why not here? (See “Magnetic Reversals and Evolutionary Leaps.”)
An associated sharp climatic cooling called the Younger Dryas cooling is also recorded widely over the northern hemisphere.
A cooling that I say was triggered by the Gothenburg magnetic reversal. (See “Not by Fire but by Ice.”)
See entire article:
Thanks to David Longenhagen for this link | 0.839953 | 3.2609 |
Astronomers claim to have discovered that a vast region of our galaxy is devoid of young stars in a groundbreaking study which promises to redefine our understanding of the Milky Way.
Scientists at the University of Tokyo believe the Extreme Inner Disk has seen no new stars for hundreds of millions of years.
The region begins just 150 light years from the galaxy’s centre but spans nearly 8,000 light years, the scientists claim.
Researchers were attempting to measure the distribution of stars within the Milky Way when they say they made the discovery.
“Our conclusions are contrary to other recent work, but in line with the work of radio astronomers who see no new stars being born in this desert,” said co-author Michael Feast.
Locating stars is pivotal to astronomers’ understanding of how the galaxy formed and developed – and a particular type of young star is key to their work.
Cepheids, aged between 10 and 300 million years’ old, pulsate in a cycle that is linked to their luminosity, enabling astronomers to judge their distance from Earth by comparing their actual brightness to the strength of light seen from our planet.
But the interstellar dust that litters our universe makes it difficult for astronomers to spot Cepheids in the inner Milky Way.
The scientists used near-infrared observations made with a telescope in South Africa to see beyond the dust, but they found almost no Cepheids in the Extreme Inner Disk.
Tokyo University’s Professor Noriyuki Matsunaga, who led the study, said: “We already found some while ago that there are Cepheids in the central heart of our Milky Way (in a region about 150 light years in radius). Now we find that outside this there is a huge Cepheid desert extending out to 8,000 light years from the centre.”
The research was published in the Monthly Notices of the Royal Astronomical Society. | 0.826189 | 3.453822 |
The latest news about space exploration and technologies,
astrophysics, cosmology, the universe...
Posted: Dec 01, 2014
Ground-based detection of super-Earth transit paves way to remote sensing of exoplanets
(Nanowerk News) Astronomers have measured the passing of a super-Earth in front of a bright, nearby Sun-like star using a ground-based telescope for the first time ("Ground-Based Transit Observations of the Super-Earth 55 Cnc e"). The transit of the exoplanet 55 Cancri e is the shallowest detected from the ground yet. Since detecting a transit is the first step in analyzing a planet's atmosphere, this success bodes well for characterizing the many small planets that upcoming space missions are expected to discover in the next few years.
This artist's conception shows the super-Earth 55 Cancri e (right) compared to the Earth (left). Astronomers using a ground-based telescope have measure the transit of 55 Cancri e for the first time. It is the shallowest transit ever detected from the ground. (Image: NASA/JPL)
The international research team used the 2.5-meter Nordic Optical Telescope on the island of La Palma, Spain, a moderate-sized facility by today's standards but equipped with state-of-the-art instruments, to make the detection. Previous observations of this planet transit had to rely on space-borne telescopes.
The host star, 55 Cancri, is located just 40 light-years away from us and is visible to the naked eye. During its transit, the planet crosses 55 Cancri and blocks a tiny fraction of the starlight, dimming the star by 1/2000th (or 0.05%) for almost two hours. This shows that the planet is about twice the size of Earth, or 16,000 miles in diameter.
"Our observations show that we can detect the transits of small planets around Sun-like stars using ground-based telescopes," says Ernst de Mooij of Queen's University Belfast in the United Kingdom, lead author of the study.
He continues, "This is especially important because upcoming space missions such as TESS and PLATO should find many small planets around bright stars and we will want to follow up the discoveries with ground-based instruments."
TESS is a NASA mission scheduled for launch in 2017, while PLATO is to be launched in 2024 by the European Space Agency; both will search for transiting terrestrial planets around nearby bright stars.
"With this result we are also closing in on the detection of the atmospheres of small planets with ground-based telescopes," says co-author Mercedes Lopez-Morales of the Harvard-Smithsonian Center for Astrophysics (CfA). "We are slowly paving the way toward the detection of bio-signatures in Earth-like planets around nearby stars."
"It's remarkable what we can do by pushing the limits of existing telescopes and instruments, despite the complications posed by the Earth's own turbulent atmosphere," says study co-author Ray Jayawardhana of York Univerity in Canada. "Remote sensing across tens of light-years isn't easy, but it can be done with the right technique and a bit of ingenuity."
The planet 55 Cancri e is about twice as big and eight times as massive as Earth. With a period of 18 hours, it is the innermost of five planets in the system. Because of its proximity to the host star, the planet's dayside temperature reaches over 3100° Fahrenheit (1700° Celsius), hot enough to melt metal, with conditions far from hospitable to life. Initially identified a decade ago through radial velocity measurements, it was later confirmed through transit observations with the MOST and Spitzer space telescopes.
Until now, the transits of only one other super-Earth, GJ 1214b circling a red dwarf, had been observed with ground-based telescopes. The Earth's roiling air makes such observations extremely difficult. But the team's success with 55 Cancri e raises the prospects of characterizing dozens of super-Earths likely to be revealed by upcoming surveys.
"We expect these surveys to find so many nearby, terrestrial worlds that space telescopes simply won't be able to follow up on all of them. Future ground-based instrumentation will be key, and this study shows it can be done," adds Lopez-Morales.
Source: Harvard-Smithsonian Center for Astrophysics | 0.809631 | 3.439904 |
Astronomers that study the galaxy through the Hubble Telescope have learned how the LMC (Large Magellanic Cloud) is rotating. By studying the galaxy through the telescope astronomers can see the stars moving slowly in clock like direction. The LMC galaxy is rotating very slowly in the milky way, approximately 163,00o light years. Astronomers estimate that the LMC completes a rotation about every 250 million years; the cloud is estimated to have a mass the 10 billion times larger than the sun.
Roeland van der Marel and Nitya Kallivayalil, scientists from the University of Virginia say, “Determining a galaxy’s rotation by measuring its instantaneous back and forth motions doesn’t allow one to actually see things change over time,” van der Marel said. “By using Hubble to study the stars’ motions over several years, we can actually for the first time see a galaxy rotate in the plane of the sky.”
The Hubble Telescope orbits the earths atmosphere taking extremely hight resolution pictures that are crystal clear and it is the only telescope of it kind. The telescope was sent into space by NASA in 1990 and provides scientists with vital research data from the images it takes. Looking through the telescope and using a series of standard candles astronomers have been able to roughly calculate the distance of the LMC. Now astronomers have learned that by studying the stars in the neighboring galaxy they can see how the LMC is rotating like a clock, a very slow clock. The massive cloud is composed of rich gases and dust is constantly forming new stars in its nitrogen rich atmosphere.
NASA’s telescope is expected to remain in orbit and function until possibly the year 2020. In 2018 NASA is expected to launch a new super telescope the James Webb Space Telescope that will be even more powerful than its predecessor Hubble Telescope. It should be exciting find out what astronomers can see with the new telescope.
How Does The Galaxy Rotate? Astronomers Learn With the Hubble Telescope. | 0.818588 | 3.505169 |
NASA’s New Horizons spacecraft has recently begun sending back the first color images of Pluto and Charon, and they are spectacular. But prior to the probe making its close approach to Pluto on July 14th, scientists have been scouting Pluto’s atmosphere using a 98-inch telescope mounted inside a highly modified Boeing 747SP.
A combined effort between NASA and the German Aerospace Center (DLR), the aircraft is called SOFIA (registration N747NA, callsign “NASA747”), which stands for Stratospheric Observatory for Infrared Astronomy. SOFIA probably isn’t the best-known 747 belonging to NASA, but it is enabling valuable scientific observations because of its unique capabilities.
And while SOFIA has been flying astronomy missions since 2010, the idea of putting a telescope in an airplane to study the stars is almost 100 years old.
In the early 1920’s, Sherman Mills Fairchild developed the then-revolutionary electrically-driven K-3 aerial camera for mapping and reconnaissance missions. While the cameras were originally intended to be pointed towards Earth and not skyward, this ultimately spurred the earliest airborne astronomy flights from biplanes during the 1920’s and 1930’s, which were undertaken primarily for observing solar eclipses.
On September 10th, 1923, the U.S. Navy attempted to measure the centerline of a solar eclipse from the air using K-3 type mapping cameras and hypersensitized film aboard 16 different aircraft flying simultaneously. While precise details about all of the aircraft that were used during the attempt are elusive, one of the aircraft involved was reportedly a Felixstowe F5L “flying boat” biplane.
The convergence of smooth running jet aircraft, improved telescope technology and infrared sensors in the 1950s and 1960s led to the field of airborne astronomy taking on research beyond eclipse observations. In 1968, Gerald Kuiper (yes, that Kuiper) aimed a 12-inch telescope through the window of a NASA Learjet. Today, Kuiper is revered as a pioneer in airborne astronomy and planetary science, his work spurring a series of unique aircraft built to carry telescopes aloft.
One of NASA’s early airborne telescopes was the Galileo Observatory, a converted Convair 990 airliner that supported scientists at the Ames Research Center. That aircraft met an untimely demise in a 1973 mid-air collision with a US Navy P-3C Orion while on final approach at Moffett Field. A replacement aircraft called Galileo II was built, but unfortunately it was destroyed in a fire following an aborted takeoff in 1985.
Despite such unfortunate luck with the two Galileo Observatory aircraft, NASA operated the Kuiper Airborne Observatory (KAO) from 1974-1995, a Lockheed C-141A Starlifter modified with a 36-inch reflecting telescope. SOFIA is KAO’s follow-on program, offering scientists increased capabilities via a higher performance aircraft with a larger aperture telescope.
The Kuiper Airborne Observatory and SOFIA on the tarmac at NASA’s Ames Research Center.
SOFIA’s donor aircraft is a Boeing 747SP widebody airliner, one of only 13 current airworthy examples. The 747SP (SP stands for “Special Performance”) was originally designed to compete with the Douglas DC-10 and Lockheed L-1011 tri-jets in the early 1970’s. Lacking a competitive product in their lineup at the time, Boeing chose to offer airline customers a scaled-down version of the 747 instead of scaling up a smaller jet.
Boeing introduced the 747SP in 1973 with changes including a fuselage shortened by over 48 feet, lighter wings, solid flaps and the removal of under-wing canoes. All of this added up to an empty 747SP weighing around 45,000 pounds less than an empty 747-200, making the jet ideal for long-range intercontinental flights. Because the shorter, lighter 747SP retained the same four engines and as the original 747, it could also fly faster and higher.
These special characteristics of the Boeing 747SP lend themselves perfectly to SOFIA’s mission, as they enable long loiter times and extended range, all while flying at higher altitudes. At an operating height of 41,000-43,000 feet, SOFIA flies above over 99 percent of the atmosphere’s water vapor, giving SOFIA opportunities to gaze into the heavens with clarity rivaled only by telescopes in orbit.
The specific 747SP aircraft that was selected for modification for the SOFIA program originally entered commercial service with Pan American World Airways in 1977, where it was christened Clipper Lindbergh, a name it still officially retains today. Pan Am sold the aircraft to United Airlines in 1986, for whom it operated in commercial service until 1995, when it was sent to storage.
SOFIA wearing an early livery during a 1998 test flight.
In 1997, it was retrieved from storage and NASA acquired it for conversion into an airborne observatory. Raytheon began the first step of SOFIA’s conversion in 1998 by installing a 13.5 foot wide retractable door behind the wing on the aft side. SOFIA’s door arcs 18 feet upward along the fuselage and can retract in flight, protecting the highly sensitive onboard instruments from the sun until conditions are ideal for data collection.
Beyond the huge door that reveals the enormous telescope onboard, SOFIA was modified with heavy shock absorbers, pressure bulkheads and counterweights to accommodate the telescope instruments. The aircraft’s interior was also retrofitted to provide space for educators to work during missions. Throughout the course of the program, SOFIA will invite thousands of science teachers, planetarium scientists and others to fly onboard. This ensures that the benefits of SOFIA’s science missions will reach as many people on Earth as possible.
SOFIA remained in budgetary and developmental purgatory until late 2009, when the optical systems were finally integrated into the airframe and it was first flown with the door open. Routine scientific flights began in 2010, and full capabilities were set to come online in 2014. Then, NASA abruptly announced that they would drastically cut SOFIA’s funding request for FY 2015, indicating that they planned to place the aircraft into storage and that, “savings from SOFIA can have a larger impact supporting other science missions.”
A 2014 report from NASA’s Inspector General found that SOFIA is one of the most expensive programs in NASA’s science portfolio. With total program life cycle costs estimated at $3 billion, SOFIA costs more than $100,000 per planned research flight hour to operate. After publicly stating that SOFIA’s “contributions to astronomical science will be significantly less than originally envisioned,” the program hung in limbo for about a year, when suddenly NASA changed their minds in early 2015.
For now, the program appears to be on stable budgetary footing, with the aircraft having flown regularly throughout the first half of the year. Even so, NASA’s spastic decision-making and SOFIA’s estimated $1 million per mission costs should illustrate that SOFIA could easily be a sacrificial lamb for future NASA budgets. Pulling the plug on SOFIA as soon as the program finally starts to perform science missions is hasty and ignores the unique capabilities that no other observatory can provide.
Seeing What We Can’t See
SOFIA is currently deployed to Christchurch, New Zealand until July 2015 and is observing parts of the sky that aren’t visible from the Northern Hemisphere with four main instruments, more than ever before. Hopefully the program will be allowed to continue unfettered now that it is finally mature enough to generate substantial scientific observations.
While there is no argument that orbital telescopes are ideally situated to capture images that improve our understanding of the universe, there are a few areas where airborne telescopes have advantages over orbital telescopes. Instruments aboard SOFIA are far easier to maintain and service, whereas missions to repair orbital telescopes (such as STS-125 in 2009) are hugely expensive and risky.
Additionally, SOFIA is not vulnerable to the ever-increasing risk of space junk, whereas the Hubble Repair mission in 2009 had a one-in-221 chance of colliding with orbital debris (although NASA deemed this risk acceptable). During the mission, a four inch piece of debris from a recently-exploded Chinese weather satellite came less than two miles away from the Hubble telescope and Space Shuttle Atlantis.
The ability to place optical instruments in the ideal place and time to observe rare astronomical events is central to appreciating the value of an asset like SOFIA. In 2011, SOFIA was at the right place at the right time to observe Pluto’s occultation in 2011. Notably, NASA says that it was the only observatory capable of doing so in the world at the time.
Ground-based telescopes can only observe a certain tract of the sky, and orbital telescopes aren’t easily repositioned. However, a telescope mounted on an intra-atmospheric aircraft that can produce a snapshot of the sky at precisely where and when desired is a unique capability, and one that is worth preserving in the event that orbital telescopes become incapacitated.
Night after night, SOFIA prowls the skies while making observations about comets, the life cycles of distant stars, the formation of planets and the chemical makeup of interstellar space. Requests from the scientific community for time aboard SOFIA far outpace the number of flight hours available, showing how the aircraft is hugely versatile for studying our celestial neighbors both near and far away.
Throughout the last century of flight, airborne telescopes have clearly proven their worth to the science community, and SOFIA should remain the pinnacle of airborne telescope technology for many years to come, especially seeing as NASA now has two retired 747 Shuttle Carriers to use for spares free of charge. The big flying telescope also sits as yet one more reminder of just how versatile the 747 design remains almost 50 years after its first flight.
Image credit: Top shot - NASA/Wikicommons, SOFIA side profile close-up - Reed Saxon/AP, Felixstowe F5L - Public domain/Wikicommons, #NASAbeyond graphic - NASA/Wikicommons, KAO/SOFIA on tarmac - NASA/Wikicommons, Boeing 747SP original livery - Public domain/Wikicommons, SOFIA interior - NASA/Wikicommons, SOFIA early livery test flight - NASA/Wikicommons, Hubble STS-125 - NASA/Wikicommons, SOFIA side profile in flight - NASA/Wikicommons, Bottom tarmac rear shot - NASA/Wikicommons | 0.840402 | 3.405284 |
Soviet lunar and planetary probes carried metallic pennants to be deposited on other planets. These
were highly durable, titanium with thermoresistant polysiloxane enamels, capable of surviving intact even on the surface of Venus.
Artistically interesting, they can provide clues to the identity of spacecraft in photographs or even the purpose of unpublicized missions.
A few dozen of each type are minted, to be installed on spacecraft and handed out to a few VIPs and top scientists.
It should be noted that in 1967, the Soviet Union was among the signers of the Outer Space Treaty, which forbids the claiming of any celestial body as territory. Thus the landing of pennants should not be misinterpreted as such.
In 1959, Luna-1 was the first spacecraft to achieve escape velocity. It was probably intended to impact the Moon, but it missed and went into a heliocentric orbit. It also carried a ball of pennants as Luna-2 did. The messages are Ianvar' 1959 (January 1959), SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (Union of Soviet Socialist Republics).
The first spacecraft to impact the Moon, in 1959. It carried two spheres (7.5 and 12 cm in diameter) filled with liquid and an explosive charge, designed to burst apart on impact and scatter pentagonal pennants. The messages are Sentiabr' 1959 (September 1959), SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (Union of Soviet Socialist Republics). The icon of the wreath of grain around the hammer and sickle is the state seal of the USSR.
Luna-2 and its pennants were actually probably vaporized. They struck the Moon at a relative velocity of 3.3 kilometers per second. Assuming kinetic energy is converted to heat, and given the specific heat of steel, the resulting temperature obtained is 11000° K.
The first spacecraft to land on the Moon. It transmitted 360º panoramic images of the surface. The messages include Ianvar' 1966 (January 1966), Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR) and the state seal. The Luna-13 lander may have carried similar of pennants, as probably did the failed landers Luna-4 to Luna-8.
The first spacecraft to orbit the Moon. It returned gamma-ray spectra of lunar rock. The messages include Mart 1966 (March 1966), Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR) and the state seal.
Luna-11 and Luna-12
Luna-12 photographed the Moon using the same type of camera as Zond-3. The messages include Luna-12 Oktiabr' 1966 (October 1966),Luna-11 Avgust 1966 (August 1966) Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR) and the state seal.
Luna-16 and Luna-20
The first robotic moon-rock-retrieval missions. The messages are Luna-16, Sentiabr'. 1970, Zemlia, Luna, Zemlia (Moon-16, September 1970, Earth, Moon, Earth), SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR) and the state seal. Luna-20 performed a similar mission and carried the same type of pennants, with the date Febral' 1972 (February 1972). Luna-15 probably had similar pennants. If it had not crashed, it would have returned moon rocks before Apollo 11.
Luna-17 and Luna-21
The Lunokhod moon-rover missions. Lunokhods were large solar-powered robots that spent several months driving around the Moon, returning images and doing mineral analysis. The messages are Luna-17, Noiabr' 1970 (Moon-17, November 1970) and Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR) and the state seal.
A more advanced robotic sample-return mission. Luna-24 drilled 1.6 meters into the moon and returned the core sample. The messages are Luna-24, Avgust. 1976, Zemlia, Luna, Zemlia (Moon-24, August 1976, Earth, Moon, Earth), SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR), the state seal and Soviet flag.
Mars-2 and Mars-3
Mars-3 was the first spacecraft to land on the red planet. Its sister ship Mars-2 crashed, but both orbiter sections sent pictures and data for 8 months. The messages are Mars-3 1971, Mars-Zemlia, Zemlia Venera Mars (Mars-3 1971, Mars-Earth, Earth Venus Mars), SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR) and the state seal. Each ship had both types of pennants shown above.
Presumably penannts were included in the 1973 Mars-6 and Mars-7 landers. It is not known if pennants were contained in the 1962 mission attempt. A sister ship of Mars-1, carrying a descent capsule, was stranded in Earth orbit.
The first interplanetary probe, Venera-1's orientation system overheated and failed. Venera-1's sister ship was stranded in orbit, and after it reentered the atmosphere, its pennant was discovered by a boy in Siberia. The first Soviet Venus probes contained a round pennant inside a metallic globe of the earth, with blue tinted oceans and gold tinted continents. The message is Zemlia Venera 1961 and SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR), the other side had the state seal.
The globe and medallion were enclosed within a protective shell of stainless steel pentagonal elements, similar to the Luna-2 ball of medals. Each pentalgonal element was inscribed with "Earth Venus 1961".
Venera-3 was the first spacecraft to impact another planet, Venus. Note the different configuration of planets in 1961 and 1965. The message is Zemlia Venera 1965 and SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR), the other side had the state seal.
The first probe to transmit data from Venus (or any planet). Venera-4 was designed to withstand 10 atmospheres pressure and was crushed at an altitude of 26 km. The messages are Iyune 1967, Zemlya, Venera (June 1967, Earth, Venus) and SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR) and the state seal. The Soviet Encyclopedia indicates Venera-4 also contained a flag-shaped pennant, red on front and blue on back.
Venera-5 to Venera-8
Sister ships, Venera-5 and -6 were strengthened to withstand 25 atmospheres, and were crushed at 19 km. Venera-7 was the first spacecraft to land on Venus. Venera-8 returns illumination information from the day side of Venus. All four probes had identical pentagonal pennants, and almost identical square pennants. Backs differed in the dates and spacecraft names. Venera-6(5), Zemlya Yanv 69, Venera Mai 69 (Earth January 1969, Venus May 1969). Venera-7, Zemlya Avg. 70, Venera Dek. 70(Earth August 1970, Venus December 1970). Venera-8, Zemlya Mart 72, Venera Iyune 72 (Earth March 1972, Venus June 1972).
The front sides differed slightly in design. Venera-5 and -6 had a border around Lenin's face reading Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR). Venera-7 and -8 were borderless, but Venera-7 has the additional text 100 GET (100 years -- anniversary of Lenin's birth).
Venera-9 to Venera-14
Venus heavy landers with cameras and soil analyzers. These missions carried identical pennants, except for years and names. Venera-9(10) 1975, Venera-11(12) 1978, Venera-13(14) 1981. The pentagonal pennant can be seen above, fastened to the landing ring of Venera-13 on the surface of Venus.
Venera-15 and Venera-16
Identical missions Venera-15 and 16 performed synthetic aperture radar mapping of the north polar region of Venus, as well as other experiments. Messages are Zemlia 1983, Venera-16, SSSR (Earth 1983, Venus-16, USSR).
Venera-Halley Missions (Vega-1 and Vega-2)
Complex missions including landers on Venus, balloon-born instruments in the Venusian clouds, and photography of Halley's comet. The messages are Zemlia XII 1984, Venera VI 1985, Aerostat b Atmosphere Venery, Venera 1984 1985 Interkosmos CNES (Earth December 1984, Venus June 1985, Balloon in Atmosphere of Venus, Venus 1984/1985 Intercosmos CNES) and SSSR, Soyuz Sovetskikh Sotsialisticheskikh Respublik (USSR) and the state seal. Intercosmos/CNES was the Russian/European join council that planned the mission.
Many of the pennant images are courtesy of Alex Panchenko Collectables. The photo of the Luna-1 pennant is courtesy of Vladimir G. Kurt.
|Home, Back to Venus| | 0.833904 | 3.559958 |
Time travel referred to travel from one point in time to another, analogous to travel from point to point in realspace or hyperspace. It does not generally refer to a body's natural experience of the flow of time along with the rest of the universe; rather, it refers to travel to the past against the natural flow of time, or travel to the future at a rate faster than that of the rest of the universe.
While time travel was an exceedingly rare phenomenon, a few cases were partially documented. No record of deliberate, physical time travel is known—all known cases involved unusual hyperdrive malfunctions, the effects of the Force, or similar exotic events.
The term time travel describes the concept of moving between different points in time, either traveling from the present to the future without experiencing the intervening period, or shifting backward in time to the past. Time travel was a rare phenomenon, but it was achieved on several occasions, mostly by accident. The known incidents mostly involved people or objects traveling to the future, however, several occurrences of time travel to the past were also documented.
Methods of time travelingEdit
Though most variations of time travel were discovered accidentally, at least one method of traveling to the future at a seemingly faster rate was widely known in the galaxy. Time dilation—though not strictly defined as time traveling, as there was no actual "skipping" over any period in time—was a phenomena that caused time to flow differently for two observers due to them being in relative motion to each other. This way, a period of time that lasted several hours from one person's point of view could take days and even years from the other person's perspective. Because of the high velocity of hyperspace travel, time dilation was a common side-effect of it, and the ship traveling in hyperspace would normally move forward in time faster than the rest of the galaxy. To counteract this effect, relativistic shielding was installed aboard hyperspace-capable starships, which aligned the hyperspace-traveling object's time perception with that of the outside world. The shielding, however, was not perfect and could malfunction in some rare cases, leaving the person inside the starship open to the effects of time dilation.
As an extension of the above effect of hyperspace, a malfunctioning hyperdrive could open an unstable hyperspace tunnel leading to another time frame, and even to a different part of the galaxy. In addition to hyperspace travel, time dilation could be achieved by entering a large mass of black holes with high gravitational fields, such as the ones that formed the Tyus Cluster. Provided that the traveler survived the dangerous trip, he could virtually emerge from the anomaly at any future time period, as time moved very fast at the center of the mass, to the point that it appeared not to exist at all. There were also several items that allowed time travel. The Darkstaff was a powerful and seemingly sentient Sith artifact, which power could be possessed by a Force-sensitive to create a Force storm leading to another time period. Another artifact, the Orb of Passage, was implied to control the flow of time; it was discovered on the planet Benja-Rihn and kept by the Jedi Order. Finally, it was rumored that the Jerni civilization used the so-called Eternity Crystal to reset the timeline in case of a major crisis.
Some species, such as the Bedlam Spirits, also had the power to manipulate time, and even claimed that they had "invented" it. Two distinct usages of the Force to travel in time were also known. The first was the simple will of the Force, as it could bind two individuals together, allowing them to relive the past in their last moments, though retaining all their memories of the future events. The other was a rare Force power used by the Aing-Tii monks called flow-walking. It allowed one to see the past and the future, though they could not change anything there, except for leaving an imprint of themselves in the Force.
The flight of the HarbingerEdit
In 5000 BBY, during the Great Hyperspace War, Jedi Master Relin Druur and his Padawan Drev Hassin tracked the Sith dreadnaught Harbinger, captained by Druur's Jedi apprentice–turned–Sith Lord Saes Rrogon, to the Phaegon system. Druur infiltrated the Harbinger and sabotaged the ship's hyperdrive. Druur then dueled Rrogon and fled the Harbinger aboard an escape pod. The Harbinger fled into hyperspace using its damaged hyperdrive, causing both the Harbinger and Druur's escape pod to travel through time to the year 41.5 ABY.
Darth Rivan and the DarkstaffEdit
During the New Sith Wars, the Sith Lord Darth Rivan had strange dreams about being called by the artifact known only as the Darkstaff and tracked it down to Almas in the Cularin system. According to Rivan's dreams, the Darkstaff had already caused some ancient tragedy in the Cularin system, and had been hidden away to prevent any further catastrophe. Rivan believed that the destruction of the planet Oblis, which created the Cularin system asteroid belt and a nexus of dark side power, was the aftermath of this event. Rivan believed that the Darkstaff drew him there, hoping to use him as a way to leave the system. Having consolidated an army of darksiders, Rivan settled on Almas, erecting a fortress there, where he began learning the mysteries of the dark side of the Force. Further investigation led Rivan to believe that the Darkstaff was not intentionally created, but was rather the byproduct of another experiment.
Measuring a meter in length and four centimeters in diameter, the Darkstaff seemed to consume any light around it. It also consumed any Force energy in the vicinity, literally feeding on the Force. The Darkstaff wanted to be discovered by Rivan so that he could use it as a weapon against his enemies, so it invaded his dreams. Its release would allow the Darkstaff to gain power, both for itself and over Rivan, until it eventually consumed Rivan himself. Rivan initially refused to go in search of the artifact, fearing that its release would cause great damage to the galaxy. However, when the Jedi assaulted Almas, he obtained the Darkstaff and it created a Force storm that swept him through time and space to the planet Ruusan, during the battles between the Jedi Army of Light and the Sith Brotherhood of Darkness several centuries later. There, with his Force power drained by the Darkstaff, he was easily slain by a Force-sensitive warrior.
Centuries later, Darth Rivan's writings were discovered by the Jedi Knights who built the Almas Academy. Word of the Darkstaff reached the ears of the smuggler Len Markus, who set out to search for it. Markus was observed removing something from the Cularin system's asteroid belt, an event which preceded the appearance of strange creatures hiding among the asteroids. Shortly after the Invasion of Naboo, the Cularin system disappeared for several years, before reappearing just as suddenly during the Clone Wars, with its inhabitants not experiencing the passage of time. It was believed that Markus found the Darkstaff, and that its release from captivity was the cause of the entire Cularin system's shift in time.
Bosbit Matarcher, the 225-year-old manEdit
In 212 BBY, the Human male Bosbit Matarcher engaged the hyperdrive on his newly purchased Delemedian starhopper, intending to take a short trip from his homeworld of Delemede. Due to faulty relativistic shielding, what he experienced as a two-hour trip took 190 years from the perspective of the rest of the galaxy. His experiences brought him brief notoriety when he arrived in 22 BBY, resulting in a HoloNet News interview. Matarcher took the experience in stride, as his run-down homeworld had become prosperous in the meantime. However, he decided to let someone else fly him home.
Matarcher's trip was not strictly defined as time "travel" to the future, however, as he did not "skip over" any period of time. Instead, time merely passed in a distorted manner for him due to the well-known effects of time dilation.
Kinnin Vo-Shay's escape from the Tyus ClusterEdit
Renowned gambler Kinnin Vo-Shay's experiences were similar to those of Bosbit Matarcher. Circa 50 BBY, Vo-Shay's ship, the Ashanda Ray, was caught in the Tyus Cluster, a mass of black holes. Vo-Shay would have died, crushed in a black hole with his ship like many travelers before him. However, one of the Tyus Cluster's previous victims was the Jedi Master Aryzah, who had managed to survive the destruction of her body as a Force ghost. She made contact with the slightly Force-sensitive Vo-Shay, and helped him fly the Ashanda Ray out of the cluster.
However, the high gravitational fields of the region had caused significant time dilation. In Vo-Shay's words, "at the center of that mass of ugly black holes, time was nonexistent." When Vo-Shay and Aryzah escaped the cluster, he found that some fifty years had passed for the rest of the Galaxy since Vo-Shay's disappearance.
The secret of Tet-AmiEdit
- "Always must a Jedi start the job he finished!"
In the last decades of the Galactic Republic, the Temple of Tet-Ami on Benja-Rihn was the subject of much speculation. Built some four thousand years earlier, the temple commemorated a great hero called Tet-Ami, the Time Guardian, who saved the armies of the capital city Carthas from a plague of insect-like beasts in an epic battle. The temple contained a statue of Tet-Ami, holding an artifact called the "Orb of Passage" which was said to control the flow of time. Sometime after the temple's construction, the orb was secretly taken by the Jedi Order, and the temple was lost. Just as the rediscovered temple was about to be excavated by an archaeological dig, the Jedi High Council sent Mace Windu to secretly enter the temple. His mission was to place the orb into the outstretched hand of the statue of Tet-Ami before the archaeologists arrived. Windu had no trouble entering the cave without being seen, and easily fought off a few ancient battle droids who guarded the temple's inner sanctum. He was surprised, however, to find that Tet-Ami's statue resembled him.
Even more surprising was what happened when Windu placed the orb in the statue's hand. Windu was sent backwards in time, appearing on a battlefield just as the Carthasian armies were about to be attacked. Windu joined the fight, and turned the tide of battle. After spending four days in the past, he returned to his own time period, arriving just as the archaeologists entered the temple. When he returned to Coruscant, Yoda revealed to Windu that the Jedi Council had long known the secrets of Tet-Ami, and were simply waiting for the orb's energies to recharge, and for a Jedi Knight named Mace Windu to join the order, take the Orb of Passage back to Carthas, and win the battle. Thus, the time paradox was neatly resolved.
The Sooma/Alzar incidentEdit
While working as diplomatic couriers around 15 BBY, the droids R2-D2 and C-3PO were assigned to escort the child Prince Plooz from the planet Sooma to his home world of Alzar. Along the way, their ship was attacked by the forces of General Sludd, a renegade from Alzar who was plotting to kill the prince in order to start a war which would allow him to conquer both planets. In an effort to escape, R2-D2 engaged the hyperdrive even though Prince Plooz, in an effort to help, had damaged the antimatter power systems. The droids and the prince jumped to hyperspace just as Sludd's electron torpedoes detonated. Whether because of the damage to the hyperdrive power systems, the explosion of the nearby electron torpedoes, or both, their ship came out of hyperspace in a starless void. Their only apparent exit was a rift which took them to the Endor system—but when they went through the rift, they discovered that they had not only traveled to another system, but to another time.
Plooz, believing himself to be in his home system, ran away from his caretakers in an escape pod which took him to the forest moon of Endor. After some adventures on Endor, where R2-D2 and C-3PO met the Ewoks of Bright Tree Village and rescued the royal toddler from a group of Duloks led by King Gorneesh, the droids and the prince returned to their ship and went back through the time rift. They arrived only minutes after they left, escaped Sludd's forces, and brought the prince back to Alzar safely.
While C-3PO and R2-D2's readings on arrival in the Endor system implied that they had traveled anywhere from ten to one hundred years into the future, the Ewoks and Duloks they met on Endor included such figures as Wicket W. Warrick and Chief Chirpa who participated in the Battle of Endor. When C-3PO returned to Endor in 4 ABY, he did not seem to recognize any of the Ewoks he had met previously, though memories of the golden droid's previous, seemingly supernatural appearance affected the Ewoks' worshipful attitude towards him.
The Bedlam Spirits and Princess LeiaEdit
At another time during the Galactic Civil War, Princess Leia Organa, fleeing from the Empire, crashed on an unknown planet. There, she discovered what seemed to be the remains of stormtroopers who had been dead for many thousands of years.
Before she could investigate further, however, she was chased by three stormtroopers and discovered a group of "spirits"—Tilotny, Horliss-Horliss, Splendid Ap, and Cold Danda Sine—who had immense powers, capable of shaping space and time. While the spirits were in the middle of a conversation, they noticed Leia and the stormtroopers who had been chasing her. The spirits decided to "play" with the four Humans, and managed to kill all of them in the process.
Once they were finished, though, Splendid Ap was tasked with returning the four beings to normal. Ap resurrected the three stormtroopers, but not having a concept of time, also transported them back 8,000 years in the past; these were the stormtroopers whose remains Leia had encountered when she crashed. Leia, however, escaped the stormtroopers' fate and was restored just as she had been previously in the correct time.
Lak Sivrak's experienceEdit
In 0 BBY, Lak Sivrak, a Shistavanen scout who had left the Imperial Survey Corps, met the Lamproid Dice Ibegon in Chalmun's Spaceport Cantina in Mos Eisley. Coincidentally, they met on the same day Luke Skywalker and Obi-Wan Kenobi contacted Han Solo and Chewbacca to arrange passage to Alderaan on the Millennium Falcon. Ibegon recruited Sivrak into the Rebel Alliance, and the two fell in love. The couple was parted when Ibegon died in Sivrak's arms during the Battle of Hoth. Sivrak continued to fight with the Alliance, until he too was killed during the Battle of Endor. In his last moments, Sivrak remembered pivotal moments of his life, including his lover's death and the day he and Ibegon saw Skywalker and Kenobi enter Chalmun's Cantina. He was guided in these reminiscences by Ibegon's spirit, which took him to earlier points in his life through the Force. During these travels, Sivrak retained his memories and thus could predict what would happen next. Though he mostly experienced events during which he was present, one trip took Sivrak to Chalmun's Cantina in the aftermath of Jabba the Hutt's death and the subsequent rebellion against the Empire which occurred after Sivrak's death. Eventually, Sivrak's travels ended when he realized that the Force had binded him and Ibegon together, letting them experience these events one more time. Reunited in spirit, the lovers observed the celebrations of the Empire's defeat on the moon of Endor.
Jacen Solo learned a Force power called "flow-walking" from the Aing-Tii. This ability allowed him to not only view the past and future, but also leave an imprint of himself there. He used this power in 35 ABY to witness the crash of the Tachyon Flier in 27 ABY, and leave an imprint of himself for his mother, Leia Organa Solo, to follow.
Ben Skywalker used flow-walking to witness Jacen while he learned the ability from the Aing-Tii.
Luke Skywalker's first meeting with his fatherEdit
In 9 BBY, young Luke Skywalker ran away from home after an argument with his uncle and guardian Owen Lars. The disagreement stemmed from Lars' refusal to give his nephew any more information about Luke's father, Anakin Skywalker (by then known as Darth Vader.)
As Luke wandered into the Tatooine desert, he became lost in a sudden sandstorm. Soon after seeing a vision of a tall dark figure, he met a boy around his age calling himself "Annie." Though Luke did not realize it, he was speaking to his father as he was in another time. The two boys realized they had much in common: both were natural pilots, both wanted to leave Tatooine someday, both could sense events before they happened, and neither one knew their father.
Discovering the body of a Tusken Raider buried in the sand, the boys took a gaffi stick from the corpse and sought shelter in a nearby cave. A pack of womp rats drove them back out into the storm, where they stumbled upon an R5-series astromech droid. Annie rigged up the astromech's motivator to explode, sending up a flare. Instead of attracting rescue, the flare attracted a krayt dragon, which attacked the two boys. Losing sight of Annie, Luke threw the gaffi stick into the throat of the dragon, killing it. Luke fell unconscious, and was later found by his uncle and a rescue party. While there was no sign of the krayt dragon or Annie, Luke was convinced that his experiences were more than just a dream.
The Eternity Crystal hoaxEdit
During the Galactic Civil War, Luke Skywalker came across an abandoned spacecraft of unknown origins while on a reconnaissance mission for the Rebel Alliance. A set of image tapes recovered from the derelict, once decoded, showed that the ship was an artifact of the extinct Jerni civilization. These tapes also talked about an artifact called the "Eternity Crystal", used by the long-lost Jerni civilization to control the flow of time. According to the tapes, this power was used to prevent conflicts and crises within their society by reversing their history and starting again on a different path. The tape also gave the location of the crystal, in a vault near Adony Station on the planet Jerne.
The Rebel leadership quickly realized that such power could be used to their advantage in the war—for that matter, it could be used to prevent the rise of the Galactic Empire and stop the war from even starting. Luke, together with his droid R2-D2 and Princess Leia Organa, was sent on a mission to Jerne to investigate.
As it turned out, the "Jerni" ship and the image tapes on board were fakes created by Imperial technicians under the orders of Darth Vader. The story of the Eternity Crystal was only the bait for a trap intended for Princess Leia, who Vader knew would want to change history to bring back her beloved Alderaan. As soon as they arrived on Jerne, the three Rebels were immediately met with opposition from the waiting Imperial garrison. They were forced to ask a group of local guerrillas and bandits led by Meeka Reen for assistance, but Reen betrayed them in an attempt to take the crystal for herself. Luckily for Skywalker and Organa, this meant Reen and her henchmen were killed by the Empire's traps, while the Rebels escaped Jerne unharmed by stealing Lord Vader's TIE/sh VIP shuttle.
Sam Heggs's accountEdit
Heggs claimed that while on Nimba Five hunting bemis, he came across a nest of grumph eggs. Soon afterward, though it was the middle of Nimba Five's long winter, he found a lush jungle nearby. In the jungle, he came across a young man being chased by a grumph. Heggs was unable to affect anything in the jungle in order to help the young man, though he was able to communicate with him. However, he somehow discovered that he was viewing an incident in the past, but that changes he made in the present would go backwards in time. Apparently, the grumph was experiencing time in reverse, so destroying an egg in the present would cause it not to exist in the past. Heggs began destroying the grumph eggs, eventually destroying the egg which erased the grumph which menaced the young man. Heggs determined that the young man was himself in an earlier time period, since he recognized his initials on the young man's backpack.
Other than Heggs's story and the sack of grumph eggs he brought with him to Mos Eisley, no evidence of this incident exists. It may only have been a nonsensical story which Heggs used to separate Travis from his bottle of Vaschean rye.
Behind the scenesEdit
Although time travel is central in many works of science fiction, it generally plays a minor role in Star Wars works. However, time travel does have rare appearances in the Expanded Universe. Time travel was also a plot device used in Alien Exodus, a canceled and thus non-canonical novel. In Alien Exodus, the humans of the Star Wars galaxy are revealed to be the descendants of a group of refugees from Earth whose ship accidentally traveled through a wormhole. This wormhole took them not just to another galaxy, but to another time, billions of years in the past: in other words, they found themselves "a long time ago, in a galaxy far, far away."
Another non-canon story which links the Star Wars universe with Earth is Into the Great Unknown part of Star Wars Tales 19. In this story, a hyperspace accident leads Han Solo and Chewbacca to crash the Millennium Falcon on an unknown planet which is obviously Earth. 126 years later, the wreckage and Han Solo's body are discovered by Indiana Jones. Depending on how long ago "a long time ago" is assumed to be, the Falcon's trip in this story may also have involved time travel. In any case, since Han Solo dies in the story, Into the Great Unknown is non-canon.
- "Le facteur X"—Casus Belli 115
- The Complete Star Wars Encyclopedia
- Book of Sith: Secrets from the Dark Side
Notes and referencesEdit
- Time travel on Wikipedia | 0.834471 | 3.871022 |
What has less mass than a black hole but more than the sun, yet is far smaller than the sun? That would be a neutron star, one of the many weird and wonderful objects in our universe.
When a star with a mass greater than eight times that of our sun has finished burning its nuclear fuel it experiences a gravitational collapse of its core which results in a violent supernova explosion. This generates a burst of radiation so bright it can briefly outshine an entire galaxy before gradually fading, and can radiate more energy than our sun will over its entire lifetime. While the outer layers of the star are blown off during the explosion to form a beautiful supernova remnant, its core collapses, creating so much pressure that its protons and electrons combine to form neutrons, subatomic particles without electrical charge. What remains after the collapse is a super-dense object called a neutron star. If the object has an even greater mass, a black hole is formed instead, with such tremendous gravity that not even light can escape, hence the name.
While a neutron star is only about 12 miles in diameter it has a mass of more than 1.4 times that of our sun. It is therefore so dense that on Earth, one teaspoonful of neutron star would weigh about two billion tons. Because of its small size and high density a neutron star has a surface gravitational field of 200 billion times that of Earth. This means, for example, that one person, standing on a neutron star, if such a feat were possible, would weigh 17% as much as all humans currently in existence. In addition, a neutron star can have a magnetic field a million times stronger than the strongest magnetic field generated on Earth, strong enough to rip apart the super-strong bonds within a molecule.
When newly formed, neutron stars rotate rapidly, at speeds of up to seven hundred times per second. During their collapse, their rate of rotation increases as they become more compact, much in the way a spinning ice skater speeds up when pulling her arms in. Over time, though, these stars usually slow down because their rotating magnetic fields radiate energy, and they may eventually take several seconds for each revolution, still pretty fast compared to the roughly 35 days it takes our sun.
Some neutron stars emit jets of fast-moving particles from their magnetic poles that produce powerful beams of light, often in the radio and x-ray wavelengths. These stars are known as pulsars. As a pulsar rotates, its jets sweep around like a spotlight in a lighthouse, visible here on Earth whenever the magnetic pole is in our line of sight. This gives us the impression of a light blinking on and off, or pulsing at regular intervals, hence the name, pulsar.
About 5% of all neutron stars are in binary systems, with companion stars that may be ordinary stars, white dwarfs or other neutron stars. It is thought that some may also have black holes as their binary companions. When neutron stars are in binary systems, instead of slowing down over time, their rotation may speed up as material from the companion star is sucked towards the neutron star, on account of its strong gravitational field.
There are currently about 2,000 known neutron stars in our own galaxy and in the neighboring Large and Small Magellanic Clouds. Some of these, in the form of pulsars, are known to have planets, though they are probably not conducive to life. One such planet was found to be made of ultra-pressurized carbon in crystalline form, in other words, a rather large diamond!
Join the Springfield Stars Club on Tuesday, January 22nd at 7:30pm at the Springfield Science Museum for a presentation by Jack Megas on “Survival - Navigating by the Stars,” a talk on how, for many cultures in the past, the stars aided survival by serving as compass, clock, calendar and almanac. Megas is an astronomy educator at the Springfield Science Museum’s Seymour Planetarium, and a retired laboratory hematologist at Bay State Medical Center. He is a past president of both the Springfield Stars Club and the Naturalist Club, and co-founder of the Connecticut River Valley Astronomers’ Conjunction, now in its 31st year. Refreshments will be served, and the public is welcome free of charge.
Copyright © Amanda Jermyn | 0.872063 | 3.980372 |
Giant galaxies weren't assembled in a day. Neither was this Hubble Space Telescope image of the face-on spiral galaxy Messier 101 (M101, R.A. 14h 3m 13s, Dec. 54° 20' 53"). It is the largest and most detailed photo of a spiral galaxy that has ever been released from Hubble. The galaxy's portrait is actually composed of 51 individual Hubble exposures, in addition to elements from images from ground-based photos. The final composite image measures a whopping 16,000 by 12,000 pixels.
The Hubble archived observations that went into assembling this image were originally acquired for a range of Hubble projects: determining the expansion rate of the universe, studying the formation of star clusters in the giant star birth regions, finding the stars responsible for intense X-ray emission, and discovering blue supergiant stars.
The giant spiral disk of stars, dust, and gas is 170,000 light-years across or nearly twice the diameter of our galaxy, the Milky Way. M101 is estimated to contain at least one trillion stars. Approximately 100 billion of these stars could be like our Sun in terms of temperature and lifetime.
The galaxy's spiral arms are sprinkled with large regions of star-forming nebulae. These nebulae are areas of intense star formation within giant molecular hydrogen clouds. Brilliant young clusters of hot, blue, newborn stars trace out the spiral arms. The disk of M101 is so thin that Hubble easily sees many more distant galaxies lying behind the galaxy.
M101 (also nicknamed the Pinwheel Galaxy) lies in the northern circumpolar constellation, Ursa Major (The Great Bear), at a distance of 25 million light-years from Earth. Therefore, we are seeing the galaxy as it looked 25 million years ago - when the light we're receiving from it now was emitted by its stars - at the beginning of Earth's Miocene Period, when mammals flourished and the Mastodon first appeared on Earth. The galaxy fills a region in the sky equal to one-fifth the area of the full moon.
The newly composed image was assembled from Hubble archived images taken with the Advanced Camera for Surveys and the Wide Field and Planetary Camera 2 over nearly 10 years: in March 1994, September 1994, June 1999, November 2002, and January 2003. The Hubble exposures have been superimposed onto ground-based images, visible at the edge of the image, taken at the Canada-France-Hawaii Telescope in Hawaii, and at the 0.9-meter telescope at Kitt Peak National Observatory, part of the National Optical Astronomy Observatory in Arizona. The final color image was assembled from individual exposures taken through blue, green, and red (infrared) filters.
Release Date: 10:00AM (EST) January 11, 2006
Release Number: STScI-PRC2006-10a
K.D. Kuntz, Goddard Space Flight Center,
Baltimore, Md., (phone) 301-286-1301, (e-mail) [email protected] or
Ray Villard, Space Telescope Science Institute,
Baltimore, Md. (phone) 410-338-4514, (e-mail) [email protected] or
Soren Larsen, ESA/Space Telescope European Coordinating Facility, European Southern Observatory,
Garching, Germany (phone) 011+4989-3200-6576, (e-mail) [email protected] or
Lars Lindberg Christensen, Hubble/ESA,
Garching, Germany (phone) 011+49-89-3200-6306, (e-mail) [email protected].
Credit for Hubble Image: NASA and ESA.
Acknowledgment: K.D. Kuntz (GSFC), F. Bresolin (University of Hawaii), J. Trauger (JPL), J. Mould (NOAO), and Y.H. Chu (University of Illinois, Urbana).
Credit for CFHT Image: Canada-France-Hawaii Telescope / J.C. Cuillandre / Coelum.
Credit for NOAO Image: G. Jacoby, B. Bohannan, M. Hanna / NOAO / AURA / NSF.
The original version of this work, with more images and videos, is available at the STScI WWW server.
Updated: March 2 '06
Best seen with MS Internet Explorer.
Back: Gallery: Hubble's Largest Galaxy Portrait Offers a New High-Definition View of M101 | 0.841761 | 3.899469 |
Is Earth's protective shield cracking? Bursts of deadly cosmic rays raises fears that our planet's magnetic field is disappearing
- Simulations indicate the Earth's magnetic shield temporarily cracked
- This was caused by magnetic reconnection of our magnetic field lines
- This allowed lower energy galactic cosmic rays to enter our atmosphere
- It could also be a sign our magnetic shield is weakening, researchers said
- This would cause widespread havoc on Earth including black outs and exposure to harmful UV radiation
It might not be something you think about every day, but you should be grateful for the Earth’s magnetic field.
It protects you from harmful radiation, charged particles and meteorites and causes the spectacular Northern Lights.
But a new study has indicated there was a temporary 'crack' in the magnetic field, that allowed dangerous galactic cosmic ray particles into our atmosphere.
Scroll down for video
A new study has indicated there was a temporary 'crack' in the magnetic field, that allowed dangerous galactic cosmic ray particles into our atmosphere. This was caused by the process of magnetic reconnection, which is visualised above
The crack indicates that Earth's magnetic shield is weakening.
Magnetic reconnection occurs wherever charged gases, called plasma, are present.
It's rare on Earth, but plasma makes up 99 per cent of the visible universe, fueling stars and filling the near-vacuum of space.
This plasma contains magnetic fields that affects the way charged particles it encounters move.
Under normal conditions, the magnetic field lines inside plasmas don't break or merge with other field lines.
But sometimes, as field lines get close to each other, the entire pattern changes and everything realign into a new configuration.
As they come together, the field lines will cancel and re-form, each performing a sort of U-turn and curving to move off in a perpendicular direction.
Magnetic reconnection taps into the stored energy of the magnetic field, converting it into heat and kinetic energy that sends particles streaming out along the field lines.
The amount of energy released can be formidable.
If this continues, it could cause widespread havoc on Earth including power black outs and exposure to harmful UV radiation
The GRAPES-3 muon telescope, at TIFR's Cosmic Ray Laboratory in Ooty, in India, recorded a burst of galactic cosmic rays of about 20 GeV, on 22 June 2015, lasting for two hours.
'The simultaneous occurrence of the burst in all nine directions suggests its origin close to Earth,' the authors wrote in the study, published in Physical Review Letters.
'It also indicates a transient weakening of Earth’s magnetic shield, and may hold clues for a better understanding of future superstorms that could cripple modern technological infrastructure on Earth, and endanger the lives of the astronauts in space.'
Numerical simulations indicate the Earth's magnetic shield temporarily cracked due to the occurrence of magnetic reconnection.
Magnetic reconnection can occur anywhere there are powerful magnetic fields, such as in the sun's magnetic environment.
As field lines get close to each other, the entire pattern changes and everything realign into a new configuration.
This allowed the lower energy galactic cosmic ray particles to enter our atmosphere.
The burst occurred when a giant cloud of plasma ejected from the solar corona, struck our planet at a speed of about 1.55 million miles (2.5 million kilometres) per hour.
This caused a severe compression of Earth's magnetosphere - the region around the planet which holds the magnetic field - from 11 to 4 times the radius of Earth.
Earth's magnetosphere extends over a radius of a million kilometres, which acts as the first line of defence, shielding us from the continuous flow of solar and galactic cosmic rays and protecting life on our planet from these high intensity energetic radiation.
The magnetic field bent these particles about 180 degree, where they were detected as a burst by the GRAPES-3 muon telescope around mid-night on 22 June 2015.
The GRAPES-3 muon telescope, pictured, is the largest and most sensitive cosmic ray monitor. In June last year it recorded a burst of galactic cosmic rays that indicated a crack in the Earth's magnetic shield
Solar flares (pictured) and coronal mass ejections explode in the sun's atmosphere, the corona, sending light and high energy particles out into space, along with a stream of charged particles known as the solar wind. Solar wind is a plasma
There is a solar storm facing Earth at the moment, The severe geomagnetic storm has generated stunning displays of Northern Lights, like this one pictured on Skye, in Scotland, and radio signal blackouts in many high latitude countries
HOW THE SOLAR WIND IS FORMED
The sun and its atmosphere are made of plasma – a mix of positively and negatively charged particles which have separated at extremely high temperatures, that both carries and travels along magnetic field lines.
Material from the corona streams out into space, filling the solar system with the solar wind.
But scientists found that as the plasma travels further away from the sun, things change. The sun begins to lose magnetic control, forming the boundary that defines the outer corona – the very edge of the sun.
The breakup of the rays is similar to the way water shoots out from a squirt gun.
First, the water is a smooth and unified stream, but it eventually breaks up into droplets, then smaller drops and eventually a fine, misty spray.
The images in a Nasa study capture the plasma at the same stage where a stream of water gradually disintegrates into droplets.
If charged particles from solar winds hit Earth's magnectic field, this can cause problems for satellite and communication equipment.
The data was analysed and interpreted through extensive simulation over several weeks by using the 1280-core computing farm that was built in-house by the GRAPES-3 team of physicists and engineers at the Cosmic Ray Laboratory in Ooty.
Solar storms can cause major disruption to human civilization by crippling large electrical power grids, global positioning systems (GPS), satellite operations and communications.
There is a solar storm facing Earth at the moment.
The severe geomagnetic storm has generated stunning displays of Northern Lights, and radio signal blackouts in many high latitude countries.
Geomagnetic storms are more disruptive now than in the past because of our greater dependence on technical systems that can be affected by electric currents.
The Earth's magnetic field, so important to life on the planet, has weakened by 15 per cent over the last 200 years and this, scientists claim, could be a sign that the Earth’s poles are about to flip.
Experts believe we are currently overdue a flip, but they are unsure when this could occur.
If a switch happens, we would be exposed to solar winds capable of punching holes into the ozone layer.
The impact could be devastating for mankind, knocking out power grids, radically changing Earth’s climate and driving up rates of cancer.
‘This is serious business’, Richard Holme, Professor of Earth, Ocean and Ecological Sciences at Liverpool University told MailOnline.
‘Imagine for a moment your electrical power supply was knocked out for a few months – very little works without electricity these days.’
HOW DOES A LIQUID IRON CORE CREATE A MAGNETIC FIELD?
Our planet’s magnetic field is believed to be generated deep down in the Earth’s core.
Nobody has ever journeyed to the centre of the Earth, but by studying shockwaves from earthquakes, physicists have been able to work out its likely structure.
At the heart of the Earth is a solid inner core, two thirds of the size of the moon, made mainly of iron.
At 5,700°C, this iron is as hot as the Sun’s surface, but the crushing pressure caused by gravity prevents it from becoming liquid.
Surrounding this is the outer core there is a 1,242 mile (2,000 km) thick layer of iron, nickel, and small quantities of other metals. The metal here is fluid, because of the lower pressure than the inner core.
Differences in temperature, pressure and composition in the outer core cause convection currents in the molten metal as cool, dense matter sinks and warm matter rises.
The 'Coriolis' force, caused by the Earth’s spin, also causes swirling whirlpools.
This flow of liquid iron generates electric currents, which in turn create magnetic fields.
Charged metals passing through these fields go on to create electric currents of their own, and so the cycle continues. This self-sustaining loop is known as the geodynamo.
The spiralling caused by the Coriolis force means the separate magnetic fields are roughly aligned in the same direction, their combined effect adding up to produce one vast magnetic field engulfing the planet.
At the heart of the Earth is a solid inner core, two thirds of the size of the moon, made mainly of iron. At 5,700°C, this iron is as hot as the sun’s surface, but the crushing pressure caused by gravity prevents it from becoming liquid
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- NFL players kneel for the anthem days after Trump's criticism | 0.872484 | 3.703695 |
JPL News: Spitzer Hears Stellar "Heartbeat" from Planetary Companion
A planet and a star are having a tumultuous romance that can be detected from 370 light-years away.
NASA's Spitzer Space Telescope has detected unusual pulsations in the outer shell of a star called HAT-P-2. Scientists' best guess is that a closely orbiting planet, called HAT-P-2b, causes these vibrations each time it gets close to the star in its orbit.
"Just in time for Valentine's Day, we have discovered the first example of a planet that seems to be causing a heartbeat-like behavior in its host star," said Julien de Wit, postdoctoral associate at the Massachusetts Institute of Technology, Cambridge. A study describing the findings was published today in Astrophysical Journal Letters.
The star's pulsations are the most subtle variations of light from any source that Spitzer has ever measured. A similar effect had been observed in binary systems called "heartbeat stars" in the past, but never before between a star and a planet.
JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech, which manages JPL for NASA. | 0.896007 | 3.03678 |
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2013 March 19
Explanation: How did the Moon form? To help find out, NASA launched the twin Gravity Recovery and Interior Laboratory (GRAIL) satellites in 2011 to orbit and map the Moon's surface gravity in unprecedented detail. Pictured above is a resulting GRAIL gravity map, with regions of slightly lighter gravity shown in blue and regions of slightly stronger gravity shown in red. Analysis of GRAIL data indicates that the moon has an unexpectedly shallow crust than runs about 40 kilometers deep, and an overall composition similar to the Earth. Although other surprising structures have been discovered that will continue to be investigated, the results generally bolster the hypothesis that the Moon formed mostly from Earth material following a tremendous collision in the early years of our Solar System, about 4.5 billion years ago. After completing their mission and running low on fuel, the two GRAIL satellites, Ebb and Flow, were crashed into a lunar mountain at about 6,000 kilometer per hour.
Authors & editors:
Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
A service of: ASD at NASA / GSFC
& Michigan Tech. U. | 0.848625 | 3.077886 |
Any iconic image of the universe you can think of was probably taken by the Hubble Space Telescope. Take the Eagle Nebula, for example, which is shown below. What you might not realize is that this spectacular, colored photograph was originally black and white. Now, the experts at NASA have shown how they, quite literally, color the universe by working from Hubble's achromatic world.
Stars, like our sun, start off as nothing more than tiny balls of gas and dust that then grow big and bright within dense clouds, like inside of the Eagle Nebula, which Hubble first photographed in 1995.
The photo itself was so spectacular that NASA gave it a name referring to the stellar formation hidden within: "Pillars of Creation." But this picture didn't start off as the colorful masterpiece you see above.
Originally, Hubble snaps multiple pictures of an object in different wavelengths that show up in arresting black and white, shown below. Experts then use colored filters to tease out the final product.
How do you go from black and white to awe-inspiring color? That's where Photoshop comes in.most abundant element in the universe.
The reason Levay uses the colors he does is because each element glows at different wavelengths, which scientists determine in labs here on Earth.
If you take a tube of pure hydrogen gas, for example, and excite the atoms so they release light, the tube will glow blue because that's the color in which hydrogen radiates most strongly. Below is an example of the colors certain gases, including Helium and Neon, release:
After layering one filtered image atop the other, the final colorful image gives astronomers an idea of where and how much of each of these elements are in the nebula.
"It's pure science that's driving the colors," Levay explains in a video by National Geographic . Each of the three colors that Levay uses in his example represents elements that exist both here on Earth and in space.
For more examples of transformed Hubble images check out Hubble's Toolbox.
Watch the full video from National Geographic below: | 0.843189 | 3.216995 |
Ceres covered in hidden ice, studies suggest
The Jet Propulsion Laboratory (JPL) and NASA have announced a series of new findings from the Dawn spacecraft currently orbiting the dwarf planet Ceres that point to the existence of ice within its crust.
Using the spacecraft’s gamma-ray and neutron detector (GRaND), researchers were able to determine the concentrations of hydrogen, iron, and potassium in the uppermost meter of Ceres’ crust. On Ceres, hydrogen is most likely to occur in the form of frozen water.
The GRaND instrument measures the number and energy of gamma rays and neutrons being absorbed and escaping from Ceres. Hydrogen is known to slow down neutrons and is associated with fewer neutrons escaping.
GRaND data has also been able to determine the ice is likely filling the pore space of a rocky material mixture that is thought to be about 10 percent ice by weight.
“On Ceres, ice is not just localized to a few craters. It’s everywhere, and nearer to the surface with higher latitudes,” said Thomas Prettyman, principal investigator of GRaND, which is based at the Planetary Science Institute in Tucson, Arizona. “These results confirm predictions made nearly three decades ago that ice can survive for billions of years beneath the surface of Ceres. The evidence strengthens the case for the presence of near-surface water ice on other main belt asteroids.”
A second study examined hundreds of craters called “cold traps”, which are permanently shadowed with temperatures below minus 260 degrees Fahrenheit (minus 162 degrees Fahrenheit) that are so cold very little water ice is converted to vapor. Researchers found deposits of bright material in 10 craters, with the presence of ice being confirmed in one of them by using Dawn’s infrared mapping spectrometer.
The study, led by Thomas Platz of the Max Planck Institute for Solar System Research in Gottingen, Germany, and published in the journal Nature Astronomy, suggests water ice can be stored in the cold traps craters on Ceres. Ice in cold traps has been observed previously on Mercury and on Earth’s Moon. However, the origins of water ice on Ceres remains a mystery.
“We are interested in how this ice got there and how it managed to last so long,” said study co-author Norbert Schorghofer of the University of Hawaii. “It could have come from Ceres’ ice-rich crust or it could have been delivered from space.”
JPL also announced in the same press release a series of bright spots inside Occator Crater have now been named. The bright spots were first observed as Dawn was approaching Ceres and are now thought to be salt deposits, although their precise origins are still under investigation. The bright spot at the center of the crater has been named Cerealia Facula and a cluster of less reflective spots to the east have been named Vinalia Faculae.
The Dawn spacecraft launched in 2007 and has been orbiting Ceres since 2015 after spending over a year orbiting the asteroid Vesta. Its mission is scheduled to conclude in 2017 after which it will be left to orbit Ceres as a perpetual satellite.
Video courtesy of NASA’s Jet Propulsion Laboratory
Paul is currently a graduate student in Space and Planetary Sciences at the University of Akransas in Fayetteville. He grew up in the Kansas City area and developed an interest in space at a young age at the start of the twin Mars Exploration Rover missions in 2003. He began his studies in aerospace engineering before switching over to geology at Wichita State University where he earned a Bachelor of Science in 2013. After working as an environmental geologist for a civil engineering firm, he began his graduate studies in 2016 and is actively working towards a PhD that will focus on the surficial processes of Mars. He also participated in a 2-week simluation at The Mars Society's Mars Desert Research Station in 2014 and remains involved in analogue mission studies today. Paul has been interested in science outreach and communication over the years which in the past included maintaining a personal blog on space exploration from high school through his undergraduate career and in recent years he has given talks at schools and other organizations over the topics of geology and space. He is excited to bring his experience as a geologist and scientist to the Spaceflight Insider team writing primarily on space science topics. | 0.900709 | 3.937944 |
Every year, NASA's Chandra X-ray Observatory
To celebrate Chandra's decade and a half in space, and to honor October as American Archives Month, a variety of objects have been selected from Chandra's archive. Each of the new images we have produced combines Chandra data with those from other telescopes. This technique of creating "multiwavelength" images allows scientists and the public to see how X-rays fit with data of other types of light, such as optical, radio, and infrared. As scientists continue to make new discoveries with the telescope, the burgeoning archive will allow us to see the high-energy Universe as only Chandra can.
PSR B1509-58 (upper left)
Pareidolia is the psychological phenomenon where people see recognizable shapes in clouds, rock formations, or otherwise unrelated objects or data. When Chandra's image of PSR B1509-58, a spinning neutron star surrounded by a cloud of energetic particles, was released in 2009, it quickly gained attention because many saw a hand-like structure in the X-ray emission. In this new image of the system, X-rays from Chandra in gold are seen along with infrared data from NASA's Wide-field Infrared Survey Explorer (WISE) telescope in red, green, and blue. Pareidolia may strike again in this image as some people report seeing a shape of a face in WISE's infrared data.
RCW 38 (upper right)
A young star cluster about 5,500 light years from Earth, RCW 38 provides astronomers a chance to closely examine many young, rapidly evolving stars at once. In this composite image, X-rays
Hercules A (middle left):
Some galaxies have extremely bright cores, suggesting that they contain a supermassive black hole that is pulling in matter at a prodigious rate. Astronomers call these "active galaxies," and Hercules A is one of them. In visible light (colored red, green and blue, with most objects appearing white), Hercules A looks like a typical elliptical galaxy. In X-ray light, however, Chandra detects a giant cloud of multimillion-degree gas (purple). This gas has been heated by energy generated by the infall of matter into a black hole at the center of Hercules A that is over 1,000 times as massive as the one in the middle of the Milky Way. Radio data (blue) show jets of particles streaming away from the black hole. The jets span a length of almost one million light years.
Kes 73 (middle right):
The supernova remnant
Mrk 573 (lower left):
Markarian 573 is an active galaxy that has two cones of emission streaming away from the supermassive black hole at its center. Several lines of evidence suggest that a torus, or doughnut of cool gas and dust may block some of the radiation produced by matter falling into supermassive black holes, depending on how the torus is oriented toward Earth. Chandra data of Markarian 573 suggest that its torus may not be completely solid, but rather may be clumpy. This composite image shows overlap between X-rays from Chandra (blue), radio emission from the VLA (purple), and optical data from Hubble (gold).
NGC 4736 (lower right):
NGC 4736 (also known as Messier 94) is a spiral galaxy that is unusual because it has two ring structures. This galaxy is classified as containing a "low ionization nuclear emission region," or LINER, in its center, which produces radiation from specific elements such as oxygen and nitrogen. Chandra observations (gold) of NGC 4736, seen in this composite image with infrared data from Spitzer (red) and optical data from Hubble and the Sloan Digital Sky Survey (blue), suggest that the X-ray emission comes from a recent burst of star formation. Part of the evidence comes from the large number of point sources near the center of the galaxy, showing that strong star formation has occurred. In other galaxies, evidence points to supermassive black holes being responsible for LINER properties. Chandra's result on NGC 4736 shows LINERs may represent more than one physical phenomenon.
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington, DC. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations. | 0.86935 | 3.927418 |
October 1, 2013
Propylene on Titan
With a thick atmosphere, clouds, a rain cycle and giant lakes, Saturn’s large moon Titan is a surprisingly Earthlike place. But unlike on Earth, Titan’s surface is far too cold for liquid water – instead, Titan’s clouds, rain, and lakes consist of liquid hydrocarbons like methane and ethane (which exist as gases here on Earth). When these hydrocarbons evaporate and encounter ultraviolet radiation in Titan’s upper atmosphere, some of the molecules are broken apart and reassembled into longer hydrocarbons like ethylene and propane.
NASA’s Voyager 1 spacecraft first revealed the presence of several species of atmospheric hydrocarbons when it flew by Titan in 1980, but one molecule was curiously missing – propylene, the main ingredient in plastic number 5. Now, thanks to NASA’s Cassini spacecraft, scientists have detected propylene on Titan for the first time, solving a long-standing mystery about the solar system’s most Earthlike moon.
[ Read the Article: Cassini Discovers Titan Atmosphere Loaded With Plastics Ingredient ] | 0.845756 | 3.276984 |
Geoffrey Burbidge, who has died aged 84, co-authored the most seminal astrophysical paper of the past 60 years, made significant individual contributions to the early study of radio galaxies, and steadfastly criticised the prevailing paradigm of big bang cosmology.
In 1957, Geoff, his wife Margaret, the astronomer Fred Hoyle and the US physicist William Fowler showed how almost all of the chemical elements are formed by nuclear reactions taking place inside stars in the course of stellar evolution. More or less violent events then propel those elements into space, providing the seeds for newborn stars and, ultimately, for us. These scientists and their monumental 104-page paper, published in Reviews of Modern Physics, have been known ever since by the acronym "B²FH".
Between 1956 and 1960, Geoff studied the energy requirements of the giant radio galaxy M87 and much more distant, even stronger, radio sources. The kind of radiation producing their radio "noise" required enormous, continuously present, energy in both particles moving at near the speed of light, and in the well-ordered, strong magnetic fields needed to bend their motion. (Similar radiation is only produced on Earth by very ingeniously constructed "synchrotron" accelerators that similarly bend the paths of injected particles having extremely high speeds. Yet nature is evidently doing that, on its own, out in deep space.) Geoff showed that the total energy requirement was at a minimum when both the particles and the magnetic fields had comparable energies. Even that minimum energy was astonishing – up to something like the total energy emitted in 100m or more supernovae. Such energies were completely unexpected then, but his startling result has since been confirmed many times.
In 1958, Geoff also produced an intriguing argument involving helium enrichment in galaxies. If the currently observed light output of galaxies comes mainly from the conversion of hydrogen into helium in their stars, those same luminosities maintained throughout galactic lifetimes would imply a very small increase in their helium content, much smaller than the amount of helium they apparently possess. At that time, Geoff interpreted this as possible evidence that galaxies must once have been very much brighter, probably for a short time in the distant past.
Ironically, both his conclusions are now generally accepted lore, if not for the reasons he advanced. His enrichment argument came to be seen as evidence that helium in the universe could not have come from stellar nucleosynthesis alone; instead, it is conventionally believed that most of the helium emerged from the primeval big bang. And it is thought that many, possibly most, galaxies go through a very bright, quasar phase early on, quasars themselves involving central black holes and the conversion of gravitational energy into other forms. At the time Geoff formulated his ideas, neither quasars nor black holes had been discovered.
As a student of Hoyle's, I had the privilege of seeing B²FH working together from the early 1960s. Later, visiting my former Cambridge flatmate Peter Strittmatter in La Jolla, California, I saw Geoff at work there. Like Toscanini encouraging his orchestra, he would urge his postdoctoral colleagues and graduate students to expand their horizons, tackle new problems, and quickly write up their results for publication. "Do it now!" was one of his most frequent, and rather loud, exhortations.
He also possessed great good humour and exceptional wit. In 1965, Strittmatter and I were invited to share Christmas dinner with the Burbidges and their house guest, Hoyle. We gave Geoff a stack of telegram forms, arguing that "letters to Nature" were clearly too slow a form of scientific communication for him. He enjoyed this joke at his expense. (Margaret received a red nylon, shoulder-to-knee night robe – "the largest red shift we could find".)
Geoff was born in Chipping Norton, Oxfordshire, the son of a builder who was a local tennis champion. His father took him to Wimbledon many times, leading to his lifelong interest in the game. At Chipping Norton grammar school Geoff excelled in history and mathematics, but learned of a wartime opportunity to study physics at Bristol University. He obtained a very good honours degree in 1946. Subsequent practical experience in a ballistics laboratory gave him a taste for highly explosive events.
As a graduate student in physics at University College London in 1947, he met Dr Margaret Peachey, the assistant director of the University of London Observatory and a distant relative of the famous astronomer Sir James Jeans. Geoff later declared that he became an astronomer because he married one. They would become the most celebrated partnership in their field, and the most efficient since the siblings William and Caroline Herschel. At times, while Margaret observed, Geoff did diamond plate-cutting and other darkroom work, putting expertise learned in his father's business to scientific use. In the late 1950s, they began a decade-long research programme, observing galaxies and deducing their masses from their measured rotation speeds. Their almost 40 papers together, many with Kevin Prendergast, broke the back of this subject.
Geoff and Margaret held a number of positions before permanently joining the new UCSD (University of California, San Diego) campus at La Jolla in 1962. With the discovery of quasars around the same time, Geoff's fortunes began to take a different turn. With his friend Hoyle, he became increasingly disenchanted with both the conventional interpretation of quasars as very distant objects with large cosmological red shifts, and with the big bang implications that others saw in the discovery of the so-called cosmic microwave background radiation in 1965. He remained a vociferous challenger of conventional interpretations of these discoveries. In 2000, he, Hoyle and Jayant V Narlikar published a substantial book detailing their objections and presenting their own interpretations (A Different Approach to Cosmology).
Geoff was elected a fellow of the Royal Society in 1968. He and his wife were jointly awarded the American Astronomical Society's Warner prize and the Royal Astronomical Society's gold medal. He received a number of other awards and honours. From 1978 to 1984 he served as a notably effective director of the Kitt Peak National Observatory in Tucson, Arizona. He was the editor of the Annual Reviews in Astronomy and Astrophysics for more than 30 years.
Those lucky enough to be invited to join him and his associate editors for a full day of planning future volumes saw him in a role few others did, encouraging open discussion, judiciously choosing topics and potential contributors, and displaying a wide breadth of knowledge of subjects and their practitioners across the entire field.
He is survived by Margaret, whom he married in 1948, and by their daughter, Sarah.
•Geoffrey Ronald Burbidge, astrophysicist and cosmologist, born 24 September 1925; died 26 January 2010
• This article was amended on 22 February 2010. The original referred to Caroline Herschel's brother as John. This has been corrected. | 0.899013 | 4.049824 |
This is the big news hitting the web today: The ALMA array may have detected something big - an Earth sized planet big or bigger sort of big - on the edge of our solar system....but I really need to put the emphasis on 'may' and 'something':
- Firstly, a lot of people are pointing out that it's a huge coincidence for ALMA, which has a tiny field of view, to have detected this object by pure chance....so either ALMA has been very lucky,or there are a lot of these things, or it's not real - some kind of illusion caused by a problem with the array.
- Second, as the authors of the paper make clear themselves, it's not at all clear what this thing is, or even how big it is. It's literally just a point on a couple of their scans.
- Lastly, the paper is a preprint - that means it's a rough draft and hasn't been peer reviewed or accepted for publication by anyone. In other words no-one has independently fact checked it, and that's a HUGE part of good science. Scientific American has good write up on this aspect of it.
|Above: The ALMA array.|
Mists and fogs on Ceres?
For years now astronomers have been puzzled by the mysterious bright areas on the surface of Ceres. At first they were just some slightly brighter patches visible to Hubble. The the dawn mission arrived, and revealed some irregularly shaped patches of the surface that seemed to have incredibly bright white surfaces.... and that's where our knowledge stopped: These patches were unlike anything we'd ever seen. They mystified us. To be frank they still do.
Just recently Dawn has been able to send back some new clues: We now know these patches are probably not ice, but a paper published this week seems to show evidence that at certain times of the Cerean day these bright patches are emitting vapours and fogs of some kind. That's deepened the mystery still further as the most likely material to evaporate and cause fogs - probably clouds of vapour crystals rather than clouds of water droplets - is ice, which has been ruled out as a cause of the bright patches. All we can do is keep gathering data, and wait for the right clues to solve the puzzle....
Vapour farming experiment approved for testing on Mars
Salt has a lot to answer for on Mars: Especially a particular group of salts that suck moisture out of the thin Martian air until they self-dissolve into tiny water droplets. This phenomena, called deliquescence, is suspect number 1 for how the seeps that are thought to cause recurring slope linea form, and earlier this year Javier Martin-Torres and his colleagues reported results from NASA’s Curiosity rover suggesting that liquid water pools just beneath the surface of Mars at night before evaporating during the day.
To test the idea in a more controlled way, the ESA ExoMars rover will carry an experiment called HABIT, which will use salts to absorb 5 millilitres of water from the atmosphere a day, and it can hold up to 25 millilitres in total. The motivation isn't pure curiosity: If the process works, it can easily be scaled up to provide water for future crewed missions to Mars. "HABIT can be easily adapted to ‘water-farms’ for in-situ resource production,” Torres told New Scientist Magazine. “We will produce Martian liquid water on Mars, that could be used in the future exploration of Mars for astronauts and greenhouses.”
|Above: The 'recurring slope linea' that form on some Martian slopes and are thought to be due to liquid water. Courtesy of NASA.|
Deal struck to build Jupiter Icy Moons Explorer mission
Airbus and the European Space Agency have signed the contract that will lead to the construction of a space probe known as JUICE (JUpiter ICy moon Explrer - the things people will do for a good acronym) to study Jupiter and its icy moons.The probe will launch in 2022 and arrive at the giant planet 7.5 years later. The 5.5-tonne probe is being built in Toulouse in France, however components will be sourced from across Europe, America, and Japan. The full price for the JUICE is expected to exceed one billion euros, one of ESA's biggest missions to date, and as well as other goals it will help us understand the potential habitability of Jupiter's icy moons..
|Above: Ganymede, one of Jupiter's potentially ocean bearing moons.| | 0.800997 | 3.180634 |
October 2, 2005
Scientists Discover 10th Planet’s Moon
LOS ANGELES -- The astronomers who claim to have discovered the 10th planet in the solar system have another intriguing announcement: It has a moon.
While observing the new, so-called planet from Hawaii last month, a team of astronomers led by Michael Brown of the California Institute of Technology spotted a faint object trailing next to it. Because it was moving, astronomers ruled it was a moon and not a background star, which is stationary.The moon discovery is important because it can help scientists determine the new planet's mass. In July, Brown announced the discovery of an icy, rocky object larger than Pluto in the Kuiper Belt, a disc of icy bodies beyond Neptune. Brown labeled the object a planet and nicknamed it Xena after the lead character in the former TV series "Xena: Warrior Princess." The moon was nicknamed Gabrielle, after Xena's faithful traveling sidekick.
By determining the moon's distance and orbit around Xena, scientists can calculate how heavy Xena is. For example, the faster a moon goes around a planet, the more massive a planet is.
But the discovery of the moon is not likely to quell debate about what exactly makes a planet. The problem is there is no official definition for a planet and setting standards like size limits potentially invites other objects to take the "planet" label.
Possessing a moon is not a criteria of planethood since Mercury and Venus are moonless planets. Brown said he expected to find a moon orbiting Xena because many Kuiper Belt objects are paired with moons.
The newly discovered moon is about 155 miles wide and 60 times fainter than Xena, the farthest-known object in the solar system. It is currently 9 billion miles away from the sun, or about three times Pluto's current distance from the sun.
Scientists believe Xena's moon was formed when Kuiper Belt objects collided with one another. The Earth's moon formed in a similar way when Earth crashed into an object the size of Mars.
The moon was first spotted by a 10-meter telescope at the W.M. Keck Observatory in Hawaii on Sept. 10. Scientists expect to learn more about the moon's composition during further observations with the Hubble Space Telescope in November.
Brown planned to submit a paper describing the moon discovery to the Astrophysical Journal next week. The International Astronomical Union, a group of scientists responsible for naming planets, is deciding on formal names for Xena and Gabrielle.
On the Net:
California Institute of Technology: http://www.caltech.edu
W.M. Keck Observatory: http://www2.keck.hawaii.edu | 0.833162 | 3.331857 |
Comet 67P/Churyumov-Gerasimenko appears to have split into two segments that briefly orbited each other and then slowly merged into a new configuration.
In a new study about periodic comets (those that orbit the Sun in fewer than 200 years), scientists now suspect that comets regularly split in two and reunite later in their life, a repeating process fundamental to comet evolution.
Postdoctoral fellow Masatoshi Hirabayashi (Purdue University), working with Daniel Sheeres (University of Colorado-Boulder) and others, studied the nucleus of comet 67P/Churyumov-Gerasimenko (67P), which has been under close scrutiny by the European Space Agency’s Rosetta spacecraft since 2014. They found two straight cracks, each a few hundred meters long and separated from each other by 750 m, on the narrow neck that connect the comet’s two large lobes.
The team found that jets of gas and dust shooting into space cause the nucleus to spin faster and faster, until internal stress forms large cracks on the surface and eventually splits the comet. Once that happens, the separated segments orbit each other for some time, ultimately going through a slow merger that results in a new shape.
“The head and body aren’t going to be able to escape from each other,” said Sheeres. “They will begin orbiting each other, and in weeks, days or even hours they will come together again during a slow collision, creating a new comet nucleus configuration.” This pattern could go on for the comet’s lifetime.
Previous studies by the University of Bern suggest the cracks on the surface might have been created by tidal forces that arose during a brush with Jupiter, but that would have required a close Jupiter flyby within a narrow range of distances. Instead, Hirabayashi’s team modeled what would happen as the spin rate increased from one rotation every 12 hours to every 7 to 9 hours. This faster spin caused more stress and the formation of cracks in the same locations as those found on 67P.
“Our spin analysis predicted exactly where these cracks would form,” said Scheeres in a press release. “We now have a new understanding of how some comets may evolve over time.”
Scheeres also said there are several factors that can cause a comet nucleus to spin faster. Gravitational torquing by the Sun or Jupiter might be involved. The spin can be affected by icy compounds like ammonia and carbon dioxide, which are present on the surfaces of comets, go from being frozen to escaping from the surface in a gas — a process called sublimation.
Other periodic comets — among them 1P/Halley — are known to have a double-lobed shape. Of the seven comets astronomers have seen at high resolution, five — including 67P and 1P/Halley — are bi-lobed.
So could this be a common characteristic among periodic comets? “The conclusion that the other comets are necessarily bi-lobate is not so obvious as with 67P,” said Uwe Keller (Max Planck Institute for Astronomy). He says other comets that undergo sublimation also have elongated shapes, but that not all elongated comets need to be of bi-lobate origin.
The analysis by Hirbayashi’s team appears in the June 1st issue of Nature. | 0.856158 | 4.037821 |
Solar flares over, Venus Express restarts science investigations
ESA’s Venus Express spacecraft has returned to routine operation after its startracker cameras were temporarily blinded last week by radiation from a pair of large solar flares.
Science observations by ESA’s Venus Express were temporarily suspended on 7 March after the two startrackers – used to help navigate and orient the spacecraft – were overwhelmed by excessive proton radiation.
The proton storm stemmed from the Coronal Mass Ejections (CMEs) emitted by the Sun, which were associated with a pair of massive solar flares that occurred early in the morning on 7 March.
With the startrackers unable to function properly, mission controllers at ESOC, ESA’s European Space Operations Centre, Darmstadt, had to place the spacecraft into a special mode to ride out the storm.
This meant that all instruments were switched off and routine scientific observations and data gathering were stopped.
“As the radiation faded, the startrackers began functioning normally again on 9 March,” said Octavio Camino, ESA’s Spacecraft Operations Manager.
“After taking some time to conduct a series of thorough spacecraft health checks, Venus Express returned to regular science operations on 12 March at 20:20 GMT.”
Waiting out the storm
This month, Venus Express is going through ‘quadrature’: a period of about five weeks during which the Sun-spacecraft-Earth angle is between 75° and 95°. They occur twice every 19 months.
During quadrature, the spacecraft must maintain a special orientation so that certain instruments are not over-exposed to sunlight and the radio antenna can still be pointed to Earth.
“At any time, if a problem is autonomously detected onboard, the spacecraft might place itself into ‘safe mode’,” says Octavio.
However, if a safe mode were to happen during quadrature operations, and the startrackers were not operating, it would be much more difficult to return the spacecraft to normal operations.
“To be very cautious, we simply stopped science activities to wait out the proton storm,” says Octavio.
The mission operations team used the gyroscopes to maintain a safe attitude while waiting for the startrackers to return to normal.
Venus Express: a very robust mission
“There were no permanent effects; Venus Express is in excellent condition and the operations team performed very well,” said Paolo Ferri, responsible for interplanetary mission operations at ESOC.
“Yes, orbiting Venus means we’re closer to the Sun – and in a potentially hazardous environment.”
“But we have a very robust mission that is once again returning a large amount of valuable scientific data.” | 0.82485 | 3.089489 |
About a week ago our colleague and a resident polar scientist on the Mars Climate Sounder (MCS) science team Dr. Paul Hayne wrote this Planetary society blog post. He talks about CO2 snowing on Mars! If you are interested to know why we think that it snows dry ice on Mars or what shape CO2 snowflakes are, go check it out! And let us know your thoughts on how it affects the areas that you are helping us to analyze!
We have now switched the data shown in Planet Four to focus on the Manhattan region, because it takes us quite a while to finish an area. (Everybody, keep clicking! Invite all your family and friends!)
Manhattan is a region within the ‘‘cryptic” terrain of the south pole of Mars. This terrain has been termed ‘‘cryptic” because even so its albedo (‘albedo’ measures the percentage of light reflected on a surface) darkens in the spring, indicating a better absorption of energy or even an absence of otherwise highly reflective ice, this terrain retains the 145 K temperature of CO2 ice until late in the season. This terrain is known to contain a host of phenomena that are inferred to arise from local gas jet activity.
The position of the Manhattan area within this cryptic terrain is indicated in the map below. Inca City by the way is such an interesting region because it shows all kinds of CO2 ice related activity while NOT being inside the cryptic region! Once we have finished Manhattan, we will switch to finish Inca City.
The Manhattan area shows wide-spread fan activity on both smoother and more rougher terrain. An example is shown below.
When zooming in on an area without clear fan activity, as shown below in the zoom-in on area 2d, one discovers channels or troughs similar looking to the arms of the spider-shaped araneiform structures, but with one essential difference: They are not centralized, like the ones from araneiforms, where a set of arms meet in a more or less pronounced center. This pattern of troughs without center features has been dubbed ‘lace’ due to its visual apprearance.
Studying the fan activity in these areas with these underlying and neighboring roughness patterns will tell us if the fans develop differently in any way, either in resulting size distributions or over time. This hopefully will provide clues on differences in ground stability and therefore different gas transport ability during the CO2 activity, which can be compared with a araneiform-creation model.
All images of these post have been taken from C.J. Hansen et al. / Icarus 205 (2010) 283–295
Planet Four’s 1st birthday is on Wednesday. To celebrate and thank you for all of your help, below are the 50 most popular images classified. We tallied the number of people who favorited each image we’ve shown in the past year, and those in the gallery below in order came up on top. Click below on any of the images to get a larger view and to get a slide show to peruse through the entire collection. If you’re interested in any particular image, you can find all the images in this Talk collection. Help us celebrate by mapping some fans and blotches today at http://www.planetfour.org
Today marks Mars’ passage through aphelion, its furthest point in its orbit from the Sun. At aphelion, Mars is moving slowest in its orbit while at perihelion, Mars is closest to the Sun and moving at its fastest velocity. Mars has a more eccentric or elliptical orbit than Earth, and has the second highest eccentricity out of the 8 planets in our Solar System.
The Red Planet’s orbital eccentricity may actually be an important factor in Mars’ climate. The Southern hemisphere right now is pointed away from the Sun and the carbon dioxide ice sheet is growing. Compared to the Northern hemisphere, Southern summers are shorter (because Mars is at perihelion during that time) and the solar insolation is more intense while the Southern winters are colder and longer. This dichotomy may be responsible for why seasonal fans and blotches are abundant during the thawing of the carbon dioxide ice sheet in Southern Spring and Summer, but fans and blotches are spotted far and in between in the same seasons in the Northern Hemisphere.
So far seasonal fans and blotches have mainly been spotted on the slopes of dunes at the Martian North Pole and tend to be smaller than their Southern hemisphere counterparts. One of the goals of Planet Four is to better study this. With your measurements of the frequencies, locations, and sizes of fans we’ll eventually compare Northern hemisphere fans to the occurrence and sizes of fans in the Southern hemisphere. | 0.856577 | 3.539282 |
A group of Chinese astronomers, led by Jan Huang from Yunnan University, China, opened two new unrelated hyper-speed stars located more than 70,000 light-years away from us. This discovery can help scientists better understand the nature of the stars of this rare class.
Hyper-speed stars are stars having speeds so high that they even exceed the second cosmic velocity, that is, the speed of escape from our Galaxy. Astronomers believe that these stars are born near the center of the Milky Way as a result of dynamic interactions between binary stars and a central supermassive black hole. While ordinary stars have a speed of about 100 kilometers per second, hyper-speed stars move at speeds of up to 1,000 kilometers per second.
Although scientists estimate that there are about 1000 hyper-velocity stars within the Milky Way, up to now only about 20 stars of this class have been found. Given that these objects can travel long distances through our Galaxy, they can provide valuable information about the distribution of the mass of the Milky Way, its halo shape from dark matter.
Huang’s team discovered two new hyper-speed stars that received the LAMOST-HVS2 and LAMOST-HVS3 designations and also reopened the LAMOST hyper-speed star using the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) -HSV1, first seen in 2014 with the same sky survey.
According to the study, the LAMOST-HVS2 star belongs to the spectral class B2V, has a mass of about 7.3 solar masses and an effective temperature of 20,600 Kelvin. The speed of this star relative to the Galaxy is 502.33 kilometers per second. The LAMOST-HVS2 star has an effective temperature of 14,000 Kelvin, a mass of the order of 4 solar masses and belongs to the spectral class B7V. The speed of the star relative to the reference system associated with our Galaxy is 408.33 kilometers per second. | 0.848097 | 3.490036 |
Sunlight sends asteroids spinning
Sunlight can cause asteroids to spin more quickly, scientists say, showing just how dynamic our solar system can be.
International teams of scientists studying two asteroids, one about 1.5 kilometres wide and the other about 114 metres wide, confirm a previously unproven theory that sunlight can affect asteroid rotation.
Dr Stephen Lowry of Queen's University Belfast in Northern Ireland says the findings boost the understanding of the physical properties and dynamics of asteroids, hunks of metal and rock rattling around in space.
"This is important as asteroids are leftovers from the formation of the solar system, along with comets, and so by studying them we gain insights into what the solar system was like some 4.5 billion years ago," he says.
In research appearing in the journals Nature and Science, the scientists focused on the so-called YORP effect, named after four scientists (Yarkovsky-O'Keefe-Radzievskii-Paddack) who inspired the theory.
The idea is the Sun's heat serves as a propulsion engine on the irregular features of an asteroid's surface.
"YORP can accelerate or decelerate the rotation rate," says Dr Mikko Kaasalainen of the University of Helsinki in Finland.
When sunlight hits the asteroid, the solar energy is absorbed and then radiated back into space.
When the asteroid is not spherical, this can create a push off parts of its surface that alters its spin.
"Depending on the exact shape, the effect on the entire asteroid's surface can lead to a net torque, which can slowly alter the time it takes the asteroid to make one full revolution," Lowry says.
The scientists calculated the expected strength of the YORP effect on the asteroids. These estimates essentially matched their measurements of the two asteroids' spin changes over a period of years.
"It really shows that the solar system is a very dynamic place and the Sun ... affects all worlds, not just Earth, not just the planets but even the smallest rocks orbiting the Sun," says Patrick Taylor of Cornell University.
Using large telescopes and radar facilities, the scientists watched as the spin of near-Earth asteroid 2000 PH5, the smaller one, increased by 1 millisecond per year.
Its orbit takes it inside and outside Earth's orbit, and it has come as close to our planet as five times the distance to the Moon.
"It is relatively small, and so more susceptible to the YORP effect. Also, it rotates very fast, with one day on the asteroid lasting just over 12 Earth minutes, implying that the YORP effect may have been acting on it for some time," Lowry says.
"Eventually it may spin faster than any known asteroid in the solar system," Lowry says.
Lowry says the YORP effect plays a role in changing asteroid orbits in the crowded asteroid belt between Mars and Jupiter, including moving them to planet-crossing orbits.
Kaasalainen says the increasing rotation speed of asteroid 1862 Apollo, the bigger one, probably will break it apart due to centrifugal forces. Noting the asteroid already has a small moonlet, he says it might have broken apart a bit already.
The researchers say the spin of this asteroid in the past 40 years has accelerated so much that it has an extra rotation per orbit around the Sun. | 0.821461 | 3.873397 |
NJIT Distinguished Professor Philip R. Goode and the research team at Big Bear Solar Observatory (BBSO) have reported new insights into the small-scale dynamics of the Sun's photosphere. The observations were made during a period of historic inactivity on the Sun and reported in The Astrophysical Journal. The high-resolution capabilities of BBSO’s new 1.6-meter aperture solar telescope have made such work possible.
“The smallest scale photospheric magnetic field seems to come in isolated points in the dark intergranular lanes, rather than the predicted continuous sheets confined to the lanes,” said Goode. “The unexpected longevity of the bright points implies a deeper anchoring than predicted.”
Following classical Kolmogorov turbulence theory, the researchers demonstrated for the first time how photospheric plasma motion and magnetic fields are in equipartition over a wide dynamic range, while unleashing energy in ever-smaller scales.
This equipartition is one of the basic plasma properties used in magnetogydrodynamic models. “Our data clearly illustrates that the Sun can generate magnetic fields not only as previously known in the convective zone but also on the near-surface layer. We believe small-scale turbulent flows of less than 500 km to be the catalyst,” said NJIT Research Professor Valentyna Abramenko at BBSO.
Tiny jet-like features originating in the dark lanes surrounding the ubiquitous granules that characterize the solar surface were also discovered. Such small-scale events hold the key to unlocking the mystery of heating the solar atmosphere, the researchers said. The origins of such events appear to be neither unequivocally tied to strong magnetic field concentrations, nor associated with the vertex formed by converging flows.
“The solar chromosphere shows itself ceaselessly changing character with small-scale energetic events occurring constantly on the solar surface, said NJIT Research Professor Vasyl Yurchyshyn, also at BBSO. Such events suggest a similarity of magnetic structures and events from the hemisphere to its granular scales. The researchers hope to establish how such dynamics can explain the movement underlying convective flows and turbulent magnetic fields.
The telescope is the crown jewel of BBSO, the first facility-class solar observatory built in more than a generation in the U.S. The instrument is undergoing commissioning at BBSO. Since 1997, under Goode’s direction, NJIT has owned and operated BBSO, located in a clear mountain lake.
The mountain lake is characterized by sustained atmospheric stability, which is essential for BBSO’s primary interests of measuring and understanding solar complex phenomena utilizing dedicated telescopes and instruments.
The images were taken with the new instrument with atmospheric distortion corrected by its 97 actuator deformable mirror. By the summer of 2011, in collaboration with the National Solar Observatory, BBSO will have upgraded the current adaptive optics system to one utilizing a 349 actuator deformable mirror.
The new telescope began operation in the summer of 2009, with support from the National Science Foundation (NSF), Air Force Office of Scientific Research, NASA and NJIT. Additional NSF support was received a few months ago to fund further upgrades to this new optical system.
The telescope will be the pathfinder for an even larger ground-based telescope, the Advanced Technology Solar Telescope (ATST), to be built over the next decade. NJIT is an ATST co-principal investigator on this NSF project.
Scientists believe that magnetic structures like sunspots hold the key to space weather. Such weather, originating in the Sun, can affect Earth's climate and environment. A bad storm can disrupt power grids and communication, destroy satellites and even expose airline pilots, crew and passengers to radiation.
The new telescope now feeds a high-order adaptive optics system, which in turn feeds the next generation of technologies for measuring magnetic fields and dynamic events using visible and infrared light. A parallel computer system for real-time image enhancement highlights it. Goode and his research team, who study solar magnetic, are expert at combining BBSO ground-based data with satellite data to determine dynamic properties of the solar magnetic fields. | 0.810894 | 3.82391 |
Twinkle, Twinkle Little Star,
How I Wonder How the Measured You
From So Afar
So what kind of equipment can measure stars, that NASA tells us are so far away it is impossible to fathom such distance.
A light-year is how astronomers measure distance in space. It’s defined by how far a beam of light travels in one year – a distance of six trillion miles.
Throughout the universe, all light travels at exactly the same speed: about 670 million miles per hour.
The main reason for using light years, however, is because the distances we deal with in space are immense. If we stick to miles or kilometers we quickly run into unwieldy numbers just measuring the distance to the nearest star: a dim red dwarf called Proxima Centauri that sits a mere 24,000,000,000,000 miles away
The Milky Way galaxy in which our sun and all the stars we see at night reside spans 100,000 light-years from one end to the other. Putting that into perspective, the duration of recorded human history is roughly 5,000 years. So light from a star at one end of our galaxy takes 20 times longer than all of recorded history to get to the other end.
A galaxy whose light took 14 billion years to reach our little planet has, in the intervening aeons, moved even further away. The current physical distance to that remote beacon, if we stopped the universe from expanding and stretched out a really long tape measure, is just over 46 billion light years! Even in light years, measuring distances across the universe becomes unwieldy. But measuring in something familiar, like miles, is truly humbling. From here to the edge of our vision spans a distance of approximately 276,000,000,000,000,000,000,000 miles.
And it’s getting bigger every day.(Source. Earthj/sky.org)
So we are being told that NASA earth made instruments can measure distances using light wave frequencies able to record how far, how hot or cold, how big and how bright to distances of 276 TRILLION MILLION Miles away.
Through atmospheres, solar radiation and solar flares. Through micrometeroids, comet tails and time warps. Through light bending gravity pulls by planetary orbits and the Asteroid belt.
Damn these guys at NASA are Goooooood!
Or are they?
If you wanted to make someone feel really, really insignificant, you’d tell them they are just a small, tiny, tiny cog in a very, very Big Wheel.
This is why the Vatican and its secrete societies of the 15th and 16th centuries created the heliocentric theory and doused 3500 years of a geocentric world view. The Kingdom of God is in the church and power that you cannot fathom, so give us your laws, your money and your soul.
Yet why has no one even questioned how the hell they can measure such light from such distance.
And doesn’t light, like a flashlight spread and flair the farther out it goes? So how can they be sure the light is from a star some godzillion miles away?
James Hubble Telescope launched to take pictures away from limits of Earth’s atmosphere, NASA tells us. (NASA Image)
The Hubble Space Telescope (HST) is a space telescope that was launched into low Earth orbit in 1990, and remains in operation. With a 2.4-meter (7.9 ft) mirror, Hubble’s four main instruments observe in the near ultraviolet, visible, and near infraredspectra. The telescope is named after the astronomerEdwin Hubble.
The Hubble Space Telescope is able to measure wavelengths from about 0.1150 to 2 micrometers, a range that covers more than just visible light. These measurements of light enable astronomers to determine certain physical characteristics of objects, such as their temperature, composition, and velocity. (Source)
Ultraviolet radiation has wavelengths of 10 – 310 nm (about the size of a virus). Young, hot stars produce a lot of ultraviolet light and bathe interstellar space with this energetic light.
Visible light covers the range of wavelengths from 400 – 700 nm (from the size of a molecule to a protozoan). Our sun emits the most of its radiation in the visible range, which our eyes perceive as the colors of the rainbow. Our eyes are sensitive only to this small portion of the electromagnetic spectrum.
Infrared wavelengths span from 710 nm – 1 millimeter (from the width of a pinpoint to the size of small plant seeds). At a temperature of 37 degrees C, our bodies give off infrared wavelengths with a peak intensity near 900 nm.
NASA tells us that it measures these waves by recording their light at one location, then another in six months. The precision for such distances, given motions of planets and solar systems, some tens and hundreds of thousands of miles, is truly unbelievable, yet that is what we are told.
Astrometry, Measuring the Great Distance, Size, Shape and Temperature of the Stars?
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our galaxy, the Milky Way.
James Bradley first tried to measure stellar parallaxes in 1729. The stellar movement proved too insignificant for his telescope, but he instead discovered the aberration of light and the nutation of the Earth’s axis. His cataloguing of 3222 stars was refined in 1807 by Friedrich Bessel, the father of modern astrometry. He made the first measurement of stellar parallax: 0.3 arcsec for the binary star 61 Cygni.
Bessel was a major figure in astronomy during his lifetime. He was elected a fellow of the Royal Society, a foreign member of the Royal Swedish Academy of Sciences in 1823, and the largest crater in the Moon’s Mare Serenitatis is named Bessel after him. Bessel’s work in 1840 contributed in some degree to the discovery of Neptune. In 1832, he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences. Bessel won the Gold Medal of the Royal Astronomical Society in 1829 and 1841.
Stellar parallax is parallax on an interstellar scale: the apparent shift of position of any nearby star (or other object) against the background of distant objects. Created by the different orbital positions of the Earth, the extremely small observed shift is largest at time intervals of about six months, when the Earth arrives at exactly opposite sides of the Sun in its orbit, giving a baseline distance of about two astronomical units between observations. The parallax itself is considered to be half of this maximum, about equivalent to the observational shift that would occur due to the different positions of the Earth and the Sun, a baseline of one au.
Stellar parallax is so difficult to detect that its existence was the subject of much debate in astronomy for hundreds of years. It was only first proven in 1838 when Friedrich Bessel made the first successful parallax measurement ever, for the star 61 Cygni, using a Fraunhofer heliometer at Königsberg Observator
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A real direct distance measurement of an astronomical object is possible only for those objects that are “close enough” (within about a thousand parsecs) to Earth. The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at close distances and methods that work at larger distances. Several methods rely on a standard candle, which is an astronomical object that has a known luminosity.
The ladder analogy arises because no one technique can measure distances at all ranges encountered in astronomy. Instead, one method can be used to measure nearby distances, a second can be used to measure nearby to intermediate distances, and so on. Each rung of the ladder provides information that can be used to determine the distances at the next higher rung.
A parsec (symbol: pc) is a unit of length used to measure the astronomically large distances to objects outside the Solar System. One parsec is the distance at which one astronomical unit subtends an angle of one arcsecond. About 3.26 light-years (31 trillion kilometres or 19 trillion miles) in length, the parsec is shorter than the distance from our solar system to the nearest star, Proxima Centauri, which is 1.3 parsecs from the Sun. Nevertheless, most of the stars visible to the unaided eye in the nighttime sky are within 500 parsecs of the Sun.
A lot of gobbly-gook of language but not a mention of how they can be so precise and accurate over such great distance all the while needing a vacuum and not debris or time/space warp, etc.
Hubble is a telescope that allegedly uses high powered mirrors to see into Deep Space, but what how what captures light from distance so great we cannot even imagine?
As you can see the entire telescope is optical in nature without only little reference to “Fixed-head star tracker” and “Radial science instrument module”.
Also optimized for ultraviolet observations were the FOC and FOS, which were capable of the highest spatial resolution of any instruments on Hubble. Rather than CCDs these three instruments used photon-counting digicons as their detectors. The FOC was constructed by ESA, while the University of California, San Diego, and Martin Marietta Corporation built the FOS.
The final instrument was the HSP, designed and built at the University of Wisconsin–Madison. It was optimized for visible and ultraviolet light observations of variable stars and other astronomical objects varying in brightness. It could take up to 100,000 measurements per second with a photometric accuracy of about 2% or better.
A digicon detector is a spatially resolved light detector using the photoelectric effect directly. It uses magnetic and electric fields operating in a vacuum to focus the electrons released from a photocathode by incoming light onto a collection of silicon diodes. It is a photon-counting instrument, so most useful for weak sources.
Digicon detectors were used on the original instruments for the Hubble Space Telescope
Asteroid Belt according to NASA
The first spacecraft to traverse the asteroid belt was Pioneer 10, which entered the region on July 16, 1972. At the time there was some concern that the debris in the belt would pose a hazard to the spacecraft, but it has since been safely traversed by 11 Earth-based craft without incident
These guys at NASA are goooooood!
The star measuring devices must operate in a vacuum we are told by the scientists, yet space is anything but a vacuum.
Micrometeoroids are very small pieces of rock or metal broken off from larger chunks of rock and debris often dating back to the birth of the solar system. Micrometeoroids are extremely common in space. Tiny particles are a major contributor to space weathering processes.
Micrometeoroids pose a significant threat to space exploration. Their velocities relative to a spacecraft in orbit average 10 kilometers per second (22,500 mph), and resistance to micrometeoroid impact is a significant design challenge for spacecraft and space suit designers (See Thermal Micrometeoroid Garment).
Cosmic dust is dust which exists in space. It is for the most part a type of small dust particles which are a few molecules to 0.1 µm in size. A smaller fraction of all dust in space consists of larger refractory minerals that condensed as matter left the stars. It is called “stardust” and is included in a separate section below.
Cosmic dust can be further distinguished by its astronomical location, there is also intergalactic dust, interstellar dust, interplanetary dust (such as in the zodiacal cloud) and circumplanetary dust (such as in a planetary ring). In the Solar System, interplanetary dust causes the zodiacal light.
Then we have the asteroid belts and thousand mile long comet trails,
Solar flares and Solar radiation.
Additionally we have light bending time warp as postulated by Ol A. Einstein himself.
The bending of light by gravity can lead to the phenomenon of gravitational lensing, in which multiple images of the same distant astronomical object are visible in the sky. General relativity also predicts the existence of gravitational waves, which have since been observed indirectly; a direct measurement is the aim of projects such as LIGO and NASA/ESA Laser Interferometer Space Antenna and various pulsar timing arrays. In addition, general relativity is the basis of current cosmological models of a consistently expanding universe.
Additionally, time is warped according to Einstein and NASA
Any object with mass warps the space-time around it, in much the same way as a heavy object deforms a stretched elastic sheet, explained study leader Ignazio Ciufolini of the Universit? di Lecce in Italy.(Source, Space.com)
It is impossible for NASA to have measured stars hundreds of trillions, much less millions of miles away when Albert, et. al tell us the time is warped, light is bent and NASA admits that itself that space is not in any way a vacuum.
They could not possible use the vacuum needed measurement devices stated, over trillion of miles, to tell us the shape, size, temperature, distance and temperature.
Especially with balls spinning like Jupiter at some 57,000 mph and our Solar system trucking around the Milkyway at over 500,000 mph, like NASA tells us.
It’s all a 500 yr. lie. All of it. | 0.961021 | 3.496559 |
A single burst of radio emission of unknown origin was detected outside our Galaxy about six years ago but no one was certain what it was or even if it was real, so astronomers have spent the last four years searching for more of these explosive, short-duration bursts.
The international research team, writing in the journal Science, ruled out terrestrial sources for the four fast radio bursts and say their brightness and distance suggest they come from cosmological distances when the Universe was just half its current age. The burst energetics indicate that they originate from an extreme astrophysical event involving relativistic objects such as neutron stars or black holes.
Study lead Dan Thornton, a PhD student at England's University of Manchester and Australia's Commonwealth Scientific and Industrial Research Organisation, said the findings pointed to some extreme events involving large amounts of mass or energy as the source of the radio bursts.
The paper describes four more bursts, removing any doubt that they are real. The radio bursts last for just a few milliseconds and the furthest one that we detected was 11 billion light years away."
Astonishingly, the findings -- taken from a tiny fraction of the sky -- also suggest that there should be one of these signals going off every 10 seconds. "The bursts last only a tenth of the blink of an eye," explained Max-Planck Institute Director and Manchester professor, Michael Kramer. "With current telescopes we need to be lucky to look at the right spot at the right time. But if we could view the sky with 'radio eyes' there would be flashes going off all over the sky every day."
The team, which included researchers from the UK, Germany, Italy, Australia and the US, used the CSIRO Parkes 64metre radio telescope in Australia to obtain their results.
Co-author Professor Matthew Bailes, from the Swinburne University of Technology in Melbourne, thinks the origin of these explosive bursts may be from magnetic neutron stars, known as 'magnetars'. He said: "Magnetars can give off more energy in a millisecond than our Sun does in 300,000 years and are a leading candidate for the burst."
Journal Reference: D. Thornton, B. Stappers, M. Bailes, B. Barsdell, S. Bates, N. D. R. Bhat, M. Burgay, S. Burke-Spolaor, D. J. Champion, P. Coster, N. D'Amico, A. Jameson, S. Johnston, M. Keith, M. Kramer, L. Levin, S. Milia, C. Ng, A. Possenti, W. van Straten. A Population of Fast Radio Bursts at Cosmological Distances. Science, 2013; 341 (6141): 53 DOI: 10.1126/science.1236789
The Daily Galaxy via University of Manchester. | 0.828006 | 3.914454 |
Updated: July 27, 2009
This notion has been the fascination of science and fiction geeks since the famous Michelson-Morley experiment, which showed that the speed of light is as fast as you can go. Even today, a hundred years later, the zeal for discovering a way of getting past the speed of light barrier is strong in the ultra-geek community.
As a proud member of the geek community, I felt I had to share my own thoughts on the subject ... Can it be really done? Can the speed of light be truly exceeded and the laws of physics sent sniveling into the corner? Or do all geeks, by nature, have an over-developed sense of imagination?
Before we can discuss this magic number (roughly 300,000 km/sec in vacuum), we need to focus on our universe first. Our universe is this crazy 4D thingie, which best can be described as the surface of a transparent, self-inflating balloon. You can see through to the other side, but the information goes round the curvy surface of the balloon. Which is why every object in the universe is getting farther apart from every other object as the balloon continues to grow.
Now, surface implies 2D, which is contrary to our perception of life, where we see and feel things as 3D objects. Similarly, this is how we envision the space. But the direct analogy is misleading. The surface of the balloon is the best human description, but it's too flawed. This is because time is part of the fabric that forms this surface. At any given moment, it's a 2D snapshot, but down the timeline, things start to look logical.
The propagation of information and the way it obeys the different laws of physics is probably the best manifest of the third dimension we're looking for. And this is where speed of light comes into play.
Most people do not realize that speed of light is not a speed per se. It is the characteristic of the medium
defining the propagation of electromagnetic radiation inside it. In other words, it's the uppermost limit of how
fast the information can travel from one point on the balloon surface to another.
In geek terms, the speed of light is inversely proportional to the square root of electric permittivity (Eo) and magnetic permeability (Uo) of the medium it travels through. In pure vacuum, the speed of light is exactly the magic number we know. In water and other transparent media, the speed changes mainly due to the difference in the electric permittivity factor.
Take a particle and send it hurling through the space. This particle will try to go as fast as it can. In a way, the vacuum will suck the particle into it, lending it speed. The emptier this vacuum is, the higher the pull on the particle - hence its speed.
The particle motion is not linear as we might expect it. The balloon surface is growing, therefore the distance between any two points is growing. The balloon surface is curved, which means that the particle path will not be a straight line as we might envision it. Instead, it will be a straight line, divided by time and space curvature, both of which are highly debatable.
Lastly, there's gravity to take into account. The best way to think of gravity is as of potholes in the road. Each object creates a tension onto the balloon surface, sort of as a rock laid on a rubber sheet. The heavier the object, the bigger the hole the object's mass will exert upon the surface of the balloon.
Thus, a particle going from point A to point B might also have to fight against gravity, which could significantly lengthen its path. And since gravity is also part of the equation, time might also change.
Overall, it's one big mess. Combined, the foul play of vacuum and other forces make sure that the speed of light is the maximal speed a particle may achieve. Even massless particles like photons and docile neutrinos are unable to overcome the intrinsic limitations of our universe. So, what do we do? How can we try to be faster than the speed of light, regardless of the physical limitations?
There are several ways to do this. Some are very real, others purely theoretical. I'm going to present all of them. Of course, do remember that the theories I raise are pure speculations, as there is no technology that can achieve what I propose. Still ...
If you're unfamiliar with Quantum Mechanics, the phrase phase means little to you. The thing is, this phase is an important if unreal part of a particle's wave function. The phase can exceed the speed of light, but unto itself, it is meaningless.
To observe a particle, you have to measure one of its eigenvalues. To do that, you have to force it into an eigenstate. The mathematical torture that explain this situation involves multiplying the wavefunction with its conjugate. And when you do that with complex numbers, the imaginary part vanishes. In layman's terms, once you observe a particle, you force its infinite number of momenta and positions into one definite set, determined by probability.
It is difficult to fully understand this, but it's a part of the algebra, so take it or leave it. Physics rules may yet change and then, we might talk about a wholly different set of equations. Still, the fact that changes are not continuous baffles people and defies simple logic. Why should not there be something in between those energy levels, you ask? Well, in four dimensions, this is what it looks like. With a few more, things might get easier to grasp. This is what the String Theory is trying to do, slap an extra half dozen dimensions onto our 4D ball, and Bob's your uncle.
Back to our phase ... it can go faster than the speed of light, definitely. But this does not really help us. To get meaningful, palpable information, we will still have to wait for the information to arrive at its usual speed.
Here's a little experiment that shows you this:
Optics 101: take a lens and project an image through it. Depending on the focal depth and whatnot, there's a certain distance where you will be able to see the projected image clearly, probably inverted and scaled. If you move the object out of focus, it will get blurry. So far, so good.
Now, what you need to do is try to see what the object looks like at the focal point. If you place a screen at the focal point, you will probably see a jumble of shades, nothing that even remotely resembles your real object. Why is this, you may wonder?
Well, any time light (electromagnetic radiation) interacts with a medium, it undergoes a Fourier Transform. In practical terms, it turns from energy into waveforms. In human terms, we are unable to interpret waveforms. We do not think or see in frequencies. We understand energy, or rather, power. The intensity of projected object is meaningful to us. Phase is just gibberish.
Luckily for us, on the screen, the light undergoes another Fourier Transform, forcing the waveforms back into energy values and the phases are lost. What happens is, the waveforms combine with their conjugates and the imaginary parts cancel each other out. Even more interestingly, when you're out of focus, due to different travel paths of the light waveforms, they only partially cancel each other out, resulting in some of the energy projected onto parts of the screen that should not contain the image, which causes the blurs that we see.
So, in a way, phase is the indicator to how much of total intensity we ought to see, but of course, it is completely dependent on time and space. This is why getting the phase ahead of the actual information is meaningless.After this lengthy introduction, we now know that phase can't really help us. You can move faster than the speed of light, but the information will be meaningless, because the phase is not a real component. There's a whole bunch of physical phenomena that demonstrates the phase going wild, but I won't go there.
To move faster than light means beating the medium, which makes it impossible given the physical laws as we know them. Bend the rules and you may go faster than the speed of light. The big, big question is how to achieve this?
Physicists are currently hunting after graviton, the particle responsible for gravity. It has not yet been found, but the hopes are high. In theory, if this particle is found and harnessed, it may be put to good use. Just like photons are used in conventional (optical) lasers, it might be possible to use gravitational laser to focus narrow beams of gravity and create temporary gravity sinkholes in the fabric of the universe.
This may require very powerful sources of energy and possibly some sort of gravitational lenses a la galaxies to focus down the particle beam, but assuming it is possible, gravitational lasers may be used to create black holes in the space. The powerful gravitational pull of black holes may cause time shifts that could be used by travelers to leap frog through the space without paying the full price of time, thus effectively making their travel faster than the speed of light.
An alternative would be to focus gravity pulses into points smaller than the Planck length or shorter than the Planck time, which might help over come the speed limitations, since both these values are calculated using the speed of light.
The gravitational voids could perhaps be dangled like a carrot in front of a donkey, i.e. fired from a spacecraft of some sort directly ahead of it, causing a vacuum/mass cascade that would accelerate the ship to travel in a medium that is even emptier than vacuum, thus easily breaching the speed of light barrier.
Deplete the vacuum
This might be done by matter-anti-matter collisions. In theory, the matter and anti-matter should annul each other completely, possibly releasing energy in the process. There's very little anti-matter in the universe free for grabbing, but assuming it could be distilled from the surroundings on the fly, it might be possible to mix it with matter to create controlled explosions.
If you've ever witnessed an explosion, you will have learned that the epicenter of the explosion remains intact. Furthermore, you may also have heard or seen fireballs collapse back onto themselves. This is caused by the vacuum that is generated in the center of the explosion, by the outward expanding ring of exploded particles.
The same theory may guide a faster-than-c travel. Creating matter-anti-matter explosions around a spacecraft could create expanding energy waves that would suck the vacuum dry, possibly more than its currently emptiness, creating a negative potential that makes anything inside the explosion bubble move faster than the speed of light.
The big problem would be protecting the spacecraft from the backlash of the collapsing explosion, but this could be compensated by additional, more powerful explosions. This means that the matter-anti-matter mechanism would have to continuously throttle up to protect the ship while providing even thinner vacuum and greater speed.
This is kind of like the positive void coefficient in nuclear reactors, and because of the exponential growth, such travel would be short in duration and costly in energy. Emphasis would also have to be placed on focusing the explosions ahead of the traveling spacecraft, as it would tend to gain on the energy front released. This would be another limiting factor, but even the energy could be focused for very short bursts, it could still provide with a substantial increase in speed.
This idea is quite tricky though. Because of the Charge-Parity (CP) violation that probably led to the fact the matter is so much more abundant than anti-matter, at least as we know it, it is possible that some of the ingredients may not be fully transformed into energy, undermining our effort. Furthermore, the explosions would not be environment friendly. There's also the risk of the whole thing spinning out of control, as there's no dampening mechanism to the reaction save for the depletion of energy sources.
Shortcut through the balloon
Today, we are forced to travel around the circumferences of our inflating balloon, even though we can see through. So maybe we could create sort of tunnels that go all the way through to the other end? This is the idea of wormholes.
Creating wormholes sounds tricky, but again, the use of gravitational lasers might help. Very massive distortions might cause tunnels deep enough to reach adjacent areas of universe and allow spacecraft to wriggle through before closing. The big question is how one would survive going through a wormhole, because of the massive gravitational pull.
Possibly, a combination of lasers and matter-anti-matter explosions might work, with explosions protecting the ship against the gravitational forces, while also lending extra speed.
Change the time
This one is really tricky. First, we know almost nothing about time as a dimension. Second, changing the time would force us to account for all sorts of problems like entropy and stuff, which makes this the least likely candidate. Still, it might be worth considering.
There's no reason to go fast; just make sure you travel great distances in a very short time. I have no idea how to do this without getting physical [sic] with all sorts of rules.
That's about it, I think. Some sci-fi food for thought. Going faster than the speed of light is just like jumping higher in a room with a low ceiling; no matter how high you jump, you will always bang your head against it. However, make the ceiling higher ... aha!
One day, we may we able to do it. For now, chlorinating the vacuum or blackholing the universe like a smallpox epidemics is still a wild dream of science geeks. The energy required for the effort would probably make the entire universe go on a strike. Well ... we can keep on dreaming. I hope you enjoyed this nonsense. Have fun. | 0.836721 | 3.332314 |
Europa is the smallest of planet Jupiter’s four largest moons and the second moon
out from Jupiter. Until 1979, it was just another astronomy textbook statistic. Then
came the close-up images obtained by the exploratory spacecraft Voyager 2, and within
days, Europa was transformed-in our perception, at least-into one of the solar system’s
(5)most intriguing worlds. The biggest initial surprise was the almost total lack of detail,
especially from far away. Even at close range, the only visible features are thin, kinked
brown lines resembling cracks in an eggshell. And this analogy is not far off the mark.
The surface of Europa is almost pure water ice, but a nearly complete absence of
craters indicates that Europa’s surface ice resembles Earth’s Antarctic ice cap. The
(10) eggshell analogy may be quite accurate since the ice could be as little as a few kilometers
thick –a true shell around what is likely a subsurface liquid ocean that , in turn, encases
a rocky core. The interior of Europa has been kept warm over the eons by tidal forces
generated by the varying gravitational tugs of the other big moons as they wheel around
Jupiter. The tides on Europa pull and relax in an endless cycle. The resulting internal heat
(15) keeps what would otherwise be ice melted almost to the surface. The cracklike marks on
Europa’s icy face appear to be fractures where water or slush oozes from below.
Soon after Voyager 2’s encounter with Jupiter in 1979, when the best images of
Europa were obtained, researchers advanced the startling idea that Europa’s subsurface
ocean might harbor life. Life processes could have begun when Jupiter was releasing a
(20 )vast store of internal heat. Jupiter’s early heat was produced by the compression of the
material forming the giant planet. Just as the Sun is far less radiant today than the primal
Sun, so the internal heat generated by Jupiter is minor compared to its former intensity.
During this warm phase, some 4.6 billion years ago, Europa’s ocean may have been liquid
right to the surface, making it a crucible for life. 【題組】
1.What does the passage mainly discuss?
(A)The effect of the tides on Europa’s interior
(B)Temperature variations on Jupiter’s moons
(C)Discoveries leading to a theory about one of Jupiter’s moons
(D)Techniques used by Voyager 2 to obtain close-up images.
3.【題組】3.In line 7, the another mentions “cracks in an eggshell” in order to help readers
(A)visualize Europa as scientists saw it in the Voyager 2 images
(B)appreciate the extensive and detailed information available by viewing Europa from far away
(C)understand the relationship of Europa to the solar system
(D)recognize the similarity of Europa to Jupiter’s other moons
4.【題組】4. It can be inferred from the passage that astronomy textbooks prior to 1979
(A) provided many contradictory statistics about Europa
(B) considered Europa the most important of Jupiter’s moons
(C) did not emphasize Europa because little information of interest was available
(D) did nor mention Europa because it had not yet been discovered
5.【題組】5. what does the author mean by stating in line 7 that “this analogy is not far off the mark”?
(A) The definition is not precise.
(B) The discussion lacks necessary information.
(C) The differences are probably significant.
(D) The comparison is quite appropriate.
6.【題組】6. IT can be inferred from the passage that Europa and Antarctica have in common which of the following?
(A) Both appear to have a surface with many craters.
(B) Both may have water beneath a thin, hard surface.
(C) Both have an ice can that is melting rapidly.
(D) Both have areas encased by a rocky exterior.
8.【題組】8. According to the passage, what is the effect of Jupiter’s other large moons on Europa?
(A) They prevent Europa’s subsurface waters from freezing.
(B) They prevent tides that could damage Europa’s surface.
(C) They produce the very hard layer of ice that characterizes Europa.
(D) They assure that the gravitational pull on Europa is maintained at a steady level.
9.【題組】9 According to the passage, what is believed to cause the thin lines seen on Europa’s surface?
(A) A long period of extremely high tides
(B) Water breaking through from beneath the surface ice
(C) The continuous pressure of slush on top of the ice
(D) Heat generated by the hot rocky core
Both in what is now the eastern and the southwestern United States, the peoples of
the Archaic era (8,000-1,000 B.C) were, in a way, already adapted to beginnings of
cultivation through their intensive gathering and processing of wild plant foods. In both
areas, there was a well-established ground stone tool technology, a method of pounding
(5)and grinding nuts and other plant foods, that could be adapted to newly cultivated foods.
By the end of the Archaic era, people in eastern North America had domesticated certain
native plants, including sunflowers; weeds called goosefoot, sumpweed, or marsh elder;
and squash or gourds of some kind. These provided seeds that were important sources of carbohydrates and fat in the diet.
(10) The earliest cultivation seems to have taken place along the river valleys of the
Midwest and the Southeast, with experimentation beginning as early as 7,000 years ago
and domestication beginning 4,000 to 2,000 years ago. Although the term “Neolithic” is
not used in North American prehistory, these were the first steps toward the same major subsistence changes that took place during the Neolithic (8,000-2,000 B.C.) period
(15)elsewhere in the world.
Archaeologists debate the reasons for beginning cultivation in the eastern part of the
continent. Although population and sedentary living were increasing at the time, there is
little evidence that people lacked adequate wild food resources; the newly domesticated
foods supplemented a continuing mixed subsistence of hunting, fishing, and gathering
(20)wild plants, Increasing predictability of food supplies may have been a motive. It has been suggested that some early cultivation was for medicinal and ceremonial plants rather than
for food. One archaeologist has pointed out that the early domesticated plants were all
weedy species that do well in open, disturbed habitats, the kind that would form around
human settlements where people cut down trees, trample the ground, deposit trash, and
(25)dig holes. It has been suggested that sunflower, sumpweed, and other plants almost
domesticated themselves, that is , they thrived in human –disturbed habitats, so humans intensively collected them and began to control their distribution. Women in the Archaic communities were probably the main experimenters with cultivation, because
ethnoarchaeological evidence tells us that women were the main collectors of plant food
and had detailed knowledge of plants.
【題組】10. The passage mainly discusses which of the following aspects of the life of Archaic peoples?
(A) The principal sources of food that made up their diet
(B) Their development of ground stone tool technology
(C) Their development of agriculture
(D) Their distribution of work between men and women
12.【題組】12 According to the passage, when did the domestication of plants begin in North America?
(A) 7,000 years ago
(B) 4,000 to 2,000 years ago
(C) Long after the Neolithic period
(D) Before the Archaic period
14.【題組】14. According to the passage, which of the following was a possible motive for the cultivation of plants in eastern North America?
(A) Lack of enough wild food sources
(B) The need to keep trees from growing close to settlements
(C) Provision of work for an increasing population
Desire for the consistent availability of food
16.【題組】16. The plant “sumpweed” is mentioned in line 25 in order to
(A) contrast a plant with high nutritional value with one with little nutritional value
(B) explain the medicinal use of a plant
(C) clarify which plants grew better in places where trees were not cut down
(D) provide an example of a plant that was easy to domesticate
18.【題組】18. According to the passage, which of the following is true about all early domesticated plants?
(A) They were varieties of weeds.
(B) They were moved from disturbed areas.
(C) They succeeded in areas with many trees.
(D) They failed to grow in trampled or damaged areas.
Many ants forage across the countryside in large numbers and undertake mass
migrations; these activities proceed because one ant lays a trail on the ground for the others
to follow. As a worker ant returns home after finding a source of food, it marks the route
by intermittently touching its stinger to the ground and depositing a tiny amount of trail
(5 )pheromone—a mixture of chemicals that delivers diverse messages as the context changes. These trails incorporate no directional information and may be followed by other ants in
Unlike some other messages, such as the one arising from a dead ant, a food trail has to
be kept secret from members of other species. It is not surprising then that ant species use
(10)a wide variety of compounds as trail pheromones. Ants can be extremely sensitive to these signals. Investigators working with the trail pheromone of the leafcutter ant Atta texana calculated that one milligram of this substance would suffice to lead a column of ants three times around Earth.
The vapor of the evaporating pheromone over the trail guides an ant along the way,
(15)and the ant detects this signal with receptors in its antennae. A trail pheromone will
evaporate to furnish the highest concentration of vapor right over the trail, in what is called a vapor space. In following the trail, the ant moves to the right and left, oscillating from side
to side across the line of the trail itself, bringing first one and then the other antenna into
the vapor space. As the ant moves to the right, its left antenna arrives in the vapor space.
(20)The signal it receives causes it to swing to the left, and the ant then pursues this new course
until its right antenna reaches the vapor space. It then swings back to the right, and so
weaves back and forth down the trail.
【題組】20. What does the passage mainly discuss?
(A) The mass migration of ants
(B) How ants mark and follow a chemical trail
(C) Different species of ants around the world
(D) The information contained in pheromones
24.【題組】24. According to the passage, why do ants use different compounds as trail pheromones?
(A) To reduce their sensitivity to some chemicals
(B) To attract different types of ants
(C) To protect their trail from other species
(D) To indicate how far away the food is
25.【題組】25. The author mentions the trail pheromone of the leafcutter ant in line 11 to point out
(A) how little pheromone is needed to mark a trail
(B) the different types of pheromones ants can produce
(C) a type of ant that is common in many parts of the world
(D) that certain ants can produce up to one milligram of pheromone
26.【題組】26. According to the passage, how are ants guided by trail pheromones?
(A) They concentrate on the smell of food.
(B) They follow an ant who is familiar with the trail
(C) They avoid the vapor spaces by moving in a straight line.
(D) They sense the vapor through their antennae.
29.【題組】29. According to the passage, the highest amount of pheromone vapor is found
(A) in the receptors of the ants
(B) just above the trail
(C) in the source of food
(D) under the soil along the trail
Native Americans probably arrived from Asia in successive waves over several
millennia, crossing a plain hundreds of miles wide that now lies inundated by 160 feet
of water released by melting glaciers. For several periods of time, the first beginning
around 60,000 B.C. and the last ending around 7,000 B.C., this land bridge was open. The
(5 )first people traveled in the dusty trails of the animals they hunted. They brought with them
not only their families, weapons, and tools but also a broad metaphysical understanding,
sprung from dreams and visions and articulated in myth and song, which complemented
their scientific and historical knowledge of the lives of animals and of people. All this they
shaped in a variety of languages, bringing into being oral literatures of power and beauty.
(10) Contemporary readers, forgetting the origins of western epic, lyric, and dramatic
forms, are easily disposed to think of “literature” only as something written. But on
reflection it becomes clear that the more critically useful as well as the more frequently employed sense of the term concerns the artfulness of the verbal creation, not its mode of presentation. Ultimately, literature is aesthetically valued, regardless of language, culture,
(15)or mode of presentation, because some significant verbal achievement results from the
struggle in words between tradition and talent. Verbal art has the ability to shape out a compelling inner vision in some skillfully crafted public verbal form.
Of course, the differences between the written and oral modes of expression are not without consequences for an understanding of Native American literature. The essential
(20)difference is that a speech event is an evolving communication, an “emergent form,” the shape, functions, and aesthetic values of which become more clearly realized over the
course of the performance. In performing verbal art , the performer assumes responsibility
for the manner as well as the content of the performance, while the audience assumes the responsibility for evaluating the performer’s competence in both areas. It is this intense
(25)mutual engagement that elicits the display of skill and shapes the emerging performance.
Where written literature provides us with a tradition of texts, oral literature offers a
tradition of performances. 【題組】30. According to the passage, why did the first people who came to North America leave their homeland?
(A) They were hoping to find a better climate.
(B) They were seeking freedom.
(C) They were following instructions given in a dream.
(D) They were looking for food.
34.【題組】34. What is the main point of the second paragraph?
(A) Public performance is essential to verbal art.
(B) Oral narratives are a valid form of literature.
(C) Native Americans have a strong oral tradition in art.
(D) The production of literature provides employment for many artists.
35.【題組】35. What can be inferred about the nature of the Native American literature discussed in the passage?
(A) It reflects historical and contemporary life in Asia.
(B) Its main focus is on daily activities.
(C) It is based primarily on scientific knowledge.
(D) It is reshaped each time it is experienced.
36.【題組】36. According to the passage, what responsibility does the audience of a verbal art performance have ?
(A) They provide financial support for performances.
(B) They judge the quality of the content and presentation.
(C) They participate in the performance by chanting responses.
(D) They determine the length of the performance by requesting a continuation.
37.【題組】37. Which of the following is NOT true of the Native American literature discussed in the passage?
(A) It involves acting.
(B) It has ancient origins.
(C) It has a set form.
(D) It expresses an inner vision.
38.【題組】38. What can be inferred from the passage about the difference between written and oral literature?
(A) Written literature reflects social values better than oral literature does.
(B) Written literature involves less interaction between audience and creator during the creative progress than oral literature does.
(C) Written literature usually is not based on historical events, whereas oral literature is.
(D) Written literature is not as highly respected as oral literature is.
39.【題組】39. What is the author’s attitude toward Native American literature?
(A) Admiring of its form
(B) Critical of the cost of its production
(C) Amused by its content
(D) Skeptical about its origins
The cities in the United States have been the most visible sponsors and beneficiaries
of projects that place art in public places. They have shown exceptional imagination in
applying the diverse forms of contemporary art to a wide variety of purposes. The
activities observed in a number of “pioneer” cities sponsoring art in public places—a
(5 ) broadening exploration of public sites, an increasing awareness among both sponsors
and the public of the varieties of contemporary artistic practice, and a growing public enthusiasm—are increasingly characteristic of cities across the country. With many
cities now undergoing renewed development, opportunities are continuously emerging
for the inclusion or art in new or renewed public environments, including buildings,
(10)plazas, parks, and transportation facilities. The result of these activities is a group of
artworks that reflect the diversity of contemporary art and the varying character and
goals of the sponsoring communities.
In sculpture, the projects range from a cartoonlike Mermaid in Miami Beach by
Roy Lichtenstein to a small forest planted in New York City by Alan Sonfist. The use
(15) of murals followed quickly upon the use of sculpture and has brought to public sites the
work of artists as different as the realist Thomas Hart Benton and the Pop artist Robert Rauschenberg. The specialized requirements of particular urban situations have further expanded the use of art in public places: in Memphis, sculptor Richard Hunt has created
a monument to Martin Luther King, Jr., who was slain there; in New York, Dan Flavin
(20) and Bill Brand have contributed neon and animation works to the enhancement of mass
transit facilities. And in numerous cities, art is being raised as a symbol of the
commitment to revitalize urban areas.
By continuing to sponsor projects involving a growing body of art in public places,
cities will certainly enlarge the situations in which the public encounters and grows
(25)familiar with the various forms of contemporary art. Indeed, cities are providing artists
with an opportunity to communicate with a new and broader audience. Artists are
recognizing the distinction between public and private spaces, and taking that into account
when executing their public commissions. They are working in new, often more durable
media, and on an unaccustomed scale.
【題組】40. What is the passage mainly about?
(A) The influence of art on urban architecture in United States cities
(B) The growth of public art in United States cities.
(C) The increase in public appreciation of art in the United States
(D) The differences between public art in Europe and the United States.
42.【題組】42. All of the following are mentioned in paragraph 1 as results of the trend toward installing contemporary art in public places in the United States EXCEPT
(A) the transfer of artwork from private to public sites
(B) artworks that represent a city’s special character
(C) greater interest in art by the American public
(D) a broader understanding of the varieties of contemporary art
43.【題組】43. According to the passage, new settings for public art are appearing as a result of
(A) communities that are building more art museums
(B) artists who are moving to urban areas
(C) urban development and renewal
(D) an increase in the number of artists in the United States.
44.【題組】44.The author mentions Roy Lichtenstein and Alan Sonfist in line 14 in order to
(A) show that certain artist are famous mostly for their public art
(B) introduce the subject of unusual works of art
(C) demonstrate the diversity of artworks displayed in public
(D) contrast the cities of Miami Beach and New York
45.【題組】45.It can be inferred from the passage that the city of Memphis sponsored a work by Richard Hunt because the city authorities believed that
(A) the sculpture would symbolize the urban renewal of Memphis
(B) Memphis was an appropriate place for a memorial to Martin Luther Ling, Jr.
(C) the artwork would promote Memphis as a center for the arts
(D) the sculpture would provide a positive example to other artists.
50.【題組】50. According to paragraph 3, artists who work on public art projects are doing all of the following EXCEPT
(A) creating artworks that are unusual in size
(B) raising funds to sponsor various public projects
(C) exposing a large number of people to works of art
(D) using new materials that are long—lasting. | 0.910652 | 3.975514 |
NASA recently announced a pair of new space missions to explore questions about the earliest stages of our solar system. One of the missions, Psyche, will send an unmanned spacecraft to 16 Psyche, a large asteroid in the primary asteroid belt between Mars and Jupiter.
Arizona State University is the lead institution for the mission. The spacecraft, to be built by NASA’s Jet Propulsion Laboratory, is scheduled to launch in 2023 and arrive at the asteroid in 2030.
David Bercovici, Yale’s Frederick William Beinecke Professor of Geophysics, is a co-investigator for the project. Part of his role will be to study the internal dynamics of 16 Psyche.
“Psyche is almost certainly an iron-nickel alloy asteroid, possibly formed after a larger body, like a dwarf planet, had its mantle stripped away from a violent collision with another asteroid. So, Psyche is probably the exposed core of a small planet,” Bercovici said.
Earth’s core is 3,000 km away, and harder to observe than distant galaxies, Bercovici explained. We can only “see” it through seismology after large earthquakes send seismic waves through and around the core. But Earth’s core is important, he explains, because it generates the planet’s magnetic field, which, with a compass, can be used to navigate, and which protects us from charged solar radiation.
“Thus, the incredible thing about this mission is that, in a way, we’re going through space to learn about the core of our own planet,” Bercovici said. | 0.842479 | 3.424104 |
A new study provides “incontrovertible evidence” that the volcanic super-eruption of Toba on the island of Sumatra about 73,000 years ago deforested much of central India, some 3,000 miles from the epicenter, researchers report.
The volcano ejected an estimated 800 cubic kilometers of ash into the atmosphere, leaving a crater (now the world’s largest volcanic lake) that is 100 kilometers long and 35 kilometers wide. Ash from the event has been found in India, the Indian Ocean, the Bay of Bengal and the South China Sea.
The bright ash reflected sunlight off the landscape, and volcanic sulfur aerosols impeded solar radiation for six years, initiating an “Instant Ice Age” that — according to evidence in ice cores taken in Greenland — lasted about 1,800 years.
During this instant ice age, temperatures dropped by as much as 16 degrees centigrade (28 degrees Fahrenheit), said University of Illinois anthropology professor Stanley Ambrose, a principal investigator on the new study with professor Martin A.J. Williams, of the University of Adelaide. Williams, who discovered a layer of Toba ash in central India in 1980, led the research.
The climactic effects of Toba have been a source of controversy for years, as is its impact on human populations.
In 1998, Ambrose proposed in the Journal of Human Evolution that the effects of the Toba eruption and the Ice Age that followed could explain the apparent bottleneck in human populations that geneticists believe occurred between 50,000 and 100,000 years ago. The lack of genetic diversity among humans alive today suggests that during this time period humans came very close to becoming extinct.
To address the limited evidence of the terrestrial effects of Toba, Ambrose and his colleagues pursued two lines of research: They analyzed pollen from a marine core in the Bay of Bengal that included a layer of ash from the Toba eruption, and they looked at carbon isotope ratios in fossil soil carbonates taken from directly above and below the Toba ash in three locations in central India.
Carbon isotopes reflect the type of vegetation that existed at a given locale and time. Heavily forested regions leave carbon isotope fingerprints that are distinct from those of grasses or grassy woodlands.
Both lines of evidence revealed a distinct change in the type of vegetation in India immediately after the Toba eruption, the researchers report. The pollen analysis indicated a shift to a “more open vegetation cover and reduced representation of ferns, particularly in the first 5 to 7 centimeters above the Toba ash,” they wrote in the journal Palaeogeography, Palaeoclimatology, Palaeoecology. The change in vegetation and the loss of ferns, which grow best in humid conditions, they wrote, “would suggest significantly drier conditions in this region for at least one thousand years after the Toba eruption.”
The dryness probably also indicates a drop in temperature, Ambrose said, “because when you turn down the temperature you also turn down the rainfall.”
The carbon isotope analysis showed that forests covered central India when the eruption occurred, but wooded to open grassland predominated for at least 1,000 years after the eruption.
“This is unambiguous evidence that Toba caused deforestation in the tropics for a long time,” Ambrose said. This disaster may have forced the ancestors of modern humans to adopt new cooperative strategies for survival that eventually permitted them to replace neandertals and other archaic human species, he said.
Merdeka.com-Village Sitoluama, district Laguboti, Toba Samosir Regency, North Sumatra, restless with unusual occurrences. The soil on the side of the House residents put out hot steam like gas and pungent-smelling.
The alleged harmful vapors showed up on Wednesday (27/5), the right side of the home page of Purasa, about ten kilometers from the Capital town of Balige, Toba Samosir Regency.
“Hot steam like gas and pungent smells coming out of the pores of the soil it is feared to threaten the safety of local people, so we report it to the authorities,” said one resident, Purasa Silalahi on Sitoluama, Saturday (30/5).
Indeed, advanced Purasa, since three weeks the temperature around her very hot, good day or night. In fact, any House floor ceramic tile feels hot.
Feeling suspicious, the conditions he intends to dig into the ground next to his house as deep as 50 centimeters and turns to steam heat with a temperature of smoke had emerged from the pit quarry. Due to fear of minerals with the condition that he immediately covered pit again.
“Hot steam and smells made us feel afraid of the gas that can be burned, so these findings are reported directly to the head of a local village,” explains Purasa.
The village chief Sitoluama, Moppo Old Pangaribuan said, hot steam that is troubling the citizens it has reported to the environmental protection agency of Toba Samosir.
The use, on its territory there has been research on 20 years ago and there is a sign or a PIN that there is oil in the area.
“First there was the research in this area. But the results to date there has been no certainty and now all of a sudden appear in the form of gas. We hope relevant agencies can examine repeated for convenience of society, “said Mappo.
Meanwhile, the Head of the environmental agency of Toba Samosir, Parulian Siregar said, his side has continued to report the discovery of the citizens over the discovery of the hot steam that is troubling.
“We tried to coordinate with the Central Department of mines and energy of North Sumatra as well as the relevant parties to know for sure the source of steam, including handling solutions,” Parulian said.
A supervolcanic eruption thought to have nearly driven humanity extinct may not have endangered the species after all, a new investigation suggests.
Supervolcanoes are capable of eruptions dwarfing anything ever seen in recorded history, expelling thousands of times more magma and ash than even a Mount St. Helens or Pinatubo. A supervolcanic eruption could wreak as much havoc as the impact of a mile-wide asteroid,by blotting out the sun with ash, reflecting its rays and cooling the Earth — a phenomenon called a “volcanic winter.” A dozen or so supervolcanoes exist today, some of them lying at the bottom of the sea.
The largest supervolcano eruption of the past 2.5 million years was a series of explosions of Mount Toba on the Indonesian island of Sumatra about 75,000 years ago. Researchers say Toba spewed out a staggering 700 cubic miles (2,800 cubic kilometers) of magma, equivalent in mass to more than 19 million Empire State Buildings. By comparison, the infamous blast from the volcanic Indonesian island of Krakatoa in 1883, one of the largest eruptions in recorded history, released about 3 cubic miles (12 cubic km) of magma.
About the same time the eruption took place, the number of modern humans apparently dropped cataclysmically, as shown by genetic research. People today evolved from the few thousand survivors of whatever befell humans in Africa at the time. The giant plume of ash from Toba stretched from the South China Sea to the Arabian Sea, and in the past investigators proposed the resulting volcanic winter might have caused this die-off. [Countdown: History’s Most Destructive Volcanoes]
However, recently scientists have suggested that Toba did not sway the course of human history as much as previously thought. For instance, prehistoric artifacts discovered in India and dating from after the eruption hinted that people coped fairly well with any effects of the eruption.
Now researchers have found that the evidence shows Toba didn’t actually cause a volcanic winter in East Africa where humans dwelled.
“We have been able to show that the largest volcanic eruption of the last two million years did not significantly alter the climate of East Africa,” said researcher Christine Lane, a geologist at the University of Oxford.
Ash in Africa
Lane and her colleagues examined ash from Toba recovered from mud extracted from two sites at the bottom of Lake Malawi, the second largest lake in the East African Rift Valley.
“We first started looking for the Toba ash a few years back, but it’s a bit like looking for a needle in a haystack, so it took a while,” Lane told OurAmazingPlanet. “Between myself and my co-author Ben Chorn, we systematically processed every centimeter of sediment between 24 to 46 meters [78 to 150 feet] depth in the central basin core. The layer is so small that if we leave any gaps in our search, we could miss it completely.”
Their analysis discovered that a thin layer of ash in this sediment about 90 feet (27 m) below the lake floor was from the last of the Toba eruptions, known as Youngest Toba Tuff.
“The Toba super-eruption dispersed huge volumes of ash across much of the Indian Ocean, Indian Peninsula and South China Sea,” Lane said. “We have discovered the layer of volcanic ash was carried about twice the distance as previously thought, over more than 7,000 kilometers [4,350 miles].”
The amount of ash found in the Malawi sediment core (a cylindrical log of sediment drilled from the ground), was more than the scientists expected to find.
“I was surprised to find so much ash in the Lake Malawi record,” Lane added. “The ash is very tiny, composed of shards of volcanic glass smaller than the diameter of a human hair. Nevertheless, in a lot of records I have worked on previously, even within just a few hundreds of miles of an eruption center, we sometimes only find less than 100 shards of glass within a gram of sediment. In Malawi, we have thousands of shards of glass per gram, which really shows how voluminous the Youngest Toba Tuff was.”
If the area had seen dramatic cooling because of all the ash spewed into the atmosphere, living matter near the lake surface would likely have died off, significantly altering the composition of the lake’s mud. However, when the researchers investigated algae and other organic matter from the layer that contained the ash from Toba, they saw no evidence of a significant temperature drop in East Africa. Apparently, “the environment very quickly recovered from any atmospheric disturbance that may have occurred,” Lane said.
But these results, detailed online April 29 in the journal Proceedings of the National Academy of Sciences, don’t mean that super-eruptions aren’t as big a risk to Earth’s denizens as previously suggested.
“It is important to realize that every volcanic eruption is different and the Youngest Toba Tuff provides only one example,” Lane said. “The impact of an eruption depends not just on the amount of ash erupted, but also the composition and volume of aerosols, how high in the atmosphere the ash is injected and the meteorological conditions at the time.”
As for what might explain the near-extinction humanity apparently once experienced, perhaps another kind of catastrophe, such as disease, hit the species. It may also be possible that such a disaster never happened in the first place — genetic research suggests modern humans descend from a single population of a few thousand survivors of a calamity, but another possible explanation is that modern humans descend from a few groups that left Africa at different times.
Future research will analyze what effects Toba may or may not have had on other lakes in East Africa.
“Whilst from this we can hypothesize that the global climatic impact was not as dramatic as some have suggested, we will need to find similarly high-resolution records of past climate from other regions that also contain Youngest Toba Tuff in order to definitively test this,” Lane said. | 0.826995 | 3.178985 |
Photomicrograph of particles from red rain sample
Red Rain in Kerala, India
From 25 July to 23 September 2001, red rain sporadically fell on the southern Indian state of Kerala. Heavy downpours occurred in which the rain was coloured red, staining clothes with an appearance similar to that of blood. Yellow, green, and black rain was also reported. Coloured rain had been reported in Kerala in as early as 1896 and several times since then.
It was initially announced that the rains were coloured by fallout from a hypothetical meteor burst, but a study commissioned by the Government of India found that the rains had been coloured by airborne spores from a locally prolific terrestrial alga. Other explanations were proposed but not until early 2006 did the coloured rains of Kerala gain widespread attention in the popular media. A controversial conjecture that the coloured particles were extraterrestrial cells was proposed by Godfrey Louis and Santhosh Kumar of the Mahatma Gandhi University in Kottayam. No information to support the extraterrestrial hypothesis has been published since 2006. - Wikipedia
the red rain of Kerala
Authors: Godfrey Louis, A. Santhosh Kumar
(Submitted on 5 Oct 2003)
Abstract: Red coloured rain occurred in many places of Kerala in India during July to September 2001 due to the mixing of huge quantity of microscopic red cells in the rainwater. Considering its correlation with a meteor airbust event, this phenomenon raised an extraordinary question whether the cells are extraterrestrial. Here we show how the observed features of the red rain phenomenon can be explained by considering the fragmentation and atmospheric disintegration of a fragile cometary body that presumably contains a dense collection of red cells. Slow settling of cells in the stratosphere explains the continuation of the phenomenon for two months. The red cells under study appear to be the resting spores of an extremophilic microorganism. Possible presence of these cells in the interstellar clouds is speculated from its similarity in UV absorption with the 217.5 nm UV extinction feature of interstellar clouds.
Comments: 20 pages, 5 figures,
paper to be submitted
Red rain collected in buckets
Between July and September of 2001, a phenomenon occurred in India that, to this day, has not been positively explained. The ‘Red Rain of Kerala’ has become one of the most discussed anomalies of recent years and, for some, its occurrence proves that we are not alone in the universe.
The red rain first fell on the Kottayam and Idukki districts of Kerala on July 25th, 2001 and the downpours were most intense during the first ten days, growing less frequent over the following eight weeks. Locals were baffled by the red staining they found on their clothes and linen and buckets, pails and bowls collected more of the coloured water. Some other hues were reported, but the scarlet tint was most prevalent. Strangely, the red rain fell in very localised areas, with normal rain falling only a few metres from where the coloured water was collected.
According to early eyewitnesses, the first red rain was preceded by a thunderclap and a bright flash in the sky. This led some to conclude that the staining was caused by dust from a high altitude meteorite burst over the region.
As the phenomenon diminished, Kerala’s red rain became just another mystery to file away. Indeed, a report from the Centre for Earth Science Studies (CESS) and the Tropical Botanical Garden and Research Institute (TBGRI) in Kerala concluded that the cause of the red rain were algal spores from local trees. The report determined that there was no volcanic, desert or meteoric dust in the rain and that no pollutants or gases had caused the odd colouring. What was not explained was why the rain fell in such localised areas, nor why the cells that were analysed contained high concentrations of aluminium and low amounts of phosphorous. Aluminium is not usually found in biological cells and phosphorous is normally found in much higher quantities.
The mystery really exploded onto the world scene in April, 2006, when Dr Godfrey Louis and his research student, A. Santhosh Kumar, published a report in the Astrophysics and Space Science journal, suggesting that the red particles were microbial, extra-terrestrial organisms. They proposed that a meteorite exploded high over Kerala, releasing in excess of 50,000kg of the alien microbes over the region. Slowly, the alien cells drifted down over the followring two months, explaining the high concentrations at the beginning of the incident that diminished over time. Unfortunately, however, no meteoric or cometary dust has been found in the samples taken from Kerala.
Tests on the cells by Louis’ team found that no DNA could be found, something unheard of in terrestrial biological organisms. Recent studies by Professor Chandra Wickramasinghe of Cardiff University have yielded positive results for DNA in the cells, but the mystery does not stop there.
Experiments in the laboratory have shown that the cells can reproduce in water heated to nearly 600?F (300?C). All known earthly microbes are killed when heated to only 250?F (130?C).
So what do we have here? Are the cells found in the Kerala red rain terrestrial spores of a previously unknown type, that sometimes defy attempts to locate DNA in its structure, that can reproduce at temperatures that would kill any known microbe or bacteria, that contain high concentrations of aluminium and low levels of phosphorous (in direct oppositions to all earth-based life). Are the cells really only hardy algae spores that are common in Kerala, as the first official report suggested?
Or is what fell on that Indian province five years ago the first definite proof that life exists in the depths of space and sometimes finds its way to Earth?
It seems that the scientific community is divided on this one…
© Steve Johnson - 2006
Small bottles like the ones shown
above can store a variety of liquids, from scientific water samples to
homemade essential oils. Finding the perfect essential oil bottles for a
specific formula can be tricky, but there is a large selection of essential oil bottles wholesale to choose from online.
The coloured rain of Kerala began falling on 25 July 2001, in the districts of Kottayam and Idukki in the southern part of the state. Yellow, green, and black rain was also reported. Many more occurrences of the red rain were reported over the following ten days, and then with diminishing frequency until late September. According to locals, the first coloured rain was preceded by a loud thunderclap and flash of light, and followed by groves of trees shedding shrivelled grey "burnt" leaves. Shrivelled leaves and the disappearance and sudden formation of wells were also reported around the same time in the area. It typically fell over small areas, no more than a few square kilometres in size, and was sometimes so localised that normal rain could be falling just a few metres away from the red rain. Red rainfalls typically lasted less than 20 minutes. Each millilitre of rain water contained about 9 million red particles, and each litre of rainwater was contained approximately 100 milligrams of solids. Extrapolating these figures to the total amount of red rain estimated to have fallen, it was estimated 50,000 kilograms of red particles had fallen on Kerala.
Description of the particles
The brownish-red solid separated from the red rain consisted of about 90% round red particles and the balance consisted of protozoans and debris. The particles in suspension in the rain water were responsible for the colour of the rain, which at times was as strongly coloured as blood. A small percentage of particles were white or had light yellow, bluish gray and green tints. The particles were typically 4 to 10 µm across and spherical or oval. Louis's images with a scanning electron microscope showed the particles as having a depressed centre, suggestive of biological cell, especially red blood cells. At still higher magnification some particles showed internal structures. - Wikipedia
purportedly showing a detached inner capsule. Source: CCAB, Cardiff University
Initially the Centre for Earth Science Studies (CESS) had said that the cause of the red rain was an exploding meteor, which had dispersed about 1,000 kg (around one ton) of material. A few days later, when the red rain continued to fall, CESS retracted this. (Debris from a meteor would not have continued to fall in the same area; it would have been dispersed by winds.) CESS and the Tropical Botanical Garden and Research Institute (TBGRI) jointly issued a statement that the particles colouring the rainwater were some type of spore. Then in November of 2001, commissioned by the Government of India's Department of Science & Technology, the CESS and TBGRI released a report which concluded that:
The colour was found to be due to the presence of a large amount of spores of a lichen-forming alga belonging to the genus Trentepohlia. Field verification showed that the region had plenty of lichens. Samples of lichen taken from Changanacherry, when cultured in an algal medium, also showed the presence of the same species of algae. Both samples (from rainwater and from trees) produced the same kind of algae, indicating that the spores seen in the rainwater could most probably have come from local sources.
Although red or orange, Trentepohlia is a Chlorophyte green alga which can grow abundantly on tree bark or damp soil and rocks, but is also the photosynthetic symbiont or photobiont of many lichens, including some of those abundant on the trees in Changanacherry area.
The report also stated that there was no dust of meteoric, volcanic, or desert origin present in the rainwater, and that the colour of the rainwater was not due to any dissolved gases or pollutants. The report concluded that heavy rains in Kerala in the weeks preceding the red rains could have caused the widespread growth of lichens, which had given rise to a large quantity of spores in the atmosphere.
However, it could find no satisfactory explanation for the apparently extraordinary dispersal, nor for the uptake of the spores into clouds. It noted, for example, that prior to the first red rainfall there had been almost continuous rain for a period of eight hours. CESS responded ‘‘While the cause of the colour in the rainfall has been identified, finding the answers to these questions is a challenge.’’
Parts of the CESS/TBGRI report were
supported by Milton
Wainwright at Sheffield University, who, together
with Chandra Wickramasinghe,
has studied stratospheric spores. In March 2006 he
said the particles were
similar in appearance to spores of a rust fungus,
later saying that he
had confirmed their similarity to spores or algae,
and found no evidence
to suggest that the rain contained dust, sand, fat
globules, or blood.
Frames (1) and (2) show the microscopic spores that colored the Keralan rains; (3) rain samples with
(a) spores settled to the bottom, (b) rainwater evaporated, and (c) spores suspended in the rainwater;
(4) Trentepohlia algae grown from the spores.
In 2003 Louis and Kumar, physicists at Mahatma Gandhi University in Kottayam, Kerala, posted an article entitled “Cometary panspermia explains the red rain of Kerala” in the on-line, non-peer reviewed arXiv web site. While the CESS report said there was no apparent relationship between the loud sound (possibly a sonic boom) and flash of light which preceded the red rain, to Louis and Kumar it was a key piece of evidence. They proposed that a meteor (from a comet containing the red particles) caused the sound and flash and when it disintegrated over Kerala it released the red particles which slowly fell to the ground. Their work indicated that the particles were of biological origin (consistent with the CESS report), not inorganic material and they invoked the panspermia hypothesis to explain the presence of cells in a supposed fall of meteoric material. Additionally, using ethidium bromide they were unable to detect DNA or RNA in the particles. Two months later they posted another paper on the same site entitled “New biology of red rain extremophiles prove cometary panspermia” in which they reported that
The microorganism isolated from the red rain of Kerala shows very extraordinary characteristics like ability to grow optimally at 300°C (572°F) and the capacity to metabolize a wide range of organic and inorganic materials.
These claims and data have yet to be reported in any peer reviewed publication. In 2006 they published a paper in Astrophysics and Space Science entitled "The red rain phenomenon of Kerala and its possible extraterrestrial origin" which reiterated their hypothesis that the red rain was biological matter from an extraterrestrial source but made no mention of their claims to having induced the cells to grow. One of their conclusions was:
If the red rain particles are biological cells and are of cometary origin, then this phenomena can be a case of cometary panspermia.
Panspermia is the hypothesis that
life on Earth was
carried here from elsewhere in the universe. Fred
Hoyle and Chandra Wickramasinghe
have been among the proponents of the theory, but it
has not been accepted
by most mainstream scientists. The paper in
Astrophysics and Space Science
prompted numerous articles in the popular media.
A quotation attributed to Carl Sagan that "Extraordinary claims require extraordinary evidence" is often used regarding the claims of alien life.
Samples of the red particles were also sent for analysis to Milton Wainwright at Sheffield University and Chandra Wickramasinghe at Cardiff University. Wickramasinghe has reported on December, 2006 that “work in progress has yielded positive for DNA”, but the results have not yet been confirmed. The absence of DNA is key to Louis and Kumar's hypothesis that the cells were of extraterrestrial origins.
Wainwright is quoted as saying:
“There appears to be an increasing tendency among scientists to come up with wild explanations when asked by the press to comment on unusual, novel phenomena. A good example is provided by comments about the recent Indian red rain phenomenon."
A correction was printed in The Observer regarding Dr. Wainwright's comment that the red rain lacked DNA. Dr. Wainwright asked in the correction to make clear that he currently had no view on whether the samples contained genetic material or not, and that it was physicist Godfrey Louis who held that view. The controversial research of Louis et al. is the only evidence suggesting that these organisms are of extraterrestrial origin.
Sainudeen Pattazh came to the conclusion that, "Regarding red rain, there was an argument that it was alien presence. But that’s just like science fiction. During 2001-02, [a] peculiar geological situation was prevailing in Kerala like caving in of wells and landslides.”
A study has been published showing a correlation between historic reports of colored rains and of meteors. In an interview The author of the paper, Patrick McCafferty, said:
"Sixty of these events (coloured rain), or 36 percent, “were linked to meteoritic or cometary activity,” he went on. But not always strongly. Sometimes, “the fall of red rain seems to have occurred after an airburst,” as from a meteor exploding in air; other times the odd rainfall “is merely recorded in the same year as a stone-fall or the appearance of a comet.” - Wikipedia
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In November of this year, the EPOXI mission spacecraft will make a close flyby of comet Hartley 2, also known as 103/P Hartley. The EPOXI name is a combination of EPOCH (Extrasolar Planet Observation and Characterization) and DIXI (Deep Impact eXtended Investigation). The goal of this flyby is to gather data that will help us understand the structure, formation and composition history of cometary nuclei. This information is important as it relates directly to our increasing understanding of the origin of our solar system.
This comet is predicted to reach naked eye brightness in late October, perhaps as bright as magnitude 5. Last night night I decided to see if I could spot the comet in the LX200 12" SCT as it is currently well placed in the constellation Lacerta. I had downloaded ephemerides for this comet from the IAU (International Astronomical Union) Minor Planet Center which indicated that the comet may currently be as bright as magnitude 8.5. I was a bit skeptical as I had "googled" this comet and there are not many amateur images out there, suggesting that it is not exactly an interesting target...yet. Gary Kronk maintains an excellent site called Cometography and there is information on this comet as well as a couple of images if you are interested.
After spending some time on the comet I decided to have a look at NGC 40, a planetary nebula in Cepheus, also known as Caldwell 2. Since I installed the 12" SCT I have been having fun observing planetary nebulas looking for features that were not visible to me with my previously smaller telescopes. NGC 40 is a wonderful target, one that deserves more popularity. The 11.6 magnitude central star is visible in most telescopes, and it is surrounded with a large circular shell of nebulosity. As you know from previous posts, planetary nebula often hold up to greater magnifications without breaking down as other targets do, and NGC 40 was no exception. I observed NGC 40 using an 8mm Ethos eyepiece, which in the 12" results in a magnification of 381x and a field of view of .3 degrees.
You can see in the sketch that at high power the nebula is no longer a neat circular haze, rather it has bright arcs on both the east and west sides. The arc on the west is the brighter of the two, and it seems to arc away from the nebula to the south in a manner reminiscent of a galactic spiral arm. This planetary nebula is approximately 3500 light years away and spans a diameter of 38 arcseconds. If you have never observed this target, it is highly recommended. | 0.880912 | 3.805561 |
The discovery marks the first time that an atmosphere has been found around another Earth-like planet
Scientists have found a planet that looks like Earth – and, for the first time, has its own hazy atmosphere.
The discovery represents a major leap forward in the hunt for a planet like our own that could support alien life.
The planet, which is 39 light years from us, has a hazy atmosphere that could have a “water world” beneath it, scientists say.
While the planet isn’t likely to be habitable, it suggests that there might be more planets out there with the kind of atmosphere that could support life. Until now, scientists have only been able to see giant “hot Jupiter” planets that are too warm to house aliens.
The “super-Earth” planet known as GJ 1132b was observed as it passed in front of a cool red dwarf star, blocking out some of the star’s light.
By measuring the slight drop in the star’s brightness, astronomers were able to work out that the planet was 1.4 times the size of Earth.
They also found that in one light wavelength band, the planet looked slightly bigger. This could be explained by an atmosphere that was opaque to some light wavelengths, but transparent to others.
“The detection of an atmosphere around the super-Earth GJ 1132b marks the first time that an atmosphere has been detected around an Earth-like planet other than Earth itself.
“With this research, we have taken the first tentative step into studying the atmospheres of smaller, Earth-like planets. We simulated a range of possible atmospheres for this planet, finding that those rich in water and/or methane would explain the observations of GJ 1132b.
“The planet is significantly hotter and a bit larger than Earth, so one possibility is that it is a ‘water world’ with an atmosphere of hot steam.”
Analyzing the chemical composition of exoplanet atmospheres could in future yield tell-tale signs of life.
Ozone, derived from oxygen released by plants, is one atmospheric life marker. Methane is another, although it can also be generated by volcanic activity.
US planetary scientist Dr Sara Seager, from the Massachusetts Institute of Technology, has compiled a list of 14,000 different molecules that could provide biosignatures of life on alien worlds.
The American space agency Nasa’s new James Webb Space Telescope (JWST), due to be launched next year as a successor to the Hubble Space Telescope, will be powerful enough to begin studying the atmospheres of Earth-like exoplanets.
There are also proposals for an even bigger High Definition Space Telescope (HDST), with a 40ft-wide mirror twice as large as the one carried by the JWST. It would directly image planets in nearby star systems and search for the fingerprints of life in their atmospheres.
The HDST, likely to be a multibillion-pound international project, is not expected to be launched until the 2030s. | 0.833964 | 3.696287 |
James A. Van Allen, Discoverer of Earth-Circling Radiation Belts, Is Dead at 91
By WALTER SULLIVAN
Published: August 10, 2006
James A. Van Allen, the physicist who made the first major scientific discovery of the early space age, the Earth-circling radiation belts that bear his name, and sent spacecraft instruments to observe the outer reaches of the solar system, died yesterday in Iowa City. He was 91.
The cause was heart failure, family members said. Dr. Van Allen was a longtime professor of physics and astronomy at the University of Iowa, and, with the discovery of the Van Allen belts of intense radiation surrounding Earth, he became a leading figure in the new field of magnetospheric physics, which grew in importance as spacecraft began exploring the planets.
A legendary lecturer and an inspiration to several generations of budding physicists and astronomers, Dr. Van Allen continued to show up at his office-laboratory until a month or so before he died.
Rapid Rise to Acclaim
James Van Allen, an unassuming but resolute investigator of cosmic rays and other space phenomena, literally rocketed to international acclaim with the launching of Explorer 1, the first successful space satellite of the United States.
It was on Jan. 31, 1958, in the early days of the space race between the United States and the Soviet Union and almost four months after the Russians stunned Americans with Sputnik 1. The American Explorer 1 may not have been first in space, but a Geiger counter developed by Dr. Van Allen sent back data of what would become known as the Van Allen radiation belts.
The radiation detector recorded two belts of charged particles trapped by Earth's magnetic field. One belt is 400 to 4,000 miles above the surface, and the other is 9,000 to 15,000 miles above the Equator, curving toward the magnetic poles. Further evidence for the encircling radiation was detected with Dr. Van Allen's instruments carried aloft aboard Explorer 2 and Explorer 3.
In the celebration of the Explorer 1 success, Dr. Van Allen posed for what became an iconic picture of the early days of spaceflight. He is standing with Wernher von Braun, whose team built the rocket, and William H. Pickering, who directed the spacecraft development, all smiling broadly and holding a model of the spacecraft high over their heads. He was the last of the three to die.
For several decades afterward, Dr. Van Allen was a staunch advocate of planetary exploration with robotic spacecraft and a critic of big-budget programs for human space flight. Describing himself as ''a member of the loyal opposition,'' he argued that space science could be done better and less expensively when left to remote-controlled vehicles.
Even before the radiation-belt discovery, Dr. Van Allen was heavily involved in early American rocket research. When, on April 16, 1945, a V-2 rocket captured from the Germans was first sent aloft from the White Sands Proving Ground in New Mexico, it carried Geiger counters provided by Dr. Van Allen. His goal was to record radiation from space before it was altered by passage through the atmosphere. Such ''cosmic rays'' had been his lifelong interest, and it had earlier been discovered that they were more intense in outer space.
It has been said that scientists fall into three categories, thinkers, organizers and doers. Dr. Van Allen was a doer.
He was born on Sept. 7, 1914, in Mount Pleasant, Iowa. A physics professor at Iowa Wesleyan College, near his hometown, recognized the 18-year-old student's skill at tinkering. The professor put him to work, at 35 cents an hour, preparing seismic and magnetic equipment for an expedition to Antarctica.
It was to be led by Adm. Richard E. Byrd with the physics professor, Dr. Thomas Poulter, as second in command. Mr. Van Allen wanted to go, but his family thought him too young. He graduated summa cum laude and went to the State University in Iowa City for his graduate work, receiving a doctorate in 1939.
He worked as a research fellow at the Carnegie Institution of Washington until 1942. He then joined the Navy and worked at the Bureau of Ordnance on the proximity fuse, which was, for the first time, effective against dive bombers. Its strictly kept secret was a tiny radar in the projectile's nose that detonated when it flew past a target. He also served as an assistant staff gunnery officer in the Pacific, winning four combat stars.
At the Johns Hopkins University Applied Physics Laboratory, from 1946 through 1950, he supervised high-altitude research, promoting development of the Aerobee rocket, which while much smaller and cheaper than the V-2, could lift a small payload almost as high.
In 1951, he joined the University of Iowa as a professor and head of the department of physics and astronomy. He and his graduate students developed the ''rockoon,'' a rocket lifted by balloon 10 to 15 miles high, where air pressure was low, then fired to soar as high as 85 miles. From icebreakers he supervised rocket shots near both the north and south geomagnetic poles in the belief that Earth's magnetic field there was channeling cosmic ray particles down into the atmosphere, causing the aurora. Such radiation was confirmed by the rockoons. | 0.827305 | 3.28195 |
Science of atmospheric phenomena with JEM-EUSO
- First Online:
- 982 Downloads
The main goal of the JEM-EUSO experiment is the study of Ultra High Energy Cosmic Rays (UHECR, 1019−1021eV), but the method which will be used (detection of the secondary light emissions induced by cosmic rays in the atmosphere) allows to study other luminous phenomena. The UHECRs will be detected through the measurement of the emission in the range between 290 and 430 m, where some part of Transient Luminous Events (TLEs) emission also appears. This work discusses the possibility of using the JEM-EUSO Telescope to get new scientific results on TLEs. The high time resolution of this instrument allows to observe the evolution of TLEs with great precision just at the moment of their origin. The paper consists of four parts: review of the present knowledge on the TLE, presentation of the results of the simulations of the TLE images in the JEM-EUSO telescope, results of the Russian experiment Tatiana–2 and discussion of the possible progress achievable in this field with JEM-EUSO as well as possible cooperation with other space projects devoted to the study of TLE – TARANIS and ASIM. In atmospheric physics, the study of TLEs became one of the main physical subjects of interest after their discovery in 1989. In the years 1992 – 1994 detection was performed from satellite, aircraft and space shuttle and recently from the International Space Station. These events have short duration (milliseconds) and small scales (km to tens of km) and appear at altitudes 50 – 100 km. Their nature is still not clear and each new experimental data can be useful for a better understanding of these mysterious phenomena.
KeywordsTransient Luminous Events Elves Sprites Jets - Atmospheric phenomena
The Transient Luminous Events are bright, short-lived, atmospheric phenomena occurring above the clouds level, some of them reaching the ionosphere.
The first suggestion on the existence of that kind of phenomena was given by the Scottish physicists C.T.R. Wilson in 1925 , who observed that at a certain altitude above the clouds level the value of the electric field connected to the thunder cloud discharge equals the critical value of the electric field allowing for the conventional breakdown mechanism. This in turn means the production of light.
The wavelengths that these phenomena may produce depend on the composition of the atmosphere above the clouds – mainly Nitrogen – and on the allowed transitions observed in the molecules.
As JEM-EUSO detects wavelengths in the range 290 to 430 nm, we will consider only the second positive line of Nitrogen with possible wavelenghts of 268 – 546 nm. Other lines are either outside the visible spectrum of JEM-EUSO or their intensity is much lower than the second positive line of Nitrogen .
2 JEM-EUSO in the TLE context
2.1 General description
The JEM-EUSO mission is devoted to the observation of Extensive Air Showers (EAS) produced by UHECRs traversing the Earth’s atmosphere from above. For each event, the detector will make accurate measurements of the energy, arrival direction and nature of the primary particle using a target volume far greater than what is achievable from ground . The corresponding increase in statistics will help to clarify the origin and sources of UHECRs as well as to bring new light onto particle physics mechanisms responsible of production, propagation and acceleration.
2.2 The detector
JEM-EUSO will be attached to the Japanese Experiment Module (JEM) of the International Space Station (ISS) at an orbit of 400 km above the surface of the Earth. The JEM-EUSO detecting system consists of a telescope with three Fresnel lenses and a focal surface made of photomultipliers and associated electronics, which converts the photons collected by the lenses into photoelectrons. The focal surface consists of some 3⋅105 pixels, each with an independent read out. The diameter of the telescope aperture is about 2.5 meters. The instrument will work in two modes: the nadir mode and the tilted mode. It is planned to have the detector work in the nadir mode for 2 years and then in the tilted mode for further 3 years. The time unit used for sampling the data is 2.5 microseconds. The field of view (FoV) of the detector is 60∘. The wavelengths measured by the detector may range from 290 to 430 nm. In addition to this main telescope part, the detection system is completed by an Atmospheric Monitoring system consisting of an Infrared Camera and a LIDAR to provide information concerning the cloud top height. A calibration system, which measures the efficiencies of the optics, of the focal surface and the data acquisition system is provided as well.
The photomultipliers of the JEM–EUSO detectors operate correctly with the total charge not exceeding 250 pC per KI per time unit, which, in the case of JEM-EUSO, is 2.5μs, which is assumed to be the Gate Time Unit (GTU). A KI is a 4 by 2 pixels unit. Assuming the 10 % efficiency of the optics and the electronics of the detector, this corresponds to 6.24⋅1015 photoelectrons per KI per second, or 1.56⋅1010 photoelectrons per KI per GTU. If this value is exceeded the voltage on the photomultipliers will be reduced so that the detection system remains safe.
3 Estimation of TLE frequency for JEM–EUSO based on Tatiana–2 experimental data
Tatiana’s UV detectors have no spatial resolution and it is impossible to definitely distinguish types of TLE, to determine their actual size and spatial light emission distribution. However, the collected statistics allows us to estimate the low limit of transient event rate expected for space-borne detectors like JEM–EUSO and its influence on their duty cycle. In the period October 2009 – January 2010 Tatiana–2 detectors orbited the Earth 797 times with 320 hours of operation time in shadowed ”night” part. During these three months 2628 events with NADC > 80 were measured. The data of Tatiana–2 satellite of TLE events is recorded in a digital way and consists of 128 ms oscillograms of ADC code (NADC) and PMT high voltage code (M). ADC code means the signal amplitude and M corresponds to a PMT gain. The average rate of TLE events from this data is 0.13 min−1 or 10−4 hr−1 km−2. The instantaneous frequency of TLE in local thunderstorm area could be significantly higher (∼10−3 hr−1 km−2). It is worth noticing that this number is order of magnitude higher than TLE frequency, measured by ISUAL [12, 13]. It could be explained by the sensitivity of the detector whose instrumental threshold is ∼1020 in photon number. As it was mentioned above, these faint flashes are distributed more evenly in global map. ISUAL can not measure them.
To estimate the number of TLE events which could be measured by JEM-EUSO or influence its operation, we should take into account the ratio of detectors fields of view. Tatiana-2 observed an area of 7⋅104 km2, JEM-EUSO in nadir mode will observe 2⋅105 km2, three times larger than Tatiana–2. It means that JEM-EUSO will measure one UV flash from atmospheric phenomena at least every third minute. In the worst case, when the size of TLE is comparable to JEM-EUSO FoV (for example in case of a large elve) or very intensive TLE which produces a huge amount of light scattered in detectors parts, it can cause a pause in EAS measurements for 70 seconds (it is the most conservative estimation of dead time within which the light source will leave JEM-EUSO FoV). Such dead time is ∼40 % of the duty cycle. This is the upper bound. To obtain more feasible numbers we should take into account energy (number of photons) distribution of observed events.
The typical event measured by Tatiana–2 satellite has about 104 photons per ms in 0.4 cm2 aperture of detector. It means that more than 106 transient photons per GTU (2.5 μs) will come in JEM-EUSO aperture (4.5 m2). The JEM-EUSO optics efficiency (0.4) and the difference between orbit altitude of ISS (≈ 400 km) and Tatiana–2 satellite (≈ 830 km) were taken into account. In these calculations spatial light distribution in transients was not considered. Transient photons may be distributed among many pixels of photo receiver and signal in each pixel could be smaller. Actual size of TLE depends on its type. In case of elves this signal will be distributed among almost all pixels and will give few photoelectrons per GTU. Smaller events will significantly affect the operation of several specific Photo Detector Modules (PDM) and just slightly reduce the FoV.
The rest of the photo detector will be illuminated by diffuse light scattered in the detector (for our estimations we will consider diffuse light as 10 % of the total number of photons per event). Diffuse light gives a signal increase of ≈0.5 photoelectrons per GTU in one pixel. This is a minor addition to background signal which will not influence detector threshold and therefore a duty cycle. The fraction of flashes which produce more than 2 photoelectrons per GTU of scattered light in each pixel is 20 % of all measured by Tatiana–2 satellite. If we consider 70 seconds pause only for these TLE the dead time becomes near 8 %. This number is consistent with other estimations of duty cycle which take into account clouds and thunderstorm regions.
4 Estimation of the TLE light collected by the JEM–EUSO experiment
The most common phenomena are ELVES – Emission of Light and VLF perturbations due to Electromagnetic Pulse Sources . They occur at the lower ionosphere, at altitudes of about 90 km. They are concentric rings of light expanding with speed close to the speed of light. The diameter of the elves disk may range from 200 to 500 km. The whole process of expansion takes up to a millisecond.
The possible mechanism of production of an elve is as follows. Firstly, a strong lightning occurs - which translates into a rapid change in the electric field in the atmosphere. This produces an electromagnetic pulse propagating upwards through the atmosphere and eventually reaches the ionosphere where it causes production of light observed as an elve. To estimate the image viewed by the JEM–EUSO detector while observing an elve example, we have estimated the parameters of the average elve basing our assumptions on the results provided by the ISUAL experiment and presented in . The occurrence rate of the elves is 35 per minute around the world. The spatially averaged brightness of an elve presented in is: 0.17±0.08 MR=1.36⋅1014 ph sr−1 m−2 s−1. The unit R stands for “Rayleigh” (unit of photon flux) typically used for these atmospheric phenomena. We assume an elve with the diameter of 300 km and the timescale of 2 ms = 800 GTU, which should allow for recording of the whole event and the observation directly in the JEM-EUSO detector in the nadir mode. This is the least favorable scenario in the sense that the geometry of the system allows for the maximum amount of light reaching the focal surface of the detector.
With all these assumptions, we get 9.25⋅1011 photons, which is an estimate for the whole event, in all wavelength channels. As elves are ionospheric phenomena, they are mostly red. The contribution of “blue” wavelengths is marginal. If we take 13 % of the obtained photons fitting our wavelength requirements (second positive line of Nitrogen), we will get the estimated number as: 1.2⋅1011 photons. This number of photons will be recorded as a total number by all pixels of the focal surface throughout the duration of the event.
The number of pixels in the JEM-EUSO detector is 315 648, it equals to about 40 000 KIs. The distribution of the photons among the separate KIs has not been considered here. Similarly, the time distribution of the incoming photons has not been taken into account in this work.
Both these factors will reduce the number of photons reaching a KI in one GTU by a few orders of magnitude. It is also important to note that the estimation relates to one such event and not to the total number of photons coming from other sources in the atmosphere. The calculations here presented are based on averaged results, while the most dangerous for the photomultipliers are the extreme cases of events producing light, for which the order of magnitude of the brightness may be a few hundred times greater.
Principal types of TLE in the upper atmosphere
Type of TLEs
Top (>80 km) diffuse Bottom (< 70 km) structured
Top – upward Bottom – downward
Giant Blue jets
Upward within decaying sprite tendrils
Sprites are associated with giant storm clouds with dimensions over 1000 km producing strong electric field in the mesosphere in a volume of over 104 km3. Sprites are massive but weak luminous flashes, appearing at altitudes of 40 – 90 km. The heads of sprites are predominantly red. The brightest region lies in the altitude range 65 – 75 km, above which there is often a faint red glow structure that extends to about 90 km. Below the bright red region, blue tendril-like filamentary structures often extend downward to 40 km. Sprites rarely appear singly, usually occurring in groups – two, three or more. The duration of sprites is of the order of milliseconds. Currents of the lightning strokes associated with sprites reach the intensity of more than 100 kA . The pictures of sprites obtained from the ground and from aircraft show complex structures that assume a variety of forms. Early research reports for these events called them “upward lightning”, “upward discharges”, “cloud – to – stratosphere discharges” and “cloud – to – ionosphere discharges”. Now they are called sprites. The tendril – streamer structure under the upper part of the phenomenon – the so called head of a sprite shows extremely interesting and as yet not fully explained phenomenon of merging streamers, which form bright spherical structures – the beads. Measurements of microsecond time resolution may help to explain the mechanism behind the phenomenon. The brightness measured by ISUAL is 1.5±1.1 MR, which translates into some 3.48⋅1011 ph in total and 1.46⋅1011 in the wavelength region detected by the JEM-EUSO. This number is the spatially integrated amount of photons recorded throughout the whole event duration.
4.3 Other types of TLE
Blue jets are optical ejections from the top of the electrically most active regions of thunderstorms. Following their emergence from the top of the thundercloud, they typically propagate upward in narrow structure in form of cones of about 15 degrees full width at vertical speeds of roughly 100 km/s, fanning out and disappearing at heights of about 40 – 50 km. At the base their diameter is about 400 m. Blue jets are rather rare events. Their appearance rate is much lower than that of sprites. Blue jets are not aligned with the local magnetic field. They are triggered by the electric field inside the cloud. Their appearance is not connected to a cloud–to–ground discharge. The brightness of blue jets is estimated as 0.5 MR .
They are much larger than the Blue Jets. Gigantic Jets originate form the cloud top and develop into a tree-like structure reaching the lower ionosphere. Their propagate upward at the speed of about 100 km/s. The ISUAL measured only 8 such events. The brightest one was 0.8 MR.
5 Conclusions and the future
The frequency of occurrence of the TLE events is large. Their characteristics have been described by different groups working with detectors into orbit and with on ground detecting systems. JEM-EUSO is unique in that its time and spatial resolution is very high and will allow time evolution measurement. Two more experiments dedicated to measuring TLEs will soon be put into orbit: ASIM and Taranis. The set of data produced by all these experiments may create an exceptional chance to further investigate the spatial and time evolution of the TLEs.
The amount of light produced by the two most common types of TLEs does not pose danger to the photomultipliers of the detector. However, these phenomena constitute a significant background to the detection of UHECRs. Many aspects of the detection of the signal from the TLEs remain to be considered in next developments of this work. One interesting path would also be to test the possibility of finding correlations between the occurrence of very energetic particles in the Earth’s atmosphere and the occurrence and magnitude of sprites. These goals are in the reach of the JEM - EUSO mission in space and, thoghether with its unique features above mentioned, they may lead to significant steps forward in the field of Transient Luminous Events research.
This work is supported partially by the grant MNiSW N307065834 and grant NCN 2014/13/B/ST10/01285 and grant of Russian Foundation for Basic Research No. 12-05-31025-mol-a. Authors wish to thank all involved in the preparation and the reviewing process of this paper.
This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution andreproduction in any medium, provided the original author(s) and source are credited.
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Open AccessThis article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and re production in any medium, provided the original author(s) and the source are credited. | 0.818711 | 3.793785 |
Auto-Gopher: Drilling Deep to Explore the Solar System
Technology Development: The ability to penetrate subsurfaces and collect pristine samples from depths of tens of meters to kilometers is critical for future exploration of bodies in our solar system. SMD is supporting development of a deep-drill sampler called the Auto-Gopher for potential deployment in future space exploration missions. The Auto-Gopher employs a piezoelectric actuated percussive mechanism for breaking formations and an electric motor to rotate the drill bit and capture powdered cuttings. It incorporates a wireline architecture; the drill is suspended at the end of a small diameter tether that provides power, communication, as well as structural support needed for lowering and lifting the drill out of the borehole. Thanks to this unique architecture, the maximum drilling depth is limited only by the length of the tether. The wireline operation used on the Auto-Gopher removes one of the major drawbacks of traditional continuous drill string systems—the need for multiple drill sections that can add significantly to the mass and the complexity of a deep drill. As such, the Auto-Gopher system mass and volume can be kept quite low for shallow or deep holes. While drilling, numerous sensors and embedded instruments can perform in situ analysis of the borehole wall. Upon reaching a preset depth, the drill is retracted from the borehole, the core and/or cuttings are removed for detailed analysis by onboard instruments, and the drill is lowered back into the hole to continue the penetration process.
Impact: The Auto-Gopher is intended to help scientists answer one of the most pressing questions in science: Has life ever existed anywhere else in the universe? Since water is a critical prerequisite for life, as we know it, NASA exploration missions are targeting bodies in the solar system that are known to have or have had flowing liquid water. The latest Planetary Decadal Survey (Vision and Voyages for Planetary Science in the Decade 2013-2022) recommended that NASA explore three solar system bodies with accessible aqueous regions: Mars; Jupiter’s moon, Europa; and Saturn’s moon, Enceladus. Each of these bodies poses different drilling-related challenges. Drilling on Mars requires penetrating dry rock and regolith that have physical properties (i.e., tensile strength, hardness, etc.) that can vary many orders of magnitude though the drill depth. A drill on Enceladus and Europa will need to operate in ice at temperatures below 100 K, while accounting for the low gravity on Enceladus or the high surface radiation on Europa. The Auto-Gopher must be designed to achieve its goals of penetrating the subsurface to great depths, capturing pristine samples, and delivering those samples to onboard instruments for analysis or for potential sample return—all in the harsh conditions encountered in space. Illustration of the Auto-Gopher concept as a wireline deep drill.
Status and Future Plans: The aim of the Auto-Gopher development effort is to demonstrate a scalable technology that makes deep drilling possible using current launch vehicles and power sources. This technology development has been accomplished in several generations including the Ultrasonic/Sonic Driller/Corer, Ultrasonic/Sonic Gopher, and the Auto-Gopher-1. In 2015, PSD awarded a project under its MatISSE program to support the next generation of Auto-Gopher technology development—the Auto-Gopher-2. In 2015, the project produced a core breaker and retaining mechanism and demonstrated their operation. This latest drill is also being designed to house electronics, sensors, and mechanisms needed for autonomous drilling, and the critical subsystems are currently being breadboarded and tested. Future planned activities include field trials to validate drill operation in harsh conditions at a U.S. gypsum quarry (gypsum can change from hard crystalline gypsum, to soft sugar gypsum, to very hard anhydrite with numerous clayrich veins) and inside a vacuum chamber, drilling in ice at approximately -100°C.
Sponsoring Organization: The research, led by PI Kris Zacny of Honeybee Robotics, is funded by the PSD’s MatISSE program, and jointly developed with the Jet Propulsion Laboratory (JPL)/California Institute of Technology. | 0.833199 | 3.394901 |
Does Electricity Energize The Galaxies?
In the cosmos there are regions where stars range in thousand light-year lines. Elsewhere, rings of stars can be found, along with galaxies stretching in filaments for enormous distances.The Milky Way contains over 200 billion stars in its spiral arms and its nucleus. Recent observations from the Sloan Digital Sky Survey (SDSS) indicate that a torus of additional stars is surrounding it at a distance of 120,000 light-years. That vast halo could mean up to a trillion stars make up our galaxy. Most of the stars discovered by SDSS are invisible to visual platforms because they are in the same plane as the galaxy, itself. However, stars are detected using infrared and X-ray instruments that can “see through” the obscuring dust.
According to Heidi Jo Newberg, associate professor of physics and astronomy at Rensselaer Polytechnic Institute: “When we find large groups of stars formed into rings it’s an indication that at least part of our galaxy was formed by a lot of smaller or dwarf galaxies mixing together.”Her colleague, Brian Yanny of FermiLab wrote: “This ring of stars may be what’s left of a collision between our Milky Way and a smaller, dwarf galaxy that occurred billions of years ago.”
Their conclusions are that dark matter sustains the ring of stars around the Milky Way. By consensus definition, those same forces are what cause the more dramatic structures like NGC7742 to appear – galactic collisions over billions of years moderated by gravity and unknown energies.
It is possible that haloes of stars are actually examples of a dense plasma focus penumbra, with NGC7742 being a dramatic example. Images taken from experiments using a “plasma gun” offer a direct analogue to the “pinch zones” surrounding the discharge from the galaxy.
In 1960, Hannes Alfvén published a paper in which he proposed a mechanism for the formation of structures in space that does not depend on gravity alone. He wrote:
“The earth, the sun and many stars possess general magnetic fields. It is possible that interstellar clouds are magnetized…This makes is likely that there should be some very general process which produces magnetic fields in fluid bodies as different as the earth’s fluid interior, the stars, and interstellar matter. The energy required for magnetization can easily be drawn from the kinetic energy of internal motions, but the difficulty is to find a workable mechanism from the production of magnetic fields.” (Alfvén, H. “On the Origin of Cosmic Magnetic Fields”, Royal Institute of Stockholm, October 28, 1960).The dense plasma focus device, or “plasma gun”, is precisely the mechanism that can influence cosmic electric currents, thereby acting on the evolution and morphology of space structures, whether they are small moons or massive galaxies.
Birkeland current filaments are the “transmission lines” through which electricity is conducted in the Universe. As a previous Picture of the Day (see right) points out, helical strands from the core of NGC 3079 are an indication that electricity is discharging from its nucleus. The swirling toroids that constrain the “young” hot stars in the halo of NGC7742 are a red flag to Electric Universe theorists.
One of the signature phenomena in a dense plasma focus is helical strands of energy that surround a powerfully radiating arc-mode discharge and a dark-current torus. The strands are helical magnetic fields that confine electrified plasma and act like power lines in space – Birkeland current filaments, in other words. That phenomenon is easily seen in cosmic formations.
It may be that filamentary strands in the penumbral clouds of stars and nebulae are energized by the gun, as several other examples illustrate.
Posted in Science For The New Agewith no comments yet. | 0.857243 | 3.939319 |
History of gravitational theory
Scientific revolutionModern work on gravitational theory began with the work of Galileo Galilei in the late 16th and early 17th centuries. In his famous (though possibly apocryphal) experiment dropping balls from the Tower of Pisa, and later with careful measurements of balls rolling down inclines, Galileo showed that gravitation accelerates all objects at the same rate. This was a major departure from Aristotle's belief that heavier objects accelerate faster. Galileo correctly postulated air resistance as the reason that lighter objects may fall more slowly in an atmosphere. Galileo's work set the stage for the formulation of Newton's theory of gravity.
Newton's theory of gravitationIn 1687, English mathematician Sir Isaac Newton published Principia, which hypothesizes the inverse-square law of universal gravitation. In his own words, “I deduced that the forces which keep the planets in their orbs must [be] reciprocally as the squares of their distances from the centers about which they revolve: and thereby compared the force requisite to keep the Moon in her Orb with the force of gravity at the surface of the Earth; and found them answer pretty nearly.”
Newton's theory enjoyed its greatest success when it was used to predict the existence of Neptune based on motions of Uranus that could not be accounted for by the actions of the other planets. Calculations by both John Couch Adams and Urbain Le Verrier predicted the general position of the planet, and Le Verrier's calculations are what led Johann Gottfried Galle to the discovery of Neptune.
A discrepancy in Mercury's orbit pointed out flaws in Newton's theory. By the end of the 19th century, it was known that its orbit showed slight perturbations that could not be accounted for entirely under Newton's theory, but all searches for another perturbing body (such as a planet orbiting the Sun even closer than Mercury) had been fruitless. The issue was resolved in 1915 by Albert Einstein's new theory of general relativity, which accounted for the small discrepancy in Mercury's orbit.
Although Newton's theory has been superseded, most modern non-relativistic gravitational calculations are still made using Newton's theory because it is a much simpler theory to work with than general relativity, and gives sufficiently accurate results for most applications involving sufficiently small masses, speeds and energies. | 0.822768 | 3.762166 |
Using data from the Palomar Transient Factory Real-Time Detection Pipeline, astronomers were able to verify and document the first-ever direct observations of a Type 1a supernova progenitor system, PTF 11kx.
Berkeley, California — Exploding stars called Type 1a supernova are ideal for measuring cosmic distance because they are bright enough to spot across the Universe and have relatively the same luminosity everywhere. Although astronomers have many theories about the kinds of star systems involved in these explosions (or progenitor systems), no one has ever directly observed one—until now.
In the August 24 issue of Science, the multi-institutional Palomar Transient Factory (PTF) team presents the first-ever direct observations of a Type 1a supernova progenitor system. Astronomers have collected evidence indicating that the progenitor system of a Type 1a supernova, called PTF 11kx, contains a red giant star. They also show that the system previously underwent at least one much smaller nova eruption before it ended its life in a destructive supernova. The system is located 600 million light years away in the constellation Lynx.
Artist’s conception of a binary star system that produces recurrent novae, and ultimately, the supernova PTF 11kx. A red giant star (foreground) loses some of its outer layers through a stellar wind, and some of it forms a disk around a companion white dwarf star. This material falls onto the white dwarf, causing it to experience periodic nova eruptions every few decades. When the mass builds up to near the ultimate limit a white dwarf star can take, it explodes as a Type Ia supernova, destroying the white dwarf.
(Animation credit: Romano Corradi and the Instituto de Astrofísica de Canarias)
By comparison, indirect observations of another Type 1a supernova progenitor system (called SN 2011fe, conducted by the PTF team last year) showed no evidence of a red giant star. Taken together, these observations unequivocally show that just because Type 1a supernovae look the same, that doesn’t mean they are all born the same way.
“We know that Type 1a supernovae vary slightly from galaxy to galaxy, and we’ve been calibrating for that, but this PTF 11kx observation is providing the first explanation of why this happens,” says Peter Nugent, a senior scientist at the Lawrence Berkeley National Laboratory (Berkeley Lab) and a co-author on the paper. “This discovery gives us an opportunity to refine and improve the accuracy of our cosmic measurements.”
“It’s a total surprise to find that thermonuclear supernovae, which all seem so similar, come from different kinds of stars,” says Andy Howell, a staff scientist at the Las Cumbres Observatory Global Telescope Network (LCOGT) and a co-author on the paper. “How could these events look so similar, if they had different origins?”
A One in a Thousand Discovery, Powered by Supercomputers
Although Type 1a supernovae are rare, occurring maybe once or twice a century in a typical galaxy, Nugent notes that finding a Type 1a progenitor system like PTF 11kx is even more rare. “You maybe find one of these systems in a sample of 1,000 Type 1a supernovae,” he says. “The Palomar Transient Factory Real-Time Detection Pipeline was crucial to finding PTF 11kx.”
The PTF survey uses a robotic telescope mounted on the 48-inch Samuel Oschin Telescope at Palomar Observatory in southern California to scan the sky nightly. As the observations are taken, the data travels more than 400 miles via high-speed networks–including the National Science Foundation’s High Performance Wireless Research and Education Network and the Department of Energy’s Energy Sciences Network (ESnet)–to the National Energy Research Scientific Computing Center (NERSC), located at Berkeley Lab. There, the Real-time Transient Detection Pipeline uses supercomputers, a high-speed parallel filesystem and sophisticated machine learning algorithms to sift the data and identify events for scientists to follow up on.
According to Nugent, the pipeline detected the supernova on January 16, 2011. He and UC Berkeley postdoctoral researcher Jeffrey Silverman immediately followed up on the event with spectroscopy observations from the Shane telescope at the University of California’s Lick Observatory. These observations revealed incredibly strong calcium signals in the gas and dust surrounding the supernova, which is extremely unusual.
The signals were so peculiar that Nugent and his UC Berkeley colleagues, Alex Filippenko and Joshua Bloom, triggered a Target of Opportunity (ToO) observation using the Keck Telescope in Hawaii. “We basically called up a fellow UC observer and interrupted their observations in order to get time critical spectra,” Nugent explains.
From the Keck observations, astronomers noticed that the clouds of gas and dust surrounding PTF 11kx were moving too slowly to be coming from the recent supernova, but moving too quickly to be stellar wind. They suspected that maybe the star erupted, or went nova, previously propelling a shell of material outwards. The material, they surmised, must be slowing down as it collided with wind from a nearby red giant star. But for this theory to be true, the material from the recent supernova should eventually catch up and collide with gas and dust from the previous nova. That’s exactly what the PTF team eventually observed.
In the months following the supernova, the PTF team watched the calcium signal drop and eventually vanish. Then, 58 days after the supernova went off, Berkeley Lab Scientist Nao Suzuki who was observing the system with the Lick telescope noticed a sudden, strong burst in calcium coming from the system, indicating that the new supernova material had finally collided with the old material.
“This was the most exciting supernova I’ve ever studied. For several months, almost every new observation showed something we’d never seen before,” says Ben Dilday, a UC Santa Barbra postdoctoral researchers and lead author of the study.
A New Kind of Type 1a Supernova
According to Dilday, it is not unusual for a star to undergo nova eruptions more than once. In fact, a “recurrent nova” system called RS Ophiuchi exists within our own Milky Way Galaxy. Located about 5,000 light years away, the system is close enough that astronomers can tell that it consists of a compact white dwarf star (the corpse of a sun-like star) orbiting a red giant. Material being blown off the red giant star in a stellar wind lands on the white dwarf. As the material builds up, the white dwarf periodically explodes, or novas, in this case, about every 20 years.
Astronomers predict that in recurring novas, the white dwarf loses more mass in the nova eruption than it gains from the red giant. Because Type 1a supernovae occur in systems where a white dwarf accretes mass from a nearby star until it can’t grow any further and explodes, many scientists concluded that recurrent nova systems could not produce Type 1a supernovae. They thought the white dwarf would lose too much mass to ever become a supernova. PTF 11kx is the first observational evidence that Type 1a supernovae can occur in these systems.
“Because we’ve looked at thousands of systems and PTF 11kx is the only one that we’ve found that looks exactly like this, we think it is probably a rare phenomenon. However, these systems could be somewhat more common, and nature is just hiding their signatures from us,” says Silverman.
The Palomar Transient Factory’s Real-Time detection pipeline is made possible with support from the DOE Office of Science, NASA, and the National Science Foundation.
Source: Linda Vu, Lawrence Berkeley National Laboratory
Image: BJ Fulton, Las Cumbres Observatory Global Telescope Network | 0.85223 | 4.028151 |
Beginning on February 6, 2011, the two STEREO spacecraft are 180 degrees apart providing Naval Research Laboratory (NRL) scientists with a 360-degree view of the Sun. NASA’s STEREO (Solar Terrestrial Relations Observatory) spacecraft were launched on October 25, 2006, and have been gathering spectacular images of solar activity, especially solar storms, since the mission began.
A key component of the STEREO mission is NRL’s Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI), a suite of five scientific telescopes that observe the solar corona and inner heliosphere from the surface of the Sun to the orbit of Earth. These unique observations are made in “stereo” by the two nearly identical solar-powered STEREO observatories with one observatory ahead of Earth in its orbit and the other trailing behind. The two observatories trace the flow of energy and matter from the Sun to Earth. The instruments aboard STEREO reveal the three-dimensional structure of coronal mass ejections, the powerful eruptions of plasma and magnetic energy from the Sun’s outer atmosphere, or corona.
SECCHI Project Scientist and NRL researcher, Dr. Angelos Vourlidas, explains the significance of this opportunity for the 360-degree view of the Sun, “for the first time, we can take snapshots of the entire atmosphere of a star. To put it in perspective, before STEREO we were like a person trying to get the pulse of a city by watching through a half-open window — not an easy task. Now, STEREO has thrown wide open the window and we can watch the Sun and its activity in its full three-dimensional glory.” Each STEREO telescope sees half the Sun at a time. By combining the two views, NRL researchers can map of the entire solar atmosphere continuously.
Before the three-dimensional view was available, researchers had to wait until an active region rotated across the visible-from-Earth disk in order to study the properties. The problem of having to wait for the proper views to appear is that the corona is highly variable, filled with regions that come and go in a matter of days and explosions that can alter the corona landscape in a matter of hours.
With this capability of a three-dimensional view of the Sun, Vourlidas sees the potential for advances in the field of heliophysics. “We can solve the puzzles behind the evolution and structure of the solar atmosphere, including its violent eruptions, because we will be able to observe every feature and source of activity at the same time all over the Sun and follow their connections that can extend to large distances around the Sun,” he explains. This opportunity for the STEREO spacecraft to view the Sun in three-dimension will be available for the next eight years.
STEREO is the third mission in NASA’s Solar Terrestrial Probes Program. STEREO is sponsored by NASA’s Science Mission Directorate, Washington, D.C. The Goddard Science and Exploration Directorate manages the mission, instruments, and science center. The Johns Hopkins University applied Physics Laboratory, Laurel, Md., designed and built the spacecraft and is operating them for NASA during the mission. | 0.849659 | 3.892318 |
Astronomers have discovered the three smallest planets yet orbiting a single red dwarf star beyond the sun.
Using data from NASA Kepler mission, the planets were found to be 0.78, 0.73 and 0.57 times the radius of Earth and orbit the KOI-961 star.
All three are rocky like the Earth, and the smallest - named KOI-961.03 - is roughly the size of Mars. The largest has been named KOI-961.01, while the middle-sized is KOI-961.02.
The location of the trio is too hot for them to be in the habitable zone - where liquid water could exist - but out of more than 700 planets confirmed to orbit other stars, only a handful are known to be rocky.
Doug Hudgins, a Kepler program scientist at NASA Headquarters in Washington said: "Astronomers are just beginning to confirm thousands of planet candidates uncovered by Kepler so far.
"Finding one as small as Mars is amazing and hints that there may be a bounty of rocky planets all around us."
John Johnson, the principal investigator of the research from NASA's Exoplanet Science Institute at the California Institute of Technology in Pasadena, said: "This is the tiniest solar system found so far.
"It's actually more similar to Jupiter and its moons in scale than any other planetary system. The discovery is further proof of the diversity of planetary systems in our galaxy."
Phil Muirhead, lead author from the new study from Caltech, added: "These types of system could be ubiquitous in the universe. This is a really exciting time for planet hunters."
Earlier this week it was suggested an Earthlike moon, reminiscent of the fictitious Tattoine could exist in a double-star system. | 0.91417 | 3.24642 |
quarta-feira, 2 de fevereiro de 2011
Scientists Discover Solar System With 6 PlanetsFeb 2, 2011 – 1:00 PM
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Scientists have found a new solar system so unlike our own that at first glance it seems almost impossible it could exist.
The planets in the new system are packed together as densely as fans in a mosh pit. Five planets sit practically on top of each other as they circle their star, called Kepler-11; a sixth circles farther out. Two of the planets lie closer together than any other known pair of planets outside our solar system.
"There's only word" to describe the new solar system, NASA's Jack Lissauer said at a news conference today, and it's "supercalifragilisticexpialidocious."
Tim Pyle, NASA
Kepler-11 is a sun-like star around which six planets orbit. At times, two or more planets pass in front of the star at once, as shown in this artist's conception of a simultaneous transit of three planets observed by NASA's Kepler spacecraft.Other astronomers tossed around words like "amazing" and "remarkable" to describe the new system, which lies about 2,000 light-years away from Earth in the constellation Cygnus. The Kepler-11 cluster is one of only a handful of solar systems known to include so many planets, and none of the others are understood as well.
The six planets of Kepler-11 may be among the latest entries on the list of "extrasolar" planets -- those outside our own solar system -- but they won't be the last.
Scientists today revealed that NASA's Kepler spacecraft, which found Kepler-11's planets, has to date spotted more than 1,200 potential planets. Astronomers need to confirm the existence of each of the new candidate planets, some of which will turn out to be false leads. But many others are likely to be verified as actual worlds orbiting other stars -- the first step, scientifically, toward figuring out where to look for life elsewhere in the universe.
Five of those candidate planets are roughly the size of Earth and could contain liquid water, but it will take "patience ... and lots of money" to find out whether those five harbor life, NASA's William Borucki said.
Even in the growing collection of new planets, the Kepler-11 system, which was described in a study published in Thursday's issue of the journal Nature, stands out. For starters there's its size. Kepler-11 boasts at least six planets, many more than most systems, and it may have even more planets that scientists have yet to detect.
It was "shocking" to find six planets orbiting one star, the University of Florida's Eric Ford, an author of the Nature study, told AOL News. He described his team's reaction as the planet count went higher and higher: "There's a second. Oh, there's a third. Oh, there's a fourth! When does it stop?"
Then there's the dense concentration of the planets. Five of Kepler-11's planets circle it more tightly than our sun is circled by its nearest planet, Mercury.
The planets of Kepler-11 are squashed together so compactly that "at first glance, you think, 'Oh, my God, how is this possible?'" says astronomer Christophe Lovis of the University of Geneva, who was not associated with the new study.
Then there's the planets' size. Five are larger than Earth but smaller than Uranus, the next-biggest planet orbiting the sun.
Sponsored LinksIn our solar system, "the largest terra incognita occurs between Earth and Uranus," and these new planets fill that gap, says astronomer Gregory Laughlin of the University of California, Santa Cruz, who was not an author of the new study. "You're seeing what planets look like in this strange regime between [Earth-like] planets and what we call the ice giants."
The Kepler-11 grouping is so unusual that it can't be explained by the old theories of how solar systems are born, says NASA's Lissauer, leader of the new study and a specialist in planetary formation.
"Something a little different has to be going on here," he says. "This is sending me back to the drawing board." Amazing Space ImagesSolar Dynamics Observatory / NASA66 photos This still from SDO caught the action in freeze-frame splendor when the sun popped off two events at once on Jan. 28. A filament, left, became unstable and erupted, while an M-1 flare and a coronal mass ejection, right, blasted into space. Neither event was headed toward Earth.
Postado por Criss Variedades às 2/02/2011 07:00:00 PM | 0.870085 | 3.147509 |
They say that we know more about space than about Earth’s oceans. That might be true; however, it by no means implies that we know all there is to know about space. Despite what physicist Lord Kelvin declared in 1900, that there is nothing new to be discovered in physics, the field had yet to be introduced to quantum mechanics, Albert Einstein, and his theory of relativity. Scientists had to rethink their knowledge of the cosmos. Nowadays, no physicist would dare dream that we possess a complete knowledge of the universe. In fact, the more we learn, it seems the more questions arise.
Our universe is vast and impenetrably dark, home to unseen forces and phenomena that have yet to be fully documented and explained. Scientists have yet to fully understand the many space mysteries that we simply don’t have the technological capability to fully explore. Some of these mysteries are downright spooky and many challenge the currently accepted laws of physics. While we struggle to develop technologies and theories to help unravel these many space mysteries, scientists can only ponder the possibilities. What follows are just fifteen of the greatest mysteries of space that are currently being contemplated.
15. What Is Dark Energy?
Dark energy comprises about 75% of the universe; however, scientists are not only uncertain about what it is, but are also not really sure how it operates. It all began in 1929, when astronomer Edwin Hubble (yeah, the telescope was named after him…) was studying supernovae and concluded that the universe is expanding. Since then, scientists have been trying to figure out how fast. Gravity, the force that draws everything towards each other, should be slowing the expansion down; it’s not. In the 1990s, astrophysicists discovered that universal expansion was actually speeding up. Something was counteracting the force of gravity; this “something” was labeled “dark energy.”
When looking out into the universe, we can’t see this dark energy; we see the light from all the matter and the rest is empty… well… space. Therefore, this dark energy must account for a large part of the makeup of the universe. In physics, this theory is called quintessence. Quintessence hypothesizes that this negative dark energy field overpowers gravity and causes all that matter to repel each other, thusly accelerating universal expansion. It’s all a theory, as scientists really don’t know what this stuff is!
14. What Are The Fermi Bubbles?
If viewed along its plane in visible light, the Milky Way galaxy appears relatively flat. If you look at Gamma-ray emissions, you’d be quite astonished, however, to see two giant formations jutting outward from the galaxy’s center, looking like a galactic hourglass. Called the Fermi Bubbles, these two huge continuous bursts of gamma-ray emissions were first discovered in 2010. They reach out over 50,000 light years; however, their cause is unknown. They contain enough gas to create 2 million Sun-size stars. Scientists have been able to determine the bubble’s age to around 6-9 million years. As to what they are or why they exist, that is another story.
We know that most galaxies contain a supermassive black hole at the center, with our Milky Way being no exception. Our black hole is believed to be located at the location of Sagittarius A-star, or simply known as Sgr A*, and has a mass equal to about 4.5 million solar masses (size when compared to that of our Sun). Due to how space-time works, when we look out into space, what we are actually seeing is the state of the universe a long, long time ago. So when the Hubble perceived Sgr A*, it was younger, taking in huge amounts of gas and dust and shining brightly as all that matter was sucked into the event horizon on its way to the black hole. Scientists believe that today, Sgr A* is much quieter, but the Fermi Bubbles could possibly be the remnants of matter that was jettisoned out from the black hole when it was more active and the galaxy was still forming. We really don’t know.
13. Where Did Saturn’s Rings Come From?
There are approximately seven groups of rings around the planet Saturn, four main ring groups and three dimmer, smaller groups, all comprised of thousands of smaller rings. They stretch over 73,000 km around the planet. These groups of rings are divided by divisions, as observed by the Voyager spacecrafts in the 1980s. The rings are composed of many small particles of ice and rocky material, ranging in size from a micron to a meter, all in continuous orbit around the planet. That’s about all that scientists can agree upon and the rest is pure theory and the source of heavy debate.
So, while there is no consensus about how the rings were formed, some theoretical models suggest they were formed early in our solar system’s history. This model states that the debris circling the planet is the remains of a moon that failed to form, or was possibly torn apart by Saturn’s tidal stresses. Some think the proto-moon might have been struck by another large object and blown apart. However, other scientists believe the rings are still in the process of being constantly replenished. They point to one of the rings, known as the E-Ring, which has been witnessed being refreshed by icy material ejected by a cryovolcano – basically an ice volcano – from the south pole of the nearby moon, Enceladus. Maybe one day sufficient evidence will be discovered to put the question to rest.
12. What Are The Mysterious Noises From Space?
Sound does not travel in space, that being said, space apparently is a very noisy place. In May 1969, the Apollo 10 astronauts were orbiting the moon. The three astronauts heard and recorded strange sounds while circling around the dark side of the moon. They said it sounded like whistling or music. It creeped them out and the men discussed whether or not they should inform Mission Control. I mean, there is not supposed to be any sound out there and the fate of their future mission status might be in jeopardy if they reported crazy stuff! The men opted for full disclosure and gave their report. An engineer calmed the men and responded that the sounds were most likely radio interference. But was it? Later, Apollo 11 reported the same mesmerizing sounds. Again, it was dismissed as interference. Apollo 15 astronaut Al Worden heard it also and disputes the interference explanation. Scientists agree that the universe is a noisy place and that every galaxy and celestial body emits some sort of radio waves. They insist that this must be what the astronauts are hearing.
Then in 1977, a radio signal from space was detected. It only lasted 22 seconds but its intensity was off the charts. Called the “Wow!” signal, it was tracked to a point near the Sagittarius constellation. It’s been searched for ever since but has never repeated. Later, in 2014, NASA launched a hydrophone array into space to record any space signals. When it was recovered, it was found to have recorded hissing, crackling, whirling, even whistling sounds. Are these the galactic radio waves scientists refer to; gravity waves and planetary radio emissions that crisscross the universe? Or, is there some other explanation for all the strange sounds that keep being heard emanating from space.
11. The Distant Monster
In 2013, an incredible planetary discovery was made. The exoplanet, called HD 106906 b, is colossal in size. We’re talking about eleven times more immense than Jupiter. Its orbit is the largest every discovered found in a star system. This distant monster has a gaping orbit 650 AU from its star. An AU is an astronomical unit; for scale, Neptune is 30 AU from our Sun. That’s a huge orbit! It’s 650 times the average distance between the Earth and the Sun.
The planet’s very existence raises a ton of questions. It just doesn’t fit into current planetary formation models. Usually planets that orbit close to their parent star, such as Earth, began as smaller, rocky bodies in space that came together and coalesced around a young star. However, this process takes too long to explain the existence of giants that formed so far away from their star. An alternative theory suggests that maybe these distant planets formed like a mini binary star system. These form when two clumps of gas collapse to form stars, close enough to exert a mutual gravitational pull on each other, binding them together in orbit. However, this doesn’t quite fit either because, as far as we know, the difference between the masses of two stars in binary systems is no more than 10-to-1. In this case, the mass ratio is over 100-to-1! We do know that HD 106906 b is only 13 million years old, and is still glowing from its formation (for comparison, Earth formed 4.5 billion years ago). This new exoplanet needs a lot of study before we can fully understand just what it is or how it came to be.
Nemesis is a theoretical dwarf star that some scientists believe is a companion to our Sun. This theory was put forward to explain the cycle of mass extinctions in Earth’s fossil record. Some scientists believe that such a star could affect the orbit of objects in the outer solar system and send them hurtling inward on collision courses with Earth. Some of the basis for this hypothesis is the apparent cyclical pattern to mass extinctions, roughly every 27 million years. Such precision is believed to have a direct relationship with astronomical forces. Therefore, in 1984, Richard Muller of the University of California, Berkley suggested that the Sun’s twin, a red dwarf star 1.5 light-years away would explain this phenomena; or possibly a brown or white dwarf, with sufficiently low mass as to cast a dim light, making it very difficult to see.
It is postulated that Nemesis would exert force over the Oort Cloud, which is comprised of icy rocks, out beyond Pluto. They have a long-term elliptical orbit around our Sun. As they get closer, their ice begins to melt away, giving them an icy-cloud tail, recognizable to us as comets. If Nemesis travels through the Oort Cloud every 27 million years, it could launch comets out of the cloud and send them in our direction, some of which would impact Earth, causing mass extinctions. Proponents point to the 12,000 year orbit for the dwarf planet Sedna. They say only a massive dimly-lit star could be responsible for keeping Sedna so far from the Sun. Though some scientists find the theory plausible, others do not. Regardless, the cyclical nature of mass extinctions has yet to be explained.
9. Where Are The White Holes?
Physicist Albert Einstein’s general theory of relativity proposes that the great expanse of space should be home to numerous white holes. The hypothetical twin to a black hole, a white hole is an area of space-time which cannot be entered from the outside, though matter is spewed from it. This is in direct opposition to a black hole which can only be entered and from which nothing, not even light, can escape. Logic supports Einstein’s theory, but scientists have yet to find evidence of their existence. Some claim we might have already seen them but that they have the same radiation levels as other cosmic phenomena, leading scientists to erroneously identify them as something else.
Though we have never observed one, Einstein’s mathematical proof dictates that if black holes exist, so must their hypothetical opposite. Of course, once we do find one, that would ultimately unleash a whole new set of questions. Where does the matter come from? Does this actually prove that the matter sucked into a black hole is transported across space-time unseen to exit out of a white hole? If so, how many light-years away is the adjacent black hole? Would they even exist in the same space-time continuum? Are they trans-dimensional gateways? Hopefully we’ll find definite proof of one soon. The directions scientific research could take from the point of discovery is the stuff of wild imagination!
8. Why Does Titan Have An Atmosphere?
Titan is the sixth and largest of Saturn’s moons. It is slightly larger than our own moon, but much more massive (density wise), and is often considered more planet-like than any other moon in our solar system. The reason being is not only that Titan appears to possess stable liquid oceans, but because the moon is the only one to have an atmosphere! Jupiter’s moon Ganymede is larger than Titan and also is believed to possess liquid oceans, albeit underneath an icy surface. However, Ganymede lacks any sort of atmosphere. Why does the smaller Titan have one?
Extending 600 km above the surface of Titan, the atmosphere is composed mainly of nitrogen, similar to that of Earth’s atmosphere, with some hydrogen and methane. Due to this, scientists are excited about the possibility of finding evidence of signs of life. Of course, we still do not know how an atmosphere could have formed on Titan. Some theories credit its existence to Saturn’s distance from the Sun. This is due to when Titan formed, the lack of the Sun’s head allowed unstable gases to be trapped in layers of ice, and were later slowly released over time, creating the atmosphere. Another theory suggests that due to Titan’s proximity and amount of time spent within Saturn’s magnetosphere, it has been sufficiently shielded from solar winds that would’ve otherwise stripped it of its atmosphere. There are currently numerous proposals being considered for unmanned research missions to Titan. Who knows what we might find?
7. The Great Attractor
There’s a point in the universe, about 200 million light-years away, that is baffling scientists around the world. This mysterious cluster in space, dubbed “The Great Attractor” is pulling our whole Milky Way galaxy towards it. Ever since the creation of the universe, it has been expanding constantly, we know this. What’s freaking everyone in astrophysics out is that we’re heading in the wrong direction. This gravitational anomaly is pulling us towards it. For something so far away to exert such gravitational force it has to be something incredible! Whatever it is, it’s yanking us towards it at a mind-boggling 600 km/s (kilometers per second)!
Okay, so you would think that someone would point the Hubble telescope towards it, at the center of the Laniakea Supercluster, in the direction of the constellation Centaurus. Well, the problem is our own galaxy, the Milky Way, with all its gas, dust, and stars, blocks our view of that portion of space and whatever is out there that is drawing us towards it. Astronomers have labeled that area of space the Zone of Avoidance, and the Great Attractor (gotta love these names) lies smack dab in the middle of the zone. First discovered in 1970, it should take billions of years before we reach our destination; however, what will happen when we get there? Well, scientists don’t really believe that will ever happen. If we did, the Milky Way will probably join other galaxies and become part of a supercluster; however, they believe that equally mysterious dark energy will destroy whatever cluster currently occupies that space in the Laniakea Supercluster. But ultimately, we don’t really know.
6. Tabby’s Star
It’s officially called KIC 8462852, but this interesting star is known by a better name, Tabby’s Star, and it’s an enigma 1,500 light-years away. Ever since they discovered Tabby’s Star, it’s baffled scientists. It seems that about 20% of the light that the star emits is being blocked from our view. Due to the amount of light being blocked, scientists are pretty sure it’s not a planet obscuring our view. Even a planet as large as Jupiter would only block about 1% of the light of a star of Tabby’s size. So what could be the culprit? Well, some have speculated it might be something called a Dyson Sphere. Well, technically maybe a Dyson Swarm, a less complete version of a Dyson Sphere.
What is a Dyson Sphere? It’s a technologically-advanced megastructure that is built around a star to harvest the star’s energy output. I know that sounds more like science fiction than science fact; however, we pretty much know how one would work, even if we lack the technological know-how to actually build one. Some other scientists are less quick to jump to the alien technology answer, and are holding out for a more mundane answer. We’ll have a better idea of what’s actually happening with Tabby’s Star when NASA launches the James Webb Space Telescope in 2018. Until then, Dyson Swarm sounds like a pretty exciting explanation!
5. What Happens Inside A Black Hole?
What happens to all the matter that is gobbled up by a black hole? Current models dictate that whatever goes in is irreversibly lost – all information gone forever. That’s due to a black hole’s gravity being so strong that not even light can escape. Now, some scientists are championing something called quantum mechanics, which says quantum information can’t be destroyed. Quantum information isn’t like normal information, like bits on a computer or knowledge in our minds. Quantum theories don’t really give a simple explanation for it. Basically, it’s theoretical and dictates the most likely location of something or the most likely result of some particular action upon something. Think of it in terms of not saying the calculated trajectory of a baseball, instead more like giving all the probable outcomes of where that baseball might possibly end up. Therefore, all of the probabilities of something occurring should add up to 1, or 100%. For instance, a 1 in 6 chance, means there are 6 possible outcomes and if you add all 6 chances, each 1/6, then you have 6/6, or 1.
Quantum theory says that if we know how a system ends, scientists can calculate how it began. Whoo! My head’s hurting already. Relating to black holes, scientists have used quantum theory and believe that quantum information of whatever got sucked in is not lost deep within, but instead remains on its boundary, the event horizon. This is called the “information paradox,” and physicists can’t really agree on a solution. So, to break it down, we still don’t know what happens to everything that goes into a black hole!
4. Are There Parallel Universes?
Some astrophysicists believe that space-time is flat, as opposed to curved, and flows on infinitely. If this is true, then what we see – commonly referred to as our universe, 14 billion light years in all directions – is just one layer in an infinite “quilted” multiverse. This is called the theory of eternal chaotic inflation, but multiverse is easier to say. The laws of quantum mechanics state that there is only a fixed set of possible particle configurations within each of these infinite cosmic layers of the multiverse. That means that some of these particle configurations are forced to repeat many times.
Basically, this means that there are an infinite number of parallel universes that are very similar, if not exactly like, our own, as well as some that differ by maybe one or two particles, and so on. However, those simple changes could result in universes that are radically different than ours. One universe might be quite similar except your engineer brother-in-law is now your graphic designer sister-in-law. Another universe might find that dolphins rule the world with humans on display in zoos and theme parks. Still other universe might exist where life never evolved at all. Radical! What do you think?
Not every scientist buys into this theory, but it is grounded in the real science of cosmic inflation and the decay of something called a false vacuum. I’m not even going to try to get into the minutiae of astrophysics, but suffice to say many physicists seriously believe other pocket universes are being generated all the time and will continue to do so infinitely. Hopefully, one day we’ll find a way to detect the presence of other parallel universes. Maybe I could give one of my other self’s a call (and remind him to stay away from that one blonde in that club that one time…).
3. Can We Travel Faster Than Light?
In 1905, Albert Einstein built his theory of special relativity around the notion that the speed of light is constant, no matter how fast something was moving in relation to the light. Einstein believed that time and space would have to expand or contract as something travelled with increasing speed. In his contemplations, he discovered a prime cosmic law: nothing can travel faster than light. His theories became the cornerstone of modern physics. Scientists have been studying this ever since. Though they’ve found evidence that some things, like dark energy, seem to travel faster than light; however, these things have no mass. Particles with mass require more energy to move them. If these particles were to travel at speeds that approached the speed of light, the amount of energy continually needed to propel them would have to increase exponentially. So, as an object nears the speed of light, its mass becomes infinite, as does the amount of energy needed to move it.
But have no fear, scientists are hard at work finding ways to cheat these laws of physics. Out of all the theories to get around Einstein’s pesky rules, the best might be one proposed by theoretical physicist Miguel Alcubierre in 1994. He proposed an Alcubierre Drive. He theorized that, by redistributing matter, you can shrink space in front of a spacecraft, the S.S. Shatner, for instance, and then stretch it behind the craft. This would create a hyper-relativistic local-dynamic space, or bubble, around the ship that would move it as fast as you want. Because space is contracting in front of the craft, the craft won’t really be moving faster than light. Instead, the craft would actually be motionless relative to the bubble. The crew of the craft wouldn’t even feel as if they were moving at all. The only problem is that to create this “warp” bubble, it would require a “weak energy condition.” Scientists can’t guarantee the stability of this kind of condition and admit it could cause weird stuff, like wormholes or time travel! But since we’ve never actually seen this type of condition, it’s all theoretical. Not impossible though…
2. Are We Alone In The Universe?
In 1996, U.S. President Bill Clinton publicly announced that fossilized microbes had been found inside a meteorite that originated from Mars. Though some scientists believe that the government jumped the gun with that announcement, as what they thought was fossils could’ve actually been the result of non-biological processes. Despite this setback, definitive proof of life beyond Earth could likely be found right around the corner! So what basis do we have for believing that there could be life elsewhere in the universe? It’s called the Drake Equation.
In 1961, radio astronomer Frank Drake created an equation to estimate the number of intelligent civilizations in our galaxy. To solve this equation, we need the following variables: the rate of formation of stars suitable for life to develop; the fraction of those stars with planetary systems; the number of planets in each of those systems with an environment suitable for life; the fraction of suitable planets where life actually emerged; the fraction of life-bearing planets where intelligent life developed; the fraction of civilizations that would release detectable signs of their existence into space; and the length of time such a civilization would continue to send those signals into space. We take all those variables and multiply them together to reach the possible number of civilizations in our Milky Way galaxy that we might be able to detect. The kicker is that we don’t actually have any certified numbers for any of these variables. Therefore, any calculation is just a rough estimate. According to this equation, even with these rough estimates plugged in, there could be as many as 50,000 alien civilizations existing today!
1. Are We The Aliens On Earth?
There is a theory, called panspermia, which says life here on Earth began out there, among the stars. This theory supposes that 3.8 billion years ago, our molten planet was hit by a rock that was carrying the primordial seeds of life. I know it sounds wild, but scientists have actually discovered meteorites that were found to contain amino acids, which are the building blocks of life. Additionally, in 2003, we took a close look at Ceres, the largest asteroid in our system. It’s coated in ice, but the surface was found to be warmer than was previously believed, which means it could support some form of life. On the surface of Ceres, there is a white spot which is believed to indicate a big piece that was ripped off – possibly by a meteor strike that occurred possibly 4 billion years ago. It is believed by some that this chunk struck Earth and released the amino acids contained therein.
To test this theory, NASA sent some terrestrial seeds into space and then later brought them back down after six months. The seeds were tested and were found to be not only viable, but they thrived! Further calculations offer the possibility of transpermia, where this type of transfer of life is happening throughout our solar system. The other planets in our solar system aren’t very hospitable for life, so any transference of amino acids was probably wasted, except for Titan. Titan is one possibility where scientists believe there is a high chance of life being discovered. Though Titan’s cryogenic hydrocarbon lakes would make any life existing there chemically different from any life on Earth, making any type of relation near impossible. Still, it is an interesting theory and a possibility.
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On the overcast morning of 2 July 1985, the eleventh Ariane 1 rocket launch (image above) took place at the Centre Spatial Guyanais in Kourou, French Guiana, an outpost of the European Community located a few degrees north of the equator on the northeast coast of South America. The last Ariane 1 to fly, it bore aloft Giotto, the first European Space Agency (ESA) interplanetary spacecraft. Giotto's destination was Comet Halley.
A "dirty snowball" containing materials left over from the birth of the Solar System 4.6 billion years ago, Halley needs about 76 years to revolve around the Sun once. Its elliptical orbit takes it as near to the Sun as between the orbits of Venus and Mercury and as far from the Sun as the cold emptiness beyond the orbit of Uranus.
Comet Halley has passed through the inner Solar System 30 times since its first verified recorded apparition in 240 B.C. In 837 A.D., it passed just 5.1 million kilometers from Earth; during that apparition, its dust tail must have spanned nearly half the sky, and its bright coma - the roughly spherical dust and gas cloud surrounding its icy nucleus - may have appeared as large as the full moon. Shortly after its apparition in the year 1301, Italian artist Giotto di Bondone painted Comet Halley. The Giotto spacecraft was named for him.
Throughout most of its known apparitions, Comet Halley was not understood to be one comet repeatedly passing through the inner Solar System. Not until 1705 did English polymath Edmond Halley determine that comets seen in 1531, 1607, and 1682 were probably one comet orbiting the Sun. He predicted that, if his hypothesis was correct, then the comet should reappear in 1758 (which it subsequently did).
The Ariane 1's third stage injected 980-kilogram Giotto into a 198.5-by-36,000-kilometer orbit about the Earth. Thirty-two hours after launch, as it completed its third orbit, flight controllers in Darmstadt in the Federal Republic of Germany commanded drum-shaped Giotto to ignite its French-built Mage solid-propellant rocket motor. The aft-pointing motor burned 374 kilograms of propellant in 55 seconds to inject the spinning 2.85-meter-tall, 1.85-meter-diameter spacecraft into orbit about the Sun.
Two months before Giotto's launch, Americans P. Tsou (Jet Propulsion Laboratory), D. Brownlee (University of Washington), and A. Albee (Caltech) proposed in a paper in the Journal of the British Interplanetary Society that a second Giotto mission be launched to fly close by one of 13 candidate comets between 1988 and 1994. They proposed that the new spacecraft, which they dubbed Giotto II, might launch on an Ariane 3 or in the payload bay of a Space Shuttle. Giotto II's "free-return" trajectory would take it as close as 80 kilometers from the target comet's nucleus, then would return it to Earth. Near the comet, Giotto II would expose sample collectors to the dusty cometary environment. Near Earth, it would eject a sample-return capsule based on the proven General Electric (GE) Satellite Recovery Vehicle (SRV) design. The capsule would enter Earth's atmosphere to deliver its precious cargo of comet dust to eager scientists.
Tsou, Brownlee, and Albee pointed out that the Mage solid-propellant motor was not required to boost Giotto into interplanetary space; that is, that the Ariane 1 could do the job itself. Giotto was, however, based on a British Aerospace-built Geos magnetospheric satellite design, which included the Mage motor. Re-testing the design without the motor would have cost time and money, so ESA elected to retain it for Giotto. After noting that the GE SRV could fit comfortably in the space reserved for the Mage, they proposed that, in Giotto II, the reentry capsule should replace the motor.
Giotto included a "whipple bumper" on its aft end to protect it from hypervelocity dust impacts. During approach to Comet Halley, the spacecraft would turn the bumper in its direction of flight. The bumper comprised a one-millimeter-thick aluminum shield plate designed to break up, vaporize, and slow impactors, a 25-centimeter empty space, and a 12-millimeter-thick Kevlar sheet to halt the partially vaporized, partially fragmented impactors that penetrated the aluminum shield.
In the case of Comet Halley, dust would impact the bumper at up to 68 kilometers per second. Tsou, Brownlee, and Albee noted that the 13 candidate Giotto II comets were all less dusty and would have lower dust impact velocities than Halley. Because of this, Giotto II would need less shielding than Giotto.
Impacting dust would, nonetheless, create challenges for Giotto II. Tsou, Brownlee, and Albee devoted much of their paper to describing how the spacecraft might successfully capture dust for return to Earth. One proposed capture system, based on the whipple bumper design, would use a shield made from ultrapure material to vaporize and slow impacting dust particles. The vapor from the impactor and the impacted part of the bumper would then be captured as it condensed. Scientists would disregard the bumper material when they analyzed the condensate.
Tsou, Brownlee, and Albee also noted that thermal blankets from the Solar Maximum Mission (SMM) satellite, launched into Earth orbit on 14 February 1980, had demonstrated that intact capture of high-velocity particles was possible. The multilayer Kapton/Mylar blankets, which were returned to Earth on board the Space Shuttle Challenger (STS 41-C, 6-13 April 1984), had been found to have collected hundreds of intact meteoroids and human-made orbital debris particles. The scientists described preliminary experiments in which gas guns were used to fire meteoroid and glass fragments at "underdense materials," such as polymer foams and fiber felts. The experiments suggested that such materials could capture at least partially intact comet dust particles.
Giotto's encounter with Comet Halley spanned 13-14 March 1986. At closest approach the spacecraft passed just 596 kilometers from Halley's nucleus. The comet's 15-by-eight-by-eight-kilometer heart turned out to be extremely dark, with powerful jets of dust and gas blasting outward into space.
The intrepid probe suffered damage from dust impacts - for example, one large particle sheered off more than half a kilogram of its structure - but most of its instruments continued to operate after the Comet Halley flyby. ESA thus decided to steer Giotto toward another comet. On 2 July 1990, five years to the day after its launch, Giotto flew past Earth at a distance of 16,300 kilometers, becoming the first interplanetary spacecraft to receive a gravity-assist boost from its homeworld. The gravity assist put it on course for Comet Grigg-Skjellurup, which it flew by at a distance of 200 kilometers on 10 July 1992. After determining that Giotto had less than seven kilograms of hydrazine propellant left on board, ESA turned it off on 23 July1992. The inert spacecraft flew past Earth a second time at a distance of 219,000 kilometers on 1 July 1999.
By that time, a comet coma sample return mission was under way with two of the Giotto II proposers playing central roles. In late 1995, Stardust became the fourth mission selected for NASA's Discovery Program of low-cost robotic missions. Brownlee and Tsou, respectively Stardust Principal Investigator and Deputy Principal Investigator, designed the mission's sample capture system. The 380-kilogram Stardust spacecraft left Earth on a free-return trajectory on 7 February 1999, and flew past Comet Wild 2 (one of the 13 Giotto II candidates) at a distance of about 200 kilometers on 2 January 2004. Stardust captured dust particles in aerogel, a silica-based material of extremely low density that was invented in the 1930s. Tsou, Brownlee, and Albee had apparently been unaware of aerogel when they proposed Giotto II in 1985.
Stardust returned to Earth on 15 January 2006. Its sample capsule streaked through the pre-dawn sky over the U.S. West Coast before parachuting to a landing on a salt pan in Utah. When opened on 17 January 2006 at NASA's Johnson Space Center, in the same lab that examined the Apollo moon rocks, Stardust's 132 aerogel capture cells were found to contain thousands of intact dust grains captured from Wild 2. Subsequent analysis indicated that some probably formed close to other stars before our Solar System was born.
"Comet Coma Sample Return via Giotto II," P. Tsou, D. Brownlee, and A. Albee, Journal of the British Interplanetary Society, Volume 38, May 1985, pp. 232-239. | 0.862238 | 3.882758 |
Chapter 5 – Solar System Orbits (Halley’s Comet)Posted: March 28, 2013
Orrery, simulates the scale and relative movement of the planets about the Sun
Kepler’s Orbits, demonstrates the first two of Kepler’s Laws
Orbit Foci, plotting the second focus
Comet Orbit, eccentric orbits
Halley’s Comet, depicts one complete orbit, 1948-2023
Pluto’s Orbit, plots the relative positions of Pluto and Neptune from 1880-2128, one complete orbit for Pluto
Solar Apex, corkscrew motion of a planet towards the Solar Apex.
Halley’s Comet is without doubt the most famous comet of all time and, as a visit to our part of the solar system is due shortly, a program would not be inappropriate.
1066 and all that
Edmund Halley (1656 – 1742) did not discover this comet but was the first to notice that the bright comets seen in 1531,1607 and 1682 had practically identical orbital data and were one and the same object reappearing in the skies about every 75 years.
Halley’s Comet can now be traced back to 611 BC, via Chinese records, but perhaps the most famous reference of all in European history is its depiction in the Bayeux Tapestry of 1066 with the inscription of INTIMIRANT STELLA. Every return of the Comet since King Harold’s reign has been recorded and this is most unusual as the longevity of comets is measured in hundreds rather than thousands of years. This indicates that Halley’s Comet is a substantial body able to survive repeated visits to the inner solar system and the relatively great heat radiated upon it from the Sun.
You should be asking the question: How do comets survive repeated crossings of all the planets without collison? Well, comets (or rather, the survivors after over 5000 million years) have learned to avoid the orbital plane which all planets occupy with highly-inclined orbits. The comet crosses this danger zone for only a few days each perihelion passage.
The program depicts one complete orbit of Halley’s Comet beginning in 1948 _ the year the Comet started its current journey towards both Earth and Sun from beyond the orbit of Neptune. The Comet will return to this aphelion position again in about 2023. The perihelion passage occurs on 10th February 1986 and the program PAUSEs briefly at this point. (See Figure 5.11.) During mid-November 1985 the comet is a binocular object below the Pleiades.
This program is a variation of the Comet Orbit program, but uses one specific orbit produced by the line LET w = 4.5. Again, only one half of the orbit is computed and PLOTted — the inward journey — but each x and y coordinate position is entered into two arrays, x(t) and y(t). These are then used in a second FOR/NEXT loop to PLOT the Comet’s journey back into deep space.
It is necessary to add PAUSE 10 to this second FOR/NEXT loop to slow the PLOTting down to the same speed as the first loop. This indicates the rapidity with which the Spectrum can PLOT pixel positions once the actual position has been computed and SAVEd in an array. Try pressing any key to cancel the PAUSE statement to see what happens.
At the top of the screen is denoted the current year against the Comet’s progress — the Comet itself is PLOTted in a different coloured pixel for the inward and outward journeys (for clarity) using inverse graphics on a black screen (BORDER 0: PAPER 0: INK 9).
The path of Halley’s comet over a 75-period. Closest approach to the Sun occurs in February 1986.
10 REM Halley’s Comet
20 BORDER 0: PAPER 0: INK 7: CLS : PAPER 5: INK 9
30 PRINT ” Halley’s Comet year= “; FLASH 1;” ”
40 PAPER 1
50 PRINT AT 11,1;”Sun”
60 PLOT 40,80: GO SUB 390
70 PAPER 5
80 LET w=4.5
90 DIM x(170): DIM y(170)
100 LET h=.212: LET g=1e6
110 LET x=g/1e3: LET y=0
120 LET i=h/4: LET v=0
130 LET r=x: LET s=y: LET z=0
140 LET x=x+i*v: LET y=y+i*w
150 GO SUB 230
160 FOR t=1 TO 170
170 LET yr=1948+INT (t/4.5)
180 PRINT AT 0,26;yr
190 LET x=x+h*v: LET y=y+h*w
200 GO SUB 230
210 LET v=v+h*b: LET w=w+h*c
220 GO SUB 260: NEXT t: STOP
230 LET e=x*x+y*y: LET d=SQR e
240 LET a=-g/e: LET b=a*x/d
250 LET c=a*y/d: RETURN
260 PLOT INK 4;40+x/5,y/5+80
270 LET x(t)=x/5: LET y(t)=y/5
280 IF y<0 THEN GO TO 300
300 PLOT OVER 1;40+x/5,y/5+80
310 PRINT #0; FLASH 1;” Comet at perihelion passage ”
320 PAUSE 300: INPUT “”
330 FOR t=169 TO 1 STEP -1
340 LET yr=2023+INT (-t/4.5)
350 PRINT AT 0,26;yr
360 PLOT INK 6;40+x(t),-y(t)+80
370 PAUSE 10: NEXT t: STOP
390 CIRCLE 40,80,8
400 CIRCLE 40,80,40
410 FOR n=1 TO 3: READ a,b: PLOT 40+a,20: DRAW 0,120,b: NEXT n
420 PRINT AT 13,1;”Earth”
430 PRINT AT 18,1;”Jupiter Saturn Uranus Neptune”: RETURN
440 DATA 40,2,105,1.1,160,.9 | 0.861327 | 3.839378 |
The latest news about space exploration and technologies,
astrophysics, cosmology, the universe...
Posted: Jan 05, 2015
New instrument reveals recipe for other Earths
(Nanowerk News) How do you make an Earth-like planet? The "test kitchen" of Earth has given us a detailed recipe, but it wasn't clear whether other planetary systems would follow the same formula. Now, astronomers have found evidence that the recipe for Earth also applies to terrestrial exoplanets orbiting distant stars.
"Our solar system is not as unique as we might have thought," says lead author Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics (CfA). "It looks like rocky exoplanets use the same basic ingredients."
Dressing presented the research today in a press conference at a meeting of the American Astronomical Society.
The key to the discovery was the HARPS-North instrument on the 3.6-meter Telescopio Nazionale Galileo in the Canary Islands. (HARPS stands for High-Accuracy Radial velocity Planet Searcher.) It is designed to accurately measure the masses of small, Earth-sized worlds. Those measurements are crucial to determine densities and therefore compositions.
How do you make an Earth-like planet? The 'test kitchen' of Earth has given us a detailed recipe, but it wasn't clear whether other planetary systems would follow the same formula. Now, astronomers have found evidence that the recipe for Earth also applies to terrestrial exoplanets orbiting distant stars. (Image: David A. Aguilar, CfA)
"Our strategy for using HARPS-North over the past year has been to focus on planets less than two times the diameter of Earth and to study a few planets really well," explains Harvard astronomer David Charbonneau (CfA), who currently heads up the HARPS-North Science Team.
Most recently the team targeted Kepler-93b, a planet 1.5 times the size of Earth in a tight, 4.7-day orbit around its star. The mass and composition of this world were uncertain. HARPS-North nailed the mass at 4.02 times Earth, meaning that the planet has a rocky composition.
The researchers then compared all ten known exoplanets with a diameter less than 2.7 times Earth's that had accurately measured masses. They found that the five planets with diameters smaller than 1.6 times Earth showed a tight relationship between mass and size. Moreover, Venus and Earth fit onto the same line, suggesting that all these worlds have similar rock-iron compositions.
As for the larger and more massive exoplanets, their densities proved to be significantly lower, meaning that they include a large fraction of water or other volatiles, hydrogen and/or helium. They also showed more diverse compositions rather than fitting into a single group like the smaller terrestrial worlds.
The team also noted that not all planets less than six times the mass of Earth are rocky. Some low-mass worlds with very low densities are known (such as the planets in the Kepler-11 system). But for typical close-in small planets, the chances are high that they share an Earth-like composition.
"To find a truly Earth-like world, we should focus on planets less than 1.6 times the size of Earth, because those are the rocky worlds," recommends Dressing.
Making Other Earths
Makes one small model planet
1 cup magnesium
1 cup silicon
2 cups iron
2 cups oxygen
1/2 teaspoon aluminum
1/2 teaspoon nickel
1/2 teaspoon calcium
1/4 teaspoon sulfur
dash of water delivered by asteroids
Blend well in a large bowl, shape into a round ball with your hands and place it neatly in a habitable zone area around a young star. Do not over mix. Heat until mixture becomes a white hot glowing ball. Bake for a few million years. Cool until color changes from white to yellow to red and a golden-brown crust forms. It should not give off light anymore. Season with a dash of water and organic compounds. It will shrink a bit as steam escapes and clouds and oceans form. Stand back and wait a few more million years to see what happens. If you are lucky, a thin frosting of life may appear on the surface of your new world.
Source: Harvard-Smithsonian Center for Astrophysics | 0.874906 | 3.401728 |
This is a composite image of the small moons of Saturn.
Click on image for full size
Epimetheus was discovered by R. Walker in 1966. Epimetheus is the 4th closest moon to Saturn, with a standoff distance of 151,422 km. Epimetheus is one of the small moons
, being 70 x 50 km (45 x 33 miles) in size. Its dimensions make Epimetheus about the size of the city of Los Angeles.
Epimetheus and Janus orbit Saturn together. They are only 50 km (33 miles) apart as they orbit Saturn, which is a little like having two moons in the same city. The fact that they are so close may mean that they are two pieces of what may once have been a single moon.
As a small moon, the composition and surface features of Epimetheus are unknown.
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Below is the second part of my interview with planetary geologist Bethany Ehlmann. In the first part, she discussed two of her recent papers on Martian geology (see citations below). In this segment, she discusses water on Mars more generally.
Bethany Ehlmann: Part of being a graduate student is that I’m still learning what’s been done before. So with that caveat…
NA: I understand. I’m writing my PhD thesis now, and I’m certainly discovering things now in the literature that I wish I had known about before I started my work!
BE: I really think it goes all the way back to Percival Lowell’s canali: artificial straight channels that he thought he saw in his telescope. It really captured the public and scientific imagination even though later scientists couldn’t replicate his find.
By the time NASA sent the first Mariner spacecraft, no one believed in the “canali” (or Martians that built them), but we weren’t sure what we’d find. Mariner revealed a cratered Mars much like the Moon. Little evidence of water. But, when the Viking orbiters started mapping, the big channel systems like Kasei Vallis, Margaritifer Terra, and Vallis Marineris were obvious.
NA: So, this was in the 1970s.
BE: Right. Then we sent Viking to the surface. Some optimistic people thought we’d find life. But, the surface was cold and very dry. And, the life detection chemical experiments didn’t provide any conclusive evidence for life. That was quite a damper. Perhaps we expected too much of Mars.
We = science community… I wasn’t born yet!
NA: The ubiquitous scientific “we”.
BE: Right. So, then the questions became ones of climate and water. Was Mars once really wet? If so, why did it change to the cold dry place it is today?
Mars exploration didn’t really become the fast-advancing discipline it is today until the late 1990s. The Pathfinder rover and Mars Global Surveyor suite of instruments followed on the heels of an announcement of potential evidence for life in a Mars meteorite ALH84001.
NA: What did Pathfinder find?
BE: Pathfinder landed in Ares Vallis, in a field of rocks and sediments thought to be the end of a large catastrophic outflow channel.
NA: What does that mean: “catastrophic outflow channel”?
BE: An enormous, single (or just a few) event flood. We only have a few Earth analogs. The Channeled Scablands in Washington State are a catastrophic outflow caused by the breaking of an ice dam of glacial Lake Bonneville some 10000 years ago. Scoured terrain, very large scale ripple marks, huge transported boulders.
NA: So, this would just be a very obvious visible sign of past running water.
BE: Exactly. But what was interesting about Pathfinder was that the rover found boulders shaped like they might have been flood transported, but there was very little chemical evidence for alteration of rocks, suggesting the water hadn’t hung around terribly long. Evidence from a thermal emission spectrometer, TES, also didn’t find much evidence for water altered minerals, suggesting most of Mars was dry.
The exception was hematite deposits found in Terra Meridiani, where we ended up sending the Opportunity rover in 2004.
NA: So, I got the feeling that Opportunity’s findings were a big deal. But, did we already know what to expect before Opportunity arrived?
BE: So there are several ways hematite can form. Many of which involve water. A few of which involve volcanic processes and not water or at least not a lot of it. “Following the water” story was the mantra that drove Mars exploration at the time. That’s why we sent one rover to these enigmatic hematite deposits in Meridiani. And another to a crater with a channel leading into it that looked like it once held a lake.
Hematite is Fe2O3, an iron oxide.
NA: And then when Opportunity arrived, scientists were able to definitively say that this hematite was the result of a past lake?
BE: Exactly. We saw that the hematite was part of a rock unit with small scale ripple marks. Sedimentologists know from our experience on Earth that these form in shallow water. The rocks were basaltic sand and sulfate salt. Some of the hematite was in little round concretions indicating they “grew” in the sediments when groundwater flushed through. Our best guess was that Meridiani looked a lot like some of the Southwest U.S. Shallow ephermeral lakes: dry, and salty. And acidic. Sand dunes interspersed shallow lakes, and a groundwater driven water system.
NA: I see. So, I guess that Opportunity was the big “ah ha” moment, although really this was the culmination of decades of work.
BE: That’s right. It confirmed standing water for a pretty long period of time on the surface of Mars. Plus more just beneath the surface. Then the story of the near infrared spectrometers like OMEGA and CRISM kicks in.
NA: Working out the details.
BE: Well, more than that. So, Opportunity’s roving revealed this shallow, salty environment: hematite (plus other iron oxides) and sulfate salts. Shortly thereafter, also 2004, OMEGA mapped out the surface of Mars and found there were actually a lot of hydrated minerals, indicating alteration of rocks by water that we just hadn’t seen before.
NA: So, water was once actually quite widespread on the surface of Mars.
BE: Exactly. One class was the sulphate salts like we saw in Meridiani. And, one was these phyllosilicates or clays which we see in Jezero crater, Nili Fossae, Mawrth Vallis, and which indicate a whole different kind of environment: a lot of water, a much longer period of time, and neutral to alkaline rather than acidic.
Jean-Pierre Bibring advanced a new paradigm to explain Mars history, based on this mineralogy. The Noachian (earliest period) where we see geomorphically well-developed valley systems was the equivalent to a “phyllosian” or clay forming period. Lots of water. Neutral to alkaline.
Then there was a global change, a little before the Hesperian catastrophic outflow channels. Perhaps a big pulse of volcanic activity? Perhaps a loss of atmosphere? In any event, Mars’ liquid water started to go away. It was more desert-like, salty, and acidic. This led to sulphate salt deposits in the theiikian period.
NA: When did this happen?
BE: Around 2.5 or 3 billion years ago. Since then Mars has been very dry and cold. Little water, maybe some ice and glacial deposits, but not extensive interaction of water and rock.
NA: You pointed me to this figure from Bibring to illustrate these changes:
NA: Right, so there’s no longer any liquid water on Mars, but there is frozen water, both in the ice caps and underground, I believe.
BE: Exactly. Lot’s of it. So now we’ve got this dry but icy current Mars. Maybe when it tilts 60 deg on its axis every few 100,000s to millions of years there’s some ephemeral water.
But we’ve got this ancient Mars that was quite wet indeed. With many different types of watery habitats. Some acidic, some alkaline. Some underground some above ground
NA: Why was there so much excitement recently when Phoenix discovered water ice just below the surface?
BE: It confirmed something researchers inferred should be there from both orbital data and climate modeling. And, it allowed us to conduct chemical measurements on the ice with Phoenix–light element, including carbon, analysis. Expect to hear results of those experiments later this year.
NA: Oh, OK. Do you have any previews for the readers now?
BE: I don’t have any special access to those results. Working on one mission team–the CRISM instrument on Mars Recon. Orbiter–keeps me busy enough 😉
NA: I can imagine. OK, so, you’ve been kind enough to grace us with your presence, but, clearly, many other people were involved in these papers we’ve been discussing.
NA: Could you briefly tell us who the key people are?
BE: Heading all the way back to Percival Lowell or just our current crop? 😉
NA: Let’s just stick to the Nature Geoscience paper and the Nature paper. I imagine that both of us might need to get back to doing some science at some point.
BE: Exactly! Plus, it’s thousands of names for the whole Mars water story.
NA: Your papers always have so many authors. I think it makes biologists suspicious.
BE: It takes a lot to get a spacecraft up in orbit and then the data into a form that can be analyzed on the ground. No more authors than some big bio lab studies or big physics projects, I think 😉
In any case, the Nature paper is led by Jack Mustard, a professor at Brown University, deputy PI of CRISM, and also my advisor. Scott Murchie is at the Applied Physics laboratory and is PI of the CRISM instrument. Stay tuned for his paper, focused on sulphates, which is in the publication process as we speak.
NA: So, in your papers do you have a “senior author”? This author would be listed last on a biological paper.
BE: Ah. Different system. Here the lead author is first. Usually then it’s in order of contribution. For large teams, it’s sometimes just alphabetical.
NA: With a name like Anthis, maybe I’m in the wrong field.
BE: I guess so, Nick. Well, you’re welcome in planetary geology any time.
NA: I’ll keep it in mind.
Now, before we each get back to doing some science, it’s time for the lightning round.
NA: It’s just three questions, so it shouldn’t be too bad.
BE: Shoot then.
NA: Question 1: Did you ever want to be an astronaut, and is that still a possibility?
BE: Haha. Well, I was one of those little kids who had bad eyes and wore glasses since the age of four. So, it was not really a possibility until PRK came along ;). I find the exploration and the science that we can do with spacecraft so exciting to be a part of, I’m not sure I’d trade it for astronaut training. But, if there were a chance to go to the Moon or Mars, I might reconsider. I am a geologist, after all, and it’s always better to see the rocks in person! And, it would be a great personal challenge.
NA: I bet.
OK, question 2: Are we more likely to find life on Mars or somewhere outside of our solar system?
BE: That’s an interesting one, especially since we’re extrapolating from a single data point (Earth). On Mars, I think it comes down to: was there enough time for life to get started before things dried up? I think if we keep our exploration going at this pace, we’ll get the answer in my lifetime. I’m sure there’s life elsewhere in the galaxy. The question is when and how we might find it
NA: Finally, question 3: if you had NASA Administrator Michael Griffin’s job, what would your priorities be?
BE: The NASA Administrator job is a tough one because you’re leading the most capable agency in the world–really set up to figure out how to be able to accomplish anything–on a limited budget.
That being said, three things. I think we need to establish a reliable means of getting humans and cargo into space, post-shuttle. This may mean one method for both, or a mix of methods. Second, I think we need to reestablish, in concert with other agencies, NASA’s preeminence in Earth observation: monitoring our planet for changes in climate, land use change. Third, we need to set up programs of robotic exploration that allow young scientists who are becoming experts in Mars, in the outer planets, in comets and asteroids clear future support to enable our rapidly evolving understanding of these bodies to continue apace, and to keep exciting the public with the new findings.
The last one is especially important. One reason I’m blogging with you is because I think what NASA does is often the most exciting stuff people don’t know about.
NA: Is there too much focus on manned space exploration right now?
BE: Manned exploration has always been the biggest budget item. I think it should be a big part of our space program. I’d love to send humans to Mars. We’d find out so much. But we need to be careful that when budget overruns happen in the manned program that they don’t swallow entire robotic missions and the scientific community that works on planetary missions.
We shouldn’t be competing with each other — human program vs robotic.
NA: I’m sure it’s a very difficult balancing act.
Well, speaking of balancing acts, I suppose we should think about our scientific careers as well. So, on that note, let’s wrap this up, since I don’t want to keep you any longer.
I really appreciate you taking your time to talk with me, and hopefully we’ll have the chance to do it again sometime.
BE: I had a great time chatting with you, too.
NA: Best of luck with your future work. It’s certainly been productive so far.
BE: Thanks, Nick. Yours as well.
Ehlmann, B.L., Mustard, J.F., Fassett, C.I., Schon, S.C., Head III, J.W., Des Marais, D.J., Grant, J.A., Murchie, S.L. (2008). Clay minerals in delta deposits and organic preservation potential on Mars. Nature Geoscience, 1(6), 355-358. DOI: 10.1038/ngeo207
Mustard, J.F., Murchie, S.L., Pelkey, S.M., Ehlmann, B.L., Milliken, R.E., Grant, J.A., Bibring, J., Poulet, F., Bishop, J., Dobrea, E.N., Roach, L., Seelos, F., Arvidson, R.E., Wiseman, S., Green, R., Hash, C., Humm, D., Malaret, E., McGovern, J.A., Seelos, K., Clancy, T., Clark, R., Marais, D.D., Izenberg, N., Knudson, A., Langevin, Y., Martin, T., McGuire, P., Morris, R., Robinson, M., Roush, T., Smith, M., Swayze, G., Taylor, H., Titus, T., Wolff, M. (2008). Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument. Nature, 454(7202), 305-309. DOI: 10.1038/nature07097 | 0.881702 | 3.271821 |
The flag is probably gone. Buzz Aldrin saw it knocked over by the rocket blast as he and Neil Armstrong left the moon 39 summers ago. Lying there in the lunar dust, unprotected from the sun’s harsh ultraviolet rays, the flag’s red and blue would have bleached white in no time. Over the years, the nylon would have turned brittle and disintegrated.
Dennis Lacarrubba, whose New Jersey-based company, Annin, made the flag and sold it to NASA for $5.50 in 1969, considers what might happen to an ordinary nylon flag left outside for 39 years on Earth, let alone on the moon. He thinks for a few seconds. “I can’t believe there would be anything left,” he concludes. “I gotta be honest with you. It’s gonna be ashes.”
There are other signs of aging at Tranquillity Base. The shiny gold foil on the base of the lunar lander is shiny no more—it would have darkened and flaked away long ago. The once-white life support backpacks, tossed out unceremoniously after Armstrong and Aldrin made their brief spacewalks, have likely turned yellow. The TV camera, the seismometer, the discarded hammer—anything made of glass or metal—are probably okay. And the famous bootprints? They may still be as crisp as the day they were made. Or, they may have the thinnest coating of dust from small grains moving around continually on the lunar surface (see “Stronger than Dirt,” Aug./Sept. 2006).
The truth is, no one knows exactly what the Apollo landing sites will look like after four decades. Nobody thought it would take us this long to go back.
And now we are.
New cameras in orbit around the moon have begun returning photos of sights unseen in a generation. Japan’s Kaguya spacecraft, which arrived in lunar orbit in October, Dave Scott and Jim Irwin’s rocket engine as they touched down in Mare Imbrium in July 1971. They and other Apollo moonwalkers routinely photographed the white patches when they looked back at their landing sites from lunar orbit before returning home. Kaguya’s best camera has a resolution, or ability to separate two objects, of 10 meters (33 feet)—just enough to make out the white patch of disturbed soil. The camera can’t quite resolve the squat, 30-foot-wide base of the Apollo 15 lander sitting in the middle of that patch. But the Kaguya photo shows a dark feature that may be the lander’s shadow.
Until Kaguya, there hadn’t been a camera good enough to spot Apollo artifacts on the moon since the last astronauts left, in 1972. Neither the U.S. Clementine nor the European SMART-1 moon probes, launched in 1994 and 2003, respectively, had enough resolution. (In case you’re wondering, even the best ground-based telescopes can’t make out Apollo hardware on the moon. They have the resolution—some produce sharper images than the Hubble Space Telescope—but the objects left by the astronauts aren’t bright enough to be seen.)
So it’s a job for lunar orbiters. Next up is Chandrayaan, India’s first planetary science spacecraft, which is due to arrive at the moon this fall with a camera twice as sharp as Kaguya’s. That should be good enough to see more than smudges in the dirt, according to Mark Robinson, a planetary scientist at Arizona State University whose own high-resolution camera will fly on NASA’s Lunar Reconnaissance Orbiter (LRO) in November. “I will be surprised if Chandrayaan can’t detect the [lunar landers],” says Robinson. The bases of the landers, six of which are still on the moon, will be only about two picture elements, or pixels, across in the five-meter-resolution images—not enough for clear identification. But in photos taken at low sun angles, says Robinson, the landers’ shadows should appear as dark streaks up to 10 pixels long. This technique has paid off in the past. Long before the first Apollo landing, scientists studying photos taken by the Lunar Orbiter 3 spacecraft noticed a shadow cast by the Surveyor 1 robot, which had landed on the moon eight months earlier.
If the Chandrayaan scientists are “really, really lucky,” says Robinson, they might also detect the shadows of the lunar rovers, the two-man buggies that astronauts left at the Apollo 15, 16, and 17 sites. The 10-foot-long rovers would be less than a pixel in size, but their shadows could be as long as four or five pixels, says Robinson.
His own instrument on the LRO will do a thorough job of “revisiting” the Apollo sites, beginning in early 2009. The narrow-angle camera can resolve details about the size of a microwave oven. As the LRO spacecraft orbits from pole to pole and the moon turns slowly beneath it, it will eventually get a look at all six Apollo landing sites. The resulting pictures should clearly show the landers and the rovers, says Robinson. Even some of the larger experiment packages left behind by the moonwalkers might be identifiable from their shadows. The LRO images should also show rover tracks and the dark areas where the astronauts scuffed up the lunar soil. The new information can then be used to refine maps of the moonwalkers’ historic traverses.
And that’s just Apollo. Some of the most fascinating pictures the LRO takes will show obscure spacecraft that nobody’s seen, or even thought much about, since they left Earth more than 40 years ago. Phil Stooke, a planetary geographer at the University of Western Ontario and author of The International Atlas of Lunar Exploration, has a list of targets he can’t wait to see, including two Russian spacecraft—Luna 9, which in 1966 made the first soft landing on the moon, and Luna 17, which in 1970 delivered the first geological rover, Lunokhod 1. Neither spacecraft’s location is precisely known, says Stooke. Nor are the exact locations of many of the craters made when orbiters and spent rocket stages crashed into the moon in the 1960s. Altogether, about 100 tons of junk is strewn across dozens of spots around the moon. Over the next two years, we’ll rediscover much of it.
Of course, the LRO’s mission is not finding old spacecraft. The orbiter is producing high-resolution maps for planning the next wave of lunar exploration. But since astronauts aren’t expected to head moonward until 2020 at the earliest, the initial users of the maps are likely to be surface-exploring robots, and the first of those could arrive as early as next summer, in time for the 40th anniversary of Apollo 11. An intense contest is under way among several groups vying for the $30 million Google Lunar X Prize, which will go to the first privately funded team that lands a rover on the moon, drives it at least 500 meters (about a third of a mile), and returns video and still images to Earth.
Just as the first X Prize spurred aircraft designer Burt Rutan to build a one-man rocketplane that flew to the edge of space and back (see “Confessions of a Spaceship Pilot,” June/July 2005), the Google prize is meant to encourage innovation in robotic exploration of the moon. So far, 13 teams have entered, from as far away as Romania and Malaysia.
The Rutan in this race is Carnegie Mellon University’s Red Whittaker, one of the world’s foremost roboticists. Whittaker-built rovers have explored volcanoes, deserts, and Antarctic ice fields. Last year one of his vehicles won the DARPA Urban Challenge, a road rally for autonomous robot cars, sponsored by the Defense Advanced Research Projects Agency. Whittaker’s X Prize team, Astrobotic Technology, is loaded with experience, starting with project manager Tony Spear, the man who led the NASA mission that in 1996 landed the Sojourner rover on Mars. The University of Arizona’s Lunar and Planetary Laboratory, currently operating the Phoenix spacecraft on Mars, is a partner. Astrobotic’s president is David Gump, a space entrepreneur who in 1989 started a venture called LunaCorp, which also planned to drive a rover around the moon and sell the video. Whittaker was to have built the robot. Although LunaCorp folded in 2003, Gump is betting that it was mostly because the company was ahead of its time.
Not that Astrobotic’s proposed “Tranquillity Trek” to the Apollo 11 site will be a cakewalk. For one thing, says Gump, the mission will cost about $100 million—far more than Google is paying in prize money. While he looks for financial backers, the technical team is working feverishly, trying to hold on to the possibility of a launch next year. Astrobotic claims that once it raises the money, it can be on the moon within 18 months.
After landing, Astrobotic’s rover will have just 14 days—a lunar day—to reach the Apollo 11 site and take pictures. Equipping the robot to withstand the frigid, two-week lunar night would have complicated the engineering and driven up the cost. So this will be a short, focused sprint to Tranquillity Base. The rover moves at “about a human walking pace,” says Gump, and will have to reach its destination before nightfall, so success requires a precision landing. The team expects to come down about half a mile from its target, with a precision measured in meters—unprecedented accuracy for a robotic planetary lander.
This is where another Astrobotic partner, Raytheon, comes in. The company built the Navy missile that intercepted and destroyed a military reconnaissance satellite falling from orbit last February. Astrobotic will license the Raytheon “digital scene matching” technology used in cruise missiles—which compares real-time pictures of the looming target with photos stored in an onboard computer—to ensure precise navigation.
Another serious contender to win the Google prize is Quantum3, based in Vienna, Virginia, and led by NASA veterans including Courtney Stadd, the agency’s former chief of staff, and Liam Sarsfield, its former deputy chief engineer. Quantum3 is counting on a new method of landing that Stadd says is different from what other teams are using. Then, instead of rolling on wheels, the lander will “hop” around the surface with small rocket blasts. The price tag, says Stadd, is much lower than $100 million, but is still more than the Google prize money. Like Astrobotic, Quantum3 is heading for the Apollo 11 site. As of May, Stadd still hoped his team could make it there by the 40th anniversary, in July 2009.
All the proposed traffic around Tranquillity Base makes some in the space community worry that the historic Apollo sites will get trampled. Beth O’Leary, a New Mexico State University anthropologist who has led a campaign, so far unsuccessful, to declare the Apollo 11 site a national historic landmark, is concerned that the robots could inadvertently destroy a priceless artifact. Despite the best intentions of the X Prize teams, she says, “it’s untried technology.”
So far, it’s a controversy without much argument. “Our top priority is protecting Apollo 11 from any disturbance,” says Gump. “We’re not rolling over any footprints.” Astrobotic’s rover will stay outside the perimeter of Armstrong and Aldrin’s farthest travels, he says. Pictures of the lander will be taken from a “respectful distance” with a telephoto lens.
Gump hasn’t given much thought to what the pictures will show. But he looks forward to the adventure playing out on live TV, “like opening Al Capone’s vault.”
Might the photos, like the vault, prove disappointing? There’s a chance—a very remote one—that the lander has been destroyed by a meteoroid. We know of at least one Apollo artifact that’s still intact, though, right where Aldrin left it on July 21, 1969. Tom Murphy and his colleagues at the University of California at San Diego still interact with it regularly. Every few nights, they point a laser at a quartz prism on the surface. Then the scientists time the beam that bounces back, a measurement useful for gravitational physics studies. In the two years he’s been pinging the Apollo retro-reflectors, Murphy has become increasingly puzzled. Despite the exquisite sensitivity of his instrument on Earth, the signal that bounces back from the moon is 10 times weaker than it should be. After ruling out other explanations, Murphy has come up with a tentative theory: The reflectors left on the moon have degraded over time. Maybe, he thinks, they have been lightly etched by all those sharp dust grains bouncing around for years on the lunar surface. If so, the once-pristine glass may now be frosted, which would explain the loss in signal strength.
It’s the kind of thing NASA engineers planning the next lunar outpost would love to know. The rest of us just want to find out what happened to the flag. We may not have long to wait.
Neil Armstrong and Buzz Aldrin left behind 66 items at Tranquillity Base, from their removable lunar overshoes (which actually stamped the iconic bootprints in the dust) to a “urine collection assembly, large” and sick bag (presumably unused — none of the Apollo 11 astronauts reported throwing up during the mission). Armstrong and Aldrin stuffed personal items in a large bag and threw it overboard just before leaving. Other objects still on the surface include tools; a TV camera, its stand, and cable; and a clothesline-like contraption for hoisting equipment back into the lander at the end of the moonwalk. The astronauts also left a mission patch memorializing the astronauts killed in the Apollo 1 launch pad fire; medals honoring Soviets Yuri Gagarin, the first human in space, and Vladimir Komarov, the first person to die during a space mission; a silicon disk etched with messages from world leaders; and a small, gold olive branch as a sign of peace. | 0.826911 | 3.122784 |
As 2005 comes to a close, let's take a look back at the show-stopping new stories that rocked the astronomical community. Last year, all eyes were on NASA's Mars rovers, but while the pair still miraculously cruise along the Martian landscape, many new and exciting developments have climbed their way to the top of this year's list.
Huygens Arrives on Titan
2005 kicked off with a spectacular feat. After a 7½-year interplanetary journey aboard Cassini, the European Space Agency’s Huygens probe finally reached Saturn’s moon Titan on January 14. Shortly after touchdown, the findings along with 350 or so first images of the large moon’s surface came flooding in to ESA headquarters. Among them: water ice and methane on the moon’s surface, haze in its atmosphere, possible drainage channels, and much more. Planetary scientists will be working this treasure trove of data for years to come.
First Exoplanet Image
The first direct image of an extrasolar planet was an elusive goal this year. But thanks to a team led by Gael Chauvin (European Southern Observatory) astronomers have finally captured the photograph. Chauvin's team found the planet candidate in April 2004, but the discovery was not picture perfect; its pitiful mass, just 5 times that of Jupiter, depended on an unproven physical connection with a brown dwarf called 2M 1207. But in May, Chauvin's team released follow-up VLT observations that clinched the case for the two objects being bound. "This confirmation, by common proper motion, that the companion is really orbiting the brown dwarf puts the entire system on firm footing," says independent commentator Geoff Marcy (University of California, Berkeley), who leads the team that has discovered the majority of the 160 or so known exoplanets.
Amateurs Make Exoplanet Discoveries
Among those known exoplanets, amateur astronomers made one of the most important discoveries this year an exoplanet milestone for the amateur community. New Zealand amateurs Grant W. Christie and Jennie McCormick made crucial observations in April that helped several international collaborations of professional astronomers nail down the existence of the planet. The newly discovered planet, just the second one found by gravitational microlensing, is roughly three times the mass of Jupiter and orbits its unnamed host star at approximately three times the average Earth-Sun distance.
Amateur astronomers have previously detected exoplanets transiting their parent stars, but only after professionals made the initial findings. However, later in the year this proved not to be the case. A day before professional astronomers announced a new transiting planet, California amateur astronomer Ron Bissinger detected a partial transit of the same object. HD 149026b is now the third transiting exoplanet detected by amateurs.
NASA Gets New Chief and Returns to Flight
Physicist and aerospace engineer Michael D. Griffin took the helm as NASA's next administrator on April 13th, just one month following his nomination. Griffin succeeded Sean O'Keefe, who resigned from the space agency in mid-February. In his first year on the job Griffin set the tone by participating in a study of the Bush administration's "Vision for Space Exploration." Along with many resolutions, the group recommended phasing out the Space Shuttle sooner than the president's proposed date of 2010, accelerating the development of a new piloted space vehicle, and curtailing spending on the International Space Station (ISS) to help fund future missions to the Moon and Mars.
An overdue servicing mission to the Hubble Space Telescope seems within reach now that the space shuttle has returned to flight. Space Shuttle Discovery launched from NASA's Kennedy Space Center on July 26, ending a 2½ year lull following the tragic Columbia disaster that grounded the fleet in 2003. Discovery returned to Earth August 9th at Edwards Air Force Base in California. A mandated follow-up "return to flight" mission is currently set for launch in May 2006.
Asteroid 2004 MN4: The Near Miss and …
The recently discovered near-Earth asteroid 2004 MN4 made headlines early this year when astronomers estimated that it had a 1-in-38 chance of hitting Earth in 2029. The threat quickly passed when old images narrowed down the asteroid's orbit well enough to guarantee that it would not hit our planet in 2029. Extremely precise radar observations by NASA's Near Earth Object Program calculate that the asteroid will pass 4.7 Earth radii (30,000 kilometers, or 18,600 miles) from Earth's surface on April 13, 2029. With an estimated diameter of 320 meters, 2004 MN4 will appear up to 2 arcseconds wide, making it barely resolvable in amateur telescopes.
…The Almost Miss: April's Total Solar Eclipse
To eclipse chasers in the Pacific Ocean on April 8th, a near miss would have been devastating. The year's hybrid solar eclipse was viewed across the land in parts of Central America and the Caribbean where the eclipse was partial. But the total phase of this hybrid solar eclipse was viewed by an estimated 1,500 passengers and crew members aboard three cruise ships since the path of totality never made landfall. Experienced eclipse-chasers aboard the MV Discovery described the eclipse as the most colorful one they'd ever seen. S&T editor in chief and observer Rick Fienberg reported the event vividly: "When totality set in, the Moon's black silhouette was rimmed with a thin and nearly complete ring of magenta fire that was in turn enveloped by a fainter and more expansive white glow the solar corona, or outer atmosphere that extended in opposite directions like a bow tie."
The next total solar eclipse happens on March 29, 2006, for parts of western and northern Africa, the eastern Mediterranean, Turkey, and Central Asia. A partial eclipse will be visible across Europe, the Middle East, most of western Asia, and most of Africa.
Bursting Stars: Gamma Ray Bursts, Magnetars, and Supernovae
A slew of observations made this year have led the way to a better understanding short-lived species of gamma-ray bursts (GRBs). Short GRBs (those lasting less than 2 seconds) flash in every direction of the sky. Until this year, astronomers could only theorize about their cause, since the bursts notoriously expire almost as quickly as they shine. The first breakthrough came as NASA's Swift Observatory recorded a short burst on May 9th lasting just 0.03 second. The space telescope swiveled around and imaged a weak, fast-fading X-ray afterglow the first ever captured from a short GRB source. By targeting the event's location, Swift took a crucial first step toward discovering the mechanism causing these types of events.
Then in mid-year, the long-standing mystery of these bursts' origins cracked open. A short burst flared on July 24th and observations of the afterglow, which lingered for 35 hours, support the leading theoretical model: that a binary system, consisting of either two neutron stars or a black hole and a neutron star, come together in an explosive flash of gamma rays. Furthermore, the observed events each occurred in the outskirts of old elliptical galaxies with minimal star formation evidence that strengthens the merger theory.
While the May 9th and July 24 events provide strong evidence that short GRBs come from mergers, a similar event observed on December 27, 2004, is too fresh in this year's recollection to be ignored. Powerful flares on magnetars neutron stars with stupendously powerful magnetic fields are viable sources of gamma rays in the universe, as the giant flare from the Milky Way magnetar SGR 1806-20 reminded us. This event was the brightest gamma-ray source from outside the solar system ever observed in the history of astronomy, perhaps only the Sun has doused Earth with more total energy than SGR 1806-20's superflare did during the two-tenths of a second that it peaked in intensity. (Thanks to the magnetar's great distance, the superflare posed no threat to humanity or Earth's biosphere.)
Then, on November 3rd, another flare occurred. Lasting just one-tenth of a second, that flare possibly originated from a magnetar in another galaxy. The powerful burst of gamma rays were detected originating from an area in Ursa Major, near M81 and M82, two relatively large galaxies located about 12 million light-years away. If the burst originated in M81 or M82, its total energy and spectrum closely resemble those of the December 2004 giant flare from SGR 1806-20.
The next most energetic explosions in the universe's arsenal are supernovae. They may seem common, but there are still quite a few attention getters waiting to happen. With impressive diligence, the powerhouse Puckett Observatory Supernova Search (POSS), an international team of volunteer amateur astronomers, made its 100th supernova discovery on July 15th. Tim Puckett, Ajai Sehgal, and Jack Newton found the 18th-magnitude stellar explosion by taking an image and manually "blinking" (comparing) it with those in the archives. The discovery was confirmed the following night. To date, Puckett and his POSS team have taken more than 850,000 images, which are distributed via the Internet. On the flip side, using his eyes, a 12-inch Newtonian reflector, and uncanny intuition, Robert O. Evans made his 40th visual discovery of a supernova on August 4th a world record. Evans spotted and recognized the new 14th-magnitude star in the barred spiral galaxy NGC 1559 and recognized the newcomer, supernova 2005df, with his prodigious memory for star fields.
Astronomers Discover "10th Planet" and Pluto Bulks Up with Two New Moons
2005 will forever be remembered as the year a new planet was discovered. Or will it? The planet debate will rage on as the year comes to a close, but one thing is for sure: In July Michael E. Brown (Caltech) and his team of astronomers announced the discovery of the largest Kuiper Belt object (KBO) ever and it's bigger than Pluto.
The object, designated 2003 UB313, is more than twice Pluto's average distance from the Sun, making it the farthest object ever seen in the solar system. At magnitude 18.9 with a highly inclined (44°) orbit, it's no wonder it was only discovered recently; no one was looking for planets so far from the plane of the solar system.
Brown and his colleagues later discovered that the potential new planet has a small moon. The satellite is about 100 times (5 magnitudes) fainter than 2003 UB313 and its diameter is about a tenth that of the main body. 2003 UB313 is currently under review by an International Astronomical Union (IAU) committee charged with deciding whether the object should be officially classified as the solar system's tenth planet or a mere trans-Neptunian object.
Perhaps to bolster its own newly exposed planet status, Pluto reveled two new moons this year. The Hubble Space Telescope (HST) took the images that revealed the discovery, giving the ninth planet three satellites in total and making it the first quadruple Kuiper Belt object.
Deep Impact Leaves Its Mark
Finally, 2005 was marked as a year of fireworks on July 4th when NASA scientists successfully slammed Deep Impact's 372-kilogram (820-pound) projectile into Comet Tempel 1. The head-on collision took place at more than 37,000 kilometers (23,000 miles) per hour, generating the explosive force of nearly 5 tons of TNT. The impactor's camera relayed a steady stream of detail-rich images until just seconds before its demise.
It's been months since the Deep Impact comet crash, and astronomers are continuing to learn about the physics of the event, the nature of the excavated debris, and the structure of the comet's nucleus. The latest findings of the $333-million mission were discussed last September, when the American Astronomical Society's Division for Planetary Sciences met in Cambridge, England.
Ring in the New Year
As a quick search of our online news archive makes abundantly clear, this annual review only scratches the surface of another amazing year in amateur astronomy and scientific space exploration. That's why S&T's editors and contributors with the help of the worldwide astronomical community work overtime to keep you in touch with the sky and its endless mysteries. In the meantime, we wish you a safe and happy New Year. | 0.94128 | 3.731625 |
NASA’s Kepler telescope has discovered the existence of a world with a double sunset - as famously depicted in Star Wars more than 30 years ago.
However, unlike Star Wars' Tatooine, the circumbinary planet - which is located more than 200 light-years from Earth - is cold, gaseous and not thought to harbor life.
Nevertheless, the discovery of Kepler-16b demonstrates the diversity of planets in our galaxy. Indeed, previous research hinted at the existence of circumbinary planets, but clear confirmation proved somewhat elusive until the telescope confirmed 16b by observing transits, where the brightness of a parent star dims from the planet crossing in front of it.
"This discovery confirms a new class of planetary systems that could harbor life," Kepler principal investigator William Borucki explained.
"Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now."
According to Laurance Doyle of the SETI Institute in Mountain View, scientists detected the new planet in the Kepler-16 system - a pair of orbiting stars that eclipse each other from our vantage point on Earth.
When the smaller star partially blocks the larger star, a primary eclipse occurs, and a secondary eclipse occurs when the smaller star is occulted, or completely blocked, by the larger star. Astronomers further observed that the brightness of the system dipped even when the stars were not eclipsing one another, hinting at a third body.
The additional dimming in brightness events, known as tertiary and quaternary eclipses, reappeared at irregular intervals of time, indicating the stars were in different positions in their orbit each time the third body passed. This indicated the third body was circling, not just one, but both stars, in a wide circumbinary orbit.
The gravitational tug on the stars, measured by changes in their eclipse times, was a good indicator of the mass of the third body. Only a very slight gravitational pull was detected, one that only could be caused by a small mass.
"Most of what we know about the sizes of stars comes from such eclipsing binary systems, and most of what we know about the size of planets comes from transits," said Doyle. "Kepler-16 combines the best of both worlds, with stellar eclipses and planetary transits in one system."
Unfortunately, Kepler-16b is an inhospitable, cold world about the size of Saturn and thought to be made up of about half rock and half gas. The parent stars are smaller than our sun, with one pegged at 69% percent the mass of the sun and the other at 20%.
Kepler-16b orbits around both stars every 229 days, similar to Venus' 225-day orbit, but lies outside the system's habitable zone, where liquid water could exist on the surface, as the stars are cooler than our sun. | 0.909966 | 3.989192 |
Mosaic of Valles Marineris from the Viking Orbiter 1, reproduced at a scale of 80 meters/pixel.
Click on image for full size
Image from: Malin Space Science Systems
Steep slopes of Valles Marineris
High resolution images returned by the Mars Global Surveyor spacecraft allow closer examination of this unusual canyon. As shown here, slopes seem to descend steeply to the north and south
debris-filled gullies with intervening rocky spurs, reminiscent of terrestrial canyons.
Scientists question whether sedimentary processes, such as the ones which formed the Earth's Grand Canyon also formed these canyons. In any case,
these images indicate that there may have been a complex and extremely active early
history for geologic processes on Mars.
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J. Vanderlei Martins, University of Maryland, Baltimore County
Tiny satellites, some smaller than a shoe box, are currently orbiting around 200 miles above Earth, collecting data about our planet and the universe. It’s not just their small stature but also their accompanying smaller cost that sets them apart from the bigger commercial satellites that beam phone calls and GPS signals around the world, for instance. These SmallSats are poised to change the way we do science from space. Their cheaper price tag means we can launch more of them, allowing for constellations of simultaneous measurements from different viewing locations multiple times a day – a bounty of data which would be cost-prohibitive with traditional, larger platforms.
Called SmallSats, these devices can range from the size of large kitchen refrigerators down to the size of golf balls. Nanosatellites are on that smaller end of the spectrum, weighing between one and 10 kilograms and averaging the size of a loaf of bread.
Starting in 1999, professors from Stanford and California Polytechnic universities established a standard for nanosatellites. They devised a modular system, with nominal units (1U cubes) of 10x10x10 centimeters and 1kg weight. CubeSats grow in size by the agglomeration of these units – 1.5U, 2U, 3U, 6U and so on. Since CubeSats can be built with commercial off-the-shelf parts, their development made space exploration accessible to many people and organizations, especially students, colleges and universities. Increased access also allowed various countries – including Colombia, Poland, Estonia, Hungary, Romania and Pakistan – to launch CubeSats as their first satellites and pioneer their space exploration programs.
Initial CubeSats were designed as educational tools and technological proofs-of-concept, demonstrating their ability to fly and perform needed operations in the harsh space environment. Like all space explorers, they have to contend with vacuum conditions, cosmic radiation, wide temperature swings, high speed, atomic oxygen and more. With almost 500 launches to date, they’ve also raised concerns about the increasing amount of “space junk” orbiting Earth, especially as they come almost within reach for hobbyists. But as the capabilities of these nanosatellites increase and their possible contributions grow, they’ve earned their own place in space.
From proof of concept to science applications
When thinking about artificial satellites, we have to make a distinction between the spacecraft itself (often called the “satellite bus”) and the payload (usually a scientific instrument, cameras or active components with very specific functions). Typically, the size of a spacecraft determines how much it can carry and operate as a science payload. As technology improves, small spacecraft become more and more capable of supporting more and more sophisticated instruments.
These advanced nanosatellite payloads mean SmallSats have grown up and can now help increase our knowledge about Earth and the universe. This revolution is well underway; many governmental organizations, private companies and foundations are investing in the design of CubeSat buses and payloads that aim to answer specific science questions, covering a broad range of sciences including weather and climate on Earth, space weather and cosmic rays, planetary exploration and much more. They can also act as pathfinders for bigger and more expensive satellite missions that will address these questions.
I’m leading a team here at the University of Maryland, Baltimore County that’s collaborating on a science-focused CubeSat spacecraft. Our Hyper Angular Rainbow Polarimeter (HARP) payload is designed to observe interactions between clouds and aerosols – small particles such as pollution, dust, sea salt or pollen, suspended in Earth’s atmosphere. HARP is poised to be the first U.S. imaging polarimeter in space. It’s an example of the kind of advanced scientific instrument it wouldn’t have been possible to cram onto a tiny CubeSat in their early days.
Funded by NASA’s Earth Science Technology Office, HARP will ride on the CubeSat spacecraft developed by Utah State University’s Space Dynamics Lab. Breaking the tradition of using consumer off-the-shelf parts for CubeSat payloads, the HARP team has taken a different approach. We’ve optimized our instrument with custom-designed and custom-fabricated parts specialized to perform the delicate multi-angle, multi-spectral polarization measurements required by HARP’s science objectives.
HARP is currently scheduled for launch in June 2017 to the International Space Station. Shortly thereafter it will be released and become a fully autonomous, data-collecting satellite.
SmallSats – big science
HARP is designed to see how aerosols interact with the water droplets and ice particles that make up clouds. Aerosols and clouds are deeply connected in Earth’s atmosphere – it’s aerosol particles that seed cloud droplets and allow them to grow into clouds that eventually drop their precipitation.
This interdependence implies that modifying the amount and type of particles in the atmosphere, via air pollution, will affect the type, size and lifetime of clouds, as well as when precipitation begins. These processes will affect Earth’s global water cycle, energy balance and climate.
When sunlight interacts with aerosol particles or cloud droplets in the atmosphere, it scatters in different directions depending on the size, shape and composition of what it encountered. HARP will measure the scattered light that can be seen from space. We’ll be able to make inferences about amounts of aerosols and sizes of droplets in the atmosphere, and compare clean clouds to polluted clouds.
In principle, the HARP instrument would have the ability to collect data daily, covering the whole globe; despite its mini size it would be gathering huge amounts of data for Earth observation. This type of capability is unprecedented in a tiny satellite and points to the future of cheaper, faster-to-deploy pathfinder precursors to bigger and more complex missions.
HARP is one of several programs currently underway that harness the advantages of CubeSats for science data collection. NASA, universities and other institutions are exploring new earth sciences technology, Earth’s radiative cycle, Earth’s microwave emission, ice clouds and many other science and engineering challenges. Most recently MIT has been funded to launch a constellation of 12 CubeSats called TROPICS to study precipitation and storm intensity in Earth’s atmosphere.
For now, size still matters
But the nature of CubeSats still restricts the science they can do. Limitations in power, storage and, most importantly, ability to transmit the information back to Earth impede our ability to continuously run our HARP instrument within a CubeSat platform.
So as another part of our effort, we’ll be observing how HARP does as it makes its scientific observations. Here at UMBC we’ve created the Center for Earth and Space Studies to study how well small satellites do at answering science questions regarding Earth systems and space. This is where HARP’s raw data will be converted and interpreted. Beyond answering questions about cloud/aerosol interactions, the next goal is to determine how to best use SmallSats and other technologies for Earth and space science applications. Seeing what works and what doesn’t will help inform larger space missions and future operations.
The SmallSat revolution, boosted by popular access to space via CubeSats, is now rushing toward the next revolution. The next generation of nanosatellite payloads will advance the frontiers of science. They may never supersede the need for bigger and more powerful satellites, but NanoSats will continue to expand their own role in the ongoing race to explore Earth and the universe. | 0.873883 | 3.592328 |
Imagine a sphere more than 2 million miles across - eight times the distance from Earth to the Moon - spinning so fast that its surface is traveling at nearly the speed of light. Such an object exists: the supermassive black hole at the center of the spiral galaxy NGC 1365.
Astronomers measured its jaw-dropping spin rate using new data from the Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency's XMM-Newton X-ray satellites.
"This is the first time anyone has accurately measured the spin of a supermassive black hole," said lead author Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) and INAF - Arcetri Observatory.
This research is being published in the Feb. 28 issue of the journal Nature, and featured in a NASA media teleconference on Feb. 27th.
A black hole's gravity is so strong that, as the black hole spins, it drags the surrounding space along. The edge of this spinning hole is called the event horizon. Any material crossing the event horizon is pulled into the black hole. Inspiraling matter collects into an accretion disk, where friction heats it and causes it to emit X-rays.
Risaliti and his colleagues measured X-rays from the center of NGC 1365 to determine where the inner edge of the accretion disk was located. This Innermost Stable Circular Orbit - the disk's point of no return - depends on the black hole's spin. Since a spinning black hole distorts space, the disk material can get closer to the black hole before being sucked in.
Astronomers want to know the black hole's spin for several reasons. The first is physical - only two numbers define a black hole: mass and spin. By learning those two numbers, you learn everything there is to know about the black hole.
Most importantly, the black hole's spin gives clues to its past and by extension the evolution of its host galaxy.
"The black hole's spin is a memory, a record, of the past history of the galaxy as a whole," explained Risaliti.
Although the black hole in NGC 1365 is currently as massive as several million Suns, it wasn't born that big. It grew over billions of years by accreting stars and gas, and by merging with other black holes.
Spin results from a transfer of angular momentum, like playing on a children's swing. If you kick at random times while you swing, you'll never get very high. But if you kick at the beginning of each downswing, you go higher and higher as you add angular momentum.
Similarly, if the black hole grew randomly by pulling in matter from all directions, its spin would be low. Since its spin is so close to the maximum possible, the black hole in NGC 1365 must have grown through "ordered accretion" rather than multiple random events.
Studying a supermassive black hole also allows theorists to test Einstein's theory of general relativity in extreme conditions. Relativity describes how gravity affects the structure of space-time, and nowhere is space-time more distorted than in the immediate vicinity of a black hole.
The team also has additional observations of NGC 1365 that they will study to determine how conditions other than black hole spin change over time. Those data are currently being analyzed. At the same time, other teams are observing several other supermassive black holes with NuSTAR and XMM-Newton. | 0.856529 | 4.008009 |
Release Date: Jan. 14, 2009
ASU Planetarium Show to Explore the Origin of Stars
The genesis of stars, including everything from what they are made of to what makes them shine, will be examined in the new star show “Clouds of Fire: The Origin of Stars” beginning Jan. 22 in the Angelo State University Planetarium.
Show times for “Clouds of Fire” will be 8 p.m. Thursdays, Jan. 22 through March 12, and at 2 p.m. Saturday, Feb. 14. The ASU Planetarium is located in the Vincent Nursing-Physical Science Building, 2333 Vanderventer.
Since earliest times, stars have intrigued men and women, who most often found explanations in their imaginations rather than in fact. Modern science, however, is helping answer questions ranging from what a star is to whether they are all alike. “Clouds of Fire” provides some of those answers and examines the connection between the creation of stars and the formation of everything else in the universe, from galaxies to planets to humans.
“People are amazed to learn that they are made of stardust,” said Dr. Mark Sonntag, director of the ASU Planetarium. “All matter, from stars to plants to people, comes from the same source. Everything in the universe has been connected since the beginning of time.”
As it explores the life and death of stars, “Clouds of Fire” utilizes images of a star-forming gas and dust cloud called the Eagle Nebula. Provided by the Hubble Space Telescope, these images allow scientists to peer into the inner workings of star cluster formation and better understand stars.
“In every show we try to feature at least one completely new visualization of something unusual in outer space,” Sonntag said. “For ‘Clouds of Fire,’ artists at Adler Planetarium in Chicago developed artwork for full-sky images, which shows the formation of the Eagle Nebula and the way the nebula evaporates over time to reveal a beautiful star cluster.”
In the long cycle of star birth and death, generation after generation of both large and small stars have created a rich blend of elements that gradually mixed with other gases and dust, forming our own solar system and everything that exists within.
Admission prices for “Clouds of Fire” are $3 for adults and $2 for children, non-ASU students and senior citizens. ASU students, faculty and staff are admitted free.
For more information, contact Dr. Sonntag in the ASU Planetarium at 942-2136. | 0.853051 | 3.211301 |
Stephanie Bernard is one in 24 million.
The University of Melbourne PhD candidate is the only Australian given access to NASA’s Spitzer Space Telescope, and she is using her time to explore one of the earliest galaxies in the universe.
Selected from hundreds of astrophysicists seeking access to the telescope for 12 months (beginning mid-2016), Ms Bernard is now analysing infrared signals from an ancient galaxy that could hold the secrets to how life developed in the universe.
“We’re strongly focused on understanding how the first generation of stars formed,” she says.
Scientists have dated the birth of the universe to about 13.8 billion years ago, when the Big Bang occurred. Ms Bernard and her supervisor, astrophysicist Dr Michele Trenti, from the School of Physics, have just received their first lot of data from Spitzer, and they are focused on a large galaxy – bigger than our own Milky Way – called 11153+0056_514, which formed sometime between 500 and 800 million years after the Big Bang.
“So what we’re doing is going back 13 billion years in time,” Ms Bernard says.
Just the process of finding a galaxy this old is a challenge, let along exploring its intricate details and origins.
“It’s like a needle in a haystack; these galaxies are just a small patch in the sky, something like 150 to 200 times smaller than the moon,” Dr Trenti says.
“We can search thousands of galaxies, and if we’re lucky, there might be one that’s 13 billion years in the past. And if you’re after the brightest galaxies at the time, those are even rarer, because galaxies start forming small and then over time they grow and they often merge into much bigger galaxies.”
Formerly known as the Space Infrared Telescope Facility, the powerful Spitzer Space Telescope is part of the NASA Great Observatories program.
It was later named after astronomer Lyman Spitzer, who in the 1940s advocated the concept of space telescopes.
The telescope was blasted into space in 2003 and NASA planned to operate it for two and a half years, possibly up to five.
Now, in its 13th year, Spitzer is still going strong, despite its original use-by-date having well and truly passed. While some of its original functions no longer work, because the telescope has run out of its liquid helium fuel, its two short wavelength infrared array cameras still operate.
And it is this infrared capability that makes access to Spitzer so important.
To use the telescope, Ms Bernard sends the coordinates of the galaxy to NASA, who then position the telescope to that area when there are enough other requests for data from that particular corner of the universe. Raw data is then emailed to Ms Bernard, who analyses it.
Ms Bernard and Dr Trenti found galaxy 11153+0056_514 using the better-known Hubble Space Telescope, but in order to explore its details further, they needed to see it in infrared, which cannot be seen with the human eye or Hubble.
Dr Trenti says seeing these galaxies in infrared is important because the universe is expanding. As the light from this galaxy travels towards us it loses energy, because space is stretched.
“These distant galaxies would have emitted high-energy UV light, but because the universe has grown approximately 10 times larger in the past 13 billion years, by the time this light reaches us, it has been stretched, and the energy is lower than what the human eye can see,” Dr Trenti says.
Given Spitzer’s age, and the fact the vastly more advanced James Webb Telescope – which will eventually replace both Hubble and Spitzer – is set to be launched in 2018, this was likely the last opportunity for Ms Bernard to use Spitzer.
The images that Spitzer has sent back to Earth over the past 13 years are spellbinding. Swirls of neon purple, green, red, blue and pink, contrasted against the darkest of black of the universe.
But it will still be some time before Ms Bernard and Dr Trenti can properly process all the data that will eventually create those stunning images. At the moment, their images look like large splotches, with no discernible detail.
But these splotches are fascinating to Ms Bernard and could hold some vital clues that could answer some of humankind’s most profound questions.
“We have a basic idea of what this galaxy should look like and so we basically comb through this image and see if we can match it with these ideas of the galaxy,” Ms Bernard says.
“Finding these first galaxies tells us a bit about what the universe was like at that time, because we can look at what the properties of the galaxy are, what sort of stars it has inside it and we can get an idea of how these processes we see in the universe today, like galaxies merging, all started.”
Exploring the early universe and getting so close to the Big Bang is at the centre of Ms Bernard and Dr Trenti’s research.
“It’s really to address one of the most fundamental questions: where did we, humanity, come from?” Dr Trenti says.
“After the Big Bang, the universe was a pretty dull place; it was only hydrogen, helium and traces of maybe a few heavier elements such as lithium, but nothing else.
“With time, tiny fluctuations in these elements grow and gravity makes them collapse and you have the physical conditions that lead to the formation of the first generation of stars and galaxies. And those produce chemical elements through fusion processes and then you have the elements – carbon, oxygen, iron – that are necessary for life.”
Banner Image: An image of the universe sent back to Earth by Spitzer. Picture: Wikimedia | 0.825065 | 3.915601 |
Artwork illustrating a black hole eating a star. (Photo : NASA)
Black holes, those ruthless, giant swirling gobs of gravity, are so strong they suck in even light and can shred any kind of matter within its intense mass. Just what would it feel like to get sucked into one of these cosmic superpowers? Now scientists can tell you what it sounds like after recording the dying cries of a star being destroyed by a black hole. It's a very low D-sharp.
"You can think of it as hearing the star scream as it gets devoured, if you like," said lead author of the study, astronomer Jon Miller of the University of Michigan.
These screams don't just tell the scientists what dying at the hands of a black hole feels like. Instead, they can be used to study the physics and nature of black holes.
"This discovery extends our reach to the innermost edge of a black hole located billions of light-years away, which is really amazing," Reis said. "This gives us an opportunity to explore the nature of black holes and test Einstein's relativity at a time when the universe was very different than it is today."
The black hole Swift J1644+57 is located 3.9 billion light-years away. NASA's Swift satellite which detects gamma-ray bursts, discovered a series of gamma-ray bursts that astronomers hadn't seen before. The signals gradually faded out, and when scientists identified it as the sound of a star being taken apart by a black hole, they corresponded the signal with a really low D-sharp.
Apparently, the black hole had been lying quietly in place and ensnared the star in its grasp once the wandering star passed through its gravitational field.
The scientists confirmed that the type of signal observed is the same as those that come from smaller black holes from material that is about to be sucked in.
The reason scientists were able to pick up the signal this is because as a black hole sucks the gas from a star, it forms a hot, swirling mass of gas called an accretion disk that shoots out X-rays. Perpendicular to those jets, the black hole ejects matter at 90 percent the speed of light - it's one of these jets that was pointing straight at Earth.
Watch a black hole eating a star: | 0.833143 | 3.681108 |
How Fast is the Universe Expanding?
The expansion or contraction of the universe depends on its content and past history. With enough matter, the expansion will slow or even become a contraction. On the other hand, dark energy drives the universe towards increasing rates of expansion. The current rate of expansion is usually expressed as the Hubble Constant (in units of kilometers per second per Megaparsec, or just per second).
Hubble found that the universe was not static, but rather was expanding!
In the 1920s, Edwin Hubble, using the newly constructed 100" telescope at Mount Wilson Observatory, detected variable stars in several nebulae. Nebulae are diffuse objects whose nature was a topic of heated debate in the astronomical community: were they interstellar clouds in our own Milky Way galaxy, or whole galaxies outside our galaxy? This was a difficult question to answer because it is notoriously difficult to measure the distance to most astronomical bodies since there is no point of reference for comparison. Hubble's discovery was revolutionary because these variable stars had a characteristic pattern resembling a class of stars called Cepheid variables. Earlier, Henrietta Levitt, part of a group of female astronomers working at Harvard College Observatory, had shown there was a tight correlation between the period of a Cepheid variable star and its luminosity (intrinsic brightness). By knowing the luminosity of a source it is possible to measure the distance to that source by measuring how bright it appears to us: the dimmer it appears the farther away it is. Thus, by measuring the period of these stars (and hence their luminosity) and their apparent brightness, Hubble was able to show that these nebula were not clouds within our own Galaxy, but were external galaxies far beyond the edge of our own Galaxy.
Hubble's second revolutionary discovery was based on comparing his measurements of the Cepheid-based galaxy distance determinations with measurements of the relative velocities of these galaxies. He showed that more distant galaxies were moving away from us more rapidly:
v = Hod
where v is the speed at which a galaxy moves away from us, and d is its distance. The constant of proportionality Ho is now called the Hubble constant. The common unit of velocity used to measure the speed of a galaxy is km/sec, while the most common unit of for measuring the distance to nearby galaxies is called the Megaparsec (Mpc) which is equal to 3.26 million light years or 30,800,000,000,000,000,000 km! Thus the units of the Hubble constant are (km/sec)/Mpc.
This discovery marked the beginning of the modern age of cosmology. Today, Cepheid variables remain one of the best methods for measuring distances to galaxies and are vital to determining the expansion rate (the Hubble constant) and age of the universe.
What are Cepheid Variables?
The structure of all stars, including the Sun and Cepheid variable stars, is determined by the opacity of matter in the star. If the matter is very opaque, then it takes a long time for photons to diffuse out from the hot core of the star, and strong temperature and pressure gradients can develop in the star. If the matter is nearly transparent, then photons move easily through the star and erase any temperature gradient. Cepheid stars oscillate between two states: when the star is in its compact state, the helium in a layer of its atmosphere is singly ionized. Photons scatter off of the bound electron in the singly ionized helium atoms, thus, the layer is very opaque and large temperature and pressure gradients build up across the layer. These large pressures cause the layer (and the whole star) to expand. When the star is in its expanded state, the helium in the layer is doubly ionized, so that the layer is more transparent to radiation and there is much weaker pressure gradient across the layer. Without the pressure gradient to support the star against gravity, the layer (and the whole star) contracts and the star returns to its compressed state.
Cepheid variable stars have masses between five and twenty solar masses. The more massive stars are more luminous and have more extended envelopes. Because their envelopes are more extended and the density in their envelopes is lower, their variability period, which is proportional to the inverse square root of the density in the layer, is longer.
Difficulties in Using Cepheids
There have been a number of difficulties associated with using Cepheids as distance indicators. For much of the last century, astronomers used photographic plates to measure the fluxes from stars. The plates were highly non-linear and often produced faulty flux measurements. Since massive stars are short lived, they are always located near their dusty birthplaces. Dust absorbs light, particularly at blue wavelengths where most photographic images were taken, and if not properly corrected for, this dust absorption can lead to erroneous luminosity determinations. Finally, it has been very difficult to detect Cepheids in distant galaxies from the ground: Earth's fluctuating atmosphere makes it impossible to separate these stars from the diffuse light of their host galaxies.
Another historic difficulty with using Cepheids as distance indicators has been the problem of determining the distance to a sample of nearby Cepheids. In recent years, astronomers have developed several very reliable and independent methods of determining the distances to the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), two of the nearby satellite galaxies of our own Milky Way Galaxy. Since the LMC and SMC contain large number of Cepheids, they can be used to calibrate the distance scale.
Technological advances have enabled astronomers to overcome a number of the other past difficulties. Detectors called CCDs (charge coupled devices- like those used in digital cameras) made possible accurate radiation flux measurements. These detectors are also sensitive in the infrared wavelengths. Dust is much more transparent at these wavelengths. By measuring fluxes at multiple wavelengths, astronomers were able to correct for the effects of dust and make much more accurate distance determinations.
These advances enabled more accurate study of the nearby galaxies that comprise the "Local Group" of galaxies. Astronomers observed Cepheids in both the metal rich inner region of the Andromeda galaxy and its metal poor outer region. (To an astronomer, a "metal" is any element heavier than helium - the second lightest element in the periodic table. Such elements are produced in stars and are ultimately released into the interstellar medium as the stars evolve.) This work showed that the properties of Cepheids did not depend sensitively on chemical abundances. Despite these advances, astronomers, limited by the Earth's atmosphere, could only measure the distances to the nearest galaxies. In addition to the motion due to the expansion of the universe, galaxies have "relative motions" due to the gravitational pull of their neighbors. Because of these "peculiar motions", astronomers need to measure the distances to distant galaxies so that they can determine the Hubble constant.
Trying to push deeper into the universe, astronomers have developed a number of new techniques for determining relative distances to galaxies: these independent relative distance scales now agree to better than 10%. For example, there is a very tight relation, called the Tully-Fisher relation, between the rotational velocity of a spiral galaxy and its luminosity. Astronomers also found that Type Ia supernova, which are thought to be due to the explosive burning of a white dwarf star, all had nearly the same peak luminosity. However, without accurate measurements of distance to large numbers of prototype galaxies, astronomers could not calibrate these relative distance measurements. Thus, they were unable to make accurate determinations of the Hubble constant.
Over the past few decades, leading astronomers, using different data, reported values for the Hubble constant that varied between 50 (km/sec)/Mpc and 100 (km/sec)/Mpc. Resolving this factor of two discrepancy was one of the most important outstanding problems in observational cosmology.
Hubble Key Project
The Key Project program outlined the major goals of the Hubble Space Telescope (HST). On of the major goals of HST was to complete Edwin Hubble's program of measuring distances to nearby galaxies. While the Hubble Space Telescope is comparable in diameter to Hubble's telescope on Mount Wilson, it had the advantage of being above the Earth's atmosphere, rather then being located on the outskirts of Los Angeles. NASA's repair of the Hubble Space Telescope restored its vision and enabled the Key Project program. The photos below show before and after images of M100, one of the nearby galaxies observed by the key project program. With the refurbished HST, it was much easier to detect individual bright stars in M100, a necessary step in studying Cepheid variables. The project also checked to see if the properties of Cepheid variables are sensitive to stellar composition.
Overall, the key project attempted to get distances to 20 nearby galaxies. With this large sample, the project calibrated and cross checked a number of the secondary distance indicators. Because M100 is close enough to us that its peculiar motion is a significant fraction of its Hubble expansion velocity, the key project team used relative distance indicators to extrapolate from the Virgo cluster, a nearby cluster of galaxies containing M100, to the more distant Coma cluster and to obtain a measurement of the Hubble constant of 70 (km/sec)/Mpc, with an uncertainty of 10%.
The key project determination of the Hubble constant is consistent with a number of independent efforts to estimate the Hubble constant: a statistical synthesis by G.F.R. Ellis and his collaborators of the published literature yielded a value between 66 and 82 (km/sec)/Mpc. However, there was still not complete consensus on the value of the Hubble constant.
WMAP and the Hubble Constant
By characterizing the detailed structure of the cosmic microwave background fluctuations, WMAP has accurately determined the basic cosmological parameters, including the Hubble constant. The current best direct measurement of the Hubble constant is 73.8 km/sec/Mpc (give or take 2.4 km/sec/Mpc including, both random and systematic errors), corresponding to a 3% uncertainty. Using only WMAP data, the Hubble constant is estimated to be 70.0 km/sec/Mpc (give or take 2.2 km/sec/Mpc), also a 3% measurement. This assumes that the universe is spatially flat, which is consistent with all available data. This measurement is completely independent of traditional measurements using Cepheid variables and other techniques. However, if we do not make an assumption of flatness, we can combine WMAP data with other cosmological data to get 69.3 km/sec/Mpc (give or take 0.8 km/sec/Mpc), a 1% solution that combines different kinds of measurements. After noting that independent observations give consistent results, it is reasonable to combine information to get the best estimate of parameters.
Parts of this page were adapted from the article "The age of the universe", D.N. Spergel, M. Bolte (UC, Santa Cruz) and W. Freedman (Carnegie Observatories). Proc. Natl. Acad. Sci. USA, Vol. 94, pp. 6579-6584, June 1997.
- More on the Hubble Constant from Space Telescope Science Institute including movies.
- Freedman, Wendy L., "The Expansion Rate and Science of the Universe", Scientific American, Nov. 1992.
- Osterbrock, D.E., Gwinn, J.A. & Brashear, R.S., "Hubble and the Expanding Universe", Scientific American, July 1993. | 0.865241 | 4.135329 |
Five. Four. Three. Two. One. Blast off! Into the sky shoots a rocket ship, quickly moving beyond our atmosphere and into outer space. In the last half-century, people have gone from just looking up in amazement at the stars glimmering in the night sky to actually living for months at a time on the International Space Station among the celestial bodies. And while humans have set foot on the moon, landing anywhere farther away has been reserved only for unmanned craft and robots.
One place people are very interested in visiting is Mars. Aside from the actual challenges of landing and spending any time in a place as unwelcoming as the red planet, there's the big hurdle of actually getting there. On average, Mars is about 140 million miles (225.3 million kilometers) from Earth. Even when at its closest point, it's still some 35 million miles (56.3 million kilometers) away from our planet [source: St. Fleur]. Using the conventional chemical rockets that typically carry us into outer space would take at least seven months to get there — not exactly a short amount of time [source: Verhovek]. Is there any way we might be able to do it faster? Enter the plasma rocket!
In lieu of using conventional rocket fuel, scientists and engineers have turned to the promise of plasma rockets to propel us to the further reaches of outer space. In this type of rocket, a combination of electric and magnetic fields are used to break down the atoms and molecules of a propellant gas into a collection of particles that have either a positive charge (ions) or a negative charge (electrons). In other words, the propellant gas becomes a plasma.
In many configurations of this engine, an electric field is then applied to eject the ions out the back of the engine, which provide thrust to the spacecraft in the opposite direction [source: Zyga]. With this technology optimized, a spaceship could theoretically reach a speed 123,000 mph (198,000 kph) [source: Verhovek]. At that speed, you could get from New York to Los Angeles in one minute! | 0.809897 | 3.187597 |
Video: "Target Earth"
Gregg Easterbrook leads an illustrated tour through the treacherous world of space rocks.
Breakthrough ideas have a way of seeming obvious in retrospect, and about a decade ago, a Columbia University geophysicist named Dallas Abbott had a breakthrough idea. She had been pondering the craters left by comets and asteroids that smashed into Earth. Geologists had counted them and concluded that space strikes are rare events and had occurred mainly during the era of primordial mists. But, Abbott realized, this deduction was based on the number of craters found on land—and because 70 percent of Earth’s surface is water, wouldn’t most space objects hit the sea? So she began searching for underwater craters caused by impacts rather than by other forces, such as volcanoes. What she has found is spine-chilling: evidence that several enormous asteroids or comets have slammed into our planet quite recently, in geologic terms. If Abbott is right, then you may be here today, reading this magazine, only because by sheer chance those objects struck the ocean rather than land.
Abbott believes that a space object about 300 meters in diameter hit the Gulf of Carpentaria, north of Australia, in 536 A.D. An object that size, striking at up to 50,000 miles per hour, could release as much energy as 1,000 nuclear bombs. Debris, dust, and gases thrown into the atmosphere by the impact would have blocked sunlight, temporarily cooling the planet—and indeed, contemporaneous accounts describe dim skies, cold summers, and poor harvests in 536 and 537. “A most dread portent took place,” the Byzantine historian Procopius wrote of 536; the sun “gave forth its light without brightness.” Frost reportedly covered China in the summertime. Still, the harm was mitigated by the ocean impact. When a space object strikes land, it kicks up more dust and debris, increasing the global-cooling effect; at the same time, the combination of shock waves and extreme heating at the point of impact generates nitric and nitrous acids, producing rain as corrosive as battery acid. If the Gulf of Carpentaria object were to strike Miami today, most of the city would be leveled, and the atmospheric effects could trigger crop failures around the world.
What’s more, the Gulf of Carpentaria object was a skipping stone compared with an object that Abbott thinks whammed into the Indian Ocean near Madagascar some 4,800 years ago, or about 2,800 B.C. Researchers generally assume that a space object a kilometer or more across would cause significant global harm: widespread destruction, severe acid rain, and dust storms that would darken the world’s skies for decades. The object that hit the Indian Ocean was three to five kilometers across, Abbott believes, and caused a tsunami in the Pacific 600 feet high—many times higher than the 2004 tsunami that struck Southeast Asia. Ancient texts such as Genesis and the Epic of Gilgamesh support her conjecture, describing an unspeakable planetary flood in roughly the same time period. If the Indian Ocean object were to hit the sea now, many of the world’s coastal cities could be flattened. If it were to hit land, much of a continent would be leveled; years of winter and mass starvation would ensue.
At the start of her research, which has sparked much debate among specialists, Abbott reasoned that if colossal asteroids or comets strike the sea with about the same frequency as they strike land, then given the number of known land craters, perhaps 100 large impact craters might lie beneath the oceans. In less than a decade of searching, she and a few colleagues have already found what appear to be 14 large underwater impact sites. That they’ve found so many so rapidly is hardly reassuring.
Other scientists are making equally unsettling discoveries. Only in the past few decades have astronomers begun to search the nearby skies for objects such as asteroids and comets (for convenience, let’s call them “space rocks”). What they are finding suggests that near-Earth space rocks are more numerous than was once thought, and that their orbits may not be as stable as has been assumed. There is also reason to think that space rocks may not even need to reach Earth’s surface to cause cataclysmic damage. Our solar system appears to be a far more dangerous place than was previously believed.
The received wisdom about the origins of the solar system goes something like this: the sun and planets formed about 4.5 billion years ago from a swirling nebula containing huge amounts of gas and dust, as well as relatively small amounts of metals and other dense substances released by ancient supernova explosions. The sun is at the center; the denser planets, including Earth, formed in the middle region, along with many asteroids—the small rocky bodies made of material that failed to incorporate into a planet. Farther out are the gas-giant planets, such as Jupiter, plus vast amounts of light elements, which formed comets on the boundary of the solar system. Early on, asteroids existed by the millions; the planets and their satellites were bombarded by constant, furious strikes. The heat and shock waves generated by these impacts regularly sterilized the young Earth. Only after the rain of space objects ceased could life begin; by then, most asteroids had already either hit something or found stable orbits that do not lead toward planets or moons. Asteroids still exist, but most were assumed to be in the asteroid belt, which lies between Mars and Jupiter, far from our blue world.
As for comets, conventional wisdom held that they also bombarded the planets during the early eons. Comets are mostly frozen water mixed with dirt. An ancient deluge of comets may have helped create our oceans; lots of comets hit the moon, too, but there the light elements they were composed of evaporated. As with asteroids, most comets were thought to have smashed into something long ago; and, because the solar system is largely void, researchers deemed it statistically improbable that those remaining would cross the paths of planets.
These standard assumptions—that remaining space rocks are few, and that encounters with planets were mainly confined to the past—are being upended. On March 18, 2004, for instance, a 30-meter asteroid designated 2004 FH—a hunk potentially large enough to obliterate a city—shot past Earth, not far above the orbit occupied by telecommunications satellites. (Enter “2004 FH” in the search box at Wikipedia and you can watch film of that asteroid passing through the night sky.) Looking at the broader picture, in 1992 the astronomers David Jewitt, of the University of Hawaii, and Jane Luu, of the Massachusetts Institute of Technology, discovered the Kuiper Belt, a region of asteroids and comets that starts near the orbit of Neptune and extends for immense distances outward. At least 1,000 objects big enough to be seen from Earth have already been located there. These objects are 100 kilometers across or larger, much bigger than whatever dispatched the dinosaurs; space rocks this size are referred to as “planet killers” because their impact would likely end life on Earth. Investigation of the Kuiper Belt has just begun, but there appear to be substantially more asteroids in this region than in the asteroid belt, which may need a new name.
Beyond the Kuiper Belt may lie the hypothesized Oort Cloud, thought to contain as many as trillions of comets. If the Oort Cloud does exist, the number of extant comets is far greater than was once believed. Some astronomers now think that short-period comets, which swing past the sun frequently, hail from the relatively nearby Kuiper Belt, whereas comets whose return periods are longer originate in the Oort Cloud.
But if large numbers of comets and asteroids are still around, several billion years after the formation of the solar system, wouldn’t they by now be in stable orbits—ones that rarely intersect those of the planets? Maybe not. During the past few decades, some astronomers have theorized that the movement of the solar system within the Milky Way varies the gravitational stresses to which the sun, and everything that revolves around it, is exposed. The solar system may periodically pass close to stars or groups of stars whose gravitational pull affects the Oort Cloud, shaking comets and asteroids loose from their orbital moorings and sending them downward, toward the inner planets.
Consider objects that are already near Earth, and the picture gets even bleaker. Astronomers traditionally spent little time looking for asteroids, regarding them as a lesser class of celestial bodies, lacking the beauty of comets or the significance of planets and stars. Plus, asteroids are hard to spot—they move rapidly, compared with the rest of the heavens, and even the nearby ones are fainter than other objects in space. Not until the 1980s did scientists begin systematically searching for asteroids near Earth. They have been finding them in disconcerting abundance.
In 1980, only 86 near-Earth asteroids and comets were known to exist. By 1990, the figure had risen to 170; by 2000, it was 921; as of this writing, it is 5,388. The Jet Propulsion Laboratory, part of NASA, keeps a running tally at www.neo.jpl.nasa.gov/stats. Ten years ago, 244 near-Earth space rocks one kilometer across or more—the size that would cause global calamity—were known to exist; now 741 are. Of the recently discovered nearby space objects, NASA has classified 186 as “impact risks” (details about these rocks are at www.neo.jpl.nasa.gov/risk). And because most space-rock searches to date have been low-budget affairs, conducted with equipment designed to look deep into the heavens, not at nearby space, the actual number of impact risks is undoubtedly much higher. Extrapolating from recent discoveries, NASA estimates that there are perhaps 20,000 potentially hazardous asteroids and comets in the general vicinity of Earth.
There’s still more bad news. Earth has experienced several mass extinctions—the dinosaurs died about 65 million years ago, and something killed off some 96 percent of the world’s marine species about 250 million years ago. Scientists have generally assumed that whatever caused those long-ago mass extinctions—comet impacts, extreme volcanic activity—arose from conditions that have changed and no longer pose much threat. It’s a comforting notion—but what about the mass extinction that occurred close to our era?
About 12,000 years ago, many large animals of North America started disappearing—woolly mammoths, saber-toothed cats, mastodons, and others. Some scientists have speculated that Paleo-Indians may have hunted some of the creatures to extinction. A millennia-long mini–Ice Age also may have been a factor. But if that’s the case, what explains the disappearance of the Clovis People, the best-documented Paleo-Indian culture, at about the same time? Their population stretched as far south as Mexico, so the mini–Ice Age probably was not solely responsible for their extinction.
A team of researchers led by Richard Firestone, of the Lawrence Berkeley National Laboratory, in California, recently announced the discovery of evidence that one or two huge space rocks, each perhaps several kilometers across, exploded high above Canada 12,900 years ago. The detonation, they believe, caused widespread fires and dust clouds, and disrupted climate patterns so severely that it triggered a prolonged period of global cooling. Mammoths and other species might have been killed either by the impact itself or by starvation after their food supply was disrupted. These conclusions, though hotly disputed by other researchers, were based on extensive examinations of soil samples from across the continent; in strata from that era, scientists found widely distributed soot and also magnetic grains of iridium, an element that is rare on Earth but common in space. Iridium is the meteor-hunter’s lodestar: the discovery of iridium dating back 65 million years is what started the geologist Walter Alvarez on his path-breaking theory about the dinosaurs’ demise.
A more recent event gives further cause for concern. As buffs of the television show The X Files will recall, just a century ago, in 1908, a huge explosion occurred above Tunguska, Siberia. The cause was not a malfunctioning alien star-cruiser but a small asteroid or comet that detonated as it approached the ground. The blast had hundreds of times the force of the Hiroshima bomb and devastated an area of several hundred square miles. Had the explosion occurred above London or Paris, the city would no longer exist. Mark Boslough, a researcher at the Sandia National Laboratory, in New Mexico, recently concluded that the Tunguska object was surprisingly small, perhaps only 30 meters across. Right now, astronomers are nervously tracking 99942 Apophis, an asteroid with a slight chance of striking Earth in April 2036. Apophis is also small by asteroid standards, perhaps 300 meters across, but it could hit with about 60,000 times the force of the Hiroshima bomb—enough to destroy an area the size of France. In other words, small asteroids may be more dangerous than we used to think—and may do considerable damage even if they don’t reach Earth’s surface.
ASTEROID 243 IDA, about 35 miles long, and its moon
(Image courtesy of NASA/NSSDC)
Until recently, nearly all the thinking about the risks of space-rock strikes has focused on counting craters. But what if most impacts don’t leave craters? This is the prospect that troubles Boslough. Exploding in the air, the Tunguska rock did plenty of damage, but if people had not seen the flashes, heard the detonation, and traveled to the remote area to photograph the scorched, flattened wasteland, we’d never know the Tunguska event had happened. Perhaps a comet or two exploding above Canada 12,900 years ago spelled the end for saber-toothed cats and Clovis society. But no obvious crater resulted; clues to the calamity were subtle and hard to come by.
Comets, asteroids, and the little meteors that form pleasant shooting stars approach Earth at great speeds—at least 25,000 miles per hour. As they enter the atmosphere they heat up, from friction, and compress, because they decelerate rapidly. Many space rocks explode under this stress, especially small ones; large objects are more likely to reach Earth’s surface. The angle at which objects enter the atmosphere also matters: an asteroid or comet approaching straight down has a better chance of hitting the surface than one entering the atmosphere at a shallow angle, as the latter would have to plow through more air, heating up and compressing as it descended. The object or objects that may have detonated above Canada 12,900 years ago would probably have approached at a shallow angle.
If, as Boslough thinks, most asteroids and comets explode before reaching the ground, then this is another reason to fear that the conventional thinking seriously underestimates the frequency of space-rock strikes—the small number of craters may be lulling us into complacency. After all, if a space rock were hurtling toward a city, whether it would leave a crater would not be the issue—the explosion would be the issue.
A generation ago, the standard assumption was that a dangerous object would strike Earth perhaps once in a million years. By the mid-1990s, researchers began to say that the threat was greater: perhaps a strike every 300,000 years. This winter, I asked William Ailor, an asteroid specialist at The Aerospace Corporation, a think tank for the Air Force, what he thought the risk was. Ailor’s answer: a one-in-10 chance per century of a dangerous space-object strike.
Regardless of which estimate is correct, the likelihood of an event is, of course, no predictor. Even if space strikes are likely only once every million years, that doesn’t mean a million years will pass before the next impact—the sky could suddenly darken tomorrow. Equally important, improbable but cataclysmic dangers ought to command attention because of their scope. A tornado is far more likely than an asteroid strike, but humanity is sure to survive the former. The chances that any one person will die in an airline crash are minute, but this does not prevent us from caring about aviation safety. And as Nathan Myhrvold, the former chief technology officer of Microsoft, put it, “The odds of a space-object strike during your lifetime may be no more than the odds you will die in a plane crash—but with space rocks, it’s like the entire human race is riding on the plane.”
Given the scientific findings, shouldn’t space rocks be one of NASA’s priorities? You’d think so, but Dallas Abbott says NASA has shown no interest in her group’s work: “The NASA people don’t want to believe me. They won’t even listen.”
NASA supports some astronomy to search for near-Earth objects, but the agency’s efforts have been piecemeal and underfunded, backed by less than a tenth of a percent of the NASA budget. And though altering the course of space objects approaching Earth appears technically feasible, NASA possesses no hardware specifically for this purpose, has nearly nothing in development, and has resisted calls to begin work on protection against space strikes. Instead, NASA is enthusiastically preparing to spend hundreds of billions of taxpayers’ dollars on a manned moon base that has little apparent justification. “What is in the best interest of the country is never even mentioned in current NASA planning,” says Russell Schweickart, one of the Apollo astronauts who went into space in 1969, who is leading a campaign to raise awareness of the threat posed by space rocks. “Are we going to let a space strike kill millions of people before we get serious about this?” he asks.
In January, I attended an internal NASA conference, held at agency headquarters, during which NASA’s core goals were presented in a PowerPoint slideshow. Nothing was said about protecting Earth from space strikes—not even researching what sorts of spacecraft might be used in an approaching-rock emergency. Goals that were listed included “sustained human presence on the moon for national preeminence” and “extend the human presence across the solar system and beyond.” Achieving national preeminence—isn’t the United States pretty well-known already? As for extending our presence, a manned mission to Mars is at least decades away, and human travel to the outer planets is not seriously discussed by even the most zealous advocates of space exploration. Sending people “beyond” the solar system is inconceivable with any technology that can reasonably be foreseen; an interstellar spaceship traveling at the fastest speed ever achieved in space flight would take 60,000 years to reach the next-closest star system.
After the presentation, NASA’s administrator, Michael Griffin, came into the room. I asked him why there had been no discussion of space rocks. He said, “We don’t make up our goals. Congress has not instructed us to provide Earth defense. I administer the policy set by Congress and the White House, and that policy calls for a focus on return to the moon. Congress and the White House do not ask me what I think.” I asked what NASA’s priorities would be if he did set the goals. “The same. Our priorities are correct now,” he answered. “We are on the right path. We need to go back to the moon. We don’t need a near-Earth-objects program.” In a public address about a month later, Griffin said that the moon-base plan was “the finest policy framework for United States civil space activities that I have seen in 40 years.”
Actually, Congress has asked NASA to pay more attention to space rocks. In 2005, Congress instructed the agency to mount a sophisticated search of the proximate heavens for asteroids and comets, specifically requesting that NASA locate all near-Earth objects 140 meters or larger that are less than 1.3 astronomical units from the sun—roughly out to the orbit of Mars. Last year, NASA gave Congress its reply: an advanced search of the sort Congress was requesting would cost about $1 billion, and the agency had no intention of diverting funds from existing projects, especially the moon-base initiative.
How did the moon-base idea arise? In 2003, after the shuttle Columbia was lost, manned space operations were temporarily shut down, and the White House spent a year studying possible new missions for NASA. George W. Bush wanted to announce a voyage to Mars. Every Oval Office occupant since John F. Kennedy knows how warmly history has praised him for the success of his pledge to put men on the moon; it’s only natural that subsequent presidents would dream about securing their own place in history by sending people to the Red Planet. But the technical barriers and even the most optimistic cost projections for a manned mission to Mars are prohibitive. So in 2004, Bush unveiled a compromise plan: a permanent moon base that would be promoted as a stepping-stone for a Mars mission at some unspecified future date. As anyone with an aerospace engineering background well knows, stopping at the moon, as Bush was suggesting, actually would be an impediment to Mars travel, because huge amounts of fuel would be wasted landing on the moon and then blasting off again. Perhaps something useful to a Mars expedition would be learned in the course of building a moon base; but if the goal is the Red Planet, then spending vast sums on lunar living would only divert that money from the research and development needed for Mars hardware. However, saying that a moon base would one day support a Mars mission allowed Bush to create the impression that his plan would not merely be restaging an effort that had already been completed more than 30 years before. For NASA, a decades-long project to build a moon base would ensure a continuing flow of money to its favorite contractors and to the congressional districts where manned-space-program centers are located. So NASA signed on to the proposal, which Congress approved the following year.
It is instructive, in this context, to consider the agency’s rhetoric about China. The Chinese manned space program has been improving and is now about where the U.S. program was in the mid-1960s. Stung by criticism that the moon-base project has no real justification—37 years ago, President Richard Nixon cancelled the final planned Apollo moon missions because the program was accomplishing little at great expense; as early as 1964, the communitarian theorist Amitai Etzioni was calling lunar obsession a “moondoggle”—NASA is selling the new plan as a second moon race, this time against Beijing. “I’ll be surprised if the Chinese don’t reach the moon before we return,” Griffin said. “China is now a strategic peer competitor to the United States in space. China is drawing national prestige from achievements in space, and there will be a tremendous shift in national prestige toward Beijing if the Chinese are operating on the moon and we are not. Great nations have always operated on the frontiers of their era. The moon is the frontier of our era, and we must outperform the Chinese there.”
Wouldn’t shifting NASA’s focus away from wasting money on the moon and toward something of clear benefit for the entire world—identifying and deflecting dangerous space objects—be a surer route to enhancing national prestige? But NASA’s institutional instinct is not to ask, “What can we do in space that makes sense?” Rather, it is to ask, “What can we do in space that requires lots of astronauts?” That finding and stopping space rocks would be an expensive mission with little role for the astronaut corps is, in all likelihood, the principal reason NASA doesn’t want to talk about the asteroid threat.
NASA’s lack of interest in defending against space objects leaves a void the Air Force seems eager to fill. The Air Force has the world’s second-largest space program, with a budget of about $11 billion—$6 billion less than NASA’s. The tension between the two entities is long-standing. Many in the Air Force believe the service could achieve U.S. space objectives faster and more effectively than NASA. And the Air Force simply wants flyboys in orbit: several times in the past, it has asked Congress to fund its own space station, its own space plane, and its own space-shuttle program. Now, with NASA all but ignoring the space-object threat, the Air Force appears to be seizing an opportunity.
All known space rocks have been discovered using telescopes designed for traditional “soda straw” astronomy—that is, focusing on a small patch of sky. Now the Air Force is funding the first research installation designed to conduct panoramic scans of the sky, a telescope complex called Pan-STARRS, being built by the University of Hawaii. By continuously panning the entire sky, Pan-STARRS should be able to spot many near-Earth objects that so far have gone undetected. The telescope also will have substantially better resolving power and sensitivity than existing survey instruments, enabling it to find small space rocks that have gone undetected because of their faintness.
The Pan-STARRS project has no military utility, so why is the Air Force the sponsor? One speculation is that Pan-STARRS is the Air Force’s foot in the door for the Earth-defense mission. If the Air Force won funding to build high-tech devices to fire at asteroids, this would be a major milestone in its goal of an expanded space presence. But space rocks are a natural hazard, not a military threat, and an Air Force Earth-protection initiative, however gallant, would probably cause intense international opposition. Imagine how other governments would react if the Pentagon announced, “Don’t worry about those explosions in space—we’re protecting you.”
Thus, the task of defending Earth from objects falling from the skies seems most fitting for NASA, or perhaps for a multinational civilian agency that might be created. Which raises the question: What could NASA, or anyone else, actually do to provide a defense?
Russell Schweickart, the former Apollo astronaut, runs the B612 Foundation (B612 is the asteroid home of Saint-Exupéry’s Little Prince). The foundation’s goal is to get NASA officials, Congress, and ultimately the international community to take the space-rock threat seriously; it advocates testing a means of precise asteroid tracking, then trying to change the course of a near-Earth object.
Current telescopes cannot track asteroids or comets accurately enough for researchers to be sure of their courses. When 99942 Apophis was spotted, for example, some calculations suggested it would strike Earth in April 2029, but further study indicates it won’t—instead, Apophis should pass between Earth and the moon, during which time it may be visible to the naked eye. The Pan-STARRS telescope complex will greatly improve astronomers’ ability to find and track space rocks, and it may be joined by the Large Synoptic Survey Telescope, which would similarly scan the entire sky. Earlier this year, the software billionaires Bill Gates and Charles Simonyi pledged $30 million for work on the LSST, which proponents hope to erect in the mountains of Chile. If it is built, it will be the first major telescope to broadcast its data live over the Web, allowing countless professional and amateur astronomers to look for undiscovered asteroids.
Schweickart thinks, however, that even these instruments will not be able to plot the courses of space rocks with absolute precision. NASA has said that an infrared telescope launched into an orbit near Venus could provide detailed information on the exact courses of space rocks. Such a telescope would look outward from the inner solar system toward Earth, detect the slight warmth of asteroids and comets against the cold background of the cosmos, and track their movements with precision. Congress would need to fund a near-Venus telescope, though, and NASA would need to build it—neither of which is happening.
Another means of gathering data about a potentially threatening near-Earth object would be to launch a space probe toward it and attach a transponder, similar to the transponders used by civilian airliners to report their exact locations and speed; this could give researchers extremely precise information on the object’s course. There is no doubt that a probe can rendezvous with a space rock: in 2005, NASA smashed a probe called Deep Impact into the nucleus of comet 9P/Tempel in order to vaporize some of the material on the comet’s surface and make a detailed analysis of it. Schweickart estimates that a mission to attach a transponder to an impact-risk asteroid could be staged for about $400 million—far less than the $11.7 billion cost to NASA of the 2003 Columbia disaster.
Then what? In the movies, nuclear bombs are used to destroy space rocks. In NASA’s 2007 report to Congress, the agency suggested a similar approach. But nukes are a brute-force solution, and because an international treaty bans nuclear warheads in space, any proposal to use them against an asteroid would require complex diplomatic agreements. Fortunately, it’s likely that just causing a slight change in course would avert a strike. The reason is the mechanics of orbits. Many people think of a planet as a vacuum cleaner whose gravity sucks in everything in its vicinity. It’s true that a free-falling body will plummet toward the nearest source of gravity—but in space, free-falling bodies are rare. Earth does not plummet into the sun, because the angular momentum of Earth’s orbit is in equilibrium with the sun’s gravity. And asteroids and comets swirl around the sun with tremendous angular momentum, which prevents them from falling toward most of the bodies they pass, including Earth.
For any space object approaching a planet, there exists a “keyhole”—a patch in space where the planet’s gravity and the object’s momentum align, causing the asteroid or comet to hurtle toward the planet. Researchers have calculated the keyholes for a few space objects and found that they are tiny, only a few hundred meters across—pinpoints in the immensity of the solar system. You might think of a keyhole as the win-a-free-game opening on the 18th tee of a cheesy, incredibly elaborate miniature-golf course. All around the opening are rotating windmills, giants stomping their feet, dragons walking past, and other obstacles. If your golf ball hits the opening precisely, it will roll down a pipe for a hole in one. Miss by even a bit, and the ball caroms away.
Tiny alterations might be enough to deflect a space rock headed toward a keyhole. “The reason I am optimistic about stopping near-Earth-object impacts is that it looks like we won’t need to use fantastic levels of force,” Schweickart says. He envisions a “gravitational tractor,” a spacecraft weighing only a few tons—enough to have a slight gravitational field. If an asteroid’s movements were precisely understood, placing a gravitational tractor in exactly the right place should, ever so slowly, alter the rock’s course, because low levels of gravity from the tractor would tug at the asteroid. The rock’s course would change only by a minuscule amount, but it would miss the hole-in-one pipe to Earth.
Will the gravitational-tractor idea work? The B612 Foundation recommends testing the technology on an asteroid that has no chance of approaching Earth. If the gravitational tractor should prove impractical or ineffective, other solutions could be considered. Attaching a rocket motor to the side of an asteroid might change its course. So might firing a laser: as materials boiled off the asteroid, the expanding gases would serve as a natural jet engine, pushing it in the opposite direction.
But when it comes to killer comets, you’ll just have to lose sleep over the possibility of their approach; there are no proposals for what to do about them. Comets are easy to see when they are near the sun and glowing but are difficult to detect at other times. Many have “eccentric” orbits, spending centuries at tremendous distances from the sun, then falling toward the inner solar system, then slingshotting away again. If you were to add comets to one of those classroom models of the solar system, many would need to come from other floors of the building, or from another school district, in order to be to scale. Advanced telescopes will probably do a good job of detecting most asteroids that pass near Earth, but an unknown comet suddenly headed our way would be a nasty surprise. And because many comets change course when the sun heats their sides and causes their frozen gases to expand, deflecting or destroying them poses technical problems to which there are no ready solutions. The logical first step, then, seems to be to determine how to prevent an asteroid from striking Earth and hope that some future advance, perhaps one building on the asteroid work, proves useful against comets.
None of this will be easy, of course. Unlike in the movies, where impossibly good-looking, wisecracking men and women grab space suits and race to the launchpad immediately after receiving a warning that something is approaching from space, in real life preparations to defend against a space object would take many years. First the necessary hardware must be built—quite possibly a range of space probes and rockets. An asteroid that appeared to pose a serious risk would require extensive study, and a transponder mission could take years to reach it. International debate and consensus would be needed: the possibility of one nation acting alone against a space threat or of, say, competing U.S. and Chinese missions to the same object, is more than a little worrisome. And suppose Asteroid X appeared to threaten Earth. A mission by, say, the United States to deflect or destroy it might fail, or even backfire, by nudging the rock toward a gravitational keyhole rather than away from it. Asteroid X then hits Costa Rica; is the U.S. to blame? In all likelihood, researchers will be unable to estimate where on Earth a space rock will hit. Effectively, then, everyone would be threatened, another reason nations would need to act cooperatively—and achieving international cooperation could be a greater impediment than designing the technology.
We will soon have a new president, and thus an opportunity to reassess NASA’s priorities. Whoever takes office will decide whether the nation commits to spending hundreds of billions of dollars on a motel on the moon, or invests in space projects of tangible benefit—space science, environmental studies of Earth, and readying the world for protection against a space-object strike. Although the moon-base initiative has been NASA’s focus for four years, almost nothing has yet been built for the project, and comparatively little money has been spent; current plans don’t call for substantial funding until the space-shuttle program ends, in 2010. This suggests that NASA could back off from the moon base without having wasted many resources. Further, the new Ares rocket NASA is designing for moon missions might be just the ticket for an asteroid-deflection initiative.
Congress, too, ought to look more sensibly at space priorities. Because it controls federal funding, Congress holds the trump cards. In 2005, it passively approved the moon-base idea, seemingly just as budgetary log-rolling to maintain spending in the congressional districts favored under NASA’s current budget hierarchy. The House and Senate ought to demand that the space program have as its first priority returning benefits to taxpayers. It’s hard to imagine how taxpayers could benefit from a moon base. It’s easy to imagine them benefiting from an effort to protect our world from the ultimate calamity. | 0.913747 | 3.63989 |
Scotland’s Sky in April, 2015
Mercury joins two brightest planets in evening sky
Spring may have arrived, but the leading constellation of our winter sky, Orion, is still on view in our early evening sky, if not for very much longer. Look for it in the south-west at nightfall, with the three stars of his Belt lying almost parallel to the horizon. Stretch their line to the left to reach Sirius in Canis Major, our brightest nighttime star, and to the right towards Taurus, with its bright star Aldebaran and the Pleiades star cluster. High in the south-south-west is Gemini, with the twins Castor and (slightly brighter) Pollux.
To the south of Gemini is Procyon, the Lesser Dog Star in Canis Minor. Together with the true Dog Star, Sirius, and the distinctive red supergiant Betelgeuse at Orion’s top-left shoulder, Procyon completes an almost-isosceles triangle which we dub “The Winter Triangle”. At present, in fact, it forms a similar but smaller triangle with Pollux and the conspicuous planet Jupiter which dominates our southern sky at nightfall. Leo stands to the left of Jupiter with its leading star, Regulus, in the handle of the Sickle.
As April’s days lengthen, our whole sky-scape shifts further westwards each evening until, by the month’s end, Orion is setting in the west as the sky darkens
The Sun climbs more than 10° northwards during April and sunrise/sunset times for Edinburgh change from 06:44/19:50 BST on the 1st to 05:32/20:49 on the 30th. Meanwhile, the duration of nautical twilight at the start and end of the night stretches from 84 to 105 minutes.
The Moon is full on the 4th when a total lunar eclipse is visible from the Pacific and surrounding areas but not from Europe. In fact, totality, with the moon just inside the northern part of the Earth’s dark umbral shadow lasts for a mere 4 min 34 sec centred at 13:00 BST, making this the briefest total lunar eclipse for 486 years. By comparison, totality lasts for 72 minutes during the next total lunar eclipse which is visible from Scotland on the morning of 28 September this year. The Moon’s last quarter on the 12th is followed by new moon on the 18th and first quarter early on the 26th.
By nightfall on the 26th, that first quarter Moon lies 6° below Jupiter in the south-south-west. Jupiter, itself, dims a little from magnitude -2.3 to -2.1 and is slow-moving in Cancer 5° to the left of the Praesepe cluster in Cancer. The star cluster is best seen through binoculars which also show the changing positions of the four main Jovian moons as they swing from side to side of the planet. The giant planet progresses into the south-west by our star map times and sets in the north-west more than five hours later.
Even though Jupiter is twice as bright as Sirius, it pales by comparison with the evening star Venus which blazes brilliantly in the west at nightfall, and sets at Edinburgh’s west-north-western horizon by 23:38 BST on the 1st and in the north-west as late as 01:08 on the 30th. This month Venus approaches from 180 million to 150 million km and swells in diameter from 14 to 17 arcseconds, its dazzling disk appearing gibbous through a telescope as its phase changes from 78% to 67% illuminated.
Venus also speeds eastwards during the period, moving from Aries to Taurus where it passes 2.7° south of the Pleiades on the 11th to end April 3° south of Elnath at the tip of the Bull’s northern horn. There should be an impressive sight on the evening of the 21st when Venus lies 7° above-right of the earthlit crescent Moon which, in turn, is 2.5° above-left of Aldebaran.
Mars, magnitude 1.4, is low and hard to spot in our western evening twilight, becoming lost from view later in the month as it tracks towards the Sun’s far side. However, after passing beyond the Sun at superior conjunction on the 10th, Mercury emerges in our twilight to begin the innermost planet’s best evening apparition of the year.
On the 19th, Mercury shines at magnitude -1.3 and stands 4° high in the west-north-west forty minutes after sunset. Mars lies 2.8° above and to its left while the sliver of the earthlit Moon is 12° high and to their left. By the month’s end Mercury is 10° high forty minutes after sunset and shines at magnitude -0.4 22° below and to the right of Venus and only 1.7° below-left of the Pleiades. Binoculars may help to pick it out at first but it should emerge as a naked-eye object as the twilight fades and it sinks to the north-western horizon by 23:00.
Saturn is on show during the second half of the night though it does not climb far above our horizon so is not well placed for the sharpest views of its stunning ring system. For Edinburgh, it rises in the south-east at 00:46 on the 1st and by 22:40 on the 30th, reaching its highest point of 15° in the south four hours later before dawn.
Shining at magnitude 0.3 to 0.1, Saturn lies in Scorpius where it creeps 1.5° westwards above the double star Graffias. As it lies below and left of the Moon on the 8th, a telescope shows the planet’s rotation-flattened disk to be 18 arcseconds wide, within rings that span 41 arcseconds and have their northern face tilted Earthwards at 25°. Although they show an amazing complexity on the small scale, the main rings, dubbed A and B, are separated by the relatively empty dark arc of the Cassini Division. B, the brightest of the rings, has A outside it and the dusky C ring within.
This is a slightly-revised version of Alan’s article published in The Scotsman on March 31st 2015, with thanks to the newspaper for permission to republish here.
Posted on 01/04/2015, in Uncategorized and tagged 2015, Alan Pickup, ASE, Astronomical Society of Edinburgh, Cassini Division, Jupiter, lunar eclipse, Mars, Mercury, moon, Night Sky, orion, Pleiades, Saturn, Scotland, Sirius, Taurus, The Scotsman, Venus. Bookmark the permalink. Leave a comment. | 0.82036 | 3.420606 |
Magnetars, the Most Magnetic Stars In the Universe
Ultra-powerful magnetic neutron stars play hide-and-seek with astronomers. They're known to erupt without warning, some for
hours and others for months, before dimming and disappearing again.
At left is an artist's rendering of an erupting neutron star. It can generate the most intense magnetic field observed in the Universe. The field strength of a magnetar is one thousand trillion times stronger than Earth's and is so intense that it heats the surface to 18 million degrees Fahrenheit.
"We only know of about 10 magnetars in the Milky Way galaxy." remarked Dr. Peter Woods of the Universities Space Research Association. "If the antics of the magnetar we are studying now are typical, then there very well could be hundreds more out there." NASA research has suggested there may be far more magnetars than previously thought.
Observing the explosions from these celestial bodies has been tricky. The answer lies in the timing. So how do the researchers observe what has never been seen? Leave it to NASA to develop the perfect piece of equipment to handle the job.
The Rossi X-ray Timing Explorer (RXTE
), launched in December 1995 from Kennedy Space Center, Fla., was designed to observe fast-moving neutron stars, X-ray pulsars and bursts of X-rays that brighten the sky and disappear.
Some pulsars spin over a thousand times a second. A neutron star generates a gravitational pull so powerful that a marshmallow impacting the star's surface would hit with the force of a thousand hydrogen bombs.
Magnetars, the most magnetic stars known, aren't powered by a conventional mechanism such as nuclear fusion or rotation, according to Dr. Vicky Kaspi. "Magnetars represent a new way for a star to shine, which makes this a fascinating field," said Kaspi.
Although not totally understood yet, magnetars have magnetic fields a thousand times stronger than ordinary neutron stars that measure a million billion Gauss
, or about a hundred-trillion refrigerator magnets. For comparison, the Sun's magnetic field is only about 5 Gauss.
In the constellation Cassiopeia, approximately 18,000 light years from Earth, a magnetar named 1E 2259 is being studied. It suddenly began bursting in June 2002, with over 80 bursts recorded within a 4-hour window. Since then, Magnetar 1E 2259 hasn't disturbed the depths of space.
Using RXTE, astronomers can study how gravity works near black holes and observe changes in X-ray brightness that last for a thousandth of a second, or for several years. They also can monitor explosive wavelengths not able to be seen in visible light.
Eta Carinae is an extremely massive star in our galaxy, and an extremely unstable one. Since 1996, a science team has been monitoring the X-ray flux from this region using RXTE. As RXTE continues to provide the first detailed monitoring of the X-ray emissions of Eta Car, coordinated observations are helping answer many scientists' questions. HST Image Credit: Jon Morse
Astronomers will be able to study this violent and bizarre space phenomenon in greater dimension when NASA's Swift
Gamma-Ray Burst Explorer is launched in mid-2004.
Swift will be about 20 times more sensitive to magnetar bursts than any other satellite.
This research project is a cooperative endeavor between NASA's Marshall Space Flight Center, the National Space Science and
Technology Center and several Alabama universities.
For further information, visit:
NASA's John F. Kennedy Space Center, Marshall Space Flight Center and Goddard Space Flight Center | 0.840536 | 3.919924 |
Earth’s Address Within Massive Supercluster of 100,000 Galaxies
Astronomers have mapped the Milky Way’s position to the outskirts of a supercluster of galaxies, newly dubbed Laniakea, meaning “Immense Heaven”.
The distribution of galaxies throughout the universe is not more-or-less even; instead, galaxies tend to cluster together, bound together by the pull of each other’s gravity. These groups can be a variety of sizes. The Milky Way Galaxy, for instance, is part of what is called the Local Group, which contains upwards of 54 galaxies, covering a diameter of 10 megalight-years (10 million light-years).
But this Local Group is just a small part of a much, much bigger structure, which researchers at the University of Hawai’i Mānoa have now mapped in detail. Coming in at over 100,000 galaxies, the massive supercluster has been given the name Laniakea — “immense heaven” in Hawaiian.
The new 3D map was created by examining the positions and movements of the 8000 closest galaxies to the Milky Way. After calculating which galaxies were being pulled away from us and which were being pulled towards us — accounting for the universe’s expansion — the team, led by astronomer R. Brent Tully, was able to map the paths of galactic migration — and define the boundaries of Laniakea.
Traditionally, the borders of galactic superclusters have been difficult to map, but studying the gravitational force acting on our neighbouring galaxies has provided some important clues. All objects inside Laniakea are being slowly but surely drawn to a single point — a force known as the Great Attractor, a gravitational anomaly with a mass tens of thousands of times the mass of the Milky Way.
“We probably need to measure to another factor of three in distance to explain our local motion,” Tully said. “We might find that we have to come up with another name for something larger than we’re a part of — we’re entertaining that as a real possibility.”
The full paper, “The Laniakea supercluster of galaxies”, can be read online in the journal Nature.
Posted in Science For The New Agewith no comments yet. | 0.812195 | 3.53315 |
Stars explode on a fairly regular basis, but they’re virtually impossible to predict. Now, for the first time ever, astronomers have captured an image of a supernova they knew was coming. Here’s how they did it.
It may sound weird, but this is the third time that astronomers have observed this particular supernova. Owing to a quirky astronomical phenomenon known as gravitational lensing, we’re basically seeing an instant replay of an event that originally happened 10 billion years ago.
Supernova Refsdal was first observed back in 2014. It showed up as four separate images in an arrangement known as an Einstein Cross. This optical illusion was caused by the gravitational forces exerted by a massive galaxy cluster, MACS J1149.5+2223, which from our perspective is in front of the supernova.
Logically, the cluster should block our view of the supernova. But its tremendous gravitational forces are bending space-time around it. Essentially, the galaxy cluster is acting like a gigantic magnifying glass.
An illustration showing gravitational lensing at work (Credit: NASA/ESA)
What’s more, the beams took alternate routes to Earth, some longer than others, which is why we’re seeing a lag effect.
Left: The circle indicates the predicted position of the newest appearance of Nefsdal. Upper right: Observations taken by Hubble in October in preparation for the anticipated explosion. Bottom right: Right on schedule, the supernova appears. (Credit: NASA/ESA)
Needless to say, the task of predicting the exact time—give or take a few days or weeks–was not easy. University of California astronomer Tommaso Treu explained it in a Hubble release:
We used seven different models of the [galaxy] cluster to calculate when and where the supernova was going to appear in the future. It was a huge effort from the community to gather the necessary input data using Hubble, VLT-MUSE, and Keck and to construct the lens models, And remarkably all seven models predicted approximately the same time frame for when the new image of the exploding star would appear.
The models predicted a “replay” of Refsdal in late 2015, or the first third of 2016. In anticipation, the Hubble Space Telescope has been scanning that particular region of the cosmos since October. Right on cue, the supernova was spotted on December 11, 2015.
The exercise was a remarkable opportunity for astronomers to test their models of how mass, including dark matter, is distributed within this galaxy cluster. [Hubble Space Telescope] | 0.874064 | 3.954655 |
3 What is an Atmosphere?A layer of gas which surrounds a world is called an atmosphere.they are usually very thin compared to planet radiusPressure is created by atomic & molecular collisions in an atmosphere.heating a gas in a confined space increases pressurenumber of collisions increaseunit of measure: 1 bar = 14.7 lbs/inch2 = Earth’s atmospheric pressure at sea levelPressure balances gravity in an atmosphere.
6 Effects of an Atmosphere on a Planet greenhouse effectmakes the planetary surface warmer than it would be otherwisescattering and absorption of lightabsorb high-energy radiation from the Sunscattering of optical light brightens the daytime skycreates pressurecan allow water to exist as a liquid (at the right temperature)creates wind and weatherpromotes erosion of the planetary surfacecreates aurorasinteraction with the Solar wind when magnetic fields are present
7 The Greenhouse EffectVisible Sunlight passes through a planet’s atmosphere.Some of this light is absorbed by the planet’s surface.Planet re-emits this energy (heat) as infrared (IR) light.planet’s temperature lower than SunIR light is “trapped” by the atmosphere.its return to space is slowedThis causes the overall surface temperature to be higher than if there were no atmosphere at all.
8 Greenhouse GasesKey to Greenhouse Effect…gases which absorb IR light effectively:water [H2O]carbon dioxide [CO2]methane [CH4]These are molecules which rotate and vibrate easily.they re-emit IR light in a random directionThe more greenhouse gases which are present, the greater the amount of surface warming.
9 Planetary Energy Balance Solar energy received by a planet must balance the energy it returns to spaceplanet can either reflect or emit the energy as radiationthis is necessary for the planet to have a stable temperature
10 What Determines a Planet’s Surface Temperature? Greenhouse Effect cannot change incoming Sunlight, so it cannot change the total energy returned to space.it increases the energy (heat) in lower atmosphereit works like a blanketIn the absence of the Greenhouse Effect, what would determine a planet’s surface temperature?the planet's distance from the Sunthe planet’s overall reflectivitythe higher the albedo, the less light absorbed, planet coolerEarth’s average temperature would be –17º C (–1º F) without the Greenhouse Effect
11 Greenhouse Effect on the Planets Greenhouse Effect warms Venus, Earth, & Marson Venus: it is very strongon Earth: it is moderateon Mars: it is weakavg. temp. on Venus & Earth would be freezing without it
12 Structure of Earth’s Atmosphere pressure & density of atmosphere decrease with altitudetemperature varies “back and forth” with altitudethese temperature variations define the major atmospheric layersexospherelow density; fades into spacethermospheretemp begins to rise at the topstratosphererise and fall of temptropospherelayer closest to surfacetemp drops with altitude
13 Atmospheres Interact with Light X raysionize atoms & moleculesdissociate moleculesabsorbed by almost all gasesUltraviolet (UV)dissociate some moleculesabsorbed well by O3 & H2OVisible (V)passes right through gasessome photons are scatteredInfrared (IR)absorbed by greenhouse gases
14 Reasons for Atmospheric Structure Light interactions are responsible for the structure we see.Troposphereabsorbs IR photons from the surfacetemperature drops with altitudehot air rises and high gas density causes storms (convection)Stratospherelies above the greenhouse gases (no IR absorption)absorbs heat via Solar UV photons which dissociate ozone (O3)UV penetrates only top layer; hotter air is above colder airno convection or weather; the atmosphere is stratifiedThermosphereabsorbs heat via Solar X-rays which ionizes all gasescontains ionosphere, which reflects back human radio signalsExospherehottest layer; gas extremely rarified; provides noticeable drag on satellites
15 Structure of Terrestrial Planet Atmospheres Mars, Venus, Earth allhave warm tropospheres (and greenhouse gases)have warm thermospheres which absorb Solar X raysOnly Earth hasa warm stratospherean UV-absorbing gas (O3)All three planets have warmer surface temps due to greenhouse effect
16 MagnetospheresThe Sun ejects a stream of charged particles, called the solar wind.it is mostly electrons, protons, and Helium nucleiEarth’s magnetic field attracts and diverts these charged particles to its magnetic poles.the particles spiral along magnetic field lines and emit lightthis causes the aurora (aka northern & southern lights)this protective “bubble” is called the magnetosphereOther terrestrial worlds have no strong magnetic fieldssolar wind particles impact the exospheres of Venus & Marssolar wind particles impact the surfaces of Mercury & Moon
18 What are Weather and Climate? weather – short-term changes in wind, clouds, temperature, and pressure in an atmosphere at a given locationclimate – long-term average of the weather at a given locationThese are Earth’s global wind patterns or circulationlocal weather systems move along with themweather moves from W to E at mid-latitudes in N hemisphereTwo factors cause these patternsatmospheric heatingplanetary rotation
19 Global Wind Patterns air heated more at equator warm air rises at equator; heads for polescold air moves towards equator along the surfacetwo circulation cells are created in each hemispherecells do not go directly from pole to equator; air circulation is diverted by…Coriolis effectmoving objects veer right on a surface rotating counterclockwisemoving objects veer left on a surface rotating clockwise
20 Global Wind PatternsOn Earth, the Coriolis effect breaks each circulation cell into three separate cellswinds move either W to E or E to WCoriolis effect not strong on Mars & VenusMars is too smallVenus rotates too slowlyIn thick Venusian atmosphere, the pole-to-equator circulation cells distribute heat efficientlysurface temperature is uniform all over the planet
21 Clouds, Rain and SnowClouds strongly affect the surface conditions of a planetthey increase its albedo, thus reflecting away more sunlightthey provide rain and snow, which causes erosionFormation of rain and snow:
22 Four Major Factors which affect Long-term Climate Change
23 Gain/Loss Processes of Atmospheric Gas Unlike the Jovian planets, the terrestrials were too small to capture significant gas from the Solar nebula.what gas they did capture was H & He, and it escapedpresent-day atmospheres must have formed at a later timeSources of atmospheric gas:outgassing – release of gas trapped in interior rock by volcanismevaporation/sublimation – surface liquids or ices turn to gas when heatedbombardment – micrometeorites, Solar wind particles, or high-energy photons blast atoms/molecules out of surface rockoccurs only if the planet has no substantial atmosphere already
24 Gain/Loss Processes of Atmospheric Gas Ways to lose atmospheric gas:condensation – gas turns into liquids or ices on the surface when cooledchemical reactions – gas is bound into surface rocks or liquidsstripping – gas is knocked out of the upper atmosphere by Solar wind particlesimpacts – a comet/asteroid collision with a planet can blast atmospheric gas into spacethermal escape – lightweight gas molecules are lost to space when they achieve escape velocitygas is lost forever!
26 Origin of the Terrestrial Atmospheres Venus, Earth, & Mars received their atmospheres through outgassing.most common gases: H2O, CO2, N2, H2S, SO2Chemical reactions caused CO2 on Earth to dissolve in oceans and go into carbonate rocks (like limestone.)this occurred because H2O could exist in liquid stateN2 was left as the dominant gas; O2 was exhaled by plant lifeas the dominant gas on Venus, CO2 caused strong greenhouse effectMars lost much of its atmosphere through impactsless massive planet, lower escape velocity
27 Origin of the Terrestrial Atmospheres Lack of magnetospheres on Venus & Mars made stripping by the Solar wind significant.further loss of atmosphere on Marsdissociation of H2O, H2 thermally escapes on VenusGas and liquid/ice exchange occurs through condensation and evaporation/sublimation:on Earth with H2Oon Mars with CO2Since Mercury & the Moon have no substantial atmosphere, fast particles and high-energy photons reach their surfacesbombardment creates a rarified exosphere
29 Martian Weather Today Seasons on Mars are more extreme than on Earth Mars’ orbit is more ellipticalCO2 condenses & sublimes at opposite poleschanges in atmospheric pressure drive pole-to-pole windssometimes cause huge dust storms
32 Climate History of Mars More than 3 billion years ago, Mars must have had a thick CO2 atmosphere and a strong greenhouse effect.the so-called “warm and wet period”Eventually CO2 was lost to space.some gas was lost to impactscooling interior meant loss of magnetic fieldSolar wind stripping removed gasGreenhouse effect weakened until Mars froze.
33 Venusian Weather Today Venus has no seasons to speak of.rotation axis is nearly 90º to the ecliptic planeVenus has little wind at its surfacerotates very slowly, so there is no Coriolis effectThe surface temperature stays constant all over Venus.thick atmosphere distributes heat via two large circulation cellsThere is no rain on the surface.it is too hot and Venus has almost no H2OVenusian clouds contain sulfuric acid!implies recent volcanic outgassing?
34 Climate History of Venus Venus should have outgassed as much H2O as Earth.Early on, when the Sun was dimmer, Venus may have had oceans of waterVenus’ proximity to the Sun caused all H2O to evaporate.H2O caused runaway greenhouse effectsurface heated to extreme temperatureUV photons from Sun dissociate H2O; H2 escapes, O is stripped
35 The Uniqueness of Earth’s Atmosphere Outgassing from volcanoes on Venus, Earth, & Mars released the same gasses:primarily water (H2O), Carbon dioxide (CO2), and Nitrogen (N2)So why did Earth’s atmosphere end up so different?why did Earth retain most of its H2O – enough to form oceans?why does Earth have so little CO2 in its atmosphere, when it should have outgassed just as much CO2 as Venus?why does Earth have so much more Oxygen (O2) than Venus & Mars?why does Earth have an ultraviolet-absorbing stratosphere?
36 The Uniqueness of Earth’s Atmosphere Earth’s H2O condensed because of the temperature.oceans formed, in which the CO2 gas dissolvedchemical reactions bound the C of CO2 into rocks like limestonelow level of atmospheric CO2 causes moderate greenhouse effecttemperatures on Earth remain where H2O can be a liquid CO2There was once liquid H2O on Mars and maybe Venus.before CO2 could dissolve out, temperatures fell/rose so thatoceans boiled away on Venus and froze out on MarsEarth’s O2 was not outgassed by volcanoes.O2 is a highly reactive chemicalit would disappear in a few million years if not replenishedno geologic process creates O2
37 The Uniqueness of Earth’s Atmosphere Earth’s O2 was created through the evolution of life.plants & microorganism release O2 via photosynthesisthey convert CO2 into O2In the upper atmosphere, O2 in converted into ozone (O3).via chemical processed involving Solar ultraviolet lightO3 absorbs Solar UV photons which heats the stratosphereVenus & Mars lack plant & microbial life.so they have no O2 in their atmospheres and no stratospheres
39 The CO2 Cycle is a Feedback Mechanism which Regulates Earth’s Climate
40 Stability of Earth’s Climate Plate tectonics causes the relative stability of Earth’s climate.plate tectonics makes the CO2 cycle workit takes about 40,000 years for the CO2 cycle to restore balanceThere have been temporary episodes of extreme cooling and heating in Earth’s history.these ice ages & hothouse period have their own feedback mechanisms
41 Studying Past LifeWe know the history of life on Earth by studying fossil records.fossils are more difficult to find as we look back to earlier epochsmore organisms which lacked skeletons leave fewer fossilserosion erases much old fossil evidencesubduction destroys fossils carries deep beneath Earth’s surfacewe have found fossils of large & small animals, plants, microorganismsthe fossil record goes back 3.5 billion yearsdeficit of 13C, a sign of life, in rocks as old as 3.85 billion years
42 Origin of Life All known organisms: build proteins from same subset of amino acidsuse ATP to store energy in cellsuse DNA molecules to transmit genesAll organisms share same genetic code…sequence of chemical basesOrganisms have similar genes.Indicates that all living organisms share a common ancestor.Life on Earth is:divided into three major groupingsplants & animals are just two tiny branches
43 Origin of Life We have no direct evidence of when or how life began. We have a plausible scenario of how chemistry begat biology:chemicals found on Earth, “sparked” by lighting, can form complex organic molecules naturallyRNA can form, and if some of it becomes self-replicating, it can lead to…DNA and full, self-replicating organisms.Alternatively, this process could have begun on Mars or Venus.life could have been transported to Earth via meteoritesorganic molecules have been found in meteorites
44 Evolution of LifeThe oceans were full of single-celled life 3.5 billion years ago.conditions on land were too inhospitable due to lack of O3 in atmosphereOrganism’s DNA is reproduced, but can change due to copying errors or external factorsa change in the base sequence of an organism’s DNA is called a mutationSome mutations are lethal, others make the cell better able to survive.those organisms which are better at adapting to their environment… thrivethis process is called natural selection, first proposed by Charles DarwinNatural selection helps some species to dominate, and creates entirely new species from older ones.life on Earth rapidly diversifiedSome 2 billion years ago, life was still confined to the oceans.
45 The Rise of OxygenSingle-celled organisms called cyanobacteria appear to have created O2 via photosynthesis as early as 3.5 billion years ago.the first O2 produced was absorbed into rocks via chemical reactionsit was not until about 2 billion years ago than the rocks were saturated with O2 and so it began to accumulate in the atmospherefossil record indicates current levels of O2 were reached 200 million yrs agoThe build-up of O2 in the atmosphere permitted:the evolution of oxygen-dependent animalsthe formation of O3 in the stratosphere, making it safe for life to move out onto dry landPlants first appeared on land some 475 million years ago.Animals soon followed…
46 The Rise of HumansSome 540 million years ago, most of the life on Earth was still one-celled and tiny.For the next 40 million years, until 500 million years ago:there was a dramatic increase in the number of species, especially animalsanimals diversified into all the basic body plans which we find todaythis incredible diversification of species is called the Cambrian explosionThe first humans appeared a few million years ago.humans civilization is 10,000 years old, industrial society 200 years oldAlthough latecomers to the scene, humans are the most successful species to survive on EarthHuman population has grown exponentiallyHow will this affect our host – the Earth?
47 Mass Extinctions Evolution of species normally occurs gradually. one species goes extinct per centuryEvolution can receive a jolt during a mass extinction.historically, this has been caused by an impacteven species not directly killed by the impact will soon go extinct due to lack of food and changes in the ecosystemspecies at the top of the food chain are most susceptibleHuman activity in recent times have driven many more species to extinction.could we be undergoing an episode of mass extinction now?what will the consequences be for humans?
48 Ozone DepletionO3 in the stratosphere shields Earth’s surface from Solar UVA depletion of O3 was observedozone hole over Antarcticadiscovered in mid-1980’sappears in Antarctic spring19791998The apparent cause of the ozone hole is a man-made chemical, CFCused as a refrigerant, CFC is inert and rises to the stratosphereSolar UV photons break down CFCs and create Cl – Chlorine gasCl serves as a catalyst in destroying O3reaction goes faster at low temperatures … like over AntarcticaMars is an example of no ozone, UV photons sterilize the surface.increased UV on Earth would increase cancer rates and genetic mutations
57 What have we learned?Describe the general atmospheric properties of each of the five terrestrial worlds.Moon and Mercury: essentially airless with very little atmospheric gas. Venus: thick CO2 atmosphere, with high surface temperature and pressure. Mars: thin CO2 atmosphere, usually below freezing and pressure too low for liquid water. Earth: nitrogen/oxygen atmosphere with pleasant surface temperature and pressure.What is atmospheric pressure?The result of countless collisions between atoms and molecules in a gas. Measured in bars (1 bar = Earth’s pressure at sea level.)Summarize the effects of atmospheres.Atmospheres absorb and scatter light, create pressure, warm the surface and distribute heat, create weather, and interact with the Solar wind to make auroras.
58 What have we learned? What is the greenhouse effect? Planetary warming caused by the absorption of infrared light from a planet’s surface by greenhouse gases such as carbon dioxide, methane, and water vapor.How would planets be different without the greenhouse effect?They would be colder, with temperatures determined only by distance from the Sun and reflectivity.Compare the greenhouse effect on Venus, Earth, & Mars.All three planets are warmed by the greenhouse effect, but it is weak on Mars, moderate on Earth, and very strong on Venus.
59 What have we learned?Describe the basic structure of Earth’s atmosphere.Pressure and density decrease rapidly with altitude. Temperature drops with altitude in the troposphere, rises with altitude in the lower part of the stratosphere, and rises again in the thermosphere and exosphere.How do interactions with light explain atmospheric structure?Solar X rays heat and ionize gas in the thermosphere. Solar ultraviolet is absorbed by molecules such as ozone, heating the stratosphere. Visible light warms the surface (and colors the sky), which radiates infrared light that warms the troposphere.Contrast the atmospheric structures of Venus, Earth, and Mars.Venus and Mars lack and ultraviolet-absorbing stratosphere.
60 What have we learned? What is a magnetosphere? Created by a global magnetic field, it acts like a protective bubble surrounding the planet that diverts charged particles from the Solar wind, channeling some to the magnetic poles where they can lead to auroras.What is the difference between weather and climate?Weather refers to short-term changes in wind, clouds, temperature, and pressure. Climate is the long-term average of weather.What creates global wind patterns?Atmospheric heating at the equator creates two huge equator-to-pole circulation cells. If the Coriolis effect is strong enough, these large cells may split into smaller cells. This split occurs on Earth, but not on Venus (because of slow rotation) or Mars (because of small size).
61 What have we learned? What causes rain or snow to fall? Convection carries evaporated (or sublimated) water vapor to high, cold altitudes, where it condenses into droplets or ice flakes, forming clouds. When the droplets or ice flakes get large enough, convection cannot hold them aloft and they fall as rain, snow, or hail.Describe four factors that can cause long-term climate change.The gradual brightening of the Sun over the history of the Solar System. Changes in a planet’s axis tilt. Changes in a planet’s reflectivity. Changes in a planet’s abundance of greenhouse gases.
62 What have we learned?Describe the processes by which an atmosphere can gain and lose gas.Gains come from outgassing, evaporation/sublimation, or bombardment, but the latter only if there’s very little atmosphere. Gases can be lost by condensation, chemical reactions with surface materials, stripping from the upper atmosphere by small particles or photons, being blasted away by impacts, or by achieving thermal escape velocity.Why are the atmospheres of the Moon & Mercury “all exosphere”?They have no current source for outgassing and they are too small and warm to hold any atmosphere they may have had in the past. They have small amounts of gas above their surfaces only because of bombardment by Solar wind particles.
63 What have we learned?Describe major, seasonal features of Martian weather today.Seasonal changes in temperature cause carbon dioxide to alternately condense and sublime at the polls, driving pole-to-pole winds and sometimes creating huge dust storms.Why did Mars’ early warm and wet period come to an end?Mars once had a thick carbon dioxide atmosphere and strong greenhouse effect. Most of the CO2 was eventually lost to space, probably because the cooling interior could no longer create a strong magnetic field to protect the atmosphere from the Solar wind. As CO2 to was lost, the greenhouse effect weakened until the planet froze.
64 What have we learned? Why is Venus so hot? At its distance from the Sun, any liquid water was destined to evaporate, alternately driving a runaway greenhouse effect that dried up the planet and heated it to its extreme temperature.Could Venus ever have had oceans?Venus probably outgassed plenty of water vapor. Early in the Solar System’s history, when the Sun was dimmer, it is possible that this water vapor could have condensed to make rain and oceans, though we cannot be sure.After studying Mars and Venus, why does Earth’s climate seem surprising?Mars and Venus both underwent dramatic and permanent climate change early in their histories. Earth has somehow maintained a relatively stable climate, even as the Sun has warmed with time. | 0.807321 | 3.59567 |
In the standard theory of gravity—general relativity—dark matter plays a vital role, explaining many observations that the standard theory cannot explain by itself. But for 70 years, cosmologists have never observed dark matter, and the lack of direct observation has created skepticism about what is really out there.
Lately, some scientists have turned the question around, from “is dark matter correct?” to “is our standard theory of gravity correct?” Most recently, Fermilab scientists Scott Dodelson and former Brinson Fellow Michele Liguori demonstrated one of the first pieces of theoretical evidence that an alternative theory of gravity can explain the large scale structure of the universe.
“To definitively claim that dark matter is the answer, we need to find it,” Dodelson explained to PhysOrg.com. “We can do this in one of three ways: produce it in the lab (which might happen at Fermilab, the soon-to-start LHC, or ultimately the International Linear Collider), see a pair of dark matter particles annihilate and produce high energy photons (there are about a half dozen experiments designed to look for this), or see a dark matter particle bump a nucleus in a large underground detector (again, about 10 experiments are looking for this). Until one or more of these things happen, skeptics are still allowed. … After they happen, skeptics will become crackpots.”
Although cosmologists have never directly observed dark matter, they have many good reasons for not giving up hope. The ways that galaxies rotate and starlight bends (gravitational lensing) stray from predictions based on visible matter. Further, the formation of large cosmic structures (such as galaxies and galaxy clusters) would have required significantly large matter perturbations when the Universe was less than a million years old that simply don’t exist in a theory of general relativity before “tacking on” dark matter.
“It is extremely important to see how well a no-dark-matter cosmology does,” said Dodelson. “[In the standard theory,] we are asking the community to believe in the existence of a particle that has never been seen. We have to be damned sure that you can't explain the universe without this huge leap. Our Figure 1 [see citation below] illustrates that, in standard gravity, a no-dark-matter model does not do well at all.”
While altering the theory of gravity may seem like pulling the rug out from under a century of observations and pain-staking calculations, an alternative theory may simply be “more correct” than today’s standard theory. Just as Einstein’s theory was “more correct” than Newton’s because it improved upon the older one by noticing more specific details (e.g. extraordinary masses and speeds), a new alternative theory may only drastically change gravity at certain scales.
“Perhaps a fundamental theory of gravity which differs from general relativity on large scales can explain the observations without recourse to new, unobserved particles,” wrote Dodelson and Liguori in their study published in Physical Review Letters. “Now more than ever before, there are very good reasons to explore this idea of modifying gravity. For, the case of dark energy also hinges on the assumption that general relativity describes gravity on larges scales. Dark energy is even more difficult to explain than dark matter, so it seems almost natural to look at gravity as the culprit in both cases.”
The new theory (or groundwork for it) under investigation would be Jacob Bekenstein’s relativistic covariant theory of gravity (TeVeS), published in 2004. Bekenstein based his theory on a modified version of Newtonian theory from the early ‘80s, dependent on gravitational acceleration and called modified Newtonian dynamics (MOND) by its founder, Mordecai Milgrom.
“MOND, the original theory on which TeVeS is based, was already quite successful at explaining galactic dynamics (even better, in some cases, than the dark matter paradigm), but it failed completely at explaining other observations—gravitational lensing in particular,” explained Liguori. “For this reason, it couldn't be considered a real alternative to dark matter. Bekenstein’s theory, by generalizing MOND, retains its good features while overcoming its main problems at the same time. This makes TeVeS a much more interesting theory than MOND. It is then worthwhile (and necessary) to test TeVeS’ predictions in detail and compare them to the standard dark matter paradigm to see if TeVeS can be a viable alternative.”
Dodelson and Liguori find Bekenstein’s theory intriguing in this context because, for one, the gravitational acceleration scale in the theory is very close to that required for the observed acceleration of the Universe. The scale is also very similar to that proposed in “post hoc” theories such as dark energy. Even more interesting is the fact that the origins of Bekenstein’s theory had nothing to do with cosmic acceleration.
But the feature of Bekenstein’s theory that Dodelson and Liguori focus on most is that the theory—unlike standard general relativity—allows for fast growth of density perturbations arising from small inhomogeneities during recombination. Building on this finding from scientists Skordis et al. earlier this year, Dodelson and Liguori have found which aspect of the theory actually causes the enhanced growth—the part that may solve the cosmological structure problem.
The pair has discovered that, while Bekenstein’s theory has three functions which characterize space-time—a tensor, vector and scalar (TeVeS)—it’s the perturbations in the vector field that are key to the enhanced growth. General relativity describes space-time with only a tensor (the metric), so it does not include these vector perturbations.
“The vector field solves only the enhanced growth problem,” said Dodelson. “It does so by exploiting a little-known fact about gravity. In our solar system or galaxy, when we attack the problem of gravity, we solve the equation for the Newtonian potential. Actually, there are two potentials that characterize gravity: the one usually called the Newtonian potential and the perturbation to the curvature of space. These two potentials are almost always very nearly equal to one another, so it is not usually necessary to distinguish them.
“In the case of TeVeS, the vector field sources the difference between the two,” he continued. “As it begins to grow, the difference between the two potentials grows as well. This is ultimately what drives the overdense regions to accrete more matter than in standard general relativity. The quite remarkable thing about this growth is that Bekenstein introduced the vector field for his own completely independent reasons. As he remarked to me, ‘Sometimes theories are smarter than their creators.’"
Dodelson and Liguori see this solution to large structure formation as an important step for a gravity theory based on baryon-only matter. Other problems that their theory (or any alternative theory) will have to confront include accounting for the mismatch in galaxy clusters between mass and light. Also, the theory must conform to at least two observations: the galaxy power spectrum on large scales, and the cosmic microwave background fluctuations, which correspond to baby galaxies and galaxy clusters.
“As Scott says, until dark matter will be observed, skeptics will be allowed,” said Liguori. “Despite the many and impressive successes of the dark matter paradigm, which make it very likely to be correct, we still don't have any final and definitive answer. In light of this, it is important to keep an eye open for possible alternative explanations. Even when, after the analysis, alternative theories turn out to be wrong, the result is still important, as it strengthen the evidence for dark matter as the only possible explanation of observations.”
Citation: Dodelson, Scott and Liguori, Michele. “Can Cosmic Structure Form without Dark Matter?” Physical Review Letters 97, 231301 (2006).
By Lisa Zyga, Copyright 2006 PhysOrg.com
Explore further: Gravitational waves may oscillate, just like neutrinos | 0.850669 | 4.071859 |
First suggested by Albert Einstein more than 100 years ago, the paradox deals with the effects of time in the context of travel at near the speed of light. Einstein originally used the example of two clocks – one motionless, one in transit. He stated that, due to the laws of physics, clocks being transported near the speed of light would move more slowly than clocks that remained stationary.
In more recent times, the paradox has been described using the analogy of twins. If one twin is placed on a space shuttle and travels near the speed of light while the remaining twin remains earthbound, the unmoved twin would have aged dramatically compared to his interstellar sibling, according to the paradox.
“If the twin aboard the spaceship went to the nearest star, which is 4.45 light years away at 86 percent of the speed of light, when he returned, he would have aged 5 years. But the earthbound twin would have aged more than 10 years!” said Kak.
The fact that time slows down on moving objects has been documented and verified over the years through repeated experimentation. But, in the previous scenario, the paradox is that the earthbound twin is the one who would be considered to be in motion – in relation to the sibling – and therefore should be the one aging more slowly. Einstein and other scientists have attempted to resolve this problem before, but none of the formulas they presented proved satisfactory.
Kak’s findings were published online in the International Journal of Theoretical Science, and will appear in the upcoming print version of the publication. “I solved the paradox by incorporating a new principle within the relativity framework that defines motion not in relation to individual objects, such as the two twins with respect to each other, but in relation to distant stars,” said Kak. Using probabilistic relationships, Kak’s solution assumes that the universe has the same general properties no matter where one might be within it.
The implications of this resolution will be widespread, generally enhancing the scientific community’s comprehension of relativity. It may eventually even have some impact on quantum communications and computers, potentially making it possible to design more efficient and reliable communication systems for space applications.
For more information, please contact Subhash Kak at 225-578-5552 or [email protected].
Subhash Kak | EurekAlert!
NASA'S OSIRIS-REx spacecraft slingshots past Earth
25.09.2017 | NASA/Goddard Space Flight Center
Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Physics and Astronomy
25.09.2017 | Health and Medicine
22.09.2017 | Life Sciences | 0.891416 | 3.880177 |
Editor's Note, Sept. 23, 2008: Smithsonian magazine profiled astrophysicist Andrea Ghez in April, 2008. Today, Ghez was one of 28 recipients of a prestigious MacArthur genius grant, acknowledging her contributions to the study of black holes in the evolution of galaxies.
From This Story
From the summit of Mauna Kea, nearly 14,000 feet above the Pacific Ocean, the Milky Way tilts luminously across the night sky, an edge-on view of our galaxy. Parts of the great disk are obscured by dust, and beyond one of those dusty blots, near the teapot of the constellation Sagittarius, lies the center of the Milky Way. Hidden there is a deeply mysterious structure around which more than 200 billion stars revolve.
Behind me atop the craggy rocks of this dormant volcano on the island of Hawaii are the twin domes of the W. M. Keck Observatory. Each dome houses a telescope with a giant mirror almost 33 feet wide and, like a fly's eye, made of interlocking segments. The mirrors are among the world's largest for gathering starlight, and one of the telescopes has been equipped with a dazzling new tool that greatly increases its power. I gaze at the nearest of the Milky Way's graceful spiral arms as I wait for technicians to flip the switch.
Then, suddenly and with the faint click of a shutter sliding open, a golden-orange laser beam shoots into the sky from the open dome. The ray of light, 18 inches wide, appears to end inside one of the blackest spots in the Milky Way. It actually ends 55 miles above the surface of Earth. The signal it makes there allows the telescope to compensate for the blur of Earth's atmosphere. Instead of jittery pictures smeared by the constantly shifting rivers of air over our heads, the telescope produces images as clear as any obtained by satellites in space. Keck was one of the first observatories to be outfitted with a laser guide; now half a dozen others are beginning to use them. The technology provides astronomers with a sharp view of the galaxy's core, where stars are packed as tightly as a summer swarm of gnats and swirl around the darkest place of all: a giant black hole.
The Milky Way's black hole is undoubtedly the strangest thing in our galaxy—a three-dimensional cavity in space ten times the physical size of our sun and four million times the mass, a virtual bottomless pit from which nothing escapes. Every major galaxy, it's now believed, has a black hole at its core. And for the first time, scientists will be able to study the havoc these mind-boggling entities wreak. Throughout this decade, Keck astronomers will track thousands of stars caught in the gravity of the Milky Way's black hole. They will try to figure out how stars are born in its proximity and how it distorts the fabric of space itself. "I find it amazing that we can see stars whipping around our galaxy's black hole," says Taft Armandroff, director of the Keck Observatory. "If you had told me as a graduate student that I'd see that during my career, I'd have said it was science fiction."
To be sure, the evidence for black holes is entirely indirect; astronomers have never actually seen one. Albert Einstein's general theory of relativity predicted that the gravity of an extremely dense body could bend a ray of light so severely that it could not escape. For example, if something with the mass of our sun were shrunk into a ball a mile and a half in diameter, it would be dense enough to trap light. (For Earth to become a black hole, its mass would have to be compressed to the size of a pea.)
In 1939, J. Robert Oppenheimer, the man credited with developing the atom bomb, calculated that such drastic compression could happen to the biggest stars after they ran out of hydrogen and other fuel. Once the stars sputtered out, Oppenheimer and a colleague posited, the remaining gas would collapse due to its own gravity into an infinitely dense point. Telescope observations in the 1960s and 1970s backed up the theory. A few researchers suggested the only possible power source for something so luminous as quasars—extremely bright beacons billions of light-years away—would be a concentration of millions of suns pulled together by what scientists later dubbed a supermassive black hole. Astronomers then found stars that seemed to whip around invisible entities in our Milky Way, and they concluded that only the pull of gravity from small black holes—containing several times the mass of our sun and known as stellar-mass holes—could keep the stars in such tight orbits.
The Hubble Space Telescope added to the evidence for black holes in the 1990s by measuring how quickly the innermost parts of other galaxies rotate—up to 1.1 million miles per hour in big galaxies. The startling speeds pointed to cores containing up to a billion times the mass of the Sun. The discovery that supermassive black holes are at the core of most, if not all, galaxies was one of Hubble's greatest achievements. "At the beginning of the Hubble survey, I would have said black holes are rare, maybe one galaxy in 10 or 100, and that something went wrong in the history of that galaxy," says Hubble scientist Douglas Richstone of the University of Michigan. "Now we've shown they are standard equipment. It's the most remarkable thing."
Even from Hubble, though, the Milky Way's core remained elusive. If our galaxy harbored a supermassive black hole, it was quiet, lacking the belches of energy seen from others. Hubble, which was serviced and upgraded for the final time in 2009, can track groups of stars near the centers of distant galaxies, but because of its narrow angle of view and our galaxy's thick dust clouds, it can't take the same kind of pictures in our galaxy. Another approach would be to track individual stars in the black hole's vicinity using infrared light, which travels through dust, but the stars were too faint and too crowded for most ground-based telescopes to resolve. Still, some astronomers in the 1990s ventured that observations of the Milky Way's core might be possible. A number of tantalizing questions could then be addressed: How do stars live and die in that wild setting? What does a black hole consume? And can we witness, at the heart of the Milky Way, the warped space and time predicted by Einstein nearly a century ago?
The Keck control room is 20 miles from the telescope, in the ranching town of Waimea. To the researchers there, the spectacular laser is visible only as a wan beam on a computer monitor. The astronomers check their notebooks and watch screens full of data from the telescope, weather readings and the latest picture of the stars they're targeting. They use a video link to talk to the telescope operator, who will spend all night at the summit. Things are going so smoothly that there isn't much to do. The telescope will stay locked on the same spot in the sky for four hours; the laser's working fine, and a camera attached to the telescope takes one 15-minute exposure after another in an automated sequence. "This is just about the dullest kind of observing there is," University of California at Los Angeles astronomer Mark Morris says to me apologetically.
Even so, there's tension in the room. This team of astronomers, led by Andrea Ghez of UCLA, is in an ongoing competition with astronomers at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. Since the early 1990s, Garching astrophysicist Reinhard Genzel and his colleagues have studied the black hole at the center of the Milky Way using the New Technology Telescope and the Very Large Telescope array in Chile. Ghez, 45, pushes her students to get the most out of each observation session at Keck. Six years ago she was elected to the National Academy of Sciences—quite an honor for someone still in her 30s. "It's easy to be at the forefront of astronomy if you have access to the best telescopes in the world," she says.
Nearly a decade ago the American and the German teams independently deduced that only a giant black hole could explain the behaviors of stars at the Milky Way's core. Stars circling a hefty mass—whether a black hole or some large star—travel through space much faster than those circling a smaller mass. In visual terms, the larger mass creates a deeper funnel in the fabric of space around which the stars revolve; like leaves circling in a whirlpool, the deeper the whirlpool, the faster the leaves spin. Other astronomers had seen fast-moving stars and clouds of gas near the center of the Milky Way, so both Ghez and Genzel suspected that a dense cluster of matter was hidden from view.
By painstakingly compiling infrared photographs taken months and years apart, the two teams tracked the innermost stars, those within one light-month of the galaxy's center. Combined, the images are like time-lapse movies of the stars' motions. "Early on, it was clear there were a few stars that were just hauling," Ghez recalls. "Clearly, they were extremely close to the center." Something was trapping them in a deep whirlpool. A black hole made the most sense.
The clincher came in 2002, when both teams sharpened their images using adaptive optics, technology that compensates for the atmosphere's blur. The scientists followed stars that orbit perilously close to the galaxy's center and found that the fastest star's top speed was 3 percent of the speed of light—about 20 million miles per hour. That's a startling speed for a globe of gas far bigger than our sun, and it convinced even the skeptics that a supermassive black hole was responsible for it.
The blur of Earth's atmosphere has plagued telescope users since Galileo's first studies of Jupiter and Saturn 400 years ago. Looking at a star through air is like looking at a penny on the bottom of a swimming pool. Air currents make the starlight jitter back and forth.
In the 1990s, engineers learned to erase the distortions with a technology called adaptive optics; computers analyze the jittering pattern of incoming starlight on a millisecond by millisecond basis and use those calculations to drive a set of pistons on the back of a thin and pliable mirror. The pistons flex the mirror hundreds of times each second, adjusting the surface to counteract the distortions and form a sharp central point.
The technology had one major limitation. The computers needed a clear guiding light as a kind of reference point. The system worked only if the telescope was aimed close to a bright star or planet, limiting astronomers to just 1 percent of the sky.
By creating an artificial guide star wherever it is needed, the Keck Observatory's laser removes that limitation. The laser beam is tuned to a frequency that lights up sodium atoms, which are left by disintegrating meteorites in a layer of the atmosphere. Keck's computers analyze the distortion in the column of air between the telescope mirror and the laser-created star.
Inside the telescope's 101-foot-tall dome, the laser system sits within a bus-size enclosure. The laser starts out with a jolting 50,000 watts of power, amplifying the light beam within a dye solution made from 190-proof ethanol. But by the time the light is adjusted to its correct color and its energy is channeled along a single path, its power dwindles to about 15 watts—still bright enough that the Federal Aviation Administration requires the observatory to shut down the laser if an airplane is expected to fly near its path. From several hundred feet away the laser looks like a dim amber pencil beam. From a bit farther it isn't visible at all. As far as the rest of the island is concerned, there is no laser show at Mauna Kea.
Identifying a black hole is one thing; describing it is another. "It's difficult to paint a picture that relates to the world as we understand it, without using mathematical complexity," Ghez says one afternoon at the Keck control center. The next day, she asks her 6-year-old son if he knows what a black hole is. His quick response: "I don't know, Mommy. Shouldn't you?"
Mark Morris thinks that "sinkhole" makes an apt metaphor for a black hole. If you were in space near the black hole," he says, "you would see things disappear into it from all directions."
Both Ghez and Morris like to imagine looking out from a black hole. "This is the thriving city center of the galaxy, compared to the suburbs where we are," says Ghez. "Stars are moving at tremendous speeds. You'd see things change on a time scale of tens of minutes." Morris picks up on this theme. "If you look at the night sky from a beautiful mountaintop, it takes your breath away how many stars there are," he says. "Now, multiply that by a million. That's what the sky at the galactic center would look like. It would be like a sky full of Jupiters, and a few stars as bright as the full Moon."
In such a magnificent setting, the laws of physics are wonderfully twisted. Ghez and Morris hope to gather the first evidence that stars do indeed travel along the weird orbital paths predicted by Einstein's relativity theory. If so, each star would trace something like a pattern from a Spirograph drawing toy: a series of loops that gradually shift in position relative to the black hole. Ghez thinks she and her colleagues are several years away from spotting that shift.
With each new finding, the Milky Way's core becomes more perplexing and fascinating. Both Ghez's and Genzel's teams were startled to discover many massive young stars in the black hole's neighborhood. There are scores of them, all just five to ten million years old—infants, in cosmic terms—and they are roughly ten times as massive as our sun. No one is entirely sure how they got so close to the black hole or how they came to be. Elsewhere in the galaxy, gestating stars require a cold, calm womb within a large cloud of dust and gas. The galactic core is anything but calm: intense radiation floods the area, and the black hole's gravity should shred gaseous nurseries before anything incubates there. As Reinhard Genzel put it at a conference several years ago, those young stars "have no damn right to be there." It's possible some of them were born farther out and migrated inward, but most theorists think they're too young for that scenario. Morris thinks the intense gravity compresses spiraling gas into a disk around the black hole, creating the new suns in a type of star birth not seen in any other galactic environment.
These young stars will self-destruct a few million years from now. And when they do, the most massive ones will leave behind small black holes. Morris theorizes that hundreds of thousands of these stellar-mass black holes, accumulated from past generations of stars, swarm around the central, supermassive black hole. The stellar-mass black holes are only about 20 miles wide, so collisions between them would be rare. Instead, Morris says, "You'll have black holes swinging past each other in the night, and stars moving through this destruction derby. A near miss between one of the black holes and a star could scatter the star into the supermassive black hole or out of the galactic center entirely." Theorists think the supermassive black hole may gobble a star once every tens of thousands of years—an event that would flood the center of the galaxy with radiation. "It would be a spectacular event," Morris says.
Astronomers see signs of such gobbling when they examine the Milky Way's interior with X-ray and radio telescopes, which detect the shock waves of past explosions. Giant black holes in other galaxies are too far away for astronomers to study in such depth, says Avi Loeb, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. That's why he hangs on every announcement from the Ghez and Genzel teams. "The advances made by the observers in such a short time have been truly remarkable," he says. "We theorists are all cheerleaders for them."
Loeb and others are painting a new picture of how the universe and its 100 billion galaxies evolved since the Big Bang 13.7 billion years ago. They believe that all galaxies started with as-yet-unexplained "seed" black holes—tens to thousands of times the mass of our sun—that grew exponentially during violent feeding cycles when galaxies collided, which they did more frequently when the universe was younger and galaxies were closer together. In a collision, some stars catapult into deep space and other stars and gases plummet into the newly combined black hole at the galaxies' center. As the black hole grows, Loeb says, it turns into a raging quasar with gas heated to billions of degrees. The quasar then blasts the rest of the gas out of the galaxy entirely. After the gas is depleted, Loeb says, "the supermassive black hole sits at the center of the galaxy, dormant and starved."
It appears that our Milky Way, with its modest-sized black hole, has absorbed only a few smaller galaxies and has never fueled a quasar. However, a fearsome collision looms. The closest large galaxy, called Andromeda, is on a collision course with the Milky Way. The two will start to merge about two billion years from now, gradually forming a massive galaxy that Loeb and his former Harvard-Smithsonian colleague T. J. Cox call "Milkomeda." The galaxies' supermassive central black holes will collide, devouring torrents of gas and igniting a new quasar for a short time in this sedate part of the universe. "We are late bloomers in that regard," Loeb notes. "It happened to most other galaxies early on." (Earth won't get thrown out of the Sun's orbit by the collision and it shouldn't be whacked by anything during the merger. But there will be a lot more stars in the sky.)
Our galaxy's disturbing future aside, Loeb hopes that soon—perhaps within a decade—we'll have the first image of the Milky Way's supermassive black hole, thanks to an emerging global network of "millimeter wave" telescopes. Named for the wavelength of the radio waves they detect, the instruments won't actually see the black hole itself. Rather, in concert they'll map the shadow it casts on a curtain of hot gas behind it. If all goes well, the shadow will have a distinctive shape. Some theorists expect the black hole to be spinning. If so, according to the counterintuitive dragging of space predicted by Einstein, our view of the shadow will be distorted into something like a lopsided and squashed teardrop. "It would be the most remarkable picture we could have," says Loeb.
On the fourth and final night of Ghez's planned observations, wind and fog at the Mauna Kea summit keep the telescope domes closed. So the astronomers review their data from previous nights. Images from the first two nights ranged from good to excellent, says Ghez; the third night was "respectable." She's says she's content: her students have enough to keep them busy, and Tuan Do from the University of California at Irvine identified a few big, young stars to add to the team's analysis. "I feel incredibly privileged to work at something I have this much fun at," Ghez says. "It's hard to believe that black holes really exist, because it's such an exotic state of the universe. We've been able to demonstrate it, and I find that really profound."
She spends most of her time overseeing the command center at Waimea, but she has been to the top of Mauna Kea to see the laser in action. As we talk about the mesmerizing sight, it is clear that Ghez appreciates an irony: astronomers love the dark and often complain about any source of light that might interfere with their observations. Yet here they are, casting a beacon of light into the heavens to help illuminate the blackest thing humanity can ever hope to see.
This story by Robert Irion won the American Astronomical Society's 2010 David N. Schramm Award for Science Journalism. | 0.88799 | 3.776843 |
Sit still for a moment. You’re still moving! I mean perfectly still. Don’t move at all.
Having trouble complying? That’s probably because, without launching yourself off this planet, you can’t. The planet you presently call home (unless someone puts this blog post in a time capsule or launches it out into space for other civilizations to discover and translate), is spinning right now. That’s what gives us the day/night cycle, as our fixed location relative to the Earth turns away from, then toward, our sun, Sol. If you were to float above the equator for an hour, you’d get to see roughly 1600km pass below you. Earth in turn is whipping around Sol at a rate of roughly 108,000km/h. And the sun isn’t exactly still either! It’s rotating in turn around the galactic centre point at a rate of roughly 220km/s — a second. That’s 792,000km/h.
To make the calculation even hairier, we also don’t know how fast our galaxy is flying away from the point of the Big Bang. We can only see so far into our own past via our best telescopes, before the opacity of the universe prevents us from seeing any further, so “where” the Big Bang happened is one of those questions that may never be answerable (though, a good answer is “everywhere”, since the relative dimensions of space are a byproduct of the initial event).
While we’re jamming about the cosmos at such breakneck speeds, we’ve got some neighbors that have achieved some small measure of stability in relation to us and our sun. Most of these neighbors accreted from the same gas disc that ignited our sun, though some of them may well have come from captured debris. Some of these stable objects are actually the result of large impacts in our solar system’s distant and shooting-gallery-like past. Our moon, for example, is widely believed to be the direct result of a massive impact very early in Earth’s existence by a body roughly the size of Mars — about one third the size of Earth.
The evidence for this theory is varied, but includes the fact that the moon shares very roughly the same composition of the Earth with the same oxygen isotopes. Save, that is, for the iron content, which would have mostly drained into the Earth’s core by the time of the impact, proving the Earth and Moon didn’t form concurrently from the same matter. There’s SOME iron on the Moon, but not nearly as much as here on terra firma.
From a computer simulation of such an impact, five hours after such a cataclysm you can see the ejecta still pluming out into space:
We know the Moon was once molten, and pretty much cooled to the point where volcanism ceased about 3 billion years ago (bya), so it had to happen sometime between the age of our solar system (roughly 4.6 billion years) and then. Obviously, it would have to have happened soon enough before the 3bya mark that volcanism would have had time to run its course, and late enough after the formation of the solar system that the Earth would have been about the right size and shape with the iron sinking down into the core (sans, of course, the material that crashed into it). Scientists used the ratios of Hafnium-182 and Tungsten-182 (what Hafnium-182 decays to), to determine that the Moon is very close to 4.527 billion years old, assuming that their measures of Hafnium-182’s half life is correct, giving us a rough time frame of about 70 million years after Earth’s accretion before the impactor went kersmash. As always, with new evidence, science refines its numbers.
Now, this impact didn’t exactly throw the moon into a perfect orbit around the Earth. That orbit is inclined about 5.1 degrees to the ecliptic — the 2D plane of Earth’s orbit around Sol — which is relatively close for the purposes of eclipses, but definitely not perfect. Also, it is slowly receding away from the Earth at a rate of 38 millimetres per year, and will eventually shear off of Earth’s orbit altogether (though scientists predict not for many billions of years). It is tidally locked with Earth, meaning it shows us the same face all the time. The fact that it is tidally locked with us, while we’re spinning, means it’s slowly leeching off our angular momentum, braking our spin and increasing its own speed. This action is responsible for the slow recession of the moon.
It’s got some eccentricities to the face it shows us, however — a wobble called “libration”. This image from Wikipedia illustrates:
Also, the moon’s orbit around Earth is elliptical. At its perigee (nearest point), it is roughly 364,397km away; at its apogee (furthest point), 406,731km. The difference in visible size is very obvious, as well, as this image illustrates:
This difference in size means that many solar eclipses do not reach totality. These annular eclipses are no less dramatic. But they do put the lie to the suggestion that the sun and moon are “exactly” aligned for eclipses. The variables are so many, that the “perfect case” scenario you see in infographics like this one from the BBC are so rare as to be nearly impossible.
That totality is possible at all, anywhere on the face of the planet, is a fun coincidence in our neighborhood’s history, but by no means a necessary condition for our universe, or our solar system, or life on our planet. And even this totality is not necessarily total. While the sun and moon are nearly perfect spheroids, the moon has a very pockmarked surface, leading to some spectacular displays during solar eclipses, known as Bailey’s Beads. While beautiful, this display betrays how imperfect even the most perfect eclipse can be. And I haven’t even touched on solar prominences and solar flares!
Pictures of Bailey’s Beads obtained from this site:
The moral of this science lesson is, of course, you must always be cautious with using the words “exact” or “perfect” around me (and my underlying linguistic prescriptivist nature!), or you might set me off on a science lesson. 🙂
Further reading, and images obtained from: | 0.858342 | 3.812298 |
Some daily events in the changing sky for August 29 September 6.
Friday, August 29
Saturday, August 30
Sunday, August 31
Monday, September 1
Tuesday, September 2
Wednesday, September 3
Thursday, September 4
Friday, Sept. 5
Saturday, Sept. 6
Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly foldout map in each issue of Sky & Telescope, the essential magazine of astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of maps; the standards are Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the even more detailed Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.
More beginners' tips: "How to Start Right in Astronomy".
This Week's Planet Roundup
Mercury (about magnitude 0) is 3° lower left of much-brighter Venus low in the west-southwest in bright twilight, as shown at the top of this page. Bring binoculars.
Venus (magnitude 3.8) is still low in the glow of sunset. Look for it above the west-southwest horizon about 30 minutes after sundown. Fainter Mercury is just to its lower left, as shown at the top of this page. Look too for little Mars, moving in day by day from the left.
Mars (a dim magnitude +1.7!) is closing in on Venus and passes 1/3° south (lower left) of it on September 11th. See the illustration at the top of this page and use binoculars!
Jupiter (magnitude 2.6, in Sagittarius) shines bright and steady in the south right after dark, and lower in the southwest later. It's above the Sagittarius Teapot and just below the smaller, dimmer Teaspoon.
Saturn is hidden behind the glare of the Sun.
Uranus and Neptune (magnitudes 5.7 and 7.8, respectively, in Aquarius and Capricornus) are well up in the southeast during evening. Use our article and finder charts.
Pluto (magnitude 14.0, in the northwestern corner of Sagittarius) is in the south-southwest right after dark. If you've got a big scope and a dark sky, use our article and finder chart.
All descriptions that relate to your horizon or zenith including the words up, down, right, and left are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America. Eastern Daylight Time (EDT) equals Universal Time (known as UT, UTC, or GMT) minus 4 hours.
To be sure to get the current Sky at a Glance, bookmark this URL:
If pictures fail to load, refresh the page. If they still fail to load, change the 1 at the end of this URL to any other character and try again. | 0.834823 | 3.165907 |
Sure! But it depends on what type of black hole. There are two main flavors of black hole: supermassive black holes, and stellar mass black holes. As their names indicate, stellar mass black holes are about the mass of a single star, and supermassive black holes are super massive.
By supermassive, we mean that they’re at least a million suns worth of mass crammed into a very tiny space. (For this kind of thing, astronomers have defined the handy unit of the solar mass: this is the mass of our sun.) They can go up to solar masses of several billion (several billion times the mass of the sun). These are usually the types of black holes people think about when they’re talking about galaxies, and the center of each galaxy should have exactly one of these. If we find a galaxy with more than one supermassive black hole in its center, we have found ourself a very unusual galaxy, which has very likely just devoured another galaxy about as large as itself. The two black holes will eventually fall together and combine to make one, larger, black hole, as the rest of the galaxy recovers from the consumption of another galaxy. We think that supermassive black holes got to be supermassive by gradually going through this process of munching on smaller galaxies and absorbing their black holes over the course of the universe’s lifetime.
Stellar mass black holes, on the other hand, are about as common as dirt. You get a stellar mass black hole any time a large star (usually more than about 8 solar masses) reaches the end of its life and dies in a spectacular supernova fashion. The mass of the star plus the energy of the supernova compresses the remaining star matter down past the density you would need to make a white dwarf or neutron star, and you’ve got yourself a new stellar mass black hole. There are tons of these black holes in the galaxy, but since they’re only as massive as the star that they formed from, they don’t have nearly as big an effect on their surroundings as the supermassive ones do. This makes them much harder to find, so we’re still getting a handle on exactly how many there should be in the galaxy, but the number can be safely rounded to “a lot.”
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Gamma rays are one of the highest energy forms of light in the Universe - its wavelength is around a picometer (that’s 10^-12 meters), which is roughly the same order of magnitude as the size of a hydrogen atom. These wavelengths are a thousand times shorter than that of visible light.
The high energies of gamma rays means that this form of light is extremely damaging to life. Ultraviolet (UV) light doesn’t penetrate far into your skin - it can damage the surface layers of your skin, giving you a sunburn, but it won’t damage anything past the first few layers of your skin. (UV light will, however, increase your chances of skin cancer, if you get severe sunburns.) Gamma rays can penetrate much further into your body, and can destroy or alter the DNA within your cells, causing drastic changes to the replication instructions of your cells. This can cause radiation sickness and/or cancer to appear, but with no surface burning of your skin.
Fortunately, our atmosphere is opaque to gamma rays, so the average level of gamma radiation coming towards our planet is blocked out by our atmosphere. Our atmosphere does a wonderful job of protecting us from the beating our cells would otherwise be taking.
On the other hand, the fact that our atmosphere is such an effective wall to this wavelength of light means that we can’t observe any of the gamma rays produced elsewhere in the universe (which is a very interesting field with a lot of science to be done) from the surface of the Earth. In order to look at this light, we have to put our telescopes into space, outside of our atmosphere. At the moment, we have the Fermi Gamma Ray Space Telescope observing the whole sky for gamma ray sources; that telescope produced the map of the sky at the top of the page. The bright line through the middle is all gamma radiation from within our own galaxy. Anything far away from that central region is probably coming from another galaxy. Individual bright points in our galaxy are likely to be coming from the aftermath of a supernova.
The moon, unlike the Earth, doesn’t have an atmosphere to protect it from any kind of battering, which means that there’s a constant flow of high energy light and small particles pounding into the surface of the moon. One of these objects smacking into the surface of the moon is called a cosmic ray (which is a highly accelerated tiny piece of grit - most of them are protons). Cosmic rays are constantly streaming throughout the universe. When they smash into the surface of the moon, they can create gamma radiation as they come to a stop.
This means that the moon itself glows faintly in gamma rays, and this is detectable by our space based telescopes, which can observe gamma rays. (Again, we couldn’t detect this from the surface of the Earth, because our atmosphere gets in the way.) The image below was produced by the Compton Gamma Ray Observatory, which was in orbit around the Earth from 1991 - 2000, when it was instructed to crash itself back into our ocean. The moon, as imaged below, is actually brighter than our sun in gamma rays - our sun, very fortunately, does not produce much in the way of gamma radiation. (If it did, the gamma radiation from such a close source might have destroyed our atmosphere, removing our shelter from this wavelength.)
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Note from the administration: Astroquizzical has a new url! All the old links should still be functional, but should redirect you to the brand new astroquizzical.com domain. Thanks for reading! | 0.868353 | 4.03051 |
Bosscha Observatory is one of the oldest star observation in Indonesia. Bosscha Observatory is located in Lembang, West Java, about 15 km in the northern city of Bandung with geographic coordinates 107 ° 36 'east longitude and 6 ° 49' south latitude. This place stands on the land area of 6 hectares, and located at an altitude of 1310 meters above sea level or at an altitude of 630 m from the plateau of Bandung.Code of the International Astronomical Union observatory to observatory Bosscha is 299.
Bosscha Observatory (formerly called Bosscha Sterrenwacht) built by the Nederlandsch-Indische Vereeniging Sterrenkundige (NISV) or the Association of the Dutch East Indies star. At the first meeting NISV, it was decided to build an observatory in Indonesia for the sake of advancing the science of Astronomy in the Dutch East Indies. And in that meeting, Karel Albert Rudolf Bosscha, a landlord at the Malabar tea plantation, willing to be the major funders and promised to provide assistance purchasing telescopes. In recognition of his services K.A.R. Bosscha in the construction of this observatory, hence the name Bosscha immortalized as the name of this observatory.
Construction of the observatory itself is spending less than 5 years since 1923 until 1928.
The first international publication Bosscha Observatory conducted in 1933. However, later observations were to be discontinued because of World War II. After the war, carried out extensive renovations to the observatory is due to the ravages of war until the end of the observatory can operate normally again.
Then on October 17, 1951, this observatory NISV handed to the government of Indonesia. After Institut Teknologi Bandung (ITB) was established in 1959, Bosscha Observatory became part of the ITB. And since then, Bosscha functioned as research institutes and Astronomy formal education in Indonesia.
There are 5 pieces of large telescopes, namely:
Zeiss double refractor telescope
The telescope is used for visual double star observing, measuring the eclipse photometry of stars, watching the image of the crater of the moon, planetary observing, watching the opposition of Mars, Saturn, Jupiter, and to observe the comet's bright and detailed image of the other heavenly bodies. The telescope has two objective lenses with a diameter of each lens is 60 cm, with hotspots or the focus is 10.7 meters.
Schmidt telescope Milky Way
This telescope is used to study the structure of the Milky Way, study the spectrum of stars, observe the asteroid, supernova, bright and Nova for the specified chemical composition, and to take pictures of sky objects. 71.12 cm diameter lens. Biconcaf-diameter lens correction biconfex 50 cm. Flame point / focus of 2.5 meters. Also equipped with a prism refracting the prime corner of 6.10, to obtain spectra of stars.This dispersion prism 312A at H-gamma every night. The tools are extra-Wedge Sensitometer telescope, to menera blackish scales bright stars, and film recorders
Bamberg refractor telescope
The telescope is used for menera bright stars, determining the distance scale, measuring the eclipse photometry of stars, watching the image of the crater of the moon, solar observations, and to observe other celestial bodies. Equipped with a photoelectric photometer to obtain the scale-bright stars of light intensity that caused electricity. Lens diameter 37 cm. Focal point of a fire or 7 meters.
Cassegrain telescope GOTO
With this telescope, the object can be directly observed by entering the object position data. Then the observation data will be entered into the data storage media directly.Binoculars can also be used to measure the star's light and strong spectral observations of stars. Dilengakapi with a spectrograph and photoelectric-photometer
Unitron refractor telescope
This telescope is used to make observations moon, lunar eclipse observation and solar eclipses, sunspots and photo shoots as well as observations of other celestial objects.With a lens diameter 13 cm, and the focus of 87 cm | 0.809713 | 3.186019 |
Nova Centauri 2013 seen from La Silla
Alpha and Beta Centauri, two of the brightest stars in the southern sky, had a new companion in late 2013 — the naked eye Nova Centauri 2013.
The nova was discovered by John Seach from Australia on 2 December 2013 as it approached naked eye brightness. Nova Centaurus 2013 is the brightest nova to have occurred so far this millennium.
This particular event is known as a classical nova, and is not to be confused with a supernova. Classical novae occur in binary star systems when hydrogen gas from the orbiting stellar partner is accreted onto the surface of the main star, causing a runaway thermonuclear event resulting in the brightening of the main star. In a classical novae the main star is not destroyed as is the case in a supernova. Instead, the star is dramatically brightened, and there is a simultaneous expansion of a debris shell.
The nova appears in the picture just to the left of Beta Centauri, the bluer and higher of the two bright stars in the lower-right part of the image. The Southern Cross and the Coal Sack Nebula are also captured near the top of the picture.
In front at the left is the ESO 3.6-metre telescope, inaugurated in 1976, it currently operates with the HARPS spectrograph, the most prolific exoplanet hunting machine in the world. Located 600 km north of Santiago, at 2400 m altitude in the outskirts of the Chilean Atacama Desert, La Silla was first ESO site in Chile and the largest observatory of its time.
Y. Beletsky (LCO)/ESO
About the Image
|Release date:||29 July 2015, 12:00|
|Size:||3500 x 2333 px|
About the Object | 0.858776 | 3.441356 |
Crystals might be defined by their symmetrical, highly organised atomic structure, but all that could change with the description of a new class of crystal that has a structure that’s always moving, so it appears messy in an instant, but highly ordered over time.
Based on the idea of a constantly moving formation of satellites that could help us hunt for gravitational waves, these theoretical "choreographic crystals" could be used to solve many problems in mathematics and computing, and might one day be discovered in nature, says a team led by physicist Latham Boyle from the Perimeter Institute for Theoretical Physics in Canada.
The discovery comes thanks to gravitational waves - ripples in the curvature of spacetime that emanate from the most explosive and violent events in the Universe. First proposed by Einstein in 1916, these fundamental constituents of the Universe (if they exist) have so far never been directly observed, but rumours started flying last week that this could all be about to change.
It’s 2016, and gravitational waves are having a bit of a moment, so Boyle and his team decided to come up with a better way of detecting them.
Right now, the recently launched LISA Pathfinder system is our best bet. It’s a trio of satellites equipped with highly sensitive detectors that orbit Earth in a triangular formation, sending a constant stream of laser beams back and forth to each other. The idea is that if gravitational waves happen to pass by these satellites, the laser beams will be disturbed, and the activity recorded by the satellite-based detectors.
While this is a pretty awesome system, and the best we have right now to detect gravitational waves, Boyle wanted to investigate how much extra ground we could cover with a system of four satellites instead of three. As it turns out, this seemingly simple question had an incredibly complex answer, as Jennifer Ouellette explains over at Gizmodo:
"Having four satellites instead of three would enable physicists to more precisely determine a gravitational wave’s amplitude (its volume or height, if we’re likening it to a sound or ocean wave), polarisation (the plane along which it vibrates), and from which direction it is traveling.
But it’s a much more complicated (and expensive) engineering challenge to build such an instrument. And as Boyle soon discovered, finding a symmetrical four-satellite orbit proved impossible."
This is because the only way you can ensure that four separate points moving around in a system can maintain absolute symmetry is in a tetrahedron formation - a basic triangular pyramid. But the problem with a tetrahedron is that this symmetry is lost as soon as you try to apply it to a three-dimentional plane.
So together with his team, Boyle came up with a new 'choreography' for his four satellites that would see them constantly moving together in a system that doesn’t look particularly ordered if you took a picture of them all in a single moment, but if you were riding on one of them and filming a movie, that movie would look the same regardless of which satellite you were on, Lisa Grossman explains at New Scientist.
Boyle calls this "choreographic symmetry", and says that different crystal structures ordered according to this formation could prove incredibly useful for mathematicians and computer scientists working on complex theoretical problems. "Boyle hopes that choreographic crystals might prove relevant to many mathematical problems, just as the static lattices of standard crystallographic theory have found applications ranging from pure number theory to error correction in computation," says Phillip Ball at Physics Focus.
While Boyle and his team have no idea whether this type of fluid crystalline structure could exist in nature, we can't rule out the possibility of them being produced synthetically at some point.
"There is precedent for this idea: quasicrystals, which have ordered but non-repeating patterns, were first proposed theoretically, then built in the lab (garnering their discoverers a Nobel prize), and finally found naturally in a meteorite that had landed in a remote part of north-eastern Russia," says Grossman.
The research has been published in Physical Review Letters. | 0.830931 | 3.902261 |
During its five-year primary mission, NASA's Fermi Gamma-ray Space Telescope has given astronomers an increasingly detailed portrait of the universe's most extraordinary phenomena, from giant black holes in the hearts of distant galaxies to thunderstorms on Earth.
But its job is not done yet. On Aug. 11, Fermi entered an extended phase of its mission -- a deeper study of the high-energy cosmos. This is a significant step toward the science team's planned goal of a decade of observations, ending in 2018.
"As Fermi opens its second act, both the spacecraft and its instruments remain in top-notch condition and the mission is delivering outstanding science," said Paul Hertz, director of NASA's astrophysics division in Washington.
Fermi has revolutionized our view of the universe in gamma rays, the most energetic form of light. The observatory's findings include new insights into many high-energy processes, from rapidly rotating neutron stars, also known as pulsars, within our own galaxy, to jets powered by supermassive black holes in far-away young galaxies.
The Large Area Telescope (LAT), the mission's main instrument, scans the entire sky every three hours. The state-of-the-art detector has sharper vision, a wider field of view, and covers a broader energy range than any similar instrument previously flown.
"As the LAT builds up an increasingly detailed picture of the gamma-ray sky, it simultaneously reveals how dynamic the universe is at these energies," said Peter Michelson, the instrument's principal investigator and a professor of physics at Stanford University in California.
Fermi's secondary instrument, the Gamma-ray Burst Monitor (GBM), sees all of the sky at any instant, except the portion blocked by Earth. This all-sky coverage lets Fermi detect more gamma-ray bursts, and over a broader energy range, than any other mission. These explosions, the most powerful in the universe, are thought to accompany the birth of new stellar-mass black holes.
"More than 1,200 gamma-ray bursts, plus 500 flares from our sun and a few hundred flares from highly magnetized neutron stars in our galaxy have been seen by the GBM," said principal investigator Bill Paciesas, a senior scientist at the Universities Space Research Association's Science and Technology Institute in Huntsville, Ala. The instrument also has detected nearly 800 gamma-ray flashes from thunderstorms. These fleeting outbursts last only a few thousandths of a second, but their emission ranks among the highest-energy light naturally occurring on Earth.
One of Fermi's most striking results so far was the discovery of giant bubbles extending more than 25,000 light-years above and below the plane of our galaxy. Scientists think these structures may have formed as a result of past outbursts from the black hole -- with a mass of 4 million suns -- residing in the heart of our galaxy.
To build on the mission's success, the team is considering a new observing strategy that would task the LAT to make deeper exposures of the central region of the Milky Way, a realm packed with pulsars and other high-energy sources. This area also is expected to be one of the best places to search for gamma-ray signals from dark matter, an elusive substance that neither emits nor absorbs visible light. According to some theories, dark matter consists of exotic particles that produce a flash of gamma rays when they interact.
"Over the next few years, major new astronomical facilities exploring other wavelengths will complement Fermi and give us our best look yet into the most powerful events in the universe," said Julie McEnery, the mission's project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.
NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership. Goddard manages the mission. The telescope was developed in collaboration with the U.S. Department of Energy's Office of Science, with contributions from academic institutions and partners in the United States, France, Germany, Italy, Japan, and Sweden. | 0.870724 | 3.989844 |
Updated at 8:54 a.m. ET.
Dark matter — the mysterious stuff that is thought to make up most of the matter in the known universe — may reveal itself during the next decade, one prominent scientist predicts.
When the moment comes, it will result in "a pivotal paradigm shift in physics," Gianfranco Bertone, a physicist with the University of Amsterdam in the Netherlands, said in a talk on dark matter research at a Royal Society Frontiers of Astronomy conference in London in November.
The elusive substance may show itself as researchers set out to test "the existence of some of the most promising dark matter candidates, with a wide array of experiments, including the Large Hadron Collider (LHC) at CERN and a new generation of astroparticle experiments underground and in space," Bertone said. [The Hunt for Dark Matter: Images and Photos]
The universe contains much more matter than scientists can currently detect. Models suggest that this unseen matter makes up about 85 per cent of the universe, but nobody is sure what this missing matter is made of. Telescopes can't observe it, because it gives off absolutely no light.
So far, the only evidence of dark matter's existence comes from the gravitational effects it exerts on visible matter. "We see the effects on all scales with astrophysical and cosmological observations," Bertone said.
But despite promising hints from numerous recent experiments, the hunt for dark matter's true identity goes on.
The key candidates for the stuff so far remain restricted to the realm of theory — weakly interacting massive particles (WIMPs), believed to constitute the bulk of dark matter, and axions, assumed to be much lighter and colder particles. It is thought that there are a lot of axions around, and that they constantly rain down on Earth from space.
A failure to find dark matter in the near future would imply that researchers might be on the wrong track and need to rethink their approach to the problem, Bertone said. [Twisted Physics: 7 Mind-Blowing Findings]
Scientists are more hopeful than ever of success despite the failure of one of the most promising detectors, the Large Underground Xenon experiment (LUX), to spot dark matter particles during its first 90-day run in 2013.
LUX is a liquid xenon experiment set up to detect the extremely rare collisions between WIMPs and regular matter on Earth. It is buried about 1 mile (1.6 kilometers) deep in a mine in the Sanford Underground Research Facility in South Dakota.
In 2014, LUX will probe for dark matter longer than ever before, during an upcoming 300-day run.
Besides hiding detectors underground, there are other ways to search for the mysterious dark matter. For example, there are direct detectors located in space, such as the Alpha Magnetic Spectrometer, which was installed on the International Space Station in 2011. AMS looks for the shower of radiation that dark matter particles are assumed to produce as they collide and annihilate. It is thought that this radiation also includes gamma rays.
Another space-based detector is NASA's Fermi telescope, which launched in 2008. This instrument is scanning the center of the Milky Way galaxy, where dark matter is believed to be concentrated, looking for excess gamma rays.
Many scientists are placing their bets on the Large Hadron Collider. Once it is up and running again in 2015, it will resume smashing particles together, in the hope of creating dark matter in the lab.
The LHC aims to create a type of matter called supersymmetric dark matter. If the LHC finds any particles that could be dark matter, its results would be compared to the data from astroparticle experiments.
"It is quite clear that unless the theoretical description of dark matter is very simple, it will be hard to identify it with a single type of experiment, whereas a combination of them should provide sufficient information," Bertone said.
Lack of matter
Although the current experiments are looking for specific particles that scientists believe dark matter may consist of, many researchers remain open to the possibility that dark matter could be made of something completely different.
It's also possible that a whole zoo of particles makes up the invisible matter, Bertone said. "Many studies today address the possibility that dark matter is made not of one but [of] many particle species."
So even if scientists do not find the particles they are currently looking for, it will not automatically mean that dark matter does not exist.
"The only way to prove that dark matter does not exist is to show that all these data have been misinterpreted, for instance because the law of gravity we adopted — Albert Einstein's Theory of General Relativity — is wrong," Bertone said. "Despite much effort, no satisfactory theory of gravity exists today that can be reconciled with all observational data without assuming the existence of some forms of dark matter."
Einstein’s general theory of relativity describes how objects warp space and time to create gravity.
But many scientists think that dark matter will end up showing its face, and soon.
"In my view, the single most promising class of dark matter experiments over the next decade are the underground detectors — LUX, XENON-1ton, LX, and others," said Dan Hooper, a physicist at Fermilab in Batavia, Ill.
The detectors "just keep getting more and more sensitive, and already rule out many otherwise attractive dark matter candidates. The LHC and gamma-ray telescopes are also very important players in the hunt for dark matter," he added.
And, Hooper said, the Fermi gamma-ray space telescope may have already spotted hints of WIMPs on a number of occasions, most recently in 2013. The telescope detected a weird light shining near the center of the Milky Way galaxy — possibly sparks of gamma rays from dark matter particles at the ends of their lives.
"The signal just keeps looking more and more solid," he said. "At this point in time, I would make an even-odds bet that Fermi is seeing dark matter annihilations.”
Editor's Note: This article has been updated to correct statements made by Gianfranco Bertone regarding the certainty of finding dark matter.
- Dark Matter Mystery Explained: A Reader's Guide (Infographic)
- Dark Matter Clues From AMS Experiment in Space (Photos)
- Top 10 Strangest Things in Space
Copyright 2014 SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. | 0.883773 | 3.925861 |
Nasa's New Horizons mission has begun its six-month flyby of Pluto – going "where no one has gone before".
The probe has been travelling for 3,282 days and is now 133 million miles from Pluto – it is 1.43 AU from the ninth planet and 32.38 AU from Earth (one AU is about 93 million miles – or the distance between Earth and the Sun).
The historic mission was launched in January 2006 and will accumulate in the closest approach to Pluto on 14 July.
At present, scientists know very little about Pluto. It was discovered in 1930 by US astronomer Clyde Tombaugh. It is the largest object in the Kuiper belt, measuring 1,400 miles wide – making it slightly smaller than the moon.
It takes 248 years to orbit the sun, with one day on Pluto lasting 6.5 days on Earth. We think it is covered in ice with surface temperatures of about minus 400C but have little solid evidence about it – which is where New Horizons is expected to bridge huge gaps in our knowledge of the planet (Pluto was declassified to a "dwarf planet" in 2006).
Mission of discovery
Scientists do not know what they will find during the mission. Principle investigator Alan Stern described it as "a mission of pure discovery".
"No one has been to this planet, no one has been to this kind of planet and no one has been to the Kuiper belt," he told IBTimes UK in December.
At present, the images we have of Pluto are of extremely poor quality in comparison to other planets in our solar system. By May, New Horizons will exceed the resolution of the Hubble Telescope, so scientists will be able to map Pluto and its moons.
Prior to this, experts will be monitoring the environment surrounding the planet and taking long-range images. Nasa said in a statement: "[In] January, February and April [we will get] a series of better and better approach movies of Pluto and its satellites orbiting around it.
"[In April] distant colour imaging of Pluto and its large moon Charon, and brightness-variation measurements of smaller moons Nix and Hydra as they rotate on their axes."
In June, the team will start to measure Pluto's compositions and map temperatures, and study the atmosphere. They will also be looking for new moons and rings.
"We are expecting to discover a whole new planet so it's very hard to make predictions," Stern said.
As well as discovering a new planet, New Horizons is also acting as belated funeral director to Tombaugh, who died in 1997 aged 90. His ashes were placed on board the probe to transport the scientists to his final resting place – the planet he discovered.
Tombaugh was tasked with finding "Planet X" while working at Percival Lowell's observatory in Arizona. He surveyed the night sky looking for any objects that moved position and eventually observed an object that shifted in two photographs in January 1930.
That his ashes be sent to space was one of Tombaugh's final requests and, honouring his wishes, Nasa placed his remains to the inside of the upper deck with the inscription "interned herein are the remains of American Clyde W Tombaugh, discoverer of Pluto and the solar system's third zone". | 0.854958 | 3.397919 |
Seven experiments made up the IEH-3 payload on the STS-95 Space Shuttle mission. The seven hitchhiker experiments were attached to a carrier system in the bay of the Shuttle orbiter for the flight in space. Some experiments were controlled from the Payload Operations Control Center at the Goddard Space Flight Center in Greenbelt, Md., while others ran automatically with pre-programmed commands which were loaded into their operating computers before launch.
Ultraviolet Spectrograph Telescope for Astronomical Research
UVSTAR was an extreme ultraviolet spectral imager designed as a facility instrument devoted to solar system and stellar astronomy research. The instrument was designed to obtain and spectrally resolve images of extended plasma sources including the plasma located around Jupiter's moon, Io, and hot stars (stars that put out more energy than regular stars). Io, which is volcanic, spews out volcanic gasses and materials that get trapped in the magnetic field of Jupiter forming a Torus ( a donut shape with Jupiter in the middle). The ultraviolet emissions from the Torus will reveal the material on Io, the energy output of Jupiter and so on. The telescope was designed to also measure the emissions from the Earth's atmosphere, acquire data from celestial targets and perform atmospheric science.
The Extreme Ultraviolet Imager (EUVI), another instrument aboard UVSTAR, took measurements of the Earth's atmosphere in the extreme ultraviolet wavelengths while in any attitude. The EUVI contained two imagers that map the intensity of helium and oxygen ions in the atmosphere by scanning along the Earth's shadow line. This instrument was designed to provide precise measurements of the Earth's ionosphere and plasmosphere.
Spectrograph/Telescope for Astronomical Research
STARLITE was a telescope and imaging spectrograph used to study astronomical targets in the ultraviolet. Targets of scientific investigation include diffuse sky background emission, scattered dust and recombination emission lines from the hot and interstellar medium, supernova remnants, planetary and reflecting nebulae, star forming regions in external galaxies and the Torus formed around Jupiter from the volcanic emissions of the moon Io.
Solar Extreme Ultraviolet Hitchhiker
The SEH experiment was designed to obtain absolute Extreme Ultraviolet (EUV)/Far Ultraviolet (FUV) fluxes (energy output) used to interpret EUV/FUV emissions from solar system objects, interplanetary medium, plasmosphere and magnetosphere (layers of the Earth's upper atmosphere). SEH was designed to measure changes in the Earth's atmosphere due to solar extreme ultraviolet and daytime temperatures.
SEH was designed to achieve solar science objectives of measuring the absolute solar EUV irradiance, the flux of radiant energy per unit area for planetary atmosphere studies. Another goal was to analyze and interpret the solar EUV data for the purpose of improving global solar atmospheric computer modeling, and thus improve our understanding of solar variability.
Solar Constant Experiment
The SOLCON instrument was designed to accurately measure the solar constant (total solar radioactive power absorbed by one square meter at the mean distance between the Earth and Sun) and identify variation during a solar cycle. This measurement was accomplished by determining the power difference required to bring two hollow points into thermal balance when one is open to the Sun and the other closed. The data will ensure continuity of the solar constant level obtained by instruments mounted on other free-flying spacecrafts. Solar energy is the only external energy source for the Earth, thus a primary driver for climate change. This study is important to researchers studying the effects of global warming.
Petite Amateur Naval Satellite
PANSAT was a small non-recoverable satellite developed by the Naval Postgraduate School (NPS) in Monterey, Calif., which was launched via a Hitchhiker Ejection System located in the cargo bay of the Space Shuttle.
The objectives of the PANSAT satellite were to enhance the education of the military officers at NPS through the development and operation of a spread spectrum satellite. Spread spectrum satellites allow communication satellites to capture and transmit a signal that normally would be lost because the original signal was too weak or had too much interference.
Normal radio frequencies, use about three kilohertz to a megahertz of bandwidth, but spread spectrum is approximately a thousand times wider. This type of communication is difficult to intercept. The low probability of interception would be important for the military during downed pilot rescues. The downed pilot could obtain his location through a GPS system and uplink the data to the orbiting satellite with minimum risk. Civilians would be able to utilize this type of communication during emergency rescues, and as a basis of establishing communication to remote areas.
PANSAT was designed to be able to demonstrate the capabilities of low-cost spread spectrum which can be used to enhance military communication through a small satellite platform. The satellite was designed to provide, store, and forward digital communication using direct sequence, spread spectrum modulation. Store and forward digital communication allows the PANSAT ground station to send data to the satellite. The satellite will then process the data and retransmit it to the ground. Simply put, it is a mini-telecommunications satellite like the ones that handle telephone calls. It operated in the frequency range of the amateur radio community.
G-764 Get Away Special Experiment
CODAG was an experiment designed to stimulate the aggregation of dust particles which occurred at the early stages of our solar system. By understanding the dust growth process in the early solar system, it is possible to answer the questions of planet formation.
The experiment consisted of a vacuum chamber equipped with windows and sensors. The dust cloud was injected into the chamber and two high speed cameras, mounted at microscopes, recorded the dust motion in a small control area. Xenon lamps illuminated the experiment chamber and the microscope plane identified the three dimensional motion. The sensors measured the scattering characteristics of the dust cloud to compare it with astronomical measurements. As the dust portion was injected into the experiment chamber, it was observed for a period of 15 minutes to five hours. The chamber was purged for a new experiment while the recorded images were compressed for the mass memory. In total, ten single experiment runs were planned.
G-238 Get Away Special Experiment
The GAS payload G-238 was sponsored by the American Institute of Aeronautics and Astronautics - National Section and managed by students at DuVal High School in Lanham, Md. Aboard the payload, there was one biological experiment. This experiment looked at the effects of space on the life cycle of the American cockroach.
The roach experiment consisted of a habitat divided into three sections: one section each for young adults, nymphs and eggs. Small holes in the habitat container supplied air to the habitat. In each section, water was supplied in small vials with a wick through the top and food was provided in the form of dog biscuits. When in space, batteries supplied power to the heaters to keep the habitat at a comfortable temperature for the insects. An eight millimeter camcorder and lights connected to a timer recorded the activity inside the habitat at regular intervals. | 0.812415 | 3.764451 |
Altair (Alpha Aquilae) is the brightest star in the constellation Aquila, and the 12th most luminous in the entire night sky. Although the star has been in the human consciousness since ancient Babylonian and Sumerian times, when it was known as “the eagle star”, the name Altair, meaning “the flying eagle” in Arabic, has only been in use by Western cultures since medieval times.
• Constellation: Aquila
• Coordinates: RA 19h 50m 47s | Dec +8° 52′ 6?
• Distance: 16.73 light years
• Star Type: White Dwarf (A7 V)
• Mass: 1.79 sol
• Radius: 1.63 sol
• Apparent Magnitude: +0.76
• Luminosity: 10.6 sol
• Surface Temperature: 6,900K – 8,500K
• Rotational Velocity: 286 km/s
• Age: 1 billion years
• Other Designations: Atair, a Aquilae, a Aql, Alpha Aquilae, Alpha Aql, 53 Aquilae, 53 Aql, BD+08°4236, FK5 745
Altair in Aquila can be seen from between latitudes of +90° and -75°, with August being the best month to see the bright star. It is also not difficult to view Altair with the naked eye, since it forms one of the vertices of the famous Summer Triangle asterism, with the other two points marked by the stars Deneb in Cygnus and Vega in Lyra. Furthermore, Altair is also a point in the equally famous line of stars known as the Family of Aquila, or sometimes, as the Shaft of Aquila, together with the stars Beta Aquilae and Gamma Aquilae.
Altair is also among the handful of stars, apart from the Sun, of which a direct image has been obtained. In 2006 and 2007, J.D. Monnier et al used more than 2,000 infrared images taken with the MIRC instrument on the CHARA array interferometer to produce a false color image that shows some detail on Altair’s surface. This image was published in 2007.
Altair is located 16.73 light years from Earth in the G-cloud, a huge interstellar cloud of gas and dust. It is a normal, A-type, white main-sequence star which is around 1.63 bigger than the Sun, with 1.8 times its mass, and 10.6 times its brightness. It is also a rapid rotator, with its spin rate of 286 km/sec representing a significant fraction of the speed (400 km/sec) needed for the star to break apart. At its current rotational speed, Altair rotates once every nine hours, in contrast to the Sun that takes around 25 days to complete one revolution.
As one result of its high spin rate, Altair has been shown to be highly oblate, with its equatorial diameter being 20% bigger than its polar diameter. A further consequence of the stars’ high spin rate is the fact that due to a phenomenon called “gravity darkening”, Altair’s effective temperature and surface gravity is measurably lower along its equator, thus reducing the stars luminosity in its equatorial region. This effect was observed through measurements made by the Navy Prototype Optical Interferometer in 2001, as well as subsequent measurements taken by the VINCI instrument at the VLT (Very Large Telescope) in northern Chile.
Altair has also been shown to be a Delta Scuti-type variable star. Typically, Delta Scuti variable stars do not vary by large amounts, and in the case of Altair, its variations in brightness are measured in mere thousandths of a magnitude. However, Altair’s brightness variations span several periods that range from 0.8 to 1.5 hours, and as a result, the only way to approximate Altair’s light curve is to add up all the periodic variations as a series of sine waves.
Altair is also a weak source of coronal X-ray emissions, with the most active sources being arranged along its equator. Although investigations into the mechanisms that produce the low-level X-ray emission are still being investigated, most researchers believe that it is caused by convection cells that migrate from the hot, polar regions to the cooler equatorial latitudes.
Altair has a long and storied history that spans several millennia, across diverse cultures. As mentioned the ancient civilizations of Sumer and Babylon knew it as “the eagle star”, with the tradition carried on by the ancient Greeks who called it Aetos (“the eagle”). Altair also figured in Western astrology, in which it has a rather bad reputation, since it portends ill-fortune and danger from snakes and other reptiles.
In old China, however, Altair was a cowherd, with the two stars on either side of it that complete the Family of Aquila representing his sons carried on a shoulder pole. Unfortunately, he was separated from his Weaving Girl wife, the star Vega, by a celestial river (Milky Way), but once a year they were able to meet, on the 7th day of the 7th lunar month, after magpies would form a bridge with their outspread wings.
In Australia, the Koori aboriginal people knew Altair as Bunjil, the wedge-tailed eagle, who had Beta and Gamma Aquilae as his wives, in the form of black swans. Other Australian aboriginal peoples, such as the people of the Murray River, knew Altair as Totyerguil, a hunter who once speared a giant Murray cod known as Otjout. However, instead of killing the fish, he only wounded it and in his attempts to get away from his murderer, Otjout left the river and churned a giant channel clear across southern Australia before ascending into the sky, where he can still be seen to this day as the constellation Delphinus. | 0.858965 | 3.916955 |
LEIDEN, Netherlands, April 30 (UPI) -- Tired of the nine-to-five, the eight-hour work day? At least Earth's 24-hour day leaves some time for eating and sleeping. On Beta Pictoris b, the alien planet with only eight hours in its day, there'd only be time for work, work, work.
Beta Pictoris b is the first alien planet to have its rotation speed successfully clocked by astronomers.
The eight-hour day of Beta Pictoris b, a gas giant roughly 10 times the size of Jupiter, is thanks to its quick rotational speed. The equator of Beta Pictoris b spins around the planet's axis at a rate of 62,000 mph, much faster than any other planet in our solar system.
By comparison, Jupiter's equator rotates at a rate of 29,000 mph, and Earth's equator spins at a speed of 1,060 mph.
"It is not known why some planets spin fast and others more slowly, but this first measurement of an exoplanet’s rotation shows that the trend seen in the solar system, where the more massive planets spin faster, also holds true for exoplanets," said study co-author Remco de Kok, an astronomer at the Leiden Observatory in the Netherlands. "This must be some universal consequence of the way planets form."
The planet in question orbits Beta Pictoris, a star which lies some 63 light-years from Earth and can be seen with the naked eye in the southern sky constellation Pictor, Latin for "The Painter’s Easel."
Because of the planet's exceptional rotation speed and gaseous state, it features an apparent oblong shape -- disproportionally wider at its center than toward its poles.
The astronomers used a analysis technique called "high-dispersion spectroscopy" sourced with readings from the European Southern Observatory's Very Large Telescope.
"We have measured the wavelengths of radiation emitted by the planet to a precision of one part in a hundred thousand, which makes the measurements sensitive to the Doppler effects that can reveal the velocity of emitting objects,” explained lead author Ignas Snellen. “Using this technique we find that different parts of the planet’s surface are moving towards or away from us at different speeds, which can only mean that the planet is rotating around its axis." | 0.871599 | 3.732989 |
May 10, 2007
Mission Could Seek Out Spock’s Home Planet
Science fiction may soon become science fact.
Astronomers at NASA's Jet Propulsion Laboratory have recently concluded that the upcoming planet-finding mission, SIM PlanetQuest, would be able to detect an Earth-like planet around the star 40 Eridani, a planet familiar to "Star Trek" fans as "Vulcan." 40 Eridani, a triple-star system 16 light-years from Earth, includes a red-orange K dwarf star slightly smaller and cooler than our sun. Vulcan is thought to orbit that dwarf star, called 40 Eridani A.When pondering the idea that SIM might be able to detect Vulcan, astronomer Dr. Angelle Tanner at Caltech had two questions: Can a planet form around 40 Eridani A? Can SIM detect such a planet?
She consulted a planetary theorist, Dr. Sean Raymond of the University of Colorado, Boulder. "Since the three members of the triple star system are so far away from each other [hundreds of astronomical units - the Earth-Sun distance], I see no reason why an Earth-mass planet would not be able to form around the primary star, 40 Eridani A," he said.
If Vulcan life were to exist on the planet, the orbit of the planet would have to lie in a sweet spot around the star where liquid water could be present on its surface. Water is an essential ingredient for any organism to live long and prosper. For 40 Eridani A, this spot, or "habitable zone," is 0.6 astronomical units from the star. That means Vulcans would get to celebrate a birthday about every six months.
The SIM PlanetQuest instrument will be so accurate, it could measure the thickness of a nickel at a distance from Earth to the moon. Using a set of mathematical models based on Newton's Laws, Tanner was able to conclude that SIM would be able to definitively determine whether there is an Earth-mass planet orbiting in the habitable zone around 40 Eridani A, and could also determine its orbit.
This is quite an exciting prospect, since NASA's Terrestrial Planet Finder mission, planned for launch after SIM, would not only be able to take a rudimentary "picture" of the planet, but also could search for signatures of life such as methane and ozone.
When asked what life would be like on Vulcan, Tanner speculated that the inhabitants might be pale. "A K dwarf star emits its light at wavelengths which are a bit redder compared to those from the sun, so I wonder whether it's harder to get a tan there," she said.
The results of Tanner's simulations will be submitted for publication in the Publications of the Astronomical Society of the Pacific.
For more information about NASA's search for new worlds, visit the PlanetQuest Web site at http://planetquest.jpl.nasa.gov. | 0.809106 | 3.461495 |
First let's look at what the team were able to say -and show - about the largest moon, Charon:
|Above: Charon, seen up close for the very first time in our solar systems 4.5 billion year history. Courtesy of NASA|
Charon's dark northern region (known informally as 'Mordor'), seems to be covered in a thin layer of dark material - although why it's gathered around Charon's north pole isn't clear. Massive cliffs stretch for hundreds of kilometres, and on the upper right a chasm perhaps nine kilometres deep can be seen. The surface has very few craters, just a few here and there. It all suggests a world whose crust has been cracked open by immense internal forces, and had its surface covered over by material welling up from deep inside - and in the (geologically) recent past. On earth that would mean volcanoes of molten rock. On an ice world like Charon that means cryolava - a mixture of liquid water and other low temperature materials, like nitrogen and ammonia. It might imply the existence of an ocean buried deep beneath Charon's crust....
On to Pluto:
First a name for the dark plain on Pluto that tickled me, as it refers to a character from one of my favourite horror stories: Cthlhu Regio. Plutonian mountains, 3500 meters high and probably made of water ice (based on how strong they must be to get so tall), have been found. But they're covered in nitrogen and methane ice - and almost no craters are on them, so they are geologically young, 100 million years old or less.
Above: A video showing where the newly discovered mountains lie on Pluto. Courtesy of NASA.
|Above: The mountains seen with a scale bar, and showing one of the huge pits in the surface. Courtesy of NASA.|
Pluto also has huge, oddly puckered, dimples in the surface. We have no idea what they are, but here's one idea:Alan Stern and Keisi Singer have had a paper accepted today where they argue that the nitrogen on Pluto - both atmospheric and surface ice - might need an internal source to sustain them... so perhaps these are the sites of huge vents, or cryovolcanoes. Saturn's moon, Enceladus....
|Above: Strength of the methane signal on Pluto. Green is more, red less. Courtesy of NASA.|
|Above: Enceladus' south polar region.Or possibly a monstrous brain... nah? Courtesy of NASA|
1. Radioactive heat... (All bodies generally have radioactive materials in their deep interiors)
2. Body could probably store heat of formation for a really long period of time. Maybe there's an ocean (implied sub-surface) that's freezing and the heat released from it, is melting the crust..
There's a lot more data to come; New Horizons will be downloading for months yet. The other sensors may well have been able to detect organic molecules, Methane, Ethane, Propane, polycylic hydrocarbons etc. It's not a given yet that either Pluto or Charon do have internal oceans, but there's clearly some source of geological energy!
There will be another conference to reveal more of the data that is streaming down on Friday - but until then you can watch the whole of today's conference here.
I think I'm justified in saying that with New Horizons at Pluto, Dawn at Ceres, Rosetta/ Philae at comet 67/P, Cassini at Saturn, Orbiters and Rovers at Mars, and other craft on their way to worlds like Jupiter... it's a really good time to be a space exploration geek! | 0.855946 | 3.446563 |
The LLAMA radio telescope, installed in a high altitude site in the Northwestern area of Argentina, at 4820 meters above sea level, can be used to conduct research in several fields of astronomy and inicially, the telescope will work as a single-dish telescope.
As part of an interferometric system of VLBI associated with ALMA, APEX and/or ASTE telescopes, this network will reach one of the highest angular resolutions that can be achieved today in astronomy, of the order of 1 milliseconds of arc (0".001) at a wavelengths of 1 mm. The antenna could also be incorporated as part of the planetary global VLBI network, and could thus contribute to achieve resolutions of the order of 20 microseconds of arc at the same wavelength. It is worth stressing that is important, in order to be able to obtain high quality images, to increase the number of telescopes forming the global network, and LLAMA may be one of those telescopes. In the world there are few instruments that can operate successfully at these frequencies since they require to be located in sites situated above 4000 meters above sea level. A few of them are the telescopes ASTE (4800 m), APEX and ALMA (5100 m) (all of them installed in northern of Chile), the Great Millimeter Telescope (GMT - 4600 m) in Mexico, and telescopes in Hawaii (USA) located at 4100 m, namely the James Clerk Millimeter Telescope (JCMT), the Caltech Submillimeter Observatory (CSO) and the Submillimeter Array (SMA). In this regard, it is easily understandable, that it is of high scientific importance to make every possible effort to increase the number of telescopes to be involved in this global network. Thereupon, the LLAMA telescope may also play an important role in this regards.
Some fields of research that could benefit from the use of LLAMA working as a single-dish telescope are mentioned in the following listing:
a) The Sun
* Structure of the lower solar atmosphere.
* Active and quiescent filaments.
* Solar flares.
* Dynamics of the chromospheres and its magnetic field.
* Extra-solar planetary systems around stars near the Sun.
* Proto-planetary disks in star located in the Solar neighborhood.
* Near-Earth objects.
c) Stellar objects
* Star forming regions, young stellar objects, and mechanisms of the star formation.
* Non-thermal processes in stellar magnetospheres.
* Interaction of stars and remnants of supernova with the interstellar medium.
d) Astrophysical jets and maser emission
* Astrophysical jets.
* Maser phenomena of the recombination lines of the hydrogen atom.
* Maser emission in star-forming regions.
* Maser emission in late stars stellar envelopes.
e) Galactic and Intergalactic interstellar medium
* Continuum radiation from extragalactic cold dust.
* Molecular material in the direction of different stellar objects.
* Intergalactic Medium using the detection of molecular absorption lines in the direction of quasars.
* Cosmic background radiation.
* Search for CO in galaxies with high redshift.
* Molecular abundance.
* Active Galactic Nuclei (AGN).
* Variation of the fundamental constants by the observation of gravitational lensing.
* High redshifts of regions with very high rate of star formation.
* Proto-clusters of galaxies.
* Space-time distortion produced by massive black holes.
g) High energies
* Search for counterparts of gamma-ray sources detected with the future array of Cherenkov telescopes. (CTA: Cherenkov Telescope Array). | 0.933751 | 3.801533 |
How does science prove our solar system is young not billions of years old? We are not talking about “evolution” which is often times confused with the general term “science” for indoctrination and political reasons. Rather science being: “a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge.” Evolution, whether it be planetary evolution, or Darwinian evolution is not science because previous fundamental knowledge within the evolutionary framework is not corrected but rather the new knowledge is corrected in order to maintain the previous knowledge regarding anything they feel that evolves in nature or the universe.
Back to answer the question, how does science prove our solar system is not billions of years old. The answer is: activity. A young solar system is going to have a lot more activity than an older one which makes space exploration more exciting! Pluto is the most recent which has surprised scientists with its activity but there is another and it’s coming from the DAWN spacecraft.
Keep in mind, evolutionary scientists do expect surprises, they feel they know a lot, but not everything but discovering evidence of youth in our solar system is a shocker. And the closer the spacecraft gets, it’s going to be even more shocking to them.
“I expected to be surprised because we knew so little about Ceres,” Christopher Russell, Dawn’s principal investigator and a planetary scientist at the University of California, Los Angeles, said in an email. “I never expected bright spots and a pyramid to be the surprises.”
Evolutionary scientists were expecting inert chunk of rock and ice, because they believe Ceres is billions of years old which sits in very cold space and if it was, this would have been a good prediction. But reality says, it is much younger because of its activity. This is not the first time, every single body our spacecrafts have explored, sent back data which confirms youth not old age.
Here are a few other examples:
- Evolution scientists have been hard at work trying to close the two billion age gap they claim Saturn has. “Planets tend to cool as they get older, but Saturn is hotter than astrophysicists say it should be without some additional energy source.” If you leave your hot coffee in room, it gets cooler because the room is cooler. But you put your coffee in a microwave (which has another energy source), it heats up, thus your energy source. Basic physics.
- Enceladus, the little Arizona-width moon that sends out five gigwatts of heat through its south-pole geysers. Currently there is no work on trying to come up with an energy source that could last for billions of years.
- Mountain range discovery: On Saturn’s third largest moon and the 11th largest in the entire solar system, there are 12 mile high and thin mountains on lapetus which was discovered by Cassini. Possible solution: tidal heating.
- No tidal heating but yet activity: “Already, these images are challenging views about how small, icy worlds work.” The land of icy mountains produced earlier “looks relatively young—so young, in fact, that it suggests the planet is still geologically active.” This is what happens when a dwarf planet is not billions of years old but rather quite young! :) There is no hope of a tidal heating explanation here, although this does prove geological activity is not necessarily produced by tidal heating which is something that was debated in this blog a number of years ago. Evidence conformation!
As the mission for its next adventure in the Kuiper Belt when it flies by, it’s going to turn up more evidence for a youthful universe that will give evolutionary scientists more work on trying to correct the data so it fits within their framework. But we creationists rejoice as new exploration brings home amazing discoveries than confirm its intelligent design features :) | 0.872671 | 3.042709 |
Supernovae and Pulsars
The principal feature that makes M 87 a particularly attractive subject for investigation, the fact that it is close enough to enable recognition of details that are lost at the greater distances, is even more pronounced in the case of our own Milky Way galaxy. Of course, our galaxy is not a giant elliptical, or even a Seyfert spiral, but it is after all, a reasonably big and reasonably old galaxy. Such a galaxy clearly must have accumulated some of the relatively old stars that are scattered around so profusely by the galactic explosions. As time goes on, one after another of these old stars will reach the age limit and explode, even while the galaxy as a whole is well below the normal limiting age. We have already found that a star which reaches the lower explosive limit (in efEect a temperature limit) explodes and produces a phenomenon that we have identified as a supernova. If we call this a Type A stellar explosion, then we can express the new conclusion that we have reached through a consideration of the probability of the presence of some very old stars in the younger galaxies by stating that in these galaxies there must also exist Type B stellar explosions that have some quite different characteristics because they occur at the age limit rather than at the temperature limit.
In the terminology of the astronomers, any full-scale explosion of a star is a supernova, and the foregoing statement therefore asserts that there are two distinct types of supernovae. The existence of two different types of these events has already been recognized observationally, and this fact is sufficient in itself to demonstrate the validity of the theoretical conclusion. We have deduced theoretically that there are two different types of stellar explosions; the observations confirm the deduction by disclosing that supernovae exist in two different types.
So far in this work we have used the term supernova only with reference to the Type A explosions, those that occur when stars reach the lower explosive limit, and whatever has been said as to the nature of these events and their products applies specifically to Type A. Throughout the discussion in the final chapters of this volume, however, it has been emphasized that the basic energy sources underlying the quasars and all associated phenomena are the explosions of stars that reach the upper destructive limit: the Type B explosions. At this point we need to recognize that the explosions of this second type are similar enough to those of Type A in their general nature and in their products that they also appear to observation as supernovae, and the available observational data therefore include some information on Type B events. Here, then, we have an opportunity to extend our inquiry to an examination of this important class of explosions in an evironment where they can be observed individually.
Unfortunately, these observations of the individual events can only be made under some rather severe handicaps. No observable supernova has occurred in our galaxy for nearly 400 years, and information about the active stage of these explosions can be obtained only from extragalactic observation, aside from such deductions as can be made from imprecise eyewitness accounts by observers of the supernovae of 1604 and earlier. Our most significant information comes from examination of the characteristics of certain astronomical objects, a few of which are known to be remnants of old supernovae and others that are similar enough to justify including them in the same category. Even at best, however, the hard evidence is scarce, and it is not surprising that there is considerable difference of opinion among the astronomers as to classification and other issues. For this reason our deductions from theory conflict with some current thought, but there is a rather general correspondence between the theoretical products of our Type A explosions and the astronomers Type I supernovae; likewise between the theoretical products of our Type B explosions and the astronomers Type II supernovae. For purposes of the subsequent discussion we will therefore equate A and B with I and II respectively.
The Type A explosion is a single event which theoretically originates from a hot, massive star at the upper end of the main sequence, a member of a group of practically identical objects. All Type I supernovae are therefore very much alike. As expressed by R. Minkowski, one of the leading investigators of these events, The Type I supernovae form a very homogeneous group.56 Current astronomical opinion regards the Type II supernovae as the ones that originate from the hot, massive stars, but this opinion is based on theory, not on observation, and our theory simply arrives at a different conclusion. The magnitude of the Type I supernova at the peak is relatively high, and the decay rate in the early stages is relatively low, but the overall life as compared to that of a Type II supernova is nevertheless short, for reasons which we will discuss later. The Type I supernovae are widely distributed among the various types of galaxies, as they occur, or at least may occur, fairly early in the life of the stars that are involved. This is another point of conflict with current thought, or more accurately, it is another aspect of the same conflict, as the current view of the supernova distribution is based on the identification of the hot, massive stars with Type II rather than Type I. This leads to confusion, as can be seen when Minkowski says that the Type II supernovae are the ones that occur in the Population I stars of the spiral arms, while at the same time he identifies all of the historical supernovae in the salar neighborhood (in a spiral arm of our galaxy) , other than the Crab Nebula, as belonging to Type I.57 In the context of the Reciprocal System of theory, the hot, massive Population I stars are highly evolved first generation objects (stars which have not yet passed through the supernova stage) . The stars that produce Type II supernovae are either much older unevolved first generation stars or members of later generations.
The Type I supernovae do not actually enter into the subject matter of the present discussion of the quasar class of phenomena, except through their association with the Type II objects, and we will therefore turn our attention to the latter, commenting further on the characteristics of Type I only where a comparison with these objects is of assistance in clarifying the Type II picture. Aside from the previously mentioned fact that it occurs much later in the life span of the star-at the very end-the most distinctive feature of the Type B explosion is that it generates enough energy to give the explosion products the speed that is required in order to carry them beyond the neutral point and into the region of motion in threedimensional time.
The total mass participating in this explosion may be either greater or less than that of the kind of a star that becomes a Type I supernova, as the Type II event may involve anything from a single dwarf star to a whole n-generation stellar system of six or eight units. But the Type B explosion converts a much larger percentage of this mass into energy, and the ratio of energy to unconverted mass is therefore considerably higher, producing a much greater average particle speed, and thereby increasing the proportion of the total mass going into the high speed explosion product. The Type B explosion also has the character of radioactivity, in that the initial outburst does not complete the action, but is succeeded by a period of gradually decreasing activity extending over a long period of time. The optical emission from a supernova comes mainly from the slow speed component of the explosion products, the material expanding outward in space, and since the amount of this material is much smaller in the Type II events, the optical magnitude of the Type II supernova at the peak is considerably less than that of the average Type I event, despite the greater total energy release in Type II. A recent investigation arrived at average magnitudes of -18.6 for Type I and -16.5 for Type II.58 The emission from Type II also drops off more rapidly at first than that from Type I, and the light curves of the two types of explosions are thus quite different. This is one of the major criteria by which the observational distinction between the two types is drawn. For example, Minkowski remarks in one case that The supernova was visible for more than 1 year. This excludes Type II.59
In view of the limited optical activity and the relatively small mass of the remnants, there has been some question as to what happens to the energy of these Type II events. Poveda and Voltjer, for instance, comment that they find it difficult to reconcile current ideas as to the energy release in the Type II supernovae with the present state of the remnants.60 This question is answered by our finding that the great bulk of the energy that is generated goes into the ultra high speed explosion products.
The radio emission is more representative of the true energy situation. Here we have to depend on observations of the remnants of old supernovae, but the results of the radio measurements on these objects are definite and unequivocal. For example, there is a nebulosity in the constellation Cygnus, known as the Cygnus Loop, which is generally conceded to be a remnant of a Type II supernova, and is estimated to be about 60,000 years old. After all of this very long time has elapsed, we are still receiving almost twice as much radiation at 400 MHz (in the radio range) from this remnant as from the remnants of all three of the historical (1006, 1572, 1604) type I supernovae combined.57
There are a number of other remnants with radio emission that is far above anything that can be correlated with Type I, including Cassiopeia A, the most intense radio source known; IC 443, which is similar to the Cygnus Loop and almost as old, and three remnants in the Large Magellanic Cloud, the strongest of which is reported to have about 200 times the emitted radio power of the Cygnus Loop.57 Likewise there are remnants whose radio emission is within the range of the Type I products, but whose physical condition indicates an age far beyond the Type I limit. These must also be assigned to Type II. In general, it seems safe to say that unless there is some evidence of comparatively recent origin, aIl remnants with measurable radio emission can be identified with Type II supernovae, even though Type I events may be more frequent in our gaIaxy.
This conclusion enables us to classify the Crab Nebula definitely as a Type II product. The radio flux from this remnant of a supernova observed in 1054 A.D. is about 50 times that of the remnant of the Type I supernova that appeared in 1006 and is therefore of practically the same age.57 The Crab Nebula was originally assigned to Type I by the astronomers, mainly on the basis of differences between it and Cassiopeia A, which was regarded as the prototype of the Type II remnant, but more recently it has been recognized that the differences between this nebula and the Type I remnants are much more pronounced. Minkowski (1968) concludes that an unbiased assessment of the evidence leads to the conclusion that the Crab Nebula is not a remnant of a supernova of Type I.57
The greater and longer-lasting radio emission of the Type II supernovae is, of course, consistent with the theoretical results of the greater total energy and the continuing character of the Type II events. Another observational confirmation of the theoretical explanation of the long time scale of Type II comes from evidence of further explosive events subsequent to the original outburst of the supernova. A current explanation of the peculiar features of Cassiopeia A attributes them to the presence of two distinct shells of expanding material. The Crab Nebula is likewise made up of two dissimilar components. Examination of the spectra of extragalactic supernovae also lends considerable support to the double shell hypothesis. The presence of multiple absorption lines in the spectra of many supernovae of Type II suggests that more than one shell has been ejected. (Minkowski) 57
It thus appears altogether possible that the A.D. 1054 supernova and the latest outburst of Cassiopeia A may have been preceded by other major explosive events in the same stars. This suggestion becomes all the more plausible when it is realized that many of the stars involved in Type II supernovae are actually star systems double or multiple stars. Both, or all, of the stars in such a system have the same chronological age, but variations in the conditions of existence can very well introduce some differences in the evolutionary age, and hence there may be a substantial interval between the explosions of the components of a multiple star.
This possibility of multiple explosions would also explain what has been a puzzling feature of Cassiopeia A. Expansion with high velocity clearly indicates that the nebulosity is the remnant of a supernova of moderate age, but no outburst in its position has been recorded.57 Even a small supernova would have been a target of intense interest at the time calculated for this event, about 1700 A.D., and the idea that an event powerful enough to produce the strongest radio source in the heavens could have passed unnoticed seems preposterous. But if there was already a strong source of optical radiation at this location, one that had originated from previous outbursts, and the supernova of 1700 A.D. did not increase the optical radiation by any striking amount, there is a good possibility that it might have escaped detection. A Type I supernova could hardly have been missed, even under these conditions, but in view of the much lower optical emission from Type II and the faster decay, this explanation is at least plausible. The increase in radio emission would have been immense, but it meant nothing at that time.
In addition to the main outburst or outbursts which constitute the principal feature of the Type II supernova, there is a long-continued supplementary generation of energy as the explosion gradually spreads through additional portions of the affected mass. This continuing action is manifested by the persistence of the radio emission, and by the evidence of energetic events within the remnants. For instance, the optical remnant of Cassiopeia A is undergoing rapid changes,61 while the Crab Nebula, another remnant, contains some formations which are highly variable in appearance and brightness and which move quite rapidly.62 Calculations alsa indicate that an input of energy into this nebula of the order 1038 erg/sec is required to sustain the observed emission.57 The current suggestion is that this energy is injected into the nebula from the central star, but the ultra high speed product emits only a relatively small amount of energy, and therefore cannot be the source of the continuing supply. The supplementary energy has to come from radioactivity within the material ejected in the primary outburst. It is the existence of this secondary energy generation in the Type II supernovae, but not in Type I, that accounts for the great difference between the maximum 165 period of observable radio emission in Type I remnants, perhaps 3000 years, and that in Type II remnants, which we can estimate at more than 100,000 years. This is somewhat similar to the difEerence that we noted between the Class II quasars, which have secondary energy generation and therefore maintain their emission for a billion years or more, and the Class I quasars, that have only the energy with which they were ejected from the galaxy of origin, and therefore fade out after a hundred million years or so.
The same factors that are responsible for the differences between the relatively slow speed products of the two types of supernovae-the remnants-also result in some significant differences between the ultra high speed products of the two kinds of events. Here, again, the general nature of the corresponding products is the same. Just as the slower component in each case is a cloud of dust and gas particles moving outward in space, so the high speed component in each case is a cloud of dust and gas particles moving outward in time. But the greater intensity and other special characteristics of the Type B explosions have some effects that make the behavior pattern of the Type B high speed component significantly different from that of its Type A counterpart, the white dwarf star.
It was mentioned previously that the compact cores of some of the larger galaxies are quite similar to the white dwarf stars in their general aspects. In both cases the constituent units, stars in the core and particles in the white dwarf, are moving with ultra high speeds in a confined space, with the result that additional time is being introduced between the units of matter and the properties of the material aggregate are altered accordingly. Such a galactic core is therefore a giant version of the white dwarf star-a white dwarf core, as we called it earlier-differing only in the nature of the fast-moving units. Similarly, we can regard the ultra high speed product of a Type B explosion as a miniature version of the quasar, as here again the essential difference is merely that the constituent units of the quasar are stars whereas those of the Type B explosion product are particles of dust and gas.
As in the case of the quasar, the energy imparted to the particles of the high speed Type B product is sufficient to carry them past the neutral point and into the region of motion in three-dimensional time. Ultimately, therefore, they will disappear from the material region of the universe, but before they can do this, they, like the quasars, must first overcome gravitation. Compared with the quasar situation, however, the gravitational effects on the supernova particles are minuscule, and the visible results are consequently quite different. The quasar is composed mainly of material particles that are individually moving with speeds less than that of light (even though the aggregates of these particles, stars, are moving at ultra high speeds) , together with fast-moving particles that are spatially confined. The visibility limit for this kind of material is a function of the spatial distance, and the quasar therefore remains as a visible object out to its overall limit of 2.00 even though the gravitational effect in the dimension of the explosion speed is eliminated at a quasar distance of 1.00. However, the ultra high speed particles produced by the Type II supernovae are not spatially confined, and their radiation is invisible beyond a distance of 1.00 in the explosion dimension.
As explained in Ghapter VI, there is a gravitational limit for each aggregate of matter within which the gravitational motion exceeds the progression, and beyond which the progression is the greater. For a star similar to the sun this limit is a little over two light years. Outside the limit the gravitational effect continues to decrease with increasing distance in accordance with the inverse square law, until at another limiting distance the entire mass exerts only one unit of force; that is, it exerts the same gravitational force that one unit of mass exerts at one unit of distance. Inasmuch as fractional units do not exist, there is no gravitational effect at all beyond this outer limit, which is about 13,000 light years for a star of one solar mass. The ultra high speed particles produced by the Type II supernova are traveling at unit speed in the explosion dimension, and their maximum period of visibility is therefore approximately 13,000 years.
In the discussion of the spatial speed of the quasar it was pointed out that only that portion of the explosion speed that is applied to overcoming gravitation has any effect on motion in space, and consequently, the faster the quasar travels the less spatial distance it moves. For instance, at the point where gravitation is down to .500, half of the 1.00 explosion speed causes movement in space, and the other half, the net outward speed, does not. The same principle also applies to radiation. At this same .500 distance, half of the radiation from the ultra high speed explosion product is observable in space and the other half is unobservable. But there are no fractional units, and during each unit of time the radiation must be either spatial or non-spatial; it cannot be divided between the two. Hence the reduction in the spatial radiation below the level of one unit of radiation per unit of time takes place in the number of units of timeduring which the radiation appears in space; that is, the radiation is intermittent.
At .500, alternate units are spatial. The natural unit of time has been evaluated in previous publications as .152 x 10-15 seconds. We thus receive radiation for this length of time, after which there is a quiet interval of .152 x 10-15 seconds, then another flash of radiation, and so on. Obviously an alternation at such extremely short intervals cannot be distinguished from continuous emission, but as the high speed explosion product moves outward the ratio of spatially active to spatially inactive units of time decreases, and when the age of this product begins to approach the 13,000 year limit the ratio becomes small enough to make the periodicity evident. Under these conditions the radiation is received as a succession of pulses. For this reason the observed ultra high speed product of the Type II supernova is known as a pulsar.
Approximately 60 pulsars have been located since the first of these objects was discovered in 1967, and it appears that this number includes most of those within range of the available facilities. According to Hewish, it does not seem likely that the number will increase significantly until new radio telescopes of greater collecting area are available.34 The distribution and observed properties of these objects have been interpreted as indicating that they are situated within the galaxy and at distances mainly within 2 or 3 Kpc. This is consistent with the theoretical conclusion that they are products of Type II supernovae. Furthermore, two of the pulsars have been definitely identified with supernova remnants, and A. J. R. Prentice has found somewhat less conclusive evidence of correlations with four more. He summarizes his report in these words, I present evidence that most pulsars may have been formed in Type II supernova explosions and initially possessed extremely high velocities, of order 1000 km s-1.63 The theoretical points of similarity between the pulsar and the quasar have also been recognized observationally. P. Morrison asserts that Quasi-stellar radio sources are analogous to pulsars in every respect save that of scale,64 and he suggests that quasars are simply giant pulsars. The situation as we find it theoretically is somewhat more complicated than this, but as a first approximation the statement is correct.
Like their Type I counterparts, the pulsars may accrete material from their surroundings and become visible as white dwarf stars. The conditions are unfavorable for such accretion, however, because of the short lifetime of these objects and the limited amount of slow speed material available for capture, and so far only one such star has been definitely located. This is the star associated with the pulsar in the Crab Nebula, where the environment seems to be quite unusual, perhaps, as suggested previously, because of an earlier explosion at the same location. The relatively low polarization of the radiation from the Crab Nebula pulsar, contrasted with the complete polarization of that from PSR 0833, the next youngest of these objects, is indicative of a significant environmental difference. Inasmuch as the pulsar radiation emanates almost entirely from particles of matter moving at ultra high speeds it is almost completely polarized on emission, and a lower polarization measurement can be taken as evidence of depolarization.
A large amount of effort has been devoted to a search for white dwarfs in the pulsar positions because of the relevance of this information to the theories which picture the pulsars as white dwarfs existing under some special conditions, and the failure ta detect them optically despite careful searches34 has weighed heavily against the white dwarf theories. Our findings are that the pulsars may assume the white dwarf status, but in most cases will not, and the lack of success in these searches is not surprising. The most likely prospects for optical detection would seem to be those pulsars in which the polarization is relatively low. PSR 0833, which has been one of the principal targets of the search, is probably one of the least likely to be emitting any significant amount of optical radiation.
From the explanation of the origin of the pulsars given in the foregoing paragraphs it is evident that the pulsation periods must be increasing at a measurable rate. Here, again, the observations confirm the theoretical conclusion. The periods of all pulsars thus far studied are systematically increasing,34 says Hewish. Since the decrease starts from the gravitational limit in all cases and follows a fixed mathematical pattern, the period of a pulsar is an indication of its age, and this correlation provides a means whereby we can arrive at some conclusions concerning the time scale of these objects.
The individual pulsar time scales will vary to some extent
because they are based on the gravitational limits. and these limits are
dependent on the stellar masses involved, but we may establish some values
on the basis of the solar mass, as an indication of the general situation.
Initially, the exploding star is outside the gravitational limit of its
nearest neighbor, and the gravitational restraint on the pulsar is mainly
due to the slow-moving remnants of the explosion. This effect decreases
rapidly, however, and within a short time the gravi-
At the gravitational limit the radiation is continuous; that is, radiation is received during 6.6 X 1015 units of time in every second. But in 900 years the pulsar, traveling at the speed of light in the explosion dimension, has moved out to a distance of 900 light years in this dimension (a distance analogous to the quasar distance of the earlier discussion) , and by reason of the attenuation of the gravitational force the radiation has been reduced to the point where it is only being received 30 times per second. The ratio of this pulsation period to the initial period is 2.2 X 1014, and the corresponding distance ratio, by reason of the inverse square relation, is the square root of this value, or 1.5 X 107. Dividing 900 years by 1.5 X 107 we obtain 6 X 10-5 light years as the effective gravitational limit. This means that at this distance, about 500 times the stellar diameter, the sum of the gravitational effects of the neighboring star and the remnants of the supernova is equal ta the space-time progression, and the radiation is still continuous. Beyond this point there is a pulsation with an increasing period.
Looking now in the other direction from the reference pulsar, toward objects of greater age, PSR 0833, the second youngest of the pulsars now known, has a period of .089 seconds, which corresponds to an age of 1470 years. This pulsar is therefore nearly 600 years older than the one in the Crab Nebula. The longest period thus far discovered is 3.475 seconds, which indicates an age of 900 years. Some still longer periods are possible before the ultimate limit of about 13,000 years is reached, but these long period pulsars will probably be faint and difficult to detect. An interesting subject for investigation is the pulsar that should theoretically exist in the supernova remnant Cassiopeia A. If this supernova occurred only 300 years ago, as the motions of the remnants indicate, these remnants should contain a pulsar with a period only one-ninth that of the pulsar in the Crab Nebula. This is 270 pulses per second, which will no doubt be difficult to detect, but not necessarily impossible.
A study of the indicated age distribution of the 50 pulsars listed in the article by Hewish in the 1970 Annual Review of Astronomy and Astrophysics discloses a rather unexpected situation. On the basis of the theoretical relation between period and age, these pulsars are distributed through an age range of at least 10,000 years. During 6000 years of this total, the first 4500 and the most recent 1500, only 6 pulsars appeared, an average of one every 1000 years. But in the intervening 4000 years 44 pulsars made their appearance, one in every 100 years. Furthermore, the rate of formation did not build up gradually to a peak and then decrease slowly, as might be expected; it rose quite suddenly, held nearly constant during the 4000 year interval, and then dropped almost as suddenly as it rose.
This seemingly anomalous distribution over the period of time involved may help to provide an explanation of the otherwise excessive number of pulsars. A rate of one per hundred years in a small section of one galaxy is clearly inconsistent with current estimates of the average number of Type II supernovae, which are in the range of one per several hundred years for an entire galaxy. However, we have already noted that a galaxy contains many clusters of stars of approximately the same age, and the large number of pulsars originating during the 4000 year period could be the result of a whole cluster of 40 stars reaching the destructive limit almost simultaneously.
Even on this basis, the indicated production of pulsars seems excessive for a region with a radius of only about 3 Kpc, and it may be advisable to give further consideration to the possibility that the pulsars may actually be located at considerably greater distances than those now accepted. Energy considerations, for example, will be favorable to a substantial increase in the distance scale when the twodimensional nature of the radiation from the pulsars is taken into account. However, it may not be necessary to take up all of the existing discrepancy by a decrease in the pulsar density, as the information now available regarding the relatively low visibility of the Type II supernovae suggests that the estimates of the rate of occurrence of these supernovae in the external galaxies are too low. There may well be many extragalactic equivalents of Cassiopeia A: supernovae that have come and gone unnoticed. But in any event, the number of pulsars now known would seem to be more consistent with a distribution over a substantially greater volume.
Indeed, there would seem to be adequate grounds for suspecting that the observed pulsars are distributed throughout the greater part of the galaxy. On this basis, the strong concentration of these objects toward the galactic plane, which is now unexplained, would be consistent with a fairly uniform distribution of the pulsars among the galactic stars, a result that we would naturally expect from the mixing action due to the motion of the galaxy.
As matters now stand, there are no available observational data of sufficient accuracy to enable making an independent check of the pulsar distribution in volume. A comparison of the estimated valumetric concentration of these objects with the corresponding values for the white dwarfs will, however, serve as a rough check on the figure of 13,000 years which we have established as the approximate life period of a pulsar. At first glance this figure seems extremely low in view of the fact that most stages of stellar existence extend into the billion year range, but when we compare the relative space densities of the two classes of objects we find that the life of the pulsars must necessarily be very short. The number of stars in the nearby regions of the galaxy is estimated at about one per 10 cubic parsecs, and about three percent of these are thought to be white dwarfs. The number of white dwarfs per cubic parsec on this basis is .003. Present estimates of the space density of the pulsars lead to a figure of 5 X 10-8 per cubic parsec.34 If we accept the current opinion that the total number of supernovae is divided about equally between the two types, the life periods of the two ultra high speed explosion products are proportional to their space densities.
Multiplying the 13,000 year life of the pulsar by this density ratio, 6 X 104, we arrive at 8 X 108, or approximately one billion years, as the life period of a white dwarf. This figure is probably somewhat low, as the indications are that the number of white dwarfs is currently underestimated, whereas, as we have noted, the space density of the pulsars is probably overestimated, but at any rate, the calculation shaws that the 13,000 year pulsar life is consistent with a billion year life span for the white dwarf.
There is some divergence between the measured rates of increase of the pulsation periods and the theoretical rates corresponding to the respective periods, but they are probably within the range of deviations that can be expected by reason of internal activity within the pulsars. Internal motion can either add to ar subtract from the normal rate of increase of the period, even to the extent, in some cases, of converting the increase into a decrease for a limited time. Sudden changes have been reported from both of the two youngest pulsars, NP 0532 and PSR 0833.
In addition to the internal motions, there may be a rotation of the pulsar as a whole, and the fine structure of the pulses is a reflection of these two factors. The so-called drifting or marching sub pulses, for example, are quite obviously effects of local motions in the pulsar that are being carried across the line of sight by the pulsar rotation. The presence or absence of accreted slow speed material may also have a significant effect. In PSR 0833, for instance, where the 100 percent polarization indicates little or no accretion, there is also little or no fine structure,34 whereas the other young pulsar, NP 0532 in the Crab Nebula, has both a substantial amount of accreted material and a complex pulse substructure.
Of course, most of the figures that we have used in the foregoing discussion of the pulsars are merely rough approximations-aside from the measured pulsation periods, almost any value quoted may be in error by a factor of 3 or 4-but they fit together closely enough to show that the pulsar theory derived from the concept of a universe of motion produces results that are consistent with what little is known about these objects. To the extent that confirmation is possible under the existing circumstances, therefore, this confirms the assertions of the theory that the pulsars are short-lived, ultra high speed products of Type II supernovae.
It is ironical, says Antony Hewish, that astronomys latest discovery, the pulsars, should have been stumbled on unexpectedly during an investigation of quasars, those starlike radio sources whose origin is still one of the outstanding problems of astrophysics.65 But contrary to the implication in this statement, the discovery of the pulsars does not generate a new problem for physical science. The existence of these objects is simply another aspect of the same problem, and when the correct basic theory is applied to the situation, all aspects of this problem-pulsars, quasars, white dwarfs, galactic explosions, and so on-are cleared up in one operation.
The foregoing pages have accomplished their defined objective by deriving a consistent and comprehensive theory of the pulsars, quasars, and associated phenomena, and confirming its validity by extensive qualitative and quantitative evidence. Once it becomes possible to summon enough scientific courage to discard the now untenable concept of a universe of matter, on which all of the hard-pressed traditional theories are based, and to replace it with the concept of a universe in which the basic entities are units of motion, the existence of quasars is one of the inevitable consequences. It has taken a great many pages ta trace the chain of reasoning all the way from the basic concept to the quasar, but this is only because of the amount of attention that has had to be given to the details. The essential elements of the theoretical development are simple, both logically and mathematically.
But it is appropriate to emphasize that this is not just a theory of the quasars and their associates; it is a general theory of the physical universe, one that is applicable to all physical phenomena, and it applies the same principles and relations to astronomical phenomena, including the quasars and the pulsars, that are utilized in dealing with the properties of matter, the behavior of electricity and magnetism, or any other physical entities or relations. The theory was not constructed for the purpose of explaining the quasars; it was in existence years before the quasars were discovered, and no additions were necessary to bring the quasar phenomena within its scope. All that had to be done was to carry the chain of reasoning a little farther in some areas.
Furthermore, the theory employs none of the far-fetched ad hoc assumptions that conventional theories find it necessary to utilize even to get a start toward an explanation of the quasar phenomena-such things as neutron stars, black holes, gravitational collapse, quarks, and the like: fanciful concepts that have no observational support whatever and are simply drawn out of thin air. Indeed , the new theory makes no assumptions at all, other than the assumptions as to the nature of space and time which constitute the basic postulates of the system. Nor does it draw anything from experience. Quasars, pulsars-even matter and radiation-appear in the theory not because they are known from observation, but because they are necessary consequences of the theory itself. The existence of each of these entities is deduced from the postulated properties of space and time without introducing anything from any other source.
Finally, it is worthy of note that the new system of theory achieves a high degree of economy of thought. The same explanations that account for the peculiar characteristics of the white dwarf stars also account for the similar characteristics of the quasars, the Seyfert galaxies, and other objects of this type. The same energy sources that produce the great galactic explosions also account for the energy emission from the radio galaxies, for the Type II supernovae, and for the large energy output from the quasars. The same factor that accounts for the nature of the motion imparted to the quasar by the primary galactic explosion also accounts for the relation of the quasar magnitude to distance, for the absence of blueshifts, and for the polarization, not only of the quasar radiation but also that of the pulsars.
The ability of the new theoretical system to provide a comprehensive and detailed explanation of these quasar phenomena with which conventional theory is completely unable to cope is a graphic illustration of the benefits that can be gained by replacing the present multitude of different parts and pieces that do not fit together very well with a solidly based and fully integrated theory from which such phenomena as the galactic explosions, the recession, the pulsars, the quasars, the elementary particles, and the other items with which the astronomers and the physicists are now having trouble, emerge as essential features of the main line of theoretical development, rather than having to be forced into the theoretical structure by all sorts of questionable expedients.
By this time it should be clear that the traditional physical theories based on the concept of a universe of matter have reached the end of the road; that a continuation of the heroic efforts that are being made to patch the holes and to bolster the elements of the theoretical structure that are failing under the load is no longer justified. After all, there are limits to what can be built on a false foundation, even with the benefit of all of the ad hoc assumptions, principles of impotence, and other ingenious devices that the modern scientist utilizes to evade contradictions and inconsistencies and to reinforce the weak spots in his arguments. As the continuing improvement in observational facilities enables penetrating deeper into the far-out regions of the universe, the never-ending task of revising and reconstructing existing theories to conform to the new knowledge becomes progressively more difficult.
The astronomers, who are dealing with physical phenomena on a gigantic scale, are acutely conscious of the awkward situation in which they are placed by the lack of any basic theoretical structure that is applicable to their new discoveries.
Total inadequacy is a harsh term, but it is fully justified under the circumstances, and in calling for a radical revision of the laws of physics to meet present-day needs Hoyle is on solid ground. The physicists cannot deny the need for such changes, as they freely concede that they are encountering equally serious difficulties along the outer boundaries of their own fields, as well as in some of the most basic areas. What we badly need is a greater synthesis, says Abraham Pais, at the same time admitting that this may lead us to revise very basic concepts.67 Sir Harrie Massey states the case in these words:
But this big theoretical advance is not something that we must await. It is already here; all that is now necessary is to recognize it. As the earlier pages of this volume and its predecessors have shown, the essential requirement is a realization that the universe which science is attempting to understand is a universe of motion, not a universe of matter. Once this understanding is achieved, and the logical consequences thereof are followed up in detail, the physicists will have the clarification for which they are asking, and the astronomers will have the revised physical laws that will enable them to bring all of the phenomena of the very large and the very fast within the scope of theoretical understanding in the same manner in which the mystery which has heretofore surrounded the quasars and their associates has been swept aside in this work. | 0.890398 | 4.077602 |
Astronomers have discovered a star 600 light-years away that stretches the definition of what can even be considered a star. That's because EBLM J0555-57Ab, the smallest star ever discovered, is the size of a planet—specifically, it's just a hair bigger than Saturn.
But the star 57Ab is much more massive than Saturn. In fact, it's 85 times the mass of Jupiter, which makes it just massive enough to fuse hydrogen into helium and become a true star. Because of its small radius, though, it was initially caught up in a case of mistaken identity.
57Ab is part of a triple star system. While the sun-mass stars EBLM J0555-57A and EBLM J0555-57B orbit around each other, 57Ab orbits only the primary star. 57Ab's small size in comparison to its sun-like companions led researchers to conclude initially that the planet-sized star was just that, a planet. The star's mistaken classification occurred in part because it was detected by transit—the general method for finding exoplanets—where one body passes in front of another and dims some of the light from the background object.
Everything about the light curve suggested a planet. "Indeed, until we measured the mass it looked just like a transiting planet," said Amaury Triaud, a Kavli Institute fellow at the University of Cambridge and an author on the paper published today in Astronomy and Astrophysics.
Current models suggest a big ball of gas has enough mass to ignite into a star at about 80 times the mass of Jupiter. To be considered a star, an object must undergo nuclear fusion in its core and fuse hydrogen into helium. Below 80 Jupiter masses, star-like objects are called brown dwarfs and only fuse hydrogen into the isotope deuterium.
So at 85 Jupiter masses, 57Ab is cutting it close to what can be considered a star. It's less than one percent the mass of the sun, and indeed, Triaud says the team has had trouble determining some information about the star as its light is completely blotted out by its larger companions.
It's also likely that 57Ab has always been this way, rather than having lost some of its mass to its host star, EBLM J0555-57A. That still doesn't quite explain how the system came into existence, though.
"It is not entirely clear how stars with very different masses, like in our case, can form so close to each other," Triaud says. "One scenario is that the stars formed further apart and somehow got closer. One way to do that is if they had very eccentric orbits, early on. Tidal forces would then tend to reduce the distance between the stars and make their orbits more circular."
The small size of 57Ab places it in a class of stars called ultracool stars. The most famous example is TRAPPIST-1, a Jupiter-sized star that is home to seven planets. (Triaud was part of the team that discovered this system.) They're ideal laboratories for studying planetary systems with giant telescopes—that is, if astronomers can manage to find them.
"It is a little ironic that those small stars are the most common stars in the cosmos, but because they are faint, we don't as much about them as we wish," Triaud says. "This is why, in parallel to our investigations into planets orbiting ultracool stars, we are also investigating the stars themselves."
Now that EBLM J0555-57Ab is officially the smallest star ever discovered, you can bet that more astronomers will be turning their telescopes to observe the strange Saturn-sized star and learn more about these mysterious ultracool objects, treading the line between planethood and stardom. | 0.857634 | 3.992723 |
Humans have gazed up at the sky in wonder since before the dawn of civilization, and the age-old question of “are we alone?” has occupied philosophers and priests for centuries on end. Today the interdisciplinary field of astrobiology strives toward an answer to this mystery by examining this history of life on Earth in an effort to search for life elsewhere and better understand our future.
Astrobiology is a collaborative effort among scientists of different fields to examine the origin, distribution, and future of life in the universe. Earth is the only known example of an inhabited planet, but this at least provides astrobiologists with a rich geological and biological history to examine the conditions that led to the formation of life. Investigation into the interplay between life and climate can lead toward a more fundamental understanding of exactly what is needed for an environment to be “habitable”. This in turn allows exoplanet-hunting astronomers to interpret their remote observations and hone in on planets that represent the best potential candidates for extraterrestrial life.
The “habitable zone” describes a range of orbits around a star where a planet could (in principle) sustain liquid water on its surface. Too close of an orbit would cause any water to boil off into steam, while too far of an orbit would cause the atmosphere to eventually plummet into global glaciation. The region between these two limits is of particular interest for astrobiologists who seek to find a rocky planet with oceans and continents, about the size of Earth, that would be capable of supporting life.
Further remote observations using spectroscopy can infer the composition of the atmosphere and even the presence of clouds, which can provide further evidence to assess the habitability of a planet. If (for example) we observed a rocky planet in the habitable zone that contained oxygen, ozone, methane, and water vapor in its atmosphere, then this could suggest evidence for the presence of life on the surface. This argument is based on our knowledge of atmospheric chemistry that finds methane is readily depleted in the presence of oxygen, so if we observe both, then there must be sources of these gases on the surface. Most methane on Earth is produced by life, so the question becomes: are there abiogenic (non-living) processes that explain the observations, or must the observations be due to biogenic (living) processes? Studying the long-term climate histories of Earth, Mars, and Venus is one way to understand the diversity of processes that can determine the ability of a terrestrial planet to support life.
Ground-based surveys continue to improve in their ability to detect smaller planets than ever before, while new space telescopes, such as the James Web Space Telescope (JWST) and Transiting Exoplanet Survey Satellite (TESS), will provide the ability to characterize the planetary atmospheres our closest neighbors. What we learn from these studies will not only help provide better targets in the search for life, but they also help us better understand the context of the cosmic environment that is home to our planet.
Examining the range of habitable environments in which life can thrive provides a window into the possible trajectories of our own civilization’s future. We currently struggle to conceive of long-term solutions to environmental and economic issues that require much deeper foresight than our civilization has yet demonstrated. Our civilization has demonstrated its ability to alter global-scale processes for centuries or millennia to come, which has even been named as the epoch of the “Anthropocene”. The discovery of an actually inhabited planet—if we ever find one—will be one of the most philosophically profound discoveries in all of human history, yet in the meantime the exploration of the worlds around us allows us to better understand the complex dynamics of the interplay of Earth’s systems with the processes of life.
How will humanity evolve with the biosphere, and how will we overcome the challenges that face us in the future? Astrobiology provides a lense into the diverse planetary processes that help us better understand our own, and it stretches our minds to conceive of the billion-year timescales that shape the history of each and every planet. The challenge of astrobiology is not only to discover life afar but also embrace our lives here in an effort to shape a better future that we have ever known. | 0.923143 | 3.973996 |
These could be the “howls” of dead stars as they feed on stellar companions.
“We can see a completely new component of the centre of our galaxy with NuSTAR`s images,” said Kerstin Perez from the Columbia University in New York.
NuSTAR, launched into space in 2012, is the first telescope capable of capturing crisp images of this frenzied region in high-energy X-rays.
The new images show a region around the supermassive black hole about 40 light-years across.
Astronomers were surprised by the pictures which reveal an unexpected haze of high-energy X-rays dominating the usual stellar activity.
When stars die, they don`t always go quietly into the night.
Unlike stars like our Sun, collapsed dead stars that belong to stellar pairs or binaries can siphon matter from their companions.
This zombie-like “feeding” process differs depending on the nature of the normal star, but the result may be an eruption of X-rays.
According to scientists, a type of stellar zombie called a pulsar could be at work.
Pulsars are the collapsed remains of stars that exploded in supernova blasts.
They can spin extremely fast. As they spin, the beams sweep across the sky, sometimes intercepting the Earth, like lighthouse beacons.
“We may be witnessing the beacons of a hitherto hidden population of pulsars in the galactic centre,” added study co-author Fiona Harrison from the California Institute of Technology.
This new result just reminds us that the galactic centre is a bizarre place, the authors concluded. | 0.846185 | 3.508017 |
A few days ago, the European Space Agency’s spacecraft Goce burned up and disintegrated in the Earth’s atmosphere. Observers in the Falkland Islands had a grand view of the spacecraft as it crossed the sky, breaking up as it went.
The debris came down somewhere in the South Atlantic. There was a lot of media discussion of the spacecraft re-entering the Earth’s atmosphere and being destroyed. Actually it never left.
Lots of the older books about space and astronomy hint there is a definite boundary between where we live and space. They imply that where we live we have air to breathe and gravity to hold everything down, while in space there is a vacuum and there is no gravity, or even microgravity.
This is just not true, either in the case of the atmosphere or gravity. As we go upwards, the air gets increasingly rarefied. That is why we put observatories at the tops of high mountains or in space to reduce or escape the effects of the atmosphere on our observations. However, there is no definite place where the air ends and space takes over.
Gravity does not end either. As you get higher, and further from the centre of the Earth, gravity weakens. Double the distance and the gravitational pull decreases by a factor of four. However, that does not end either. It reaches far out into space, getting weaker and weaker.
If there is any reasonable boundary it would be where the atmosphere has become so rarefied it blends in with the solar wind, or at such a distance that the Earth’s gravitational attraction is about the same as all the other gravitational attractions acting on any body at that location.
Spacecraft do not stay in orbit because there is no gravity. If we could build a tower 400 kilometres high, to where many satellites orbit, we would find the gravitational attraction at the top to be just a little weaker than it is at the Earth’s surface.
If we were dumb enough to step off, we would head straight down at high speed. When we launch a spacecraft, we lift it above most of the atmosphere and then gradually turn the rocket so that it is moving more or less parallel with the Earth’s surface.
The engines continue to operate, accelerating it to around 30,000 km/h, parallel with the ground. When the right speed is reached, the engines are shut down and the spacecraft released. With no means of propulsion, the spacecraft starts a long, curving fall to the Earth’s surface.
However, it never hits because the Earth curves away beneath it. The best description is that it is in free fall. In free fall, there is no sensation of weight. We could experience exactly this feeling in a falling elevator, but not for as long. Chris Hadfield and the other astronauts in the International Space Station were falling around the Earth. Inside the ISS there is plenty of gravity, so it is not a microgravity environment; it is more an environment where gravity is not as apparent.
Since the atmosphere extends far into space, all our orbiting spacecraft are actually moving in it. If we are high enough, say 2,000 kilometres, the air is so thin that the drag will probably not affect us for centuries or longer. At lower altitudes, spacecraft such as the International Space Station, orbiting about 420 km above the ground, experience much more drag, and without an occasional boost, the ISS would soon come down.
The only manned spacecraft so far to truly re-enter the Earth’s atmosphere were those carrying the Apollo astronauts. And in future, people returning from new missions to the Moon and of course our first expeditions to Mars.
— Venus shines brightly, low in the southwest after sunset. Jupiter and Mars rise around 8 p.m. and 1 a.m. respectively. Look for Mercury low in the southeast before dawn. The Moon reaches Last Quarter on the 25th.
Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory, Penticton, BC, V2A 6J9. Tel (250) 497-2300, Fax (250) 497-2355, E-mail: [email protected] | 0.872849 | 3.853571 |
Subsets and Splits