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astrophysicists offer proof that famous image shows forming planets
A recent and famous image from deep space marks the first time we’ve seen a forming planetary system, according to a study by U of T astrophysicists.
The team, led by Daniel Tamayo from the Centre for Planetary Science at U of T Scarborough and the Canadian Institute for Theoretical Astrophysics, found that circular gaps in a disk of dust and gas swirling around the young star HL Tau are in fact made by forming planets.
“HL Tau likely represents the first image taken of the initial locations of planets during their formation,” says Tamayo. “This could be an enormous step forward in our ability to understand how planets form.”
The image of HL Tau, taken in October 2014 by the state-of-the-art Atacama Large Millimeter/submillimeter Array (ALMA) located in Chile’s Atacama Desert, sparked a flurry of scientific debate.
While those who observed the original image claimed that planets were most likely responsible for carving the gaps, some remained skeptical. It had been suggested that the gaps, especially the outer three, could not represent forming planets because they are so close together. It was argued that planets massive enough to carve such gaps should be scattered violently by the force of gravity and ejected from the system early on in its development.
But Tamayo’s study is the first to suggest the gaps are evidence of planetary formation because the gaps are separated by amounts consistent with what’s called a special resonant configuration. In other words, these planets avoid violent collisions with each other by having specific orbital periods where they miss each other, similar to how Pluto has avoided Neptune for billions of years despite the two orbits crossing one another.
Tamayo created two videos to show how HL Tau would appear in both resonant and non-resonant configurations.
The system can be much more stable in a resonant configuration and it’s a natural state for planets in the HL Tau system to migrate to says Tamayo.
The HL Tau system is less than a million years old, about 17.9 billion kilometres in radius and resides 450 light years from Earth in the constellation Taurus.
Since young systems like HL Tau are shrouded by a thick cloud of gas and dust, they can’t be observed using visible light. ALMA resolves that issue by using a series — or an array — of telescopes located 15 kilometres apart that use much longer wavelengths. The result is unprecedented access to high resolution images that Tamayo says will continue to revolutionize the study of planetary formation.
“We’ve discovered thousands of planets around other stars and a big surprise is that many of the orbits are much more elliptical than those found in our solar system” said Tamayo.
This and future ALMA discoveries may be the key to connecting these discovered planets to their original birth locations.
While the HL Tau system remains stable in its relatively young age, Tamayo says over billions of years it will act as a “ticking time bomb.” Eventually the planets will scatter, ejecting some and leaving the remaining bodies on elliptical orbits like the ones found around older stars.
Our solar system does not seem to have undergone such a dramatic scattering event, notes Tamayo. Future observations could also go a long way in determining whether our solar system is typical or an oddity ideally suited for life.
“If further observations show these to be the typical starting conditions around other stars, it would reveal our solar system to be a remarkably special place,” says Tamayo.
The findings are available online and will be published in the upcoming edition of Astrophysical Journal. | 0.865973 | 3.920814 |
NASA's New Horizons spacecraft is set to fly past Pluto this July 14. The 12-hour flyby will provide the best view humanity has ever gotten of the former ninth planet, and should show us lots of new things about the icy world. Here are a few thins we learned at a NASA event for New Horizons this past weekend that you should keep in mind as the astronomically important even approaches.
It's been a long time coming
The Pluto mission is the first exploration of the outer solar system since Voyager 2 crossed the boundary of Neptune's orbit in 1989. But maybe a flyby is the first step toward further exploration. In the same way that Pioneer 10 and 11 and Voyager 1 and 2 paved the way for the Galileo and Cassini missions to Jupiter and Saturn, the discoveries made by New Horizons could pave the way for future orbital and lander missions on Pluto.
The spacecraft will go silent during the flyby
All told, New Horizons will spend about 12 hours in the Pluto system. As such, the NASA and Johns Hopkins University researchers behind the mission want to use all available resources to monitor the target. New Horizons will ping Earth as it begins the flyby, then focus solely on imaging the Pluto system and concentrating on its other scientific payload, such as a dust collector that will show how much debris is still in the system—a leftover from the collision that formed the five known moons.
New Horizons doesn't exactly have a Google Fiber connection
Once New Horizons clears the Pluto system, it will begin sending information back to Earth, and the scientists finally get confirmation that their long journey was a success. The craft was built with as few moving parts as possible, so it will literally turn around to talk to Earth. New Horizons will transmit 64 GB of information back to NASA at 1 KB per second, a trickle compared to even the 56K connection speeds of 1990s dial-up internet. The entire process of downlinking the information to the Deep Space Network will take 16 months. The data will take years to process.
We may discover even more moons
Information gathered from the Hubble Space Telescope shows that the moons are all the same color, suggesting they have a probable common origin, likely a collision between Pluto and another object that scattered ices into the surrounding region, eventually forming the moons. Today we know of Charon, which is large enough to make the Pluto system the first known binary dwarf planet system. And we know there are four known smaller moons: Hydra, Nix, Styx, and Kerberos. The smallest, Styx, is less than 18 miles in diameter. The New Horizons team believes there may be more moons too small for Hubble to detect but visible to New Horizons.
You get to see the images almost as fast as NASA does
We're eagerly the best new images of Pluto, and the NASA / JHU team is releasing them to this website almost as soon as they come in, creating a fast turnaround time for some astonishing views. It currently takes about 9 hours round-trip for NASA to send a message to New Horizons and for the craft to send information back.
This is the beginning of the "third zone"
A quarter century ago, when Voyager 2 crossed the orbit of Neptune in 1989, the Kuiper Belt was unknown to NASA. Pluto was still a distant ninth planet then, and the family of Pluto-sized worlds in the area had yet to be discovered. But now that these icy worlds are known (leading to the reclassification of Pluto to a "dwarf planet" to make way for a great number of objects of similar sizes), astronomers think of Pluto as the beginning of the "third zone" of the Solar System, past the inner rocky planets like our homeworld and the outer gas giants that make up zone number two.
New Horizons will keep exploring – if it gets the money
The flyby isn't the end of the line for New Horizons. A Hubble search of Kuiper Belt objects had spotted three objects that might make good targets for another flyby. The New Horizons team has since narrowed it down to two, but there's only enough fuel to redirect the spacecraft toward one of them. But a followup flyby depends on budget approval, which hasn't happened yet. The craft has enough power to last until at least the mid 2030s. | 0.861458 | 3.669085 |
Hubble telescope spots new Pluto moon
NASA's Hubble Space Telescope has spotted a new moon orbiting the dwarf planet Pluto, the fifth such satellite to be discovered and the smallest one to date.
The moon, provisionally named S/2012 (134340) 1, or P5, travels in an orbit around Pluto that is 95,000 kilometres in diameter and lies in the same plane as the orbits of its other moons.
"The moons form a series of neatly nested orbits, a bit like Russian dolls," said Mark Showalter, a planetary astronomer at the SETI Institute in Mountain View, Calif., who led the team that discovered the new moon.
P5 is irregular in shape and measures 10 to 25 kilometres across. Its orbit is the second closest to the dwarf planet, next to the largest moon, Charon, which was discovered in 1978 and measures about 1,000 kilometres across.
Astronomers have speculated that for every circuit around Pluto that P5 makes, Charon likely makes three.
A speck in Hubble's eye
P5 was detected as a speck of light on nine images taken at the end of June and early July by Hubble's wide field camera.
The last Pluto moon Hubble spotted was P4 in 2011. Five years prior to that, the telescope detected two other small moons, known as Nix and Hydra.
"The discovery of so many small moons indirectly tells us that there must be lots of small particles lurking unseen in the Pluto system," said Harold Weaver of the Applied Physics Laboratory at Johns Hopkins University in Laurel, Md., in a NASA news release.
Weaver was part of the team that found P5. The team also included S. Alan Stern, Andrew J. Steffl and Marc W. Buie of the Southwest Research Institute in San Antonio, Texas.
Astronomers suspect Pluto's many moons resulted from a collision between the dwarf planet and another object in the Kuiper belt, which is the region at the outer edge of the solar system where Pluto and other small icy objects reside.
Pluto, which is smaller than the Earth's moon, was demoted from a planet to a dwarf planet in 2006 after the International Astronomical Union introduced new guidelines for classifying celestial bodies.
Astronomers hope to learn even more about Pluto and its moons when the New Horizons spacecraft makes a high-speed fly-by past the distant dwarf planet in July 2015, getting as close as 10,000 kilometres from Pluto.
Scientists hope the NASA spacecraft will bring back the first detailed images of Pluto, which is so small and far away that even the Hubble can only barely detect very large features on its surface. | 0.852889 | 3.580811 |
A neutrino is a subatomic particle that has no electrical charge and negligible mass. The mass of the neutrino is much smaller than that of the other known elementary particles. Cosmological observations imply that the sum of the three masses must be less than one millionth that of the electron. A neutrino does not interact with strong nuclear force. It only interacts with weak subatomic force and gravity. For each neutrino, there also exists a corresponding antiparticle, called an antineutrino, which also has half-integer spin and no electric charge. They are distinguished from the neutrinos by having opposite signs of lepton number and chirality.
Neutrinos are created by various radioactive decays, including in beta decay of atomic nuclei or hadrons, nuclear reactions such as those that take place in the core of a star or artificially in nuclear reactors, nuclear bombs or particle accelerators, during a supernova, in the spin-down of a neutron star, or when accelerated particle beams or cosmic rays strike atoms.
Here at MathsOne, one of the Best Maths Tuition Centres in Kerala we educate our students in daily fascinations that we have overlooked and therefore broaden their horizons | 0.805974 | 3.127484 |
While a full moon refers to the moment when the moon's Earth-facing side is fully illuminated by sunlight, a new moon refers to the moment when the moon's Earth-facing side is fully in shadow. (Unfortunately, that means the Black Moon will be more or less invisible, even if the moon is high in the sky).
The lunar calendar almost lines up with Earth's calendar year, so there is typically one full moon and one new moon each month. A second full moon in a single calendar month is sometimes called a "Blue Moon." A Black Moon is supposedly the flip side of a Blue Moon: the second new moon in a single calendar month. The next Black Moon takes place on July 31 (in the Western Hemisphere).
A Black Moon (in some parts of the world)
The Black Moon is a somewhat unusual celestial event — they occur about once every 32 months, and they sometimes only occur in certain time zones.
From most of the Western Hemisphere, the new moon occurring on Wednesday, July 31 is a Black Moon. Officially, it occurs at 11:13 p.m. EDT (0313 GMT on Aug. 1).
For the Eastern Hemisphere (Europe, Africa, Asia, Australia), this new moon occurs after midnight on the calendar date of Aug. 1. For this part of the world, this particular new moon is not the second one in the calendar month, but rather, the first! So, it does not qualify as a Black Moon, and those places will have to wait until the end of the next month for theirs.
The next new moon will arrive on Aug. 30 for all parts of the world except for the U.S. West Coast, where it will occur on Aug. 29 at 11:37 p.m. PDT. In all other time zones, it will be Aug. 30, so every part of the world that did not experience a Black Moon in July will get a Black Moon on Aug. 30. The next Black Moon won't arrive until April 30, 2022.
Seeing (or not seeing) a Black Moon
At its "new moon" phase, the moon is always black. It happens at that time of the month when the moon passes through the same part of the sky as the sun and as such, the moon's dark or unilluminated side faces Earth. So there really is nothing to see.
Actually, that's not always true, since there are times when the new moon passes directly between Earth and the sun and Earthlings can then see the moon's black silhouette crossing in front of the sun, causing a solar eclipse. That, in fact, actually happened with this month's first new moon, on July 2, creating a total solar eclipse over South America.
Wait for the crescent
If you have ever wondered where the term "new moon" originated, it simply refers to the start of a new lunar cycle. The time frame from one new moon to the next is called a synodic month, which, on average, lasts 29.53 days. This is the period of the moon's phases, because the moon's appearance depends on the position of the moon with respect to the sun as seen from the Earth. The word "synodic" is derived from the Greek word sunodikos, which means "meeting," for at new moon, the moon "meets" the sun.
But unlike a "supermoon," which gets countless numbers of people scurrying for vantage points to see a slightly larger and slightly brighter-than-average full moon, with a Black Moon, you simply can't see it.
A couple of evenings later, however, on Aug. 2, you'll be able to pick out a slender sliver of a waxing crescent moon low in the western twilight sky about 30 or 40 minutes after sunset local time.
Some people mistakenly refer to the appearance of any thin lunar crescent as the "new moon." This fallacy has even spread into popular literature. In his classic work "A Night to Remember," about the sinking of the Titanic, author Walter Lord quotes a fireman in a lifeboat who caught sight of a narrow crescent low in the dawn sky and exclaimed, "A new moon!"
A note on branding
As one who has been involved in the broadcasting field for nearly 40 years, I'd like to point out that we live in a time when the news media is seemingly obsessed with "branding." This marketing strategy involves creating a differentiated name and image — often using a tagline — in order to establish a presence in people's mind. In recent years in the field of astronomy, for example, we've seen annular eclipses — those cases when the moon is too small to completely cover the disk of the sun — become branded as "Ring of Fire" eclipses. A total eclipse of the moon — when the moon's plunge through the Earth's shadow causes the satellite to turn a coppery red color — is now referred to as a "Blood Moon."
When a full moon is also passing through that part of its orbit that brings it closest to Earth — perigee — we now brand that circumstance as a supermoon. That term was actually conjured up by an astrologer back in 1979 but quite suddenly became a very popular media brand after an exceptionally close approach of a full moon to Earth in March 2011. It surprises me that even NASA now endorses the term, although it seems to me the astronomical community in general shies away from designating any perigee full moon as "super."
Then there is Blue Moon. This moniker came about because a writer for Sky & Telescope Magazine misinterpreted an arcane definition given by a now-defunct New England Almanac for when a full moon is branded "blue," and instead incorrectly reasoned that in a month with two full moons, the second is called a Blue Moon. That was a brand that quietly went unnoticed for some 40 years, until a syndicated radio show promoted the term in the 1980s and it then went viral. So now, even though the second full moon in a month is not the original definition for a Blue Moon, in popular culture we now automatically associate the second full moon in a calendar month with a Blue Moon.
So are you ready for yet another lunar brand? The newest one is Black Moon.
- 'Black Moon' Isn't a Sign of the End Times
- The Moon: 10 Surprising Facts
- Moon Photography Tips from Astrophotographers: A Visual Guide
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer's Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. Follow us on Twitter @Spacedotcom and on Facebook. | 0.858581 | 3.562485 |
Loud sounds tend to startle us. But imagine being surprised by a sound six times louder than you expect. A balloon-borne instrument called ARCADE, (Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission) was supposed to be used to search for heat signature from the first stars to form after the Big Bang. Instead it found an unexplained “booming” radio static that fills the sky.
In July 2006, the instrument launched from NASA’s Columbia Scientific Balloon Facility in Palestine, Texas, and flew to an altitude of 36,000 meters (120,000 feet) where the atmosphere thins into the vacuum of space. Its mission lasted four hours.
The team, led by Alan Kogut of NASA’s Goddard Space Flight Center said they found the radio noise almost immediately. “We were calibrating the instrument, and we saw this big point in the graph. I said, ‘What the heck is this — this shouldn’t be here.’ We spent the next year trying to make that point go away, but it didn’t.”
Detailed analysis has ruled out an origin from primordial stars, user error or a mis-identified galactic emission, and the scientists are sure there aren’t more radio sources than we expect. “Radio source counts are well known and they don’t even come close to making up the detected background,” said Kogut. “New sources, too faint to observe directly would have to vastly outnumber the number everything else in the sky.”
Dale Fixsen of the University of Maryland at College Park, added that to get the signal they detected, radio galaxies would have to be packed “into the universe like sardines,” he said. “There wouldn’t be any space left between one galaxy and the next.”
The sought-for signal from the earliest stars remains hidden behind the newly detected cosmic radio background. This noise complicates efforts to detect the very first stars, which are thought to have formed about 13 billion years ago — not long, in cosmic terms, after the Big Bang. Nevertheless, this cosmic static may provide important clues to the development of galaxies when the universe was less than half its present age. Unlocking its origins should provide new insight into the development of radio sources in the early universe.
“This is what makes science so exciting,” says Michael Seiffert, a team member at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “You start out on a path to measure something — in this case, the heat from the very first stars — but run into something else entirely, something unexplained.”
ARCADE’s revolutionary design makes it super-sensitive to cosmic noise. Chilled to 2.7 degrees above absolute zero by immersion into more than 500 gallons of liquid helium, each of ARCADE’s seven radiometers alternately views the sky and a calibration target. The project allows for significant high school and undergraduate student participation. ARCADE is the first instrument to measure the radio sky with enough precision to detect this mysterious signal.
This is the same temperature as the cosmic microwave background (CMB) radiation, the remnant heat of the Big Bang that was itself discovered as cosmic radio noise in 1965. “If ARCADE is the same temperature as the microwave background, then the instrument’s heat cannot contaminate the cosmic signal,” Kogut explains.
“We don’t really know what this signal is,” said Seiffert. “We’re relying on our colleagues to to study the data and put forth some new theories.”
Source: NASA, AAS Press Conference | 0.832216 | 4.07903 |
About 9 months ago NASA’s New Horizons spacecraft flew past the binary dwarf planets Pluto and Charon more than 9 years after launch. Everyone knew they would be frigid little worlds but the great risk was that they might turn out to be geologically boring. The relief when the first images finally arrived – New Horizons’ telecoms are pretty slow – was obvious on the faces at mission control. Even non-Trekkies, such as me, will be thrilled by the first in-depth, illustrated account (Moore, J.M. and 41 others 2016. The geology of Pluto and Charon through the eyes of New Horizons. Science, v. 351, p. 1284-1293), part of a five-article summary of early findings; the other 4 are on-line and scheduled for full publication later (summaries in Science, 18 March 2016, v. 351, p. 1280-1284). A gallery of images can be seen here and an abbreviated summary of the series here.
They are astonishing places, even at a resolution of only about 1 km (270 m for some parts), and only one fully illuminated hemisphere was imaged for each because of the short duration of the fly-by. Pluto is by no means locked in stasis, for one of its largest features, Sputnik Planum, is so lightly cratered that is must be barely 10 Ma old at most. It is a pale, heart-shaped terrane dominated by smooth plains, which have a tiled or cellular appearance, with flanking mountains up to 9 km high that appear to be a broken-up chaos. Much of it is made of frozen nitrogen, carbon monoxide and methane. The dominant nitrogen ice has low strength which accounts for the large area of very low relief. The highly angular mountains are water ice that is buoyant and stronger relative to the others making up Sputnik Planum. Across the plain are areas of pitting and blades that seem to have formed by ice sublimation (solid to gas phase transitions) much like terrestrial snow or ice fields that have begun to degrade, and there are even signs of glacier-like flow.
4 Ga old cratered, upland terranes surrounding Sputnik Planum display grooved, ‘washboard’ and a variety of other surface textures reminiscent of dissection. The may have formed by long-term lateral flow (advection) of nitrogen ice and perhaps some melting. It is in this rugged part of Pluto that colour variation is spectacular, with yellows, blues and reds, probably due to deposition of hydrocarbon ‘frosts’ condensed from the atmosphere. That Pluto is still thermally active is shown by a few broad domes with central depressions that suggest volcanism, albeit with a magma made of ices. Areas of aligned ridges and troughs provide signs of tectonics, possibly extensional in nature.
Charon shows little sign of remaining active and capable of remoulding its surface. The hemisphere that has been imaged is spectacularly bisected by a 200 km wide belt of roughly parallel escarpments, ridges and troughs with a relief of about 10 km. Superimposed by large craters the extensional system probably dates back to the early history of the outer Solar System. Dominated by water ice it seems that Charon’s surface may have lost any more volatile ices by sublimation and loss to space. This suggests that superficial differences between two small worlds of similar density may be explained by Charon’s lower mass and gravitational field, resulting in the loss of its most volatile components that partly veneer the surface of Pluto.
Being hugely distant from any other sizeable body it is likely that the energy used to form cryovolcanic eruptions and deform the surface of both dwarf planets is due to internal radioactivity. Their similar mean density around 1.9 implies rocky cores that could host the required unstable isotopes. Being the only Kuiper Belt objects that have been closely examined naturally suggests that the rest of the myriad bodies that clutter it are similar. There are currently as many as 9 other sizable bodies suspected of eccentrically orbiting the Sun in the Kuiper Belt, including one that may be ten times more massive than Earth – a candidate for a ninth planet to replace Pluto, which was removed from that status following redefinition in 2006 of what constitutes a bona fide planet. | 0.867784 | 3.692425 |
Astronomers have recently discovered a massive exo-planet in a planetary system that rears four suns, just 125 light-years from Earth. The yet to be named exo-planet is over 10 times the size of Jupiter, the largest planet in the Solar System. Though, scientists believe the exo-planet most likely does not have an actual surface to stand on – just like Jupiter, which is a gas giant. According to those who discovered the exo-planet in the four-sun system, if they were able to send out a spacecraft into the upper atmosphere, they would see one initial sun, a luminous red dot in the sky, and a second star which shines even brighter than Venus does in Earth’s night sky.
If a telescope was to be used while on the exo-planet, the small-scale star would be seen to be the second of a binary system. However, this system yields two additional stars. An astronomer at the Jet Propulsion Laboratory, Lewis Roberts, stated seeing these stars would depend upon what kind of sky that would be present, though the chances are that at least one of the host stars would be able to be viewed at any point in time.
Astronomers discovered the four-sun system, known as 30 Ari, a few years ago, but until recent they believed their observations concluded that the system was composed of three stars which were orbited by one exo-planet. The fourth star in the system was revealed following additional telescopes, with a Robo-AO adaptive optics system, being used at the Palomar Observatory in San Diego, California.
Adaptive optics allowed scientists to use the ground-based telescopes to “see” better by taking out the effects of the atmosphere that create an altered vision which makes the stars look like they are twinkling, due to atmospheric perturbations. Roberts said scientists now have the ability to analyze faint stars than were previously undetected.
Roberts and his team published their findings in the Astronomical Journal. They described 30 Ari as a double binary star system. The team explained the exo-planet orbits around the main host star, known as 30 Ari. Scientists say they have split up the four-star system into Ari A and Ari B.
The exo-planet takes around 355 days to complete its orbit, similar to Earth. Primarily, the exo-planet is locked in orbit around Ari B, the secondary binary system, at a distance of 30 astronomical units. One astronomical unit is the distance between the Earth and the Sun – 93 million miles.
Around 1,670 astronomical units beyond Ari B, lies Ari A. Both binary systems orbit around a central mass that is located in between them. Roberts said that one other quadruple star system as been discovered, with one exo-planet. Though, he claims even more systems like Ari A and Ari B may soon be detected. “There are other known quadruple systems – there are even known quintuple systems,” he said. “As we find more and more exo-planets, we’ll probably find some of them in systems like these,” he claimed.
Previous observations of systems like these have suggested that stars may influence the orbit and even the size and mass of nearby exo-planets. Thus, these new findings may provide insight and new information about how this stellar phenomenon would differ in star systems containing two, three, and four stars. The researchers do not believe the newly-discovered star, 30 Ari, has had a major influence on the orbit of the nearby exo-planet, and in the coming years they hope to find out why this alteration did not happen.
By Alex Lemieux
Photo by European Southern Observatory – Flickr License | 0.874445 | 3.840773 |
A mysterious, unseen, planetary object with a mass somewhere between that of Mars and Earth may be lurking in the outer reaches of our solar system, according to new research.
Scientists at the University of Arizona’s Lunar and Planetary Laboratory (LPL) put forward evidence that this unknown “planetary mass object” may explain why the plane of the solar system is warped in the outer reaches of the Kuiper Belt.
The Kuiper Belt lies beyond the orbit of Neptune and hosts a vast number of minor planets, mostly small, icy bodies and a few dwarf planets.
All planets in our solar system orbit around the sun on the same plane but, according to the measurements made by the research team, the most distant Kuiper Belt objects (KBOs) appear to be tilted away from this by about eight degrees.
This indicates that something unknown is warping the average orbital plane of the outer solar system.
“The most likely explanation for our results is that there is some unseen mass,” says Kat Volk, lead author of the study. “According to our calculations, something as massive as Mars would be needed to cause the warp that we measured.”
The tilt angles of the orbital planes of more than 600 objects in the Kuiper Belt were analyzed for the study.
“We expect each of the KBOs’ orbital tilt angle to be at a different orientation, but on average, they will be pointing perpendicular to the plane determined by the sun and the big planets,” Volk said.
As the team observed KBOs further out, they found that the average plane actually warps away from the invariable plane.
They noted that the chance of the warp being a statistical fluke was no more than 2 percent.
The paper also ruled out the possibility that the mysterious object could be ‘Planet 9’, pointing out that this planet is predicted to be much bigger and much farther out. Planet 9’s existence is unconfirmed, but is expected to be located at more than 200 times Earth’s distance from the sun.
“That is too far away to influence these KBOs,” Volk said.
The data does not rule out the possibility that the warp could result from more than one planetary mass object.
Details of the study conducted will be published in the Astronomical Journal.
Contributed by RT.com of RT.com.
Delivered by The Daily Sheeple
by Mike Adams
June 27, 2017
Fake news network CNN is reeling under a massive scandal involving three top-level CNN journalists — including one Pulitzer Prize-winning editor — who got caught fabricating completely fake news accusing a Trump associate of collusion with Russia.
“That article — like so much Russia reporting from the U.S. media — was based on a single anonymous source, and now, the network cannot vouch for the accuracy of its central claims,” writes Glenn Greenwald from The Intercept. CNN was forced to pull the story as every single “fact” cited by CNN writers unraveled and was proven to be utterly false.
The entire “Russian collusion” narrative still being desperately pushed by the delusional Left, it turns out, is nothing but “spy fiction.” It’s not just this one story from CNN that’s blatantly false, of course: It’s thousands of stories published over the last two years on President Donald Trump and his presidential campaign. Almost everything CNN publishes is rooted in falsehood or fabricated fiction that we’re supposed to believe actually came from “anonymous sources.” What CNN how demonstrates is that, inside the mainstream media, “anonymous sources” simply means “we just made sh#t up and published it.”
CNN is “no longer a news organization,” said Tucker Carlson in a widely televised analysis of the collapse of CNN’s remaining credibility. “It is a campaign with a political mission” that routinely publishes fake news to achieve the political goal of destroying President Trump and brainwashing the American public.
So far, three journalists have resigned from CNN, and a top CNN producer has even been caught on camera saying the entire Russian narrative being pushed by CNN is “bullsh#t.” (See video link below.)
Even the people who work at CNN know it’s all fake, yet they participate in the fakery by telling themselves it’s “a business,” and business is booming in the Trump era. According to CNN, it’s far more important to feed the delusional frenzy of Left-wing hatred in America than to get stories factually correct. In this way, CNN has become a journo-terrorist organization, feeding the very kind of radical Left-wing hatred and violence that recently led to the attempted mass executions of Republican lawmakers on a baseball field in Virginia.
As I wrote about CNN in November, 2016 as CNN’s fakery became apparent,
Members of the leftist media smugly claim they advocate love, compassion and progressivism, but any honest analysis of their content leads to the conclusion that their reporters are journo-terrorists. They deliberately fabricate falsehoods about their political enemies to effectively hypnotize their readers into being terrified of them. FALSE FEAR is the mantra of the journo-terrorists.
[The voters] have been programmed with so many layers of disinformation and fear that they can no longer recognize the difference between what’s real vs. fiction. They are trapped in a mental prison of fear, carefully constructed by the leftist media for the sole purpose of exerting absolute control over the psychology of the electorate.
In effect, CNN and other formerly “mainstream” news outlets have abused their power to run a full-on campaign of fake news narratives to deliberately misinform the public and achieve the political overthrow of President Trump.
But CNN is hardly alone when it comes to embarrassing retractions regarding Russia. Over and over, major U.S. media outlets have published claims about the Russia Threat that turned out to be completely false — always in the direction of exaggerating the threat and/or inventing incriminating links between Moscow and the Trump circle. In virtually all cases, those stories involved evidence-free assertions from anonymous sources that these media outlets uncritically treated as fact, only for it to be revealed that they were entirely false.
The Intercept goes on to cite totally fake news from the Washington Post, which faked a story that claimed Russian hackers had penetrated the U.S. electricity grid — a claim that turned out to be entirely fabricated and baseless. Yet the fabricated nature of the story didn’t story MSNBC from running with the false narrative, accusing Putin of attempting to freeze Americans to death during a cold winter. As Greenwald writes:
Literally every facet of that story turned out to be false. First, the utility company — which the Post had not bothered to contact — issued a denial, pointing out that malware was found in one laptop that was not connected either to the Vermont grid or the broader U.S. electricity grid. That forced the Post to change the story to hype the still-alarmist claim that this malware “showed the risk” posed by Russia to the U.S. electric grid, along with a correction at the top repudiating the story’s central claim.
But then it turned out that even this limited malware was not connected to Russian hackers at all and, indeed, may not have been malicious code of any kind. Those revelations forced the Post to publish a new article days later entirely repudiating the original story.
As President Trump asked in a recent tweet, what about all the other fake news stories CNN has published over the last two years?
It seems like CNN should be forced to issue a full retraction of almost everything it has published over the last two years.
Through revelations like these, the credibility of CNN, NYT and the Washington Post has utterly collapsed. Only complete fools believe anything they read in these fiction rags. Time after time, these publications have been caught fabricating “anonymous sources” to spin the stories they want to publish, even when those stories are knowingly false.
Rarely do the stories get retracted, and for every retraction that does take place, there are a thousand other fake news stories published on their websites that never get removed or corrected. The mainstream media has literally become the very FAKE NEWS they accused the independent media of pushing.
Yet Google, the world’s leader in “fake search” which just got slapped with a $2.7 billion fine by EU regulators for rigging search results, continues to highlight CNN, the NYT, Washington Post and other fake news pushers as “credible” news sources on Google News. Everywhere across the ‘net, CNN is still treated as if it’s a legitimate news organization, when the raw truth is that CNN has been utterly and exhaustively discredited as a fake news fiction rag… a mouthpiece for the Democrats, operating with the goal of overthrowing the legitimately elected President of the United States.
In sum, anything is fair game when it comes to circulating accusations about official U.S. adversaries, no matter how baseless, and Russia currently occupies that role (more generally: the less standing and power one has in official Washington, the more acceptable it is in U.S. media circles to publish false claims about them, as this recent, shockingly falsehood-ridden New York Times article about RT host Lee Camp illustrates; it, too, now contains multiple corrections).
Conservative radio host Sean Hannity has even called for CNN’s head honcho Jeff Zucker to be fired over the fake news. As Breitbart News reports:
Hannity made the call just hours after it was announced that three employees including the executive editor of a new investigative unit resigned after CNN was forced to retract an article connecting a Russian investment firm to associates of President Trump.
He also said he doubted the official narrative being fed out of CNN headquarters, suggesting that the employees may have been paid to resign, perhaps to spare Zucker’s reputation.
As Greenwald writes in The Intercept, CNN has become a very real threat to America:
The importance of this journalistic malfeasance when it comes to Russia, a nuclear-armed power, cannot be overstated. This is the story that has dominated U.S. politics for more than a year. Ratcheting up tensions between these two historically hostile powers is incredibly inflammatory and dangerous. All kinds of claims, no matter how little evidence there is to support them, have flooded U.S. political discourse and have been treated as proven fact.
This is why I have openly called for the investigation, arrest and prosecution of anti-America journo-terrorists operating inside fake news networks like CNN. The network is not a “news” organization; it is a propaganda front that seeks the overthrow of the U.S. government and the destruction of democracy. CNN needs to be criminally investigated for the simple reason that it continues to knowingly push vile, hate-filled dangerous propaganda that is driving America toward a violent civil war. If CNN continues on its current path, its actions are literally going to result in mass bloodshed and death, perhaps followed by an actual civil war in America.
That seems to be what CNN wants. We the People must stop their poison from harming our nation and destroying this Republic.
In the mean time, if you want to stay informed about real news, read Censored.news which aggregates top headlines in real time from the most censored independent news websites in the world.
Shattering the stereotype of the lazy pothead, new research suggests cannabis users are actually more satisfied, more successful, and even more likely to volunteer in their communities than their nonsmoking counterparts.
Last week, the Independent described to its readers how the research was carried out:
“The study, conducted by market researchers BDS Analytics, surveyed consumers and abstainers across a wide variety of mental, social and financial factors. These included life satisfaction levels, attitudes towards parenting and employment data.
“The survey analysed extensive data from two US states that have voted to legalise the sale of cannabis — California and Colorado.”
Among other surprising findings, researchers discovered that weed consumers make significantly more money than those who abstain, with Californians who use the plant earning nearly $24,000 more a year. This could be related to the fact that 20 percent of California pot consumers hold a master’s degree while only 12 percent of non-smokers in the state can say the same.
Researchers found a similar situation in Colorado, where 64 percent of cannabis users have full-time jobs versus 54 percent of abstainers. Given those numbers, perhaps it’s not surprising that weed consumers in the state generally feel better about their personal lives than non-smokers.
Marijuana consumption is also associated with healthier habits and a more active social life, researchers for BDS Analytics found. In Colorado, for instance, 36 percent of smokers described themselves as “very social people,” compared to 28 percent for those who avoid the plant. Additionally, in both Colorado and California, those who consume cannabis enjoy outdoor recreation at significantly higher rates.
Perhaps the most surprising discovery, however — given the cliched image of the slacker on the couch eating Cheetos and watching reruns of Family Guy — is that users tend to be more generous with their time. Nearly 40 percent of California’s weed enthusiasts volunteer in their communities, researchers found, whereas only 25 percent of abstainers have decided to do the same.
In a press release, head of consumer research for BDS, Linda Gilbert, says all these data points lead to a very real and increasingly apparent conclusion:
“Cannabis consumers are far removed from the caricatures historically used to describe them.”
The Iranian parliament speaker says the US and some regional states claim to be fighting terror, while they are in fact promoting it.
Iranian Parliament Speaker Ali Larijani has accused the US of playing with terrorism instead of fighting the scourge, calling for increased pressure against the promoters and sponsors of terrorist ideology.
Larijani made the remarks in an address to the second meeting of parliament speakers of Eurasian countries in the South Korean capital, Seoul, on Tuesday.
“In fact, the US strategy is playing with terrorism, not fighting it,” he said, calling on Eurasian states to “increase the costs for those promoting the ideology of terrorism and their sponsors in propaganda, political and security fields.”
He said the US and some regional states claim to be fighting terrorism, but “it is clear to everyone that they are in fact supporting the terrorists in different ways.”
Larijani also expressed dismay that “terrorism and violent extremism have turned into a devastating global threat endangering international peace and security.”
Terrorism has left thousands of defenseless people dead or wounded and made millions displaced in countries such as Syria, Libya, Iraq, Afghanistan and Yemen, he pointed out.
The Iranian parliament speaker further touched on the “shameful crimes” committed by terrorist groups such as Daesh, citing the twin terrorist attacks in Tehran as an example.
On June 7, gunmen mounted almost simultaneous assaults on Iran’s Parliament and the Mausoleum of the late founder of the Islamic Republic of Iran, Imam Khomeini. Daesh claimed responsibility for the assaults, which killed 18 people and injured over 50 others.
Elsewhere in his comments, Larijani said the Syria crisis has deepened due to foreign interference.
Iran supports the Syrian government’s measures in its fight against terror outfits and stresses the Arab nation’s role in determining the country’s political structure, he said.
The officials also noted that coordinated efforts by Iran, Russia and Turkey within the framework of the peace process in Astana have helped reduce violence and establish a ceasefire in Syria.
Additionally, he emphasized that the Saudi aggression against Yemen has created a human tragedy in the impoverished Arabian Peninsula state.
The political and military support of some world powers for the Saudi aggression has prolonged the Yemen conflict and increased civilian casualties there, Larijani said.
The Islamic Republic believes that the military strategy in Yemen is useless and urges a halt to clashes as well as the resumption of intra-Yemeni talks.
Referring to a recent bill approved by the US Senate to impose economic sanctions on Iran and Russia, Larijani said such measures are against US commitments under international law on non-interference in domestic and international affairs of other countries.
He also underlined the need for taking retaliatory measures by the two countries’ governments and parliaments to foil the bans and prevent such “arbitrary and coercive behavior.”
“This was not a chemical weapons strike…That’s a fairy tale… He was told we did not have evidence of Syrian involvement and yet Trump says: ‘Do it’.”
Liberty Blitzkrieg’s Mike Krieger notes that part of Trump’s appeal to many of his voters was, at least ostensibly, the idea that he would employ a less hawkish/neocon foreign policy than his opponent Hillary “We Came, We Saw, He Died” Clinton.
While it’s still too early to decisively say that Trump will usher in yet another foreign policy disaster for these United States and the world, it’s certainly not looking good.
The lobbing of tomahawk missiles into Syrian based on the fairytale that Assad launched a chemical weapons attack was the first sign that Trump is easily manipulated and impulsive. In fact, the episode bothered me so much I wrote a post detailing the dire ramifications titled, Prepare for Impact – This is the Beginning of the End for U.S. Empire. I suggest taking a read if you missed it the first time, it’s my most popular post of the year.
While that was bad enough, Trump’s cozying up to the barbaric, terrorist-supporitng leaders of Saudi Arabia has been by far the most concerning aspect of his foreign policy (if you can call it that) so far. This policy has become even more dangerous now that the 30-year old princeling who is leading the Saudis’ increasingly aggressive stance in the region has been named crown prince. It appears Trump is willing to let the Saudis do whatever they want in the region, which is guaranteed to have disastrous implications for America and the Middle East.
But a new Seymour Hersh article is out showing that the US knew there was no Assad chemical attack in April, but President Trump decided to bomb anyway.
And the details are shocking… as TheAntiMedia.org’s Darius Shahtahmasebi details, never one to accept the U.S. government’s official explanation of events without question, Pulitzer Prize-winning journalist Seymour Hersh has investigated Donald Trump’s decision to strike the al-Shayat Airbase in Syria in April of this year, which the president launched amid widespread allegations that the Syrian government committed a chemical weapons attack.
In a report entitled “Trump’s Red Line,” published Sunday in the daily German newspaper Die Welt, Hersh asserts that President Donald Trump ignored important intelligence reports when he made the decision to attack Syria after pictures emerged of dying children in the war-torn country.
For those of us without goldfish memories, Hersh’s recent investigation is reminiscent of his previous examination of the alleged chemical weapons attacks in 2013, detailed in an article entitled “Whose Sarin?” That article was published in the London Review of Books.
The official White House explanation for the events in April of this year was that Donald Trump was moved by the suffering of “beautiful” Syrian babies – the same Syrian babies he doesn’t want to set foot in the United States – and decided to punish the Syrian government for the attack two days after it allegedly occurred. This punishment came in the form of an airstrike despite the lack of a thorough investigation regarding what took place that fateful day in April and who was ultimately culpable (though the Trump administration insisted they were certain that Syrian President Bashar al-Assad was to blame).
In that context, it should come as no surprise that Trump acted rashly without consideration of the facts on the ground. However, what is most disturbing about Hersh’s account is the fact that, according to his source, Trump was well aware that the U.S. had no solid intelligence linking the Syrian government to a chemical weapons attack — and that’s because, according to Hersh’s article, it’s doubtful a chemical weapons attack occurred at all.
“The available intelligence made clear that the Syrians had targeted a jihadist meeting site on April 4 using a Russian-supplied guided bomb equipped with conventional explosives. Details of the attack, including information on its so-called high-value targets, had been provided by the Russians days in advance to American and allied military officials in Doha, whose mission is to coordinate all U.S., allied, Syrian and Russian Air Force operations in the region.”
“None of this makes any sense,” one officer reportedly told colleagues upon learning of the decision to bomb Syria, according to Hersh. “We KNOW that there was no chemical attack … the Russians are furious. Claiming we have the real intel and know the truth … I guess it didn’t matter whether we elected Clinton or Trump.”
According to Hersh, Trump “could not be swayed” by 48 hours worth of intense briefings and decision-making following the initial reports of the alleged chemical weapons attack. Hersh, who reportedly reviewed transcripts of real-time communications, explains that there is a “total disconnect” between the president and his military advisers and intelligence officials.
As is the case with Syrian military operations, Russia gave the U.S. details of the carefully planned attack on a meeting in Khan Sheikhoun, according to Hersh’s admittedly anonymous sources. The Russians had employed a drone to the area days before the attack to develop the intelligence necessary to coordinate it.
According to Hersh’s sources, the United States and its Russian counterpart routinely share information regarding planned attacks in order to avoid collisions. However, they also permit “coordination,” a practice that involves giving the other side a “hot tip about a command and control facility,” which then helps the other side carry out their attack.
Therefore, there was no surprise chemical weapons attack, as the Trump administration alleged. In fact, Russia had actually warned its American counterpart on the off-chance that there were any CIA assets on the ground who should have been forewarned of an impending attack.
“They [the Russians] were playing the game right,” a senior adviser told Hersh.
“Russian and Syrian intelligence officials, who coordinate operations closely with the American command posts, made it clear that the planned strike on Khan Sheikhoun was special because of the high-value target. ‘It was a red-hot change. The mission was out of the ordinary – scrub the sked,’ the senior adviser told me. ‘Every operations officer in the region’ – in the Army, Marine Corps, Air Force, CIA and NSA – ‘had to know there was something going on. The Russians gave the Syrian Air Force a guided bomb and that was a rarity. They’re skimpy with their guided bombs and rarely share them with the Syrian Air Force. And the Syrians assigned their best pilot to the mission, with the best wingman.’ The advance intelligence on the target, as supplied by the Russians, was given the highest possible score inside the American community.”
Hersh confirms Russia’s account of the incident, in which Russian authorities alleged that the Syrian Air Force bombed a “terrorist warehouse,” and that secondary bombings dispersed dangerous chemicals into the atmosphere.
Strangely, if Hersh’s reporting is accurate, it is not clear why Russia didn’t give the detailed account at the time — and why the Russians didn’t emphasize that they had shared information with the U.S. military well in advance of the attack, as this would have cast further doubt on the official U.S. narrative. In that context, Russia could have provided proof of any prior communications that took place within the so-called deconfliction channel. It also doesn’t explain why Russia’s president, Vladimir Putin, appeared to endorse two competing theories behind the events at Khan Sheikhoun.
However, Hersh continues:
“A team from Médecins Sans Frontières, treating victims from Khan Sheikhoun at a clinic 60 miles to the north, reported that ‘eight patients showed symptoms – including constricted pupils, muscle spasms and involuntary defecation – which are consistent with exposure to a neurotoxic agent such as sarin gas or similar compounds.’ MSF also visited other hospitals that had received victims and found that patients there ‘smelled of bleach, suggesting that they had been exposed to chlorine.’ In other words, evidence suggested that there was more than one chemical responsible for the symptoms observed, which would not have been the case if the Syrian Air Force – as opposition activists insisted – had dropped a sarin bomb, which has no percussive or ignition power to trigger secondary explosions. The range of symptoms is, however, consistent with the release of a mixture of chemicals, including chlorine and the organophosphates used in many fertilizers, which can cause neurotoxic effects similar to those of sarin.”
Hersh is not the first high-profile investigator to cast major doubts on the Trump administration’s official narrative regarding the events at Khan Sheikhoun. MIT professor emeritus Theodore Postol, who previously worked as a former scientific advisor to the U.S. military’s Chief of Naval Operations, poked major holes in the claims that the Syrian government had launched a chemical weapons attack at Khan Sheikhoun, noting the “politicization” of intelligence findings (you can access all of his reports here). Postol argued that there was no possible way U.S. government officials could have been sure Assad was behind the attack before they launched their strike, even though they claimed to be certain. Postol took the conversation even further, asserting that the available evidence pointed to an attack that was executed by individuals on the ground, not from an aircraft. Former weapons inspector Scott Ritter had similar concerns regarding the White House’s conclusions, as did former U.K. ambassador to Syria Peter Ford. The mainstream media paid almost zero attention to these reports, a slight that exposes the media’s complicity in allowing these acts of war to go ahead unquestioned.
“This was not a chemical weapons strike,” the adviser said. “That’s a fairy tale. If so, everyone involved in transferring, loading and arming the weapon – you’ve got to make it appear like a regular 500-pound conventional bomb – would be wearing Hazmat protective clothing in case of a leak. There would be very little chance of survival without such gear. Military grade sarin includes additives designed to increase toxicity and lethality. Every batch that comes out is maximized for death. That is why it is made. It is odorless and invisible and death can come within a minute. No cloud. Why produce a weapon that people can run away from?”
According to Hersh’s source, within hours of viewing the footage of the ‘attack’ and its aftermath, Trump ordered his national defense apparatus to plan for retaliation against the Syrian government. Hersh explains that despite the CIA and the DIA (Defense Intelligence Agency) having no evidence that Syria even had sarin, let alone that they used it on the battlefield, Trump was not easily persuaded once he had made up his mind.
“Everyone close to him knows his proclivity for acting precipitously when he does not know the facts,” the adviser told Hersh. “He doesn’t read anything and has no real historical knowledge. He wants verbal briefings and photographs. He’s a risk-taker. He can accept the consequences of a bad decision in the business world; he will just lose money. But in our world, lives will be lost and there will be long-term damage to our national security if he guesses wrong. He was told we did not have evidence of Syrian involvement and yet Trump says: ‘Do it.”’ [emphasis added]
At a meeting on April 6, 2017, at his Mar-a-Lago resort in Florida, Trump spoke with his national security officials regarding the best way to move forward. The meeting was not to decide what to do, Hersh explains, but how best to do it (and how to keep Trump as happy as possible).
Trump was given four options. The first one was dismissed at the outset because it involved doing nothing. The second one was the one that was decided upon: a minimal show of force (with advance warning to Russia). The third option was the strike package that Obama was unable to implement in 2013 in the face of mounting public opposition and Russia’s threats of intervention. This plan was Hillary Clinton’s ultimate fantasy considering she was encouraging it moments before Trump’s lone strike actually took place. However, this would have involved extensive air strikes on Assad’s airfields and would have drawn in the Russian military to a point of no return. The fourth option involved the direct assassination of the Syrian president by bombing his palaces, as well as his underground bunkers. This was not considered, either.
As we all witnessed in April, the second option was adopted, and the airbase Trump struck was up and running again in less than 24 hours, making it a very symbolic and empty show of force.
Hersh’s insight into the way Trump is conducting his foreign policy does not bode well for the future of the Syrian conflict (or anywhere else in the world, for that matter). Trump was not interested in the intelligence or the facts on the ground — if he had been, he would have waited until an investigation had determined culpability before ordering a strike.
Missing from Hersh’s account, however, is the fact that it was newly appointed national security advisor General H.R. McMaster who laid out the military strike proposals to the president at his resort on April 6. McMaster replaced former national security advisor Michael Flynn after the latter was forced to resign due to leaks from within the intelligence community. Due to Flynn’s alleged ties to Russia, it seems unlikely he would have proposed such a strike on Russia’s close ally to begin with.
It is unclear whether McMaster proposed the strikes in order to appease Trump or because McMaster ultimately wants Trump to adopt a tougher stance against Syria and Russia; McMaster has a history of pro-interventionism and anti-Russian sentiment.
Those commentators who can review these startling revelations but still condone Trump’s actions with a lazy ‘Assad is still a bad guy and must be overthrown’ mindset argument are being intellectually dishonest, with themselves and others. As was the case in 2013, there is still very little evidence that Assad has ever used chemical weapons — particularly in the attacks that the U.S. has tried to pin on him — yet this is the standard by which the corporate media and our respective governments have instructed us to judge Assad. Even without this conclusive evidence, shortly after the April events, U.S. ambassador to the U.N. Nikki Haley stated Assad will fall from power.
Hersh’s investigation bolsters many claims that the U.S. acted rashly without first conducting or ordering an impartial inquiry regarding what happened in April of this year. Hersh’s report also serves as a reminder to the world of the warpath we are continuing down, spearheaded by an impulsive and reckless megalomaniac who has no interest in ascertaining fact from fiction.
* * *
Liberty Blitzkrieg’s Mike Krieger also notes that just as interesting as the information above, is the fact that Hersh had to turn to a German newspaper to publish it. This makes perfect sense, because the one area where U.S. corporate press maintains unassailable consistency is when it comes to cheerleading for an interventionist, imperial foreign policy based on unverified claims and outright lies. Trump’s little fireworks display checked all those boxes, which is why the corporate media drooled all over the bombing, celebrating Trump for the first time of his Presidency. As Hersh notes:
After the meeting, with the Tomahawks on their way, Trump spoke to the nation from Mar-a-Lago, and accused Assad of using nerve gas to choke out “the lives of helpless men, women and children. It was a slow and brutal death for so many … No child of God should ever suffer such horror.”
The next few days were his most successful as president. America rallied around its commander in chief, as it always does in times of war.
Trump, who had campaigned as someone who advocated making peace with Assad, was bombing Syria 11 weeks after taking office, and was hailed for doing so by Republicans, Democrats and the media alike. One prominent TV anchorman, Brian Williams of MSNBC, used the word “beautiful” to describe the images of the Tomahawks being launched at sea. Speaking on CNN, Fareed Zakaria said: “I think Donald Trump became president of the United States.”
A review of the top 100 American newspapers showed that 39 of them published editorials supporting the bombing in its aftermath, including the New York Times, Washington Post and Wall Street Journal.
Which once again goes to show just how worthless, irresponsible and downright dangerous U.S. corporate media really is.
Finally, as Ron Paul rages below, Republicans cannot let go of “regime change” for Syria and new Cold War with Russia — even as the Democrats are starting to back away. Will the mainstream media stick with the narrative as well? Or is it all about to come crashing down?
“…one shouldn’t put one’s trust in speeches like that from the gentlemen, for on such occasions the gentlemen liked to say agreeable things, but they had little or no significance and, once uttered, they were forgotten for all time, but admittedly, on the very next occasion one got caught again in their trap.” (Franz Kafka)
With these words Kafka described the modern condition, each one of us trapped in the sticky web of technology and deceit designed to manipulate us to act and think against our selves, to accept the role of monkeys offered bananas in a cage, surrendering the struggling to escape it.
The most dangerous element of that technology is the constant and increasing flood of images of war, of “terror,” of cities destroyed, cultures erased, entire progressive socio-economic systems torn apart, or threatened with destruction, not by the “terrorists” but by the states that declared their “war on terror,” by the states that in reality created the terror in all its forms; the worst being the constant threat of instant and universal annihilation in a nuclear war.
That threat, the threat of nuclear war is more dangerous with every passing day as we see the NATO build-up along Russia’s western borders echoing the Nazi build-up before their invasion in 1941, the rolling invasion of Syria by American and allied forces, the hysterical rhetoric and military movements against North Korea, and the increasing contempt for Chinese sovereignty. Any of these threats from the United States could lead to nuclear war but the threat that concerns all of us is the one against Russia because a nuclear war with Russia is, as President Putin pointed out recently, not survivable. Yet, it is the threat against Russia that is building, building, building; increased military pressure on all fronts, increased economic warfare, called “sanctions,” increased hybrid warfare ranging from hacking of Russian computer systems, to direct attacks on Russian forces in Syria, from expulsion of diplomats to verbal abuse against and assassination of ambassadors. But the extent of the danger is to be seen not outside the United States but in the internal political turmoil that is taking place inside the United States.
Their propaganda against Russia as the “enemy” trying to destroy America through various forms of subversion is daily fare in all the mass media. The alleged subversion is stated as fact. The fact that the allegations are patently absurd means nothing when those who mould opinion refuse to say so and openly lie to the people with every word they utter. But the level of the threat against Russia is signalled by the willingness among the war faction to sacrifice anyone, no matter who they are or what position, in order to advance this propaganda. We now watch as the US Congress holds hearings in which senior government officials are called to defend themselves against charges of having had Russian connections. The President of the country is himself subject to a barrage of accusations of treason.
This scandal is not just about the bickering between the losing party in the US elections and the winning party with the losers willing to risk the security of the people of the country in a bid to take power denied them at the ballot box. There is an element of that. The war faction does want to have its finger directly on the button. Elections and democracy mean nothing to them so long as they take the power. But they could have used any scandal to try to do that. They have concocted the “Russian threat to democracy” because they want war with Russia and to convince the people of the United States and the world that this war is necessary and just, are willing to destroy even their own leaders, and their country’s democratic system, as weak and non-representative of the needs of the people as it is, in order to achieve their purpose.
The longer this spectacle in the United States goes on the worse it is going to get. But those under attack do not seem to understand what is happening to them, that they are being used to advance this propaganda, that they are being set up as scapegoats and in fact they even play along with the game, with Jeff Sessions, the US Attorney-General, today, the 13 of June, telling the US Senate Intelligence investigative committee that the accusation he “colluded” with Russia was “an appalling and detestable lie” but playing his role in this propaganda show by adding,
“that he was concerned the President did not realise the severity of the threat from Russia interference that can never be tolerated.”
The former FBI Director James Comey, a man with deep state connections, testified to the same committee that he was fired because of his investigation into the Russian allegations even though he provided no proof there was anything to investigate. Again, the facts don’t matter. The only thing that matters is the impression left, that Russia has and is attempting to subvert the United States and has succeeded in infiltrating its agents into the presidency and senior government and military levels.
To further advance this propaganda theme purges are necessary to add to the drama and we have seen Comey leave, General Flynn resign and others forced out of office or threatened with it. But the main objective of these hearings and the mass media coverage of them is to generate peoples hostility towards Russia, and this seems to be succeeding, as polls indicate. The next level of the propaganda war will be to create such an intense situation in the United States that the calls for war by the people will be the natural reaction of their outrage and, in any case, this is what the war faction and media will tell us, that the people demand action.
President Putin can meet with celebrities like Oliver Stone to correct the facts and state the truth. He can successfully dance circles around bubble headed American journalists in interviews, but he cannot control the mass media in the west that rarely allows Russian points of view to be heard. Still the attempt must be made.
The United States is in a crisis. The games being played there are dangerous for its people. The logic of the demands made by those making the allegations means that President Trump must resign or be charged with treason. If he refuses to go there will be attempts to force him. If he is forced out, the people that voted for him and support him will feel rightly cheated and they will react. And who is to replace him? It can only be one of the war faction or a puppet and if that cannot issue be resolved peacefully then the military could step in to “manage” things in a time of “threat” and “urgency.” There have been coup d’états before in the United States. We are witnessing another now.
The United States is in a crisis generated by people who have no idea how to control all the possible consequences of the events they have begun and because of this they are very dangerous to themselves and to the world. While the Russians prepare for the worst and hope for the best we in the west must do what we can to challenge the war propaganda, the propaganda of hostility and hatred that is inflicted on us by the criminals in control of the western governments and western media. Each of us is just one voice, but our voices united become a shout and with our shout we can level the walls of hostility that keep us from the peaceful coexistence that the peoples of world need to continue the struggle for economic and social justice, for real democracy, for progress, against the forces of reaction and fascism that always threaten us. Let’s not get “caught again in their trap.”
Christopher Black is an international criminal lawyer based in Toronto. He is known for a number of high-profile war crimes cases and recently published his novel “Beneath the Clouds”. He writes essays on international law, politics and world events, especially for the online magazine “New Eastern Outlook.”
Featured image: New Eastern Outlook | 0.874127 | 3.109911 |
For the first time ever, scientists are witnessing the birth of a galaxy from a time that stretches back to near the Big Bang.
It’s a remarkable first for the scientific community: astronomers in Europe have witnessed star-forming gas clouds in the early universe, which represent the building blocks of the very first galaxies.
The European Southern Observatory’s ALMA telescope in Chile was used to make the discovery, as scientists looked deep into space and past the galaxies in the foreground to spot the faint glow of ionized carbon, according to a UPI report.
Astronomers were trying to glimpse some of the oldest known galaxies in the universe, dating back to just 800 million years after the Big Bang, when they spotted a signal of glowing carbon on the side of galaxy BDF 3299.
Andrea Ferrara, an astronomer from Italy’s Scuola Normale Superiore and a co-author study, said that this is the most distant detection ever of such an emission, according to the report. This allows scientists to watch galaxies in the early stages of their development.
Scientists believe that at the beginning of time, space was filled with gas clouds, and as stars began to form, the dust began to clear in a process that is called reionization.
Researchers believe they have spotted this dust before it collapsed into stars via ALMA, and it was spotted near BDF 3299 because newly formed stars had cleared the dust out of the center of the galaxy.
This is a big deal to scientists because they’ve been trying to understand the “interstellar medium” and the formation of stars and galaxies, Ferrara said according to the report.
Reionization is a term used in Big Bang cosmology to describe the process of reionizing matter in the universe, the second of two ajor phase transitions of gas. The first phase is the change of hydrogen in the universe, a process called recombination. | 0.83602 | 3.658439 |
In astronomy, axial precession is a gravity-induced and continuous change in the orientation of an astronomical body's rotational axis. In particular, it can refer to the gradual shift in the orientation of Earth's axis of rotation in a cycle of 25,772 years; this is similar to the precession of a spinning-top, with the axis tracing out a pair of cones joined at their apices. The term "precession" refers only to this largest part of the motion. Earth's precession was called the precession of the equinoxes, because the equinoxes moved westward along the ecliptic relative to the fixed stars, opposite to the yearly motion of the Sun along the ecliptic; the discovery of the precession of the equinoxes is attributed in the West to the 2nd-century-BC astronomer Hipparchus. With improvements in the ability to calculate the gravitational force between planets during the first half of the nineteenth century, it was recognized that the ecliptic itself moved, named planetary precession, as early as 1863, while the dominant component was named lunisolar precession.
Their combination was named general precession, instead of precession of the equinoxes. Lunisolar precession is caused by the gravitational forces of the Moon and Sun on Earth's equatorial bulge, causing Earth's axis to move with respect to inertial space. Planetary precession is due to the small angle between the gravitational force of the other planets on Earth and its orbital plane, causing the plane of the ecliptic to shift relative to inertial space. Lunisolar precession is about 500 times greater than planetary precession. In addition to the Moon and Sun, the other planets cause a small movement of Earth's axis in inertial space, making the contrast in the terms lunisolar versus planetary misleading, so in 2006 the International Astronomical Union recommended that the dominant component be renamed the precession of the equator, the minor component be renamed precession of the ecliptic, but their combination is still named general precession. Many references to the old terms exist in publications predating the change.
"Precession" and "procession" are both terms. "Precession" is derived from the Latin praecedere, while "procession" is derived from the Latin procedere. The term "procession" is used to describe a group of objects moving forward; the stars viewed from Earth are seen to proceed in a procession from east to west daily, due to the Earth's diurnal motion, yearly, due to the Earth's revolution around the Sun. At the same time the stars can be observed to anticipate such motion, at the rate of 50 arc seconds per year, a phenomenon known as the "precession of the equinoxes". In describing this motion astronomers have shortened the term to "precession". In describing the cause of the motion physicists have used the term "precession", which has led to some confusion between the observable phenomenon and its cause, which matters because in astronomy, some precessions are real and others are apparent; this issue is further obfuscated by the fact that many astronomers are physicists or astrophysicists. The term "precession" used in astronomy describes the observable precession of the equinox, whereas the term "precession" as used in physics describes a mechanical process.
The precession of the Earth's axis has a number of observable effects. First, the positions of the south and north celestial poles appear to move in circles against the space-fixed backdrop of stars, completing one circuit in 26,000 years. Thus, while today the star Polaris lies at the north celestial pole, this will change over time, other stars will become the "north star". In 3200 years, the star Gamma Cephei in the Cepheus constellation will succeed Polaris for this position; the south celestial pole lacks a bright star to mark its position, but over time precession will cause bright stars to become south stars. As the celestial poles shift, there is a corresponding gradual shift in the apparent orientation of the whole star field, as viewed from a particular position on Earth. Secondly, the position of the Earth in its orbit around the Sun at the solstices, equinoxes, or other time defined relative to the seasons changes. For example, suppose that the Earth's orbital position is marked at the summer solstice, when the Earth's axial tilt is pointing directly toward the Sun.
One full orbit when the Sun has returned to the same apparent position relative to the background stars, the Earth's axial tilt is not now directly toward the Sun: because of the effects of precession, it is a little way "beyond" this. In other words, the solstice occurred a little earlier in the orbit. Thus, the tropical year, measuring the cycle of seasons, is about 20 minutes shorter than the sidereal year, measured by the Sun's apparent position relative to the stars. After about 26 000 years the difference amounts to a full year, so the positions of the seasons relative to the orbit are "back where they started". For identical
Vaska Easoff known as Letgohand Vaska, is a 1996 Hungarian comedy film directed by Péter Gothár. The film was selected as the Hungarian entry for the Best Foreign Language Film at the 69th Academy Awards, but was not accepted as a nominee. Maksim Sergeyev as Vászka, a pityeri tolvaj Evgeniy Sidikhin as Ványka, a falusi tolvaj Valentina Kasyanova as Luvnya Boris Solominovits as Fetyka At the Hungarian Film Week of 1996, the film won the Grand Prize, Péter Gothár won the Best Director award, Francisco Gózon won the Best Cinematographer, Enikő Eszenyi won the Best Actress and Antal Cserna the Best Actor. At the 31st Karlovy Vary International Film Festival, the film was nominated for the Crystal Globe and Péter Gothár won the Best Director Award. At the 1996 Chicago International Film Festival, the film won the Audience Choice Award. List of submissions to the 69th Academy Awards for Best Foreign Language Film List of Hungarian submissions for the Academy Award for Best Foreign Language Film Vaska Easoff on IMDb
Homophobia encompasses a range of negative attitudes and feelings toward homosexuality or people who are identified or perceived as being lesbian, bisexual or transgender. It has been defined as contempt, aversion, hatred or antipathy, may be based on irrational fear and ignorance, is related to religious beliefs. Homophobia is observable in critical and hostile behavior such as discrimination and violence on the basis of sexual orientations that are non-heterosexual. Recognized types of homophobia include institutionalized homophobia, e.g. religious homophobia and state-sponsored homophobia, internalized homophobia, experienced by people who have same-sex attractions, regardless of how they identify. Negative attitudes toward identifiable LGBT groups have similar yet specific names: lesbophobia is the intersection of homophobia and sexism directed against lesbians, biphobia targets bisexuality and bisexual people, transphobia targets transgender and transsexual people and gender variance or gender role nonconformity.
According to 2010 Hate Crimes Statistics released by the FBI National Press Office, 19.3 percent of hate crimes across the United States "were motivated by a sexual orientation bias." Moreover, in a Southern Poverty Law Center 2010 Intelligence Report extrapolating data from fourteen years, which had complete data available at the time, of the FBI's national hate crime statistics found that LGBT people were "far more than any other minority group in the United States to be victimized by violent hate crime."The term homophobia and its usage have been criticized by several sources as unwarrantedly pejorative. Although sexual attitudes tracing back to Ancient Greece (8th to 6th centuries BC to the end of antiquity have been termed homophobia by scholars, is used to describe an intolerance towards homosexuality and homosexuals that grew during the Middle Ages by adherents of Islam and Christianity, yet the term itself is new. Coined by George Weinberg, a psychologist, in the 1960s, the term homophobia is a blend of the word homosexual, itself a mix of neo-classical morphemes, phobia from the Greek φόβος, phóbos, meaning "fear", "morbid fear" or "aversion".
Weinberg is credited as the first person to have used the term in speech. The word homophobia first appeared in print in an article written for the May 23, 1969, edition of the American pornographic magazine Screw, in which the word was used to refer to heterosexual men's fear that others might think they are gay. Conceptualizing anti-LGBT prejudice as a social problem worthy of scholarly attention was not new. A 1969 article in Time described examples of negative attitudes toward homosexuality as "homophobia", including "a mixture of revulsion and apprehension" which some called homosexual panic. In 1971, Kenneth Smith used homophobia as a personality profile to describe the psychological aversion to homosexuality. Weinberg used it this way in his 1972 book Society and the Healthy Homosexual, published one year before the American Psychiatric Association voted to remove homosexuality from its list of mental disorders. Weinberg's term became an important tool for gay and lesbian activists and their allies.
He describes the concept as a medical phobia: phobia about homosexuals.... It was a fear of homosexuals which seemed to be associated with a fear of contagion, a fear of reducing the things one fought for — home and family, it was a religious fear and it had led to great brutality as fear always does. In 1981, homophobia was used for the first time in The Times to report that the General Synod of the Church of England voted to refuse to condemn homosexuality. However, when taken homophobia may be a problematic term. Professor David A. F. Haaga says that contemporary usage includes "a wide range of negative emotions and behaviours toward homosexual people," which are characteristics that are not consistent with accepted definitions of phobias, that of "an intense, illogical, or abnormal fear of a specified thing." Five key differences are listed as distinguishing homophobia, as used, from a true phobia. Homophobia manifests in different forms, a number of different types have been postulated, among which are internalized homophobia, social homophobia, emotional homophobia, rationalized homophobia, others.
There were ideas to classify homophobia and sexism as an intolerant personality disorder. In 1992, the American Psychiatric Association, recognizing the power of the stigma against homosexuality, issued the following statement, reaffirmed by the Board of Trustees, July 2011: "Whereas homosexuality per se implies no impairment in judgment, reliability, or general social or vocational capabilities, the American Psychiatric Association calls on all international health organizations, psychiatric organizations, individual psychiatrists in other countries to urge the repeal in their own countries of legislation that penalizes homosexual acts by consenting adults in private. Further, APA calls on these organizations and individuals to do all, possible to decrease the stigma related to homosexuality wherever and whenever it may occur." Many world religions contain anti-homosexual teachings, while other religions have varying degrees of ambivalence, neutrality, or incorporate teachings that regard homosexuals as third gender.
Within some religions which discourage homosexuality, there are people who view homosexuality positively, some religious denominations bless or conduct same-sex marriages. There exist so-called Queer religions, dedicated to serving the spiritual needs of LGBTQI persons. Queer theology seeks to provide a counterpoint to religious homophobia. In 2015, attorney and autho | 0.915441 | 4.055931 |
A majesticspiral galaxy swirling with dark tendrils of gas stands out in a new photo ofone of the most densely packed regions of the universe.
The newphoto shows the galaxy NGC 4911 in the dense Coma Cluster of galaxies. A clutchof newborn stars can be seen sparkling inside pink hydrogen gas behind darkerlanes of dust and gas in the image, which was taken during a long exposureusing the Hubble Space Telescope. [New photo of galaxy NGC 4911.]
The outerspiral arms are visible as a smoky white glow amidst a background packed withother galaxies.
Almost 1,000galaxies reside in the ComaCluster, making it one of the densest collections of galaxies in the universe.Collisions among these galaxy systems continue in the present epoch to churnstar formation at vigorous rates and alter one another's shapes.
In thisimage, the gravitational influence of nearby galaxy, called NGC 4911A, in theupper right is exerting a tug on the galaxy's arms, loosening material thatwill eventually be dispersed through the Coma Cluster's center to fuel further starsand clusters between existing galaxies.
The ComaCluster is 320 million light-years away in the constellation Coma Berenices.
The imagewas formed from a considerably long 28 hours of exposure time, the SpaceScience Telescope Institute said in a statement. It combined observations fromthe 2006, 2007, and 2009 Wide Field Planetary Camera 2 and Advanced Camera forSurveys.
- ImageGallery: Amazing Galaxies
- The 10 Most Amazing Hubble Discoveries
- StrangeHook-Shaped Galaxy Photographed By Hubble Telescope | 0.860918 | 3.410773 |
“Although this small companion appears to have a mass that is comparable to the mass of planets around stars, we don’t think it formed like a planet,” said astronomer Kevin Luhman of Penn State University, co-author of the study April 5 in The Astrophysical Journal. “This seems to indicate that there are two different ways for nature to make small companions.”
Luhman’s team made the discovery with the Hubble Space Telescope and the Gemini Observatory.
The new object and its companion brown dwarf are orbiting as a binary pair, 15 astronomical units from each other. If they were superimposed on our solar system, the companion would be orbiting midway between Saturn and Uranus.
The oddball object’s mass is somewhere between five and 10 Jupiter masses, making it too small to fuse deuterium. The International Astronomical Union currently uses this fusion line, which occurs at about 13 Jupiter masses, as the defining characteristic of a brown dwarf.
But the object appears to be around the same age as its binary partner, which doesn’t fit conventional ideas about planet formation. Traditional theories describe planets forming from the gaseous disk that swirls around the equator of a newly formed star.
Particles in the gas and dust cloud collide, and gradually accrete into larger objects, eventually becoming planets. These rocky planets can grow into sizes up to 10 Earth masses before they become gas giants.
And 1 million years is much shorter than the expected time for a planet to be born this way. Planets can form this quickly when there is a gravitational instability in the gaseous disk, but the brown dwarf’s disk probably didn’t have enough material to form a planet larger than a single Jupiter mass. | 0.857788 | 3.652169 |
Comparing Astronomers to Cosmologists
Astronomers and cosmologists are scientists who study space in an attempt to better understand the universe. Though cosmology is a branch of astronomy and both of these careers require an interest in solving difficult problems, cosmologists often focus their study on the future, origins and evolution of our universe, along with its galaxies. The following article will outline some of the key similarities and other differences between astronomers and cosmologists.
|Job Title||Educational Requirements||Median Salary (2019)*||Job Growth (2018-2028)*|
|Cosmologist||Doctoral degree||$122,220 (for all physicists and astronomers)||9% (for all physicists and astronomers)|
Source: *U.S. Bureau of Labor Statistics
Responsibilities of Astronomers vs. Cosmologists
Astronomers and cosmologists are both concerned with developing theories about the way the universe works. Though they share a desire to improve our understanding of space and can often be found working in the same places, the focus of their research is very different. Astronomers are primarily interested in celestial bodies, like planets, stars, and galaxies, and use equipment like telescopes and complex computer systems to observe and record data. Cosmologists, on the other hand, study theoretical concepts about the universe as a whole, including the Big Bang theory and particle physics; they use data collected by satellites and other spacecraft to test these theories.
Astronomers are scientists who study space. Because space is so vast, there are many different subcategories in the field of astronomy; many astronomers choose to focus their research in a particular area, such as solar astronomy, radio astronomy, or planetary astronomy. The majority of astronomers can be found working in colleges and universities, teaching courses and conducting research. Many astronomers are also employed by the federal government, particularly at the National Aeronautics and Space Administration (NASA) and the U.S. Department of Defense. While most astronomers spend a significant amount of time working in offices, laboratories, or classrooms, some travel frequently to present at conferences or contribute to international research projects.
Job responsibilities of an astronomer include:
- Using scientific instruments to measure energy output from extraterrestrial and celestial bodies
- Developing new instruments, equipment, and software to observe and analyze data
- Contributing to professional journals, research papers, and other publications
- Fundraising to support continuing research efforts
- Creating programs of study for college-level astronomy courses and providing instruction to students
Cosmologists work to learn more about the origins, age, and evolution of the universe as a whole. They are typically concerned with broad theories like string theory, dark energy, and multiverse theory. Modern cosmologists use data collected by satellites and telescopes to map and measure things like the estimated age of the universe and its rate of expansion. The vast majority of cosmologists work in academia, usually under the supervision of the department of physics or astronomy at major colleges and universities. They act not only as professors of cosmology, but also conduct their own research or work as part of a team to test and refine theories.
Job responsibilities of a cosmologist include:
- Collaborating with mathematicians, computer scientists, and other cosmologists to conduct research
- Developing and implementing new approaches to existing cosmologic theory
- Supervising the work of undergraduate and graduate students, both in the classroom and in a research setting
- Preparing and delivering presentations at national and international conferences
If a career as an astronomer interests you, you might also consider becoming an aerospace engineer who designs many of the spacecraft and satellites astronomers use in their research. If you find a career as a cosmologist interesting, you may wish to learn more about a career as a computational biologist, which is a scientist who applies theoretical concepts to better understand biological systems. | 0.840168 | 3.156153 |
If you see a car along that road,” Tyler Nordgren warned me, “don’t look at the headlights. It’ll ruin your night vision for 2 hours.” Nordgren and I had pitched our tents under the brow of Mount Whitney in the Alabama Hills, a field of boulders near Death Valley. We watched it get dark, and in the nighttime horizon, the sky was perforated by stars and streaked by the Milky Way. Or, to put it in approximate scientific terms, it was probably a 3 on the Bortle Scale, the 9-level numeric metric of night sky brightness.
Even so, we could still see domes of hazy light from 200-odd miles south in Los Angeles and 250 miles east in Las Vegas. That encroaching urban glow was like highlighter calling attention to the issue that Nordgren, a prophet whose cause is light pollution, wanted to illustrate for me.
“We’re losing the stars,” the 45-year-old astronomer told me. “Think about it this way: For 4.5 billion years, Earth has been a planet with a day and a night. Since the electric light bulb was invented, we’ve progressively lit up the night, and have gotten rid of it. Now 99 percent of the population lives under skies filled with light pollution.”
Nordgren is an affable, engaging, and quotable Cassandra, an enthusiastic and patient teacher who loves his subject and wants you to love it, too. Those attributes, along with a book for a lay audience, Stars Above, Earth Below, A Guide to Astronomy in the National Parks, have pushed him to center stage of a small but impassioned movement to preserve natural night skies. When he is not lecturing at the University of Redlands, a California liberal arts college, Nordgren is a much sought-after itinerant preacher intent on bringing people revelation of the stars they have, almost everywhere, lost sight of.
Almost the entire eastern half of the United States, the West Coast, and almost every place with an airport large enough to receive commercial jets, are too lit up to get a good view of stars. The phenomenon is illustrated by the First World Atlas of Artificial Night Sky Brightness. Based on spacecraft images of Earth in 1997, it shows a spectrum from black, representing the natural night sky, to pink, in which artificial light effectively erases any view of the stars at all. Green is where you lose visibility of the Milky Way. The map of the contiguous 48 states—and much of Europe—looks like a video-game screen showing a carpet bombing, the map a splash of green, yellow, red, and pink.
For roughly the past two decades, at least two-thirds of the U.S. population have not been able to see the Milky Way at all, and it will get worse before it gets better. The dawn of light-emitting diode (LED) lighting is expected to significantly lower costs and spur consumption. In addition, LED lighting produces light with a bluer cast, which is more effectively scattered by the atmosphere. “This has the potential to be the nail in the coffin for seeing stars in most communities,” Nordgren tells me.
Nordgren wears his hair in the style of a naval officer, cropped on the sides, and I sense that he probably looks much like the boy he once was, who had his sights on becoming an astronaut. Poor vision forced him to settle on becoming on a mere astronomer. He wrote his doctoral thesis at Cornell on dark matter in spiral galaxies, graduating in 1997. Carl Sagan, whose popular TV series Cosmos had inspired Nordgren to begin with, was there at the time, and Nordgren still regrets that whenever he was in the presence of his idol he would lose his capacity for speech. He couldn’t even find the courage to introduce himself, and when finally he did, Sagan had said, “I know who you are.”
The light pollution issue first came up in 1992 when Nordgren went to Cal Tech’s Palomar Observatory near San Diego. At the time it had the world’s largest telescope. Already, though, the night glow from the surrounding area was forcing astronomers to go elsewhere.
“In 2005, I went back to Palomar to do some work on Adaptive Optics, looking at storm clouds moving atop Uranus and Neptune, and it was really a shock,” Nordgren recalled. Giant housing, casinos, resorts. In ’92, you were like, ‘Look how bad this is!’ Then in ’05 we were just an island in a sea of lights.”
Light pollution was threatening to pull down the curtain on future research for astronomers, Nordgren said, making existing observatories useless and efforts to build new ones in the U.S. more difficult as they had to be built in places that put astronomers in conflict with environmentalists and Native Americans.
The light pollution problem grew significantly during a period that was, courtesy of the Hubble Space Telescope, a golden age in astronomy. Hubble went into orbit in 1990 and sent back images of space, unencumbered by backlighting, that would have made Galileo’s head spin. But Hubble, despite its marvels, somewhat confused the issue, leading people to assume that astronomy would proceed apace even if astronomers were being shown to obstructed-view seats. The trouble is that Hubble isn’t sustainable. Its costs are, as it were, astronomical. It requires space shuttle missions to maintain, and there are no more of those, so Hubble will be gone in a few years. The next project to replace it is over budget and far behind schedule. The long-term solution will rely on terrestrial observatories.
Finding places to put these, though, isn’t easy. As astronomers lose the functionality of existing observatories to light pollution, and move to places like Mount Graham in Arizona and Mauna Kea, the location of the W.M. Keck Observatory in Hawaii, they’ve been protested, sued, and made to feel like wanton intruders, wreckers of the environment, and defilers of sacred spaces. Really ambitious observatory projects, therefore, look overseas. When the Square Kilometer Array Telescope came up for bidding, a process like hosting the Olympics, the U.S. wasn’t in the race. Foreign observatories bring with them concerns about long-term political stability.
The question of light pollution gripped Nordgren. Like Sagan, he decided that educating the public was key. When he got his first sabbatical in 2007-2008, he decided he’d spend the time normally reserved for lab work and writing to travel to national parks to give talks. He knew from experience how visitors to the national parks wanted to reconnect to the stars above. But almost all national parks programs were about things on the land. He wanted to remind visitors that the parks, as the last preserves of natural night, were also about the skies. He devoted three weeks in each of a dozen places, among them the Rocky Mountain National Park, the Grand Tetons, Glacier, Acadia, and Great Basin.
“I was reluctant to tell other astronomers what I wanted to do,” he said. “There’s a view that astronomers should be in observatories. I remember one guy at Cornell saying, ‘Tyler, if you do education, you’re wasting your Ph.D.’ ” This was something Sagan had run into, people who assumed he wasn’t a serious scientist because he was on television. “But Carl was a good scientist,” Nordgren said. And when Nordgren did share his plans he got a warm reception. “Some people said, ‘I wish I’d thought of that!’ ” The parks rangers themselves were mostly very receptive, with some exceptions.
“There were some who had no idea what to make of what I was doing,” he said. “I remember folks at the Great Smoky Mountains, when I said I wanted to work with astronomy and night skies, the ranger said, ‘We call it ‘The Great Smokies.’ We don’t do a lot of astronomy here.’ He was baffled. And then I’d run into people in management for whom it was a 9-to-5 job. When it got dark they went home, so they never saw firsthand the night sky programs, and this was 2007-2008, when budgets were very tight.”
In addition to his night skies curriculum, Nordgren created an arts program called See the Milky Way. It’s gone on for five years, with poster designs for 30 parks, monuments, and dark skies preserves.
The national parks odyssey also resulted in Stars Above, Earth Below, his guide which, though it sold out of a relatively modest 3,000-copy first print run and sells now through print-on-demand, found an enduring and loyal audience among rangers.
One of them was Kelly Carroll, a National Parks ranger at Great Basin. He invited Nordgren to keynote the annual astronomy festival he organized and was immediately won over.
“Every once in a while a scientist comes along who knows how to speak about science to the general public,” Carroll told me. “Tyler has a way of speaking about light pollution and the aesthetics of the issue. He helps make the connection of what it means to us to lose the night skies as human beings.”
Carroll, who was a geologist with the U.S. Geological Survey prior to joining the National Parks Service, told me that the need for someone like Nordgren is great. People are barely aware that “we’ve had an incredible part of our humanity taken away from us, but it’s been so gradual they don’t feel the loss,” he said.
Rangers tell Nordgren that the night programs get more attendance than all other programs put together. One great success story is Great Basin National Park which, in 2009, put on three night skies programs that drew 300 people. The following year they did 20 that were well-attended, so they instituted it as a primary offering. Since then overnight attendance has increased to about 9,000 a year. And while traditional daytime programs average about 25 to 30 people, the astronomy programs, which are mainly interpretive programs about night skies, typically pull in 150 to 175.
“The first time people come out for dark skies, and we get Bortle Class 1 and 2 here, it affects them deeply,” Carroll said. “They’re blown away. The connection with the stars is inside all of us, but it has been sequestered away.”
Christian Luginbuhl, an astronomer who worked with Nordgren at the Naval Observatory Flagstaff Station, explains to me that Tyler helps participants understand the cultural value of the nighttime sky. “It’s also one thing all of humanity has in common,” he tells me. “It’s the same sky in the Sahara as it is over Philadelphia. It’s also the same sky as Native Americans gazed up at 10,000 years ago. People think of light pollution as an astronomer’s concern, but Tyler helps establish this broad value, that it matters to everyone.”
I trained my eyes straight upwards, to the zenith, and settled in as Nordgren used a laser pointer to explain what we could see in the night sky: giant clouds of interstellar dust and plumes of vaporized debris, some the size of the Earth. He talked about the surface of Titan, a moon of Saturn with Earth-like features, where under a smoggy orange layer it all looks like Minnesota’s Land of 10,000 Lakes, with fractal shores and frozen methane raining out of the sky.
“We’re 25,000 light years from the center of the galaxy,” Nordgren said. “We’re way on the fringe of our own galaxy.”
“What is 25,000 light years in the other direction?” I asked.
“Then you’d be in an intergalactic area.”
“What would that be like if you were moving through it?”
“Nothing. It would be nothing.”
“But what’s nothing?” I said. “There can’t be nothing.”
He considered the matter. “No one knows,” he said. “I guess it would be like being in an inky blackness. I don’t know if you would have a perception of moving. You’d see like six stars. You know what it would be like? It would be like being in Los Angeles.”
He meant a night sky in Los Angeles.
We spend some time taking photographs, fiddling with camera settings, a lesson in shooting in the dark to augment my brief alfresco astronomy class. “Over the last decade there has been a revolution in photography,” Nordgren tells me. “Everyone has a camera now. In the 1950s, Ansel Adams went to photograph the national parks. Some feel that started the modern environmental movement. We’re there again. People are so stunned when they see the night sky photos they think they’re fake. Maybe this will be the impetus of a night sky environmental movement.”
After a cold but pleasant night by Mount Whitney, the view near dawn was splendid, the pale blue night above brightening to a spray of colors in the horizon. It wasn’t, though, the sunrise I took it to be. It was Zodiacal light, or false dawn. The beauty of a life in astronomy, at least as it’s described by Nordgren, is that every moment, it seems, is a phenomenon described in a way that’s both precise and lovely in its description.
“What you’re seeing,” Nordgren explained, “is that in the plane of our solar system, in the disk the planets orbit the sun in, there are grains of dust that float in there, in the same plane. Those grains of dust reflect and scatter sunlight. It’s exactly like the sunbeam you’d see in your house.”
“The stars are still out there,” Nordgren told me. “They’re just waiting for us to pay attention again.”
Todd Pitock has written for Discover, The Atlantic and The New York Times, among others.
This article was originally published in our “Light” issue in March, 2014. | 0.862246 | 3.390632 |
Hubble's Space Telescope examined eight chosen quasars from the deep space – each of them is being gravitationally lensed by a large galaxy. The images of these ancient monsters show the smallest clusters of dark matter ever found.
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The Inexhaustible Hubble
You have probably heard this before – but dark matter is still dark. Not in the sense that it has a dark color but in the sense that we still have no idea what exactly it is. And it takes scientists to the brink of insanity because it fills the majority of the Universe – almost like it is laughing at us from every corner of the Universe. Nonetheless, scientists keep on studying it – sometimes in quite a detail but really it is always just indirect study. Recently, exactly this was done by Hubble's Space Telescope and it discovered something new about dark matter.
How To See Something That Cannot Be Seen?
Using sophisticated processes we detected (at least we hope) gigantic clusters of dark matter in galaxies. But theories predict that dark matter should create even much smaller clusters. And it was good old Hubble that detected these small clusters or at least indirectly detected something that we do not know what it is made from but it should be precisely these small clusters of dark matter.
How do you even find something we cannot see and about what we know next to nothing? Ideally, you use gravity because that is the one force that dark matter should use to interact with the rest of the Universes common matter. The gravity of dark matter should be “visible” in how the common matter in the Universe is arranged. When there is some dark matter it should attract even regular matter towards it thanks to its gravity. And where there is enough regular matter, it collapses and a star is born. And where there is a lot of matter (including dark matter) that is how galaxies and even galaxy clusters get born.
Galaxies & Math Working Together
This is all based on a presupposition. Dark matter is cold. That means that its particles should be moving relatively slow. And if that is the case that dark matter should be capable of creating even smaller than galactic clusters. Such “mini-clusters” were never found until now – by Hubble.
Anna Nierenberg and her colleagues from NASA seem to have detected clusters of dark matter with a mass of roughly ten million Suns. And their observations seem to also confirm that dark matter is truly cold.
During their research, Nierenberg and her colleagues observed eight quasars that – thanks to a bit of luck – are being gravitationally lensed by the object between us and the quasars. These quasars were roughly ten billion light-years away and are being lensed by large galaxies about two billion light-years away. In these cases the gravitational lens causes us to see the quasar multiple times.
The scientists started with the idea that if there is a cluster of dark matter somewhere between the Hubble telescope and the quasar it will disrupt the lensed image. You can sort of imagine the clusters as an optical defect on the glass of the lens. And with a bit of math, you can calculate the size of the optical defect on the lens.
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NASA's Hubble Space Telescope will begin searching for an object beyond Pluto that a spacecraft can explore next summer.
The space agency's New Horizons spacecraft, launched in 2006, is on what NASA calls an edge-of-the-solar system mission. The spacecraft now is on its way to Pluto, which was classified as a planet for 75 years until it was re-classified as a dwarf planet in 2006.
New Horizons, which is set to fly past Pluto and its moons in July 2015, has already logged more than 3 billion miles on its historic voyage to send back information about worlds on the outskirts of the solar system. It flew around the moons of Jupiter, before heading deeper into space.
NASA has never before sent a spacecraft to Pluto, so next summer's flyby will be a first.
Hubble comes into play as NASA figures out what the spacecraft will explore after it visits Pluto.
The space telescope will focus on a small area of sky in the area known as the Kuiper Belt for the outbound spacecraft to visit. The Kuiper Belt is a vast debris field of icy bodies left over from the solar system's formation 4.6 billion years ago.
NASA noted that a sizeable object in the Kuiper Belt has never been seen up close because the belt is so far from the sun, stretching out to a distance of 5 billion miles into a never-before-visited frontier of the solar system.
Hubble is scheduled to scan an area near the constellation Sagittarius, searching for objects of interest. But this won't be an easy task for Hubble and the scientists that manage it.
Hubble is powerful enough to see galaxies near the horizon of the universe but finding an object in the Kuiper Belt is akin to finding the proverbial needle in a haystack, according to NASA. A Kuiper Belt object is generally about the size of Manhattan Island and as dark as charcoal.
Astronomers working around the globe have put in requests to use the space telescope, but there are far more requests than Hubble can handle in a year. The applications are reviewed by a group of scientists who look for projects that call on Hubble's unique capabilities and cannot be handled by ground-based telescopes.
NASA noted that Hubble was used for the New Horizons mission before it was launched about eight years ago, searching the skies for objects that the spacecraft could target. Hubble, for instance, discovered four small moons that orbit Pluto and its largest satellite, Charon. The telescope also was used to create a detailed map of Pluto's surface. The map will be used to plan New Horizons' work to capture close-up photos during the 2015 flyby.
The space telescope has been making a lot of progress in space exploration.
Last December, Hubble spotted a huge water plume emanating from the south pole of Europa, the sixth-closest moon to Jupiter and the sixth-largest moon in the solar system.
NASA's 2015 proposed budget includes funding for a robotic mission to study this new find on Europa.
NASA is looking to launch the first of a series of robotic missions to Europa in the mid 2020s.
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed. Her email address is [email protected].
Read more about emerging technologies in Computerworld's Emerging Technologies Topic Center. | 0.850404 | 3.464972 |
So, you want to be a star? Well, you’ve got a long way to go. But don’t worry. Stick with me and you’ll go far.
The first thing you’ve got to do is be a huge cloud of gas, out in interstellar space. It’ll especially help if you’re a Giant Molecular Cloud. These are regions of the interstellar medium which have very high densities and very low temperatures. That will help you out when it’s time to begin collapsing.
Speaking of which, that’s the next step. Once you are dense enough, the inward pull of gravity will overcome the outward push caused by heat. This can be calculated using the Virial Theorem.
In this equation, the force of gravity is on the left side and the pressure caused by the cloud’s temperature is on the right. Sometimes this is quantified in terms of a mass, known as the Jeans Mass.
Are you not quite dense enough to achieve this? Don’t worry. All you have to do is wait for a supernova to create a shockwave and cause you to collapse. Or you can take advantage of a tidal interaction with another galaxy to give you the push (or in this case, pull) you need. Once you’ve gotten the initial push, you can relax for a bit. As the collapse happens, your density, will be increasing. Since the Jeans Mass depends inversely on density, as your density increases, the collapse will speed up.
You just need to sit back and wait for a bit until your temperature starts to go up. During the initial part of your collapse, you don’t really need to worry about this. The excess heat caused by the collapse is easily radiated away as infrared radiation, so your temperature will remain relatively constant. However, as your density starts to increase, your opacity will go up as well. This means that light will have a harder time escaping. Since infrared radiation is the way you get rid of heat, that means that your temperature will start increasing.
If you’ve attained a high enough density at this point, your core will continue contracting as the temperature goes up. At this point, you have successfully become a protostar! Once you’ve reached this point, you’re almost there. But don’t get complacent, you aren’t done yet. As a protostar, you should continue gaining mass from the surrounding cloud via accretion.
As mass accretes, your temperature will begin to rise. Remember the Virial Theorem from earlier? Well, you can see that since the left side depends on and the right side depends on , if your mass is increasing, the left side will grow faster than the right side. For a protostar to remain in equilibrium, the left side and right side should remain equal. Since the radius doesn’t change much, the temperature must increase.
Be careful not to run out of mass at this point, because if you do you will only become a brown dwarf. You need to have a mass of at least 0.085 solar masses to be able to fuse hydrogen into helium. Once you reach a temperature of Kelvin, you will be all set to begin fusion! As you reach the onset of fusion, you will be a fully fledged star. Congratulations, you’ve made down a difficult road. Now you can put up your feet, form a planet (or nine), and clean up any leftover gas and dust. Then, for the next few hundred million to tens of billions of years, you can sit back, relax, and shine away!
(Adapted from a paper I wrote for a class.)
Cover Image: The Westerlund 2 star forming region, from APOD. | 0.856768 | 3.80432 |
Take a moment to picture the apocalypse.
There’s a good chance your mind might have conjured up an image of an enormous asteroid barrelling down through the atmosphere, wreathed in fire, slamming into the earth and creating worldwide dust storms, heat, and general death.
This is a fairly accurate doomsday scenario – one that has happened before and will happen again. For over four billion years, the Earth has been constantly clobbered by asteroids and other objects zooming around the solar system. While the majority have burned up harmlessly in the atmosphere, others have smashed into the surface and caused global devastation.
We’ve only really begun to understand the real threat of these impacts in the past few decades. In an iconic 1980 paper, for example, physicist Luis Alvarez and his geologist son Walter reported the discovery of a thin band of extra-terrestrial sediment between layers of Cretaceous and Tertiary rock – compelling evidence that an asteroid caused a mass extinction 65 million years ago.
Unfortunately for the dinosaurs, they didn’t have the capability to detect, predict or prevent asteroids. Luckily for us, we’ve learnt a thing or two from their misfortune.
Since the late 1990s, a host of telescopes around the globe have been scanning the Earth’s neighbourhood to discover and monitor threatening asteroids. These survey programs are primarily funded by NASA and are mostly ground-based, although the near-infrared NEOWISE space telescope also spent most of 2010 spotting near-Earth objects (NEOs) from orbit.
Together, these programs have discovered nearly 20,000 NEOs so far, with the total increasing every month. That’s a lot of fast-moving objects to keep tabs on – so how exactly do we know which ones might kill us?
Figuring out risk in any field is a tricky task. Consider an everyday example: how dangerous is a car on a given road? This answer depends on a range of slippery factors, from vehicle speed to road conditions to driver skill, and even if we were able to draw solid connections between these factors, risk is a function of probability so we would still need to figure out a statistical tool to quantify the danger.
Now consider the much more complex task of putting a number on the risk posed by an asteroid. For starters, it’s difficult to measure its exact orbit, and, of course, that orbit can change over time as the asteroid interacts with other celestial bodies.
Knowing an object’s size, speed and other characteristics are also crucial in risk calculations, but in space these are generally only estimations.
Determining the risk sounds like trying to figure out the chances of a car having an accident without knowing who is driving, where, or at what speed.
But evaluating asteroids in this way is crucial to alert scientists and the world to potentially dangerous impacts.
To get a better handle on things, boffins have worked out several scales to classify the danger.
The first, the Torino Impact Hazard Scale, was hashed out in 1999 by a group of scientists from the International Astronomical Union (IAU), at a meeting in the Italian city of Turin. The result is akin to the Richter scale: it assigns incoming events an integer from zero to 10, where zero means a negligible threat and 10 means a massive, inevitable collision that would cause global devastation.
Simple, right? It’s meant to be – the Torino scale was designed to clearly communicate risks to the public.
But the model takes into account more than just whether an object is making a beeline for the Earth. It also considers the probability of impact; the date of collision, which dictates how much we need to worry right now; and the energy of the impact – deduced from the object’s size, density and velocity – which indicates how significant the devastation might be.
An object with a Torino score of zero, for example, might be a small object that would burn up completely in the atmosphere and therefore have no chance of doing damage.
Bear in mind, however, that the Chelyabinsk meteor that exploded over Russia in 2013 would have scored zero on this scale. Although its effects injured 1500 people, its impact energy was comparatively small and it didn’t survive its fiery entry into the Earth’s atmosphere.
As the numbers on the Torino scale climb, the risks begin to rise. When an asteroid is assigned a score of three, astronomers are alerted. This doesn’t necessarily mean that the object is dangerous – just that it has a 1% or greater chance of collision and could cause localised damage, so it must be monitored.
The potential for destruction only goes up from here. A score of five indicates close encounter events that pose a serious but still uncertain threat, capable of doing serious damage across a large region.
Events with a score of six or seven could inflict global damage. Not only would these need to be studied closely to see if they continue on a collision course with Earth, but also – depending on how imminent the collision is – NASA would likely notify relevant governments worldwide to start creating contingency plans.
From eight upwards, the forecast begins to look grim. Objects in this range are certain to smash into the Earth. A score of eight is a once-in-50-year event that would cause local destruction if it impacted on land and a possible tsunami offshore. An event of nine would cause unprecedented regional devastation on land and a major tsunami, and is estimated to occur once every 10,000 to 100,000 years.
And then comes the cherry on top: a perfect score of 10. This would be given to an asteroid certain to slam into the Earth and cause the kind of planet-wide climatic catastrophe that could destroy civilisation as we know it – like the Chicxulub impact, destroyer of the dinosaurs.
This type of event is predicted to occur once every 100,000 years, which doesn’t seem like that long in the grand scheme of things.
However, it’s heartening to note that the vast majority of NEOs discovered thus far have been slapped with a score of zero.
When first discovered, some asteroids can appear to be on course with the Earth according to complex orbital calculations. But the numbers are normally based on only a few days of observations, and further monitoring can give a better indication of the object’s true path and allow it to be either upgraded or downgraded on the scale.
In this sense, the Torino scale is analogous to hurricane forecasting, where predictions of the storm’s path and ferocity are updated as more data is collected.
Four was the highest score ever assigned to an object: the 370-metre diameter asteroid called 99942 Apophis. In December 2004 it caused a mild panic when astronomers calculated that it had a 2.7% probability of smashing into earth in 2029. But follow-up observations refined the orbit and eventually eliminated the potential for an impact, downgrading the rock to level zero.
Everything else discovered so far has also been downgraded to zero.
But this means the same level on the Torino scale contains thousands of asteroids all with diverse properties, and so scientists came up with more technical and precise tool to tease out further information.
Developed by NEO specialists in 2002, the Palermo Technical Impact Scale quantifies threats in more mathematical detail. Like the Torino model, it looks at an object’s predicted impact energy and date of collision, but it aims to prioritise NEOs according to how much they deserve observation and analysis.
The scale is logarithmic for scientific convenience: objects that pose no threat are assigned negative values, while more threatening ones are given positive values.
The scale also compares the risk posed by an asteroid to the “background risk”: the average risk posed by other objects of a similar size over the years between now and the predicted impact. This background risk is taken as the status quo, so when an approaching object rises above the background level, corresponding to a positive Palermo scale score, it indicates an unusual and concerning event.
This means an object that scores a minus-2 is only 1% as likely to occur as a random background event of the same size in the intervening years. A score of zero means that the event is just as likely as a background event, and a score of plus-2 means the event is 100 times more likely than a background event.
This allows scientists to fine-tune their study of possible impacts, and in particular to carefully prioritise and analyse events that score zero on the Torino scale.
Neither scale is perfect. Both, for example, tend to flag asteroids as concerning before orbital data is detailed enough to accurately predict their paths. This creates a communication issue around the urgency of the risk, sometimes inciting panic where none is warranted.
An alternative scale was proposed in 2003 by Brian Marsden of the Minor Planet Centre. Called the Purgatorio Ratio, it balances the accuracy of an asteroid’s orbit with the amount of time before its predicted impact. An object with an uncertain orbit and a predicted impact date many decades away would get a much lower rating, even if at first glance it seems to be on a collision course with Earth.
The Purgatorio Ratio is appealing because it eliminates some of the unnecessary urgency attached to asteroids in the vicinity of Earth, potentially reducing media sensation. Yet since the ratio isn’t promoted by NASA, which funds the bulk of asteroid search programs, it isn’t widely used.
But it is certainly complementary to the other scales. Assessing asteroid risk is a multi-dimensional and complex problem, so it’s a good idea to prepare a range of tools to deal with it.
And in the end, none of the scales can decide how we should act if faced with a serious and imminent asteroid threat. Ultimately, if we need to act to mitigate disaster then that terrifying and crucial choice is completely up to us. | 0.822746 | 3.893033 |
This week leading up to the September equinox offers you a fine chance to catch an elusive phenomenon in the pre-dawn sky.
We’re talking about the zodiacal light, the ghostly pyramid-shaped luminescence that heralds the approach of dawn. Zodiacal light can also be seen in the post-dusk sky, extending from the western horizon along the ecliptic.
September is a great time for northern hemisphere observers to try and sight this glow in the early dawn. This is because the ecliptic is currently at a high and favorable angle, pitching the zodiacal band out of the atmospheric murk low to the horizon. For southern hemisphere observers, September provides the best time to hunt for the zodiacal light after dusk. In March, the situation is reversed, with dusk being the best for northern hemisphere observers and dawn providing the best opportunity to catch this elusive phenomenon for southern observers.
Cory Schmitz’s recent outstanding photos taken from the Nevada desert brought to mind just how ephemeral a glimpse of the zodiacal light can be. The glow was a frequent sight for us from dark sky sites just outside of Tucson, Arizona—but a rarity now that we reside on the light-polluted east coast of the U.S.
In order to see the zodiacal light, you’ll need to start watching before astronomical twilight—the start of which is defined as when the rising Sun reaches 18 degrees below the local horizon—and observe from as dark a site as possible under a moonless sky.
The Bortle dark sky scale lists the zodiacal light as glimpse-able under Class 4 suburban-to-rural transition skies. Under a Class 3 rural sky, the zodiacal light may extend up to 60 degrees above the horizon, and under truly dark—and these days, almost mythical—Class 1 and 2 skies, the true nature of the zodiacal band extending across the ecliptic can become apparent. The appearance and extent of the zodiacal light makes a great gauge of the sky conditions at that favorite secret dark sky site.
The source of the zodiacal light is tiny dust particles about 10 to 300 micrometres in size scattered across the plane of the solar system. The source of the material has long been debated, with the usual suspects cited as micrometeoroid collisions and cometary dust. A 2010 paper by Peter Jenniskens and David Nesvorny in the Astrophysical Journal cites the fragmentation of Jupiter-class comets. Their model satisfactorily explains the source of about 85% of the material. Dust in the zodiacal cloud must be periodically replenished, as the material is slowly spiraling inward via what is known as the Poynting-Robertson effect. None other than Brian May of the rock group Queen wrote his PhD thesis on Radial Velocities in the Zodiacal Dust Cloud.
But even if you can’t see the zodiacal light, you still just might be able to catch it. Photographing the zodiacal light is similar to catching the band of the Milky Way. In fact, you can see the two crossing paths in Cory’s images, as the bright winter lanes of the Orion Spur are visible piercing the constellation of the same name. Cory used a 14mm lens at f/3.2 for the darker image with a 20 second exposure at ISO 6400 and a 24mm lens at f/2.8 with a 15 second exposure at ISO 3200 for the brighter shot.
Under a truly dark site, the zodiacal light can compete with the Milky Way in brightness. The early Arab astronomers referred to it as the false dawn. In recent times, we’ve heard tales of urbanites mistaking the Milky Way for the glow of a fire on the horizon during blackouts, and we wouldn’t be surprised if the zodiacal light could evoke the same. We’ve often heard our friends who’ve deployed to Afghanistan remark how truly dark the skies are there, as military bases must often operate with night vision goggles in total darkness to avoid drawing sniper fire.
Another even tougher but related phenomenon to spot is known as the gegenschein. This counter glow sits at the anti-sunward point where said particles are approaching 100% illumination. This time of year, this point lies off in the constellation Pisces, well away from the star-cluttered galactic plane. OK, we’ve never seen it, either. A quick search of the web reveals more blurry pics of guys in ape suits purporting to be Bigfoot than good pictures of the gegenschein. Spotting this elusive glow is the hallmark of truly dark skies. The anti-sunward point and the gegenschein rides highest near local midnight.
And speaking of which, the September equinox occurs this weekend on the 22nd at 4:44 PM EDT/20:44 Universal Time. This marks the beginning of Fall for the northern hemisphere and the start of summer for the southern.
The Full Harvest Moon also occurs later this week, being the closest Full Moon to the equinox occurring on September 19th at 7:13AM EDT/11:13 UT. Said Moon will rise only ~30 minutes apart on successive evenings for mid-northern latitude observers, owing to the shallow angle of the ecliptic. Unfortunately, the Moon will then move into the morning sky, drowning out those attempts to spy the zodiacal light until late September.
Be sure to get out there on these coming mornings and check out the zodiacal light, and send in those pics in to Universe Today! | 0.828882 | 3.841798 |
At one time or another, all science enthusiasts have heard the late Carl Sagan’s infamous words: “We are made of star stuff.” But what does that mean exactly? How could colossal balls of plasma, greedily burning away their nuclear fuel in faraway time and space, play any part in spawning the vast complexity of our Earthly world? How is it that “the nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies” could have been forged so offhandedly deep in the hearts of these massive stellar giants?
Unsurprisingly, the story is both elegant and profoundly awe-inspiring.
All stars come from humble beginnings: namely, a gigantic, rotating clump of gas and dust. Gravity drives the cloud to condense as it spins, swirling into an ever more tightly packed sphere of material. Eventually, the star-to-be becomes so dense and hot that molecules of hydrogen in its core collide and fuse into new molecules of helium. These nuclear reactions release powerful bursts of energy in the form of light. The gas shines brightly; a star is born.
The ultimate fate of our fledgling star depends on its mass. Smaller, lightweight stars burn though the hydrogen in their core more slowly than heavier stars, shining somewhat more dimly but living far longer lives. Over time, however, falling hydrogen levels at the center of the star cause fewer hydrogen fusion reactions; fewer hydrogen fusion reactions mean less energy, and therefore less outward pressure.
At a certain point, the star can no longer maintain the tension its core had been sustaining against the mass of its outer layers. Gravity tips the scale, and the outer layers begin to tumble inward on the core. But their collapse heats things up, increasing the core pressure and reversing the process once again. A new hydrogen burning shell is created just outside the core, reestablishing a buffer against the gravity of the star’s surface layers.
While the core continues conducting lower-energy helium fusion reactions, the force of the new hydrogen burning shell pushes on the star’s exterior, causing the outer layers to swell more and more. The star expands and cools into a red giant. Its outer layers will ultimately escape the pull of gravity altogether, floating off into space and leaving behind a small, dead core – a white dwarf.
Heavier stars also occasionally falter in the fight between pressure and gravity, creating new shells of atoms to fuse in the process; however, unlike smaller stars, their excess mass allows them to keep forming these layers. The result is a series of concentric spheres, each shell containing heavier elements than the one surrounding it. Hydrogen in the core gives rise to helium. Helium atoms fuse together to form carbon. Carbon combines with helium to create oxygen, which fuses into neon, then magnesium, then silicon… all the way across the periodic table to iron, where the chain ends. Such massive stars act like a furnace, driving these reactions by way of sheer available energy.
But this energy is a finite resource. Once the star’s core becomes a solid ball of iron, it can no longer fuse elements to create energy. As was the case for smaller stars, fewer energetic reactions in the core of heavyweight stars mean less outward pressure against the force of gravity. The outer layers of the star will then begin to collapse, hastening the pace of heavy element fusion and further reducing the amount of energy available to hold up those outer layers. Density increases exponentially in the shrinking core, jamming together protons and electrons so tightly that it becomes an entirely new entity: a neutron star.
At this point, the core cannot get any denser. The star’s massive outer shells – still tumbling inward and still chock-full of volatile elements – no longer have anywhere to go. They slam into the core like a speeding oil rig crashing into a brick wall, and erupt into a monstrous explosion: a supernova. The extraordinary energies generated during this blast finally allow the fusion of elements even heavier than iron, from cobalt all the way to uranium.
The energetic shock wave produced by the supernova moves out into the cosmos, disbursing heavy elements in its wake. These atoms can later be incorporated into planetary systems like our own. Given the right conditions – for instance, an appropriately stable star and a position within its Habitable Zone – these elements provide the building blocks for complex life.
Today, our everyday lives are made possible by these very atoms, forged long ago in the life and death throes of massive stars. Our ability to do anything at all – wake up from a deep sleep, enjoy a delicious meal, drive a car, write a sentence, add and subtract, solve a problem, call a friend, laugh, cry, sing, dance, run, jump, and play – is governed mostly by the behavior of tiny chains of hydrogen combined with heavier elements like carbon, nitrogen, oxygen, and phosphorus.
Other heavy elements are present in smaller quantities in the body, but are nonetheless just as vital to proper functioning. For instance, calcium, fluorine, magnesium, and silicon work alongside phosphorus to strengthen and grow our bones and teeth; ionized sodium, potassium, and chlorine play a vital role in maintaining the body’s fluid balance and electrical activity; and iron comprises the key portion of hemoglobin, the protein that equips our red blood cells with the ability to deliver the oxygen we inhale to the rest of our body.
So, the next time you are having a bad day, try this: close your eyes, take a deep breath, and contemplate the chain of events that connects your body and mind to a place billions of lightyears away, deep in the distant reaches of space and time. Recall that massive stars, many times larger than our sun, spent millions of years turning energy into matter, creating the atoms that make up every part of you, the Earth, and everyone you have ever known and loved.
We human beings are so small; and yet, the delicate dance of molecules made from this star stuff gives rise to a biology that enables us to ponder our wider Universe and how we came to exist at all. Carl Sagan himself explained it best: “Some part of our being knows this is where we came from. We long to return; and we can, because the cosmos is also within us. We’re made of star stuff. We are a way for the cosmos to know itself.” | 0.841576 | 3.832192 |
On Friday morning, NASA's Dawn spacecraft will arrive at Ceres, becoming the first probe ever to orbit a dwarf planet.
Ceres is the largest object in the asteroid belt between Mars and Jupiter, and the closest dwarf planet to Earth. Dawn is expected to provide a wealth of information about Ceres' evolution and composition.
While Dawn's work will be the first in-depth examination of Ceres, astronomers have learned a bit about the dwarf planet already using NASA's Hubble Space Telescope, Europe's Herschel Space Observatory and other instruments. Here are seven weird facts about Ceres. [Dawn's Arrival at Dwarf Planet Ceres: Full Coverage]
1. It was the first asteroid to be discovered
Ceres was first spotted on Jan. 1, 1801 by Sicilian astronomer Giuseppe Piazzi. The asteroid was found after Piazzi followed up on mathematical predictions (later determined to be false) that there should be a planet between Mars and Jupiter.
At first Ceres was called a planet, but as more asteroid belt members were discovered, Ceres was demoted to asteroid. Its status changed again in 2006 when it was promoted to dwarf planet — a classification it shares with Pluto, which was demoted from full-fledged planet that same year in a move that remains controversial today.
2. It was named after the Roman goddess of agriculture
Piazzi called his discovery Ceres after the Roman goddess of harvests and corn. She also was considered the patron goddess of Sicily, according to the Encyclopedia Britannica. In 1803, the element cerium was named after the dwarf planet. Cerium is the most abundant of rare-Earth metals, the encyclopedia says, and (among other occurrences) it is found as a fission product of plutonium, thorium and uranium.
3. It has mysterious bright spots
As Dawn sped towards the dwarf planet in late 2014 and early 2015, astronomers found two surprise bright spots at about 19 degrees north latitude on Ceres, inside a crater. There don't seem to be any mounds or features close to these spots, which suggests that they are not volcanic in origin.
The bright spots indicate a highly reflective material, likely water ice or salts, researchers say. Dawn team members hope the spacecraft will solve the mystery.
4. Ceres may have a water-vapor plume
The Herschel Space Observatory recently spotted water vapor emanating from Ceres. The plumes appeared to be generated from two locations (including close to where the white spots were found) and could be a product of icy volcanoes, scientists have said.
The vapor may also have sublimated off after a meteorite strike exposed subsurface ice to space. The plume's nature is another mystery for Dawn to investigate.
5. Ceres may harbor a subsurface ocean
Water-vapor geysers would hint at the presence of a subsurface ocean on Ceres, which might be capable of supporting life as we know it, some scientists say.
Icy moons of the outer solar system such as the Jovian satellite Europa and Saturn's moon Enceladus are thought to have underground oceans, which are apparently kept liquid by tidal forces generated by the gravity of neighboring moons and their huge host planets. Ceres would not experience such tidal forces but could possibly retain some radioactive heat from elements in its interior.
6. It's round
Unlike other members of the asteroid belt, Ceres is round, because it's large enough for gravity to mold its shape into a sphere. (Ceres is about 590 miles, or 950 kilometers, wide.) Scientists also believe that round bodies tend to have differentiated interiors, meaning that there are different zones inside of them. Ceres probably has a rocky core, an icy mantle, perhaps some subsurface liquid water and a dusty top layer.
7. It may have an atmosphere
Ceres is relatively far from the sun, but scientists believe its surface temperatures could rise as high as minus 37 degrees Fahrenheit. If there is any water ice at the surface, it would quickly sublimate — change directly to a gas — which could generate an atmosphere around the dwarf planet. That said, there have only been a few observations of possible sublimation to date. Dawn will be on the lookout for more.
Editor's Note:The online Slooh community observatory will air a special Ceres webcast featuring live telescope views of the dwarf planet on Friday beginning at 1 p.m. ET. You can watch it live directly at www.slooh.com, or here at Space.com. | 0.862583 | 3.719903 |
On Wednesday, July 24th, the people of the Great Lakes region were treated to a spectacular sight when a meteor streaked across the sky. The resulting fireball was observed by many onlookers, as well as the University of Western Ontario’s All-Sky Camera Network. This array runs across southern Ontario and Quebec and is maintained in collaboration with NASA’s Meteoroid Environment Office (MEO) at the Marshall Space Flight Center.
What is especially exciting about this event is the possibility that fragments of this meteorite fell to Earth and could be retrieved. This was the conclusion reached by Steven Ehlert at the MEO after he analyzed the video of the meteorite erupting like a fireball in the night sky. Examination of these fragments could tell astronomers a great deal about the formation and evolution of the Solar System.
The meteorite was observed by countless people who live in the area surrounding Lake Ontario. This included people as far north as Ottawa and Montreal (in Ontario and Quebec) to as far south as Detroit and Toledo, Michigan. From west to east, residents of Kitchener/Waterloo, Ontario, to Rochester and Syracuse, New York, reported seeing the fireball.
Peter Brown is a professor and the Canada Research Chair of physics and astronomy at UWO who specializes in the study of meteors and comets. Shortly after the event, he confirmed that 10 all-sky cameras of UWO’s Southern Ontario Meteor Network (SOMN) recorded a bright fireball over western Ontario. As Brown explained:
“This fireball likely dropped a small number of meteorites in the Bancroft area, specifically near the small town of Cardiff. We suspect meteorites made it to the ground because the fireball ended very low in the atmosphere just to the west of Bancroft and slowed down significantly. This is a good indicator that material survived.”
According to an analysis of the footage and eye-witness testimony, the fireball first became visible just south of Oshawa, Ontario (over Lake Ontario), at 2:44 A.M. EDT (11:44 A.M. PDT) when the meteorite was at an altitude of 93 km (58 mi). The meteor is believed to have measured roughly 30 cm (12 inches) in diameter before it began to burn and break up.
It then traveled northward over Clarington and west of Peterborough before winking out just west of Bancroft. The fireball it created was as bright as a Full Moon and resulted in a number of bright flares near the end of its flight. These were likely the result of fragments that broke loose and fell to the ground (each of which would be in the gram-sized mass range.
Brown and his colleagues at UWO and the Royal Ontario Museum are currently connecting with people from the area where the fragments could have landed. Hoping to collect them for analysis, he and his colleagues are seeking people may have heard anything unusual on the night in question (which could indicate a piece landing near them) or who may have found any possible fragments.
“Meteorites are of great interest to researchers as studying them helps us to understand the formation and evolution of the solar system,” said Brown. However, this event was of great importance to researchers because there is good-quality footage of the meteorite’s passage through the atmosphere that could provide valuable insight into where the rock came from in our Solar System.
For those who live in the area, Brown and his colleagues have some tips for finding and collecting fragments. Meteorites can be recognized by their dark exterior and often scalloped pattern. They are also likely to be denser than ordinary rocks, and those that have higher metal contents will be detectable using a magnet.
If you come across a meteorite fragment, it is best to put it in a clean plastic bag or wrap it in aluminum foil. They should also be handled as little as possible and stored in a cool, dry place to preserve their scientific value. Also, for residents of Canada, meteorites are the property of the owner of the land where they are found. And remember to first obtain permission of the land-owner before searching on their grounds.
So if you’re in the general area of Bancroft, Ontario, and feel like poking around with a magnet and some sharp eyes, go nuts! What you find could be of immense use to scientists. Just be sure you know who’s property your meteorite-hunting on!
Further Reading: University of Western Ontario | 0.826024 | 3.475255 |
When galaxies collide, the result is nothing short of spectacular. While this type of event only takes place once every few billion years (and takes millions of years to complete), it is actually pretty common from a cosmological perspective. And interestingly enough, one of the most impressive consequences – stars being ripped apart by supermassive black holes (SMBHs) – is quite common as well.
This process is known in the scientific community as stellar cannibalism, or Tidal Disruption Events (TDEs). Until recently, astronomers believed that these sorts of events were very rare. But according to a pioneering study conducted by leading scientists from the University of Sheffield, it is actually 100 times more likely than astronomers previously suspected.
TDEs were first proposed in 1975 as an inevitable consequence of black holes being present at the center of galaxies. When a star passes close enough to be subject to the tidal forces of a SMBH it undergoes what is known as “spaghetification”, where material is slowly pulled away and forms string-like shapes around the black hole. The process causes dramatic flare ups that can be billions of times brighter than all the stars in the galaxy combined.
Since the gravitational force of black holes is so strong that even light cannot escape their surfaces (thus making them invisible to conventional instruments), TDEs can be used to locate SMBHs at the center of galaxies and study how they accrete matter. Previously, astronomers have relied on large-area surveys to determine the rate at which TDEs happen, and concluded that they occur at a rate of once every 10,000 to 100,000 years per galaxy.
However, using the William Herschel Telescope at the Roque de los Muchachos Observatory on the island of La Palma, the team of scientists – who hail from Sheffield’s Department of Physics and Astronomy – conducted a survey of 15 ultra-luminous infrared galaxies that were undergoing galactic collisions. When comparing information on one galaxy that had been observed twice over a ten year period, they noticed that a TDE was taking place.
Their findings were detailed in a study titled “A tidal disruption event in the nearby ultra-luminous infrared galaxy F01004-2237“, which appeared recently in the journal Nature: Astronomy. As Dr James Mullaney, a Lecturer in Astronomy at Sheffield and a co-author of the study, said in a University press release:
“Each of these 15 galaxies is undergoing a ‘cosmic collision’ with a neighboring galaxy. Our surprising findings show that the rate of TDEs dramatically increases when galaxies collide. This is likely due to the fact that the collisions lead to large numbers of stars being formed close to the central supermassive black holes in the two galaxies as they merge together.”
The Sheffield team first observed these 15 colliding galaxies in 2005 during a previous survey. However, when they observed them again in 2015, they noticed that one of the galaxies in the sample – F01004-2237 – appeared to have undergone some changes. The team them consulted data from the Hubble Space Telescope and the Catalina Sky Survey – which monitors the brightness of astronomical objects (particularly NEOs) over time.
What they found was that the brightness of F01004-2237 – which is about 1.7 billion light years from Earth – had changed dramatically. Ordinarily, such flare ups would be attributed to a supernova or matter being accreted onto an SMBH at the center (aka. an active galactic nucleus). However, the nature of this flare up (which showed unusually strong and broad helium emission lines in its post-flare spectrum) was more consistent with a TDE.
The appearance of such an event had been detected during a repeat spectroscopic observations of a sample of 15 galaxies over a period of just 10 years suggested that the rate at which TDEs happen was far higher than previously thought – and by a factor of 100 no less. As Clive Tadhunter, a Professor of Astrophysics at the University of Sheffield and lead author of the study, said:
“Based on our results for F01004-2237, we expect that TDE events will become common in our own Milky Way galaxy when it eventually merges with the neighboring Andromeda galaxy in about 5 billion years. Looking towards the center of the Milky Way at the time of the merger we’d see a flare approximately every 10 to 100 years. The flares would be visible to the naked eye and appear much brighter than any other star or planet in the night sky.”
In the meantime, we can expect that TDEs are likely to be noticed in other galaxies within our own lifetimes. The last time such an event was witnessed directly was back in 2015, when the All-Sky Automated Survey for Supernovae (aka. ASAS-SN, or Assassin) detected a superlimunous event four billion light years away – which follow-up investigations revealed was a star being swallowed by a spinning SMBH.
Naturally, news of this was met with a fair degree of excitement from the astronomical community, since it was such a rare event. But if the results of this study are any indication, astronomers should be noticing plenty more stars being slowly ripped apart in the not-too-distant future.
With improvements in instrumentation, and next-generation instruments like the James Webb Telescope being deployed in the coming years, these rare and extremely picturesque events may prove to be a more common experience. | 0.90481 | 4.122942 |
Origins of Habitable Planets, the first research programme hosted by GoCAS, was a cross-disciplinary thematic programme on planet formation. The six week programme was led by Dr. Leonardo Testi of the European Southern Observatory, local host was Eva Wirström. The aim was to try to tie together astronomy, physics and chemistry to advance our understanding of how planets which can harbour life are formed.
In a popular science talk on June 3 Leonardo Testi compared the chemical complexity on Earth, for example in the human body, with the very different one found in the Sun and the gas giants, and posed the question of how they are linked. What is needed for a habitable planet is a finely tuned source of energy, liquid water and complex molecules. It is known that the first simple life forms existed soon after the formation of Earth. The process from a diffuse cloud to a sun and a planetary system is also a process from atoms and simple molecules to life.
One of the questions the programme has worked with is how much of those processes are happening in the gas phase and how much in the solid state, i.e. how far the complexity of molecules goes in the interstellar medium. As for now, the most complex molecules that have been found around protostars consist of 10–11 atoms. To be able to watch the dust molecules in the gas clouds, radio telescopes observing millimeter wave lengths are used. To avoid disturbances from the atmosphere telescopes are built in special places, such as the ALMA telescope in the Atacama desert in Chile, one of the driest places on earth.
Molecules such as glycolaldehyde, formamide, acetone and ethyl formate have been discovered, but not yet amino acids. Those consists of an amine group and a carboxylic acid group, with side-chains. In the form of proteins they are the second-largest component of the human body, after water. To find amino acids is one of the goals of the ALMA telescope and of radio astronomy. The three themes of the GoCAS programme have been: to organize what we know of complex molecules and how molecules are formed in an interstellar medium, to review current and future techniques to observe complex molecules and planetary systems, and to discuss how planets are actually formed and how common our own solar system is. | 0.901262 | 3.505457 |
An on-orbit demonstration of asteroid deflection is a key test that NASA and other agencies wish to perform before any actual need is present. The DART mission is NASA's demonstration of kinetic impactor technology, impacting an asteroid to adjust its speed and path. DART will be the first-ever space mission to demonstrate asteroid deflection by kinetic impactor.
Launch Window: opens July 22, 2021
DART Impact: September 30, 2022
Illustration of how DART's impact will alter the orbit of Didymos B about Didymos A. Telescopes on Earth will be able to measure the change in the orbit of Didymos B to evaluate the effectiveness of the DART impact.
DART's target is the binary asteroid system Didymos, which means "twin" in Greek (and explains the word "double" in the mission's name). Didymos is the ideal candidate for humankind's first planetary defense experiment, although it is not on a path to collide with Earth and therefore poses no actual threat to the planet. The Didymos system is composed of two asteroids: the larger asteroid Didymos A (diameter: 780 meters, 0.48 miles), and the smaller moonlet asteroid, Didymos B (diameter: 160 meters, 525 feet), which orbits the larger asteroid. The DART spacecraft will impact Didymos B nearly head-on, shortening the time it takes the small asteroid moonlet to orbit Didymos A by several minutes.
Didymos is an eclipsing binary asteroid as viewed from Earth, meaning that Didymos B passes in front of and behind Didymos A as it orbits about the larger asteroid as seen from Earth. Consequently, Earth-based telescopes can measure the regular variation in brightness of the combined Didymos system to determine the orbit of Didymos B. After the impact, this same technique will reveal the change in the orbit of Didymos B by comparison to measurements prior to impact. The timing of the DART impact in fall 2022 is chosen to minimize the distance between Earth and Didymos to enable the highest quality telescopic observations. Didymos will still be roughly 11 million kilometers (6.8 million miles) from Earth at the time of the DART impact, but telescopes across the world will be able to contribute to the global international observing campaign to determine the effect of DART's impact.
The DART demonstration has been carefully designed. The impulse of energy that DART delivers to the Didymos binary asteroid system is low and cannot disrupt the asteroid, and Didymos's orbit does not intersect Earth's at any point in current predictions. Furthermore, the change in Didymos B's orbit is designed to bring its orbit closer to Didymos A. The DART mission is a demonstration of capability to respond to a potential asteroid impact threat, should one ever be discovered.
The Lowell Discovery Telescope at Lowell Observatory in Arizona, one of the telescopes across the globe that will be used to evaluate the result of the DART impact. (Credit: Lowell Observatory)
The DART mission is being developed and led for NASA by the Johns Hopkins University Applied Physics Laboratory. NASA's Planetary Defense Coordination Office is the lead for planetary defense activities and is sponsoring the DART mission. Current U.S. partner institutions on DART include NASA Goddard Space Flight Center, NASA Johnson Space Center, NASA Langley Research Center, NASA Glenn Research Center, NASA Marshall Space Flight Center, NASA Kennedy Space Center, NASA's Launch Services Program, Jet Propulsion Laboratory, SpaceX, Aerojet Rocketdyne, Lawrence Livermore National Laboratory, Auburn University, University of Colorado, Lowell Observatory, University of Maryland, New Mexico Tech with Magdalena Ridge Observatory, Northern Arizona University, and Planetary Science Institute.
LICIACube, DART's companion cubesat, is contributed by Agenzia Spaziale Italiana (ASI) and built by Argotec. LICIACube will be deployed from the DART spacecraft roughly five days prior to DART's impact to capture images of the event and its effects. LICIACube Italian partner institutions include Istituto Nazionale di Astrofisica (INAF) research facilities of Osservatorio Astronomico di Roma, Instituto di Astrofisica e Planetologia Spaziali, Astronomical Observatory of Trieste, Osservatorio Astronomico di Padova, and Arcetri Astrophysical Observatory, and also L'Istituto di Fisica Applicata "Nello Carrara" (IFAC), Politecnico di Milano, and Universita di Bologna.
Illustration of ESA's Hera spacecraft and its two companion cubesats investigating Didymos B and the crater produced by DART's impact. (Credit: ESA)
The Hera mission, a program in the European Space Agency's (ESA) space safety and security activities, is planned to launch in 2024 and rendezvous with the Didymos system in 2026, roughly four years after DART's impact. During Hera's mission, the main spacecraft and its two companion cubesats will conduct detailed surveys of both asteroids, with particular focuses on the crater left by DART's collision and a precise determination of the mass of Didymos B. Hera's detailed post-impact investigations will substantially enhance the planetary defense knowledge gained from DART's asteroid deflection test.
The two missions, DART and Hera, are being designed and operated independently, but their combination will boost the overall knowledge return to a significant degree. NASA's DART mission is fully committed to international cooperation, and ESA's Hera team members are welcomed as full members of the DART team, to contribute to DART's planetary defense investigations and to fully inform Hera's mission.
Both DART and Hera team members are part of the largely international collaboration known as AIDA—Asteroid Impact and Deflection Assessment. AIDA is the international collaboration among planetary defense and asteroid science researchers that will combine the data obtained from NASA's DART mission, which includes ASI's LICIACube, and ESA's Hera mission to produce the most accurate knowledge possible from the first demonstration of an asteroid deflection technology. AIDA is the combined effort of the DART, LICIACube, and Hera teams, along with other researchers worldwide, to extract the best possible information for planetary defense and Solar System science from these groundbreaking space missions. The AIDA collaboration exemplifies the acknowledgment that planetary defense is an international effort and that scientists and engineers around the world seek to solve problems related to planetary defense through international collaborations. | 0.873526 | 3.901132 |
Nobel Prize 2019 in Physics awarded to James Peebles, Michel Mayor and Didier Queloz
The Nobel Prize in Physics 2019 was awarded to James Peebles and jointly to Swiss astronomers Michel Mayor and Didier Queloz for their discovery of an exoplanet.
The 2019 Nobel Prize in Physics was awarded to James Peebles in one half for theoretical discoveries in physical cosmology and other half jointly to Michel Mayor and Didier Queloz for the discovery of an exoplanet.
The Nobel Prize announcement was done by the Secretary-General of the Royal Swedish Academy of Sciences, Goran K. Hansson.
The Nobel Prize in Physics 2019 recognises the work in understanding the structure and history of the universe and the first discovery of an exo-planet, as the discoveries have completely changed the conception of the world.
Nobel Prize in Physics 2019 winners
1. James Peebles
The Nobel laureate's theoretical framework on physical cosmology, which he developed over two decades, has formed the core foundation of the modern understanding of the history of the Universe, starting from the Big Bang to present.
Peebles had built upon the work done by Albert Einstein on the origin of the Universe by understanding the time succeeding the Big Bang.
2. Michel Mayor and Didier Queloz
Michel Mayor and Didier Queloz have been honoured with the 2019 Nobel Prize for their work in discovering unknown worlds. The duo made the first discovery of an exoplanet, orbiting a solar-type star, 51 Pegasi in 1995.
The discovery paved way for a revolution of kinds in astronomy, as over 4000 exoplanets have been found since then in the Milky Way galaxy. Many new worlds have been discovered of different sizes, forms and orbits including many super-earths.
Nobel Prize in Physics 2019 winners: Background
James Peebles is an Albert Einstein Professor of Science at the Princeton University, US. Peebles’ theoretical framework has formed the basis of the contemporary ideas of the universe.
His work revealed that the matter known to humans including planets and stars make up only five percent, while the remaining 95 percent is made up of unknown dark matter.
Michel Mayor and Didier Queloz both are professors at the University of Geneva. Queloz also teaches at the University of Cambridge in the UK.
In a historic discovery in 1995, the two swiss astronomers, using custom-made instruments detected a gaseous ball orbiting a star 50 light-years away from the Sun.
The astronomers, using the phenomenon known as the Doppler effect, proved that the planet known as 51 Pegasus b, was orbiting its star.
Nobel Prize in Physics 2018 winners
The 2018 Nobel Prize in Physics was awarded in two halves as well, one half to Arthur Ashkin for inventing optical tweezers and the other half jointly to Gérard Mourou and Donna Strickland for their method of generating high-intensity and ultra-short optical pulses. | 0.819518 | 3.235032 |
A new explanation for the Moon’s origin has it forming inside the Earth when our planet was a seething, spinning cloud of vaporized rock, called a synestia.
Lead author Simon Lock said, “The commonly accepted theory as to how the moon was formed is that a Mars-size body collided with the proto-Earth and spun material into orbit. That mass settled into a disk and later accreted to form the moon. The body that was left after the impact was the Earth. This has been the canonical model for about 20 years.”
Lock said that it’s a compelling story but probably wrong. Getting enough mass into orbit in the canonical scenario is actually very difficult, and there’s a very narrow range of collisions that might be able to do it.”
“There’s only a couple-of-degree window of impact angles and a very narrow range of sizes … and even then some impacts still don’t work.”
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Co-author Sarah Stewart, a professor of Earth and planetary sciences at the University of California, Davis said, “This new work explains features of the moon that are hard to resolve with current ideas.”
“This is the first model that can match the pattern of the moon’s composition.”
The researchers noted that tests have shown that the isotopic “fingerprints” for both the Earth and moon are nearly identical, suggesting that both came from the same source. But in the canonical story, the moon formed from the remnants of just one of the two colliding bodies.
It’s not just similarities between the Earth and moon that raise questions about the conventional wisdom — their differences do as well.
Many volatile elements that are relatively common on Earth, such as potassium, sodium, and copper, are far less abundant on the moon.
Lock said, “There hasn’t been a good explanation for this.”
“People have proposed various hypotheses for how the moon could have wound up with fewer volatiles, but no one has been able to quantitatively match the moon’s composition.”
The scenario outlined by Lock and colleagues still begins with a massive collision, but rather than creating a disc of rocky material, the impact creates the synestia.
Lock said, “It’s huge. It can be 10 times the size of the Earth, and because there’s so much energy in the collision, maybe 10 percent of the rock of Earth is vaporized, and the rest is liquid … so the way you form the moon out of a synestia is very different.”
The phenomenon includes a “seed” — a small amount of liquid rock that gathers just off the center of the doughnut-like structure. As the structure cools, vaporized rock condenses and rains down toward the center of the synestia. Some of the rain runs into the moon, causing it to grow.
Lock said, “The rate of rainfall is about 10 times that of a hurricane on Earth. Over time, the whole structure shrinks, and the moon emerges from the vapor. Eventually, the whole synestia condenses and what’s left is a ball of spinning liquid rock that eventually forms the Earth as we know it today.”
Lock said that the model addresses each of the problems with the canonical model for the moon’s creation.
Since both the Earth and moon are created from the same cloud of vaporized rock, they naturally share similar isotope fingerprints. The lack of volatile elements on the moon, meanwhile, can be explained by it having formed surrounded by vapor and at 4,000‒6,000 degrees Fahrenheit.
Lock said, “This is a dramatically different way of forming the moon. You just don’t think of a satellite forming inside another body, but this is what appears to happen.”
Lock was quick to note that the work is still taking shape.
He said, “This is a basic model. We’ve done calculations of each of the processes that go into forming the moon and show that the model could work, but there are various aspects of our theory that will need more interrogation.
“For example, when the moon is in this vapor, what does it do to that vapor? How does it perturb it? How does the vapor flow past the moon? These are all things we need to go back and examine in more detail.”
The study was published this week in the Journal of Geophysical Research: Planets. | 0.827386 | 3.470374 |
Crescent ♏ Scorpio
Moon phase on 30 August 2098 Saturday is Waxing Crescent, 4 days young Moon is in Scorpio.Share this page: twitter facebook linkedin
Previous main lunar phase is the New Moon before 3 days on 26 August 2098 at 15:52.
Moon rises in the morning and sets in the evening. It is visible toward the southwest in early evening.
Moon is passing first ∠0° of ♏ Scorpio tropical zodiac sector.
Lunar disc appears visually 0.1% wider than solar disc. Moon and Sun apparent angular diameters are ∠1902" and ∠1901".
Next Full Moon is the Harvest Moon of September 2098 after 11 days on 10 September 2098 at 17:33.
There is low ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at big angle, so their combined tidal force is weak.
The Moon is 4 days young. Earth's natural satellite is moving from the beginning to the first part of current synodic month. This is lunation 1220 of Meeus index or 2173 from Brown series.
Length of current 1220 lunation is 29 days, 8 hours and 24 minutes. It is 2 hours and 8 minutes shorter than next lunation 1221 length.
Length of current synodic month is 4 hours and 20 minutes shorter than the mean length of synodic month, but it is still 1 hour and 49 minutes longer, compared to 21st century shortest.
This New Moon true anomaly is ∠10.1°. At beginning of next synodic month true anomaly will be ∠26.9°. The length of upcoming synodic months will keep increasing since the true anomaly gets closer to the value of New Moon at point of apogee (∠180°).
4 days after point of perigee on 26 August 2098 at 01:27 in ♌ Leo. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 8 days, until it get to the point of next apogee on 7 September 2098 at 19:51 in ♒ Aquarius.
Moon is 376 778 km (234 119 mi) away from Earth on this date. Moon moves farther next 8 days until apogee, when Earth-Moon distance will reach 405 924 km (252 229 mi).
1 day after its descending node on 29 August 2098 at 10:54 in ♎ Libra, the Moon is following the southern part of its orbit for the next 13 days, until it will cross the ecliptic from South to North in ascending node on 12 September 2098 at 21:33 in ♈ Aries.
13 days after beginning of current draconic month in ♈ Aries, the Moon is moving from the second to the final part of it.
7 days after previous North standstill on 22 August 2098 at 13:44 in ♊ Gemini, when Moon has reached northern declination of ∠28.393°. Next 4 days the lunar orbit moves southward to face South declination of ∠-28.462° in the next southern standstill on 4 September 2098 at 08:51 in ♑ Capricorn.
After 11 days on 10 September 2098 at 17:33 in ♓ Pisces, the Moon will be in Full Moon geocentric opposition with the Sun and this alignment forms next Sun-Earth-Moon syzygy. | 0.848363 | 3.121609 |
July 7, 2004
A Gemini team led by Karl Galzebrook of Johns Hopkins University has just released some spectacular results obtained from the Gemini Deep Deep Survey (GDDS) in the British journal Nature.
The team found that at last two-thirds of massive galaxies appeared after the first 3 billion years following the Big Bang. However, a significant fraction of them are already in place in the early Universe.
The GDDS was completed using the Gemini North telescope and the Gemini Multi-Object Spectrograph (GMOS-N). The team observed four widely-separated 30 arcmin2 fields. The spectroscopic exposure time for each field was about 30,000 seconds. The spectrograph was operated in the Nod & Shuffle mode. This technique enables the removal of contamination by the earth’s atmospheric luminescence to a high degree. Spectra of several hundred distant galaxies were obtained and measured.
As has been suspected, massive, evolved galaxies are found at an epoch earlier than half of the present age of the universe. However, the discovery of such massive, evolved galaxies at much greater distances than expected – and hence at earlier times in the history of the universe – is a challenge to our understanding of how galaxies form. Hierarchical galaxy formation is the model whereby massive galaxies form from an assembly of smaller units. The most massive objects form more slowly, thus appear last. The GDDS results challenge this model.
The GDDS represent a unique and extremely deep spectroscopic data set providing significant new insights into galaxy populations in the era of a few billion years after the Big Bang.
For more details see the News and views Nature article “Old before their time” by Gregory D. Wirth (Nature, vol. 430, 8 July 2004, pp. 149-150) and the original GDDS III article “A high abundance of massive galaxies 3-6 billion years after the Big Bang” (Nature, vol. 430, 8 July 2004, pp. 181-184). The figures are from this article.
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The GEMMA Podcast
A podcast about Gemini Observatory and its role in the Era of Multi-Messenger Astronomy. Featuring news related to multi-messenger astronomy (MMA), time-domain astronomy (TDA), our visiting instrument program, and more through interviews with astronomers, engineers, and staff both here at Gemini (North and South) and abroad. | 0.82776 | 3.548703 |
by Kim Malville
What’s happening in the skies this month?
Jupiter dominates the skies this month. It is in retrograde in Gemini, moving slowly to the west. Try out some binoculars to view its brightest four inner moons, which nightly change their positions.
In the early evening the constellation of Orion will be due south. Look for the three stars of the Hunter’s belt. Above the belt to the left is the red giant Betelgeuse. On the lower right is the bright blue star Rigel. The belt stars align with the bright Dog Star Sirius. The Hunter is Greek. In Hindu mythology, this constellation is the father of humankind, Prajapati. The star Sirius is Rudra, the fierce form of the god Shiva. He has just shot an arrow into Prajapati, to prevent him from having intercourse with his daughter, Rohini, the bright red star that we know as Aldebaran, the red eye of Taurus the Bull. The arrow appears as the three stars in the body of Prajapati. These are two remarkably different stories!
February 1: Look to the western skies about 45 minutes after sunset. If you look carefully you will find Mercury below a thin sliver of the moon.
February 10: Jupiter is above and to the left of the moon.
Rosetta wakes up and calls home
As I write this column on 20 January 2014, the Rosetta Spacecraft awakened from two years of hibernation and called to us. The spacecraft, which carries a 220-pound lander called Philae, has been hibernating for most of the past three years to save power. It is due to reach its destination, the 2.4-mile diameter comet called 67P/Churyumov-Gerasimenko in August. The lander is named after the Nile island Philae where an obelisk was found that helped decipher the Rosetta Stone.
At a distance of 500 million miles from Earth and just inside of Jupiter’s orbit, radio transmissions, traveling at the speed of light, take 45 minutes to reach the earth. (Reminds me of a joke: When the airline flight attendant asked the photon if he had any bags to check, he said, “No, I’m travelin’ light.”).
Rosetta was put into hibernation in June 2011 when its path took it so far from the Sun that its solar panels would harvest minimal energy. Starting in four months Rosetta will begin firing its thrusters to begin zeroing in on the target comet. Today, the separation is nine million km. By mid-September, it will have been reduced to just 10km. The plan is for Rosetta to escort the comet for 17 months, as it moves closer towards the Sun, monitoring the changes that take place.
Comets are the pristine remains of the gas cloud that produced our solar system some 4.6 billion years ago. The mission should provide more clues about how the solar system came into existence, much like the Rosetta Stone, which provided a blueprint for deciphering ancient Egyptian hieroglyphs. Comets are giant ice blobs mostly covered by a dark tar-like substance. The oceans of the earth may have been formed by hundreds of thousands of comets hitting the earth some three billion years ago. These comets may have contained organic molecules, such as amino acids or even more complex molecules, which could have been the seeds for life on earth. These wonderful objects may thus have carried both water and life to the earth.
One of Rosetta’s first tasks will be to scout for a suitable landing location for its piggyback-riding Philae probe. It is outfitted with twin harpoons laced with tethers that will be fired into the comet’s surface to anchor Philae and keep it from bouncing back into space after touchdown.
Philae will drill into the comet and extract core which will be analyzed by organic chemistry experiments. Those results will be beamed up to Rosetta, which will in turn be transmitted to Earth.
The mystery rock on Mars
After 10 years of wheeling around Mars, NASA’s Opportunity rover has discovered a new rock shaped like a jelly doughnut that appeared out of thin Martian air.
In late December, Opportunity snapped an image of a rocky outcropping with no rock the size and shape of a jelly doughnut. But 12 days later, when the rover took another picture of the same area, the jelly doughnut-like rock was there. The Opportunity team has come up with two theories to explain the rock’s mysterious and sudden appearance. One idea is that Opportunity’s wheels somehow flicked the rock out of the ground and into field of view of Opportunity. The second theory is that the rock was thrown into place when a meteorite hit the planet some distance away. In any case, the brightness of the rock indicates that its surface is newly exposed to light and may reveal something intriguingly new.
The Opportunity team has just started to take a closer look at the rock to figure out its composition. So far, those results have been baffling. For example, they discovered that the red “jelly” part is very high in sulfur and magnesium, and that it has twice as much of the element manganese as anything they’ve ever seen on Mars. The Opportunity team reports that they are “completely confused”, and having a wonderful time, arguing amongst themselves. By the time you read this column ten days from now, perhaps the mystery will be solved.
A new supernova
One day after Rosetta called home, an exploding star was discovered by a group of students at the University College London. It is the closest supernova found in more than 30 years and should be a cornucopia of astronomical information. Almost as remarkable, it was discovered beneath the thick atmosphere of London. This kind of supernova is produced by white dwarf stars when they collide with each other or when a white dwarf become unstable because a neighboring star dumps too much gas on it. The supernova is in the galaxy M82, otherwise known as the Cigar Galaxy, about 12 million light-years away in the constellation Ursa Major, the Big Dipper. Instead of a delay of 45 minutes from Rosetta, there has been a delay of 12 million years for these photons to reach us. Come to think of it, light is not all that fast! | 0.899317 | 3.051079 |
From going distances that humans can’t reach to ensuring our safety, rockets improve our lives in more ways than you might think. Sit back and count down to these rocket facts that’ll make you realize the science behind these projectiles.
- NASA has launched a total of 166 manned rockets to space missions.
- Rockets have been used in space travel for over 70 years.
- NASA rockets cost $500 million to build and launch.
- China has launched more rockets than any country in the world.
- There are 4 types of rockets: solid-fuel, liquid fuel, ion, and plasma rockets.
- The term rocket comes from the Italian rocchetta, which translates to “bobbin” or “little spindle.”
- The Chinese were experimenting with rocket mechanisms as early as 995 AD in the Song dynasty.
- The 4 main parts of a rocket are the nose cone, fins, rocket body, and engine.
- The cargo on a rocket is called the payload.
- A rocket must travel at 7 miles per second to escape the Earth’s gravity.
- Astronautics is the study of rocket science.
- Solid-fuel rockets were the first large-scale rockets.
- Robert H. Goddard is known as the father of modern rocketry, inventing the more powerful liquid-fuel rockets.
- Ion rockets use electrical energy from solar cells.
- Plasma rockets are still in development. They are powered through stripping negative electrons from hydrogen atoms
- The first rockets were Chinese fireworks.
- Rockets work more efficiently in space than in our atmosphere.
- Most rockets are launched from the ground because the rocket exhaust thrust is bigger and stronger than the rocket’s weight on Earth.
- It takes a NASA space shuttle 8-1/2 minutes to get to space.
- The smallest space rocket stands 33 feet tall.
A rocket ship beats the vacuum of space.
Space is a giant vacuum with no air or atmosphere. Spacecraft can move through the vacuum through its engines. Rocket engines work through a chemical reaction that pushes it forward. The resulting rocket exhaust is expelled in the opposite direction of the ship at high speeds. This enables the ship to navigate and sustain its trajectory through space. That’s definitely one of the rocket facts to keep in mind.
Rockets were first used as weapons.
During the war between the Chinese empire and Mongol invaders, the Chinese devised a gunpowder-fueled arrow. The retreating Mongols described these projectiles as “arrows of flying fire.” These fire-arrows were the first solid-propellant rockets. From there, further experiments with cased gunpowder led to the development of military rockets and missiles.
You can make a rocket at home.
Learning how to build a rocket can help you understand the science behind it better. You may not believe it, but you can build a simple rocket out of random stuff lying around your house. With paper and a fizzy tablet, you can demonstrate the mechanism and principles of a rocket.
Rocket power is measured in thrust.
Rockets are self-propelling projectiles. Using up the fuel in the body, the rocket exhaust keeps it moving in the same trajectory. The force inside a rocket’s engine is called thrust. Since rockets weigh millions of kilograms, they must exert the same amount of force to propel itself through and out of the atmosphere.
The first rocket in space was launched by Germany in 1942.
Germany launched the first rocket capable of reaching space in 1942. Dubbed the V-2 rocket, it was not actually intended for space travel. Instead, the V-2 was constructed as a ballistic missile during WWII. Nonetheless, it was revealed in a flight test to be the first man-made object to fly into space.
The first rocket was invented in China around 1100 AD
The rockets invented in the 10th century China used solid propellants and were mainly used as weapons and fireworks. It was not until the 1920s that rocket science was studied further. By the 1930s and 1940s, professional rocket engineering started to take off.
The largest rocket is over 300 feet tall.
Standing at 363 feet tall with a thrust of 7.6 million pounds, NASA’s Saturn 5 rocket is the largest one to date. The Saturn 5 was used for Lunar missions between the 1960s and early 1970s.
There is a Chinese legend about a rocket-powered chair.
With its origins tracing back to China, one of the first mentions of rockets as transportation was found in Chinese folklore. According to the legend, a Chinese official named Wan-Hu once assembled a rocket-powered flying chair. The chair had two large kites attached to either side, each equipped with 47 arrow rockets.
You can probably guess where this goes. On the scheduled takeoff, Wan Hu had his servants light the 47 fire arrows. The arrows did go off, but when the smoke cleared, Wan Hu and his chair were nowhere to be found. The gag is that if it did actually happen, he was probably just obliterated by the blast. Definitely one of the funnier rocket facts.
Liquid-fuel rockets are more powerful than solid-fuel rockets...
Solid-fuel rockets were invented first in 13th century China. However, it was liquid-fuel rockets that eventually paved the way for space travel. Liquid-fuel rockets are equipped with more reactive oxidizers, causing a stronger chemical reaction and stronger propulsion. To escape Earth’s gravity, spacecraft must travel 4.9 miles per second – which is almost the speed of the world’s fastest production sports car.
...but solid-fuel rockets are safer.
With great power comes great responsibility – and sometimes, great danger. Liquid-fuel rockets have more chemical components, so it’s more volatile. It costs more to store and handle liquid-fuel rockets safely.
Rockets have been used for rescue operations.
Aside from military ammo and space travel, rockets also serve a purpose in safety and rescue. In the 19th and 20th centuries, rockets were used to launch lines to damaged ships that can’t be reached. From these lines, a buoy was sent through for passengers to grasp and escape with. Ships even used to have a designated rocket brigade, or a group of responders who would fire the rockets.
Rockets launch in 3 stages.
Rockets aren’t one solid hunk of metal. If you’ve ever seen a rocket in space on cartoons or TV shows, you’d notice how it breaks apart. Essentially, a rocket breaks off into sections while in flight. The first stage of a rocket launch is ignition. From takeoff, the burning rocket exhaust will push the rocket forward. Once the fuel runs out, the section will break off. From there, the second stage fuel reserve will be used until the payload reaches orbit.
Rockets are loud.
Rocket sound is so loud, it can destroy the rocket. When a space rocket is launched, acoustic waves can generate up to 180db of sound – which is almost as loud as a nuclear explosion. To avoid this, a sound suppressor system is built into the launch pad. The system uses water to absorb the sound waves from the rocket as it launches.
The Saturn V rockets were the most successful rockets ever launched.
Not only is it the biggest rocket, but it is also the most successful one with 13 completed launches. Currently, at least two Saturn V stages from the Apollo missions are still in space. NASA is still tracking them as Near-Earth Objects. How’s that for amazing rocket facts?
Rockets have reached the farthest known place from Earth.
As of 2018, Voyager 1 and 2 are 13 billion miles (21 billion km) away from Earth. They twin rockets are now the most distant human made objects from the planet. The satellites reached a previously unseen region of space known as the heliosheath in early 2009. Currently, they are heading for the heliopause, which is technically the end of the solar system.
The first example of rocket science was from a wooden duck in Ancient Greece.
It wasn’t exactly a rocket, but it was the first known experiment to demonstrate the principles of rocket science. According to Ancient Greek literature, a man named Archytas flew a wooden pigeon through a line using a steam exhaust.
Elton John performed his hit Rocket Man at the launch of the Discovery Spacecraft.
The legendary musician played the aptly-named hit track at the Space Shuttle Discovery launch site in 1998.
There is a comic character named Rocket.
Guardians of the Galaxy’s resident raccoon was apparently inspired by The Beatles’ track, Rocky Raccoon. How’s that for rocket facts?
Huntsville, Alabama is known as Rocket City.
The U.S. town of Huntsville, Alabama is called Rocket City because it basically started America’s legacy with space travel. The rockets that launched the Lunar missions were all constructed in Huntsville. NASA’s Space Camp was also founded and currently based in Huntsville.
Some flares work like rockets.
Rockets can also serve as distress signals. In fact, most modern flares use rocket mechanisms. Rocket flares use a trigger and launching system similar to spacecraft and missiles.
A rocket caused the first space-related death.
The first space-related fatality occurred when a rocket exploded at the Soviet Union’s Baikonur Space Center in Kazakhstan. The explosion killed 165 people, including the head of Soviet rocket forces. The accident was denied until 1990.
The Space Race caused a lot of rocket explosions.
The Space Race was a period in the 1960’s where the Soviet Union and the U.S. competed in space travel. At a time where rocket engineering wasn’t fully understood yet, numerous flight tests ended up in flames.
Rockets are extremely hot.
When a rocket is active, temperatures in the main engine combustion chamber can reach 3,315.6°C.
There is no margin of error for rockets.
One of the important rocket facts to note: The tragic explosion of the Space Shuttle Challenger killed 7 crew members. Upon inspection, the sudden explosion was triggered by faulty O-rings in the shuttle’s right solid rocket booster.
Rockets help us gather data.
Sounding rockets are sent to space carrying instruments that take readings from 50 kilometers (31 mi) to 1,500 kilometers (930 mi) above the Earth’s surface. We owe most of what we know about space to these rockets.
William Leitch first proposed the concept of using rockets for space.
In his 1861 essay, A Journey Through Space, Leitch first wrote about rocket-fuelled space flight.
The term ‘rocket’ was first used in the 17th century.
The term originated from the Italian rocchetto (a rocket) in 1610. However, the term rocket ship was not used until 1927.
Rockets are sensitive.
One of the scarier rocket facts: Even a minor error can end catastrophically for rockets and the crew aboard it. There has been one case of a Soyuz rocket suddenly having an emergency landing. Thankfully, the crew was unharmed. However, an investigation revealed a faulty sensor that was damaged during assembly.
Rockets are used to deliver cargo to the International Space Station.
There’s definitely no FedEx in space, so NASA has to use rockets to send supplies to its home base. However, the rise of 3D printing technology now offers a cheaper and more efficient alternative.
SpaceX wants to colonize Mars.
The brainchild of Elon Musk, Space Exploration Technologies Corp. seeks to discover and reach life on Mars as soon as possible – through rockets, of course. However, SpaceX also delivers cargo to the ISS. Isn’t that one of the rocket facts to look forward to? | 0.857708 | 3.099514 |
Last command sent to ESA's Planck space telescope
23 October 2013ESA's Planck space telescope has been turned off after nearly 4.5 years soaking up the relic radiation from the Big Bang and studying the evolution of stars and galaxies throughout the Universe's history.
|Planck and the cosmic microwave background. Credit: ESA|
Project scientist Jan Tauber sent the final command to the Planck satellite this afternoon at 12:10:27 UT, marking the end of operations for ESA's 'time machine'.
Launched in 2009, Planck was designed to tease out the faintest relic radiation from the Big Bang – the Cosmic Microwave Background (CMB). The CMB preserves a picture of the Universe as it was about 380 000 years after the Big Bang, and provides details of the initial conditions that led to the Universe we live in today.
"Planck has provided us with more insight into the evolution of the Universe than any mission has before," says Alvaro Giménez, ESA's Director of Science and Robotic Exploration.
"Planck's picture of the CMB is the most accurate 'baby photo' of the Universe yet, but the wealth of data still being scrutinised by our cosmologists will provide us with even more details."
The mission began drawing to a close in August, when the satellite was nudged away from its operational orbit around the Sun-Earth 'L2' point towards a more distant long-term stable parking orbit around the Sun.
In the last weeks, the spacecraft has been prepared for permanent hibernation, with the closing activities using up all of the remaining fuel and finally switching off the transmitter.
Jan Tauber sent the final command to Planck from ESA/ESOC on 23 October 2013.
"It is with much sadness that we have carried out the final operations on the Planck spacecraft, but it is also a time to celebrate an extraordinarily successful mission," says Steve Foley, the Planck Spacecraft Operations Manager at ESA's European Space Operations Centre (ESOC).
"Planck was a sophisticated spacecraft flying a complex mission, but with tight teamwork from the mission controllers, flight dynamics specialists, ground stations and our industrial partners, Europe received excellent scientific value for its investment," adds Paolo Ferri, Head of Mission Operations.
ESA member states provided key technologies such as the innovative cooler that allowed the mission's instrumentation to be maintained at just one-tenth of a degree above the coldest temperature reachable in the Universe, -273.15°C, so that the spacecraft's own heat did not swamp the signal from the sky. This enabled temperature variations of just a few millionths of a degree to be distinguished in the CMB.
But cooling instruments to these extreme temperatures cannot be maintained forever and, indeed, the High Frequency Instrument (HFI) exhausted its liquid helium coolant in January 2012, just as expected.
The Low Frequency Instrument (LFI) meanwhile was able to operate at somewhat higher temperatures using the remaining two coolers and continued making observations until 3 October. After conducting post-science activities, it was manually switched off on 19 October.
The mission's original target was to complete two whole surveys of the sky but, in the end, Planck completed five full-sky surveys with both instruments. Moreover, by mid-August, LFI had completed its eighth survey of the entire sky.
|New cosmic recipe. Credit: ESA|
"Planck continued using LFI right up until last week, exceeding all expectations and providing us with bountiful data to work with in the future," says Jan Tauber, ESA's Planck project scientist.
The first detailed image of the faint signal from the CMB from Planck was released earlier this year, after foreground emission from our own Milky Way Galaxy as well as all other galaxies had been removed. These latter data resulted in a new catalogue of objects, including many never-before-seen galaxy clusters in the distant Universe.
The 2013 data release provided revised values for the relative proportions of the ingredients of the Universe, namely normal matter that makes up stars and galaxies, dark matter, which has thus far only been detected indirectly by its gravitational influence, and dark energy, a mysterious force thought to be responsible for accelerating the expansion of the Universe.
"Planck has given us a fresh look at the matter that makes up our Universe and how it evolved, but we are still working hard to further constrain our understanding of how the Universe expanded from the infinitely small to the extraordinarily large, details which we hope to share next year," says Dr Tauber.
For more on Planck's science highlights, see our article published on 18 October: Celebrating the legacy of ESA's Planck mission.
Launched in 2009, Planck was designed to map the sky in nine frequencies using two state-of-the-art instruments: the Low Frequency Instrument, which includes the frequency bands 30-70 GHz, and the High Frequency Instrument, which includes the frequency bands 100-857 GHz. HFI completed its survey in January 2012, while LFI continued to make science observations until 3 October 2013, before being switched off on 19 October.
Planck's first all-sky image was released in 2010 and the first scientific data were released in 2011. The first image of the CMB was released in March 2013. The next set of cosmology data will be released in 2014.
The Planck Scientific Collaboration consists of all the scientists who have contributed to the development of the mission, and who participate in the scientific exploitation of the data during the proprietary period. These scientists are members of one or more of four consortia: the LFI Consortium, the HFI Consortium, the DK-Planck Consortium, and ESA's Planck Science Office. The two European-led Planck Data Processing Centres are located in Paris, France and Trieste, Italy.
The LFI consortium is led by N. Mandolesi, Agenzia Spaziale Italiana ASI, Italy (deputy PI: M. Bersanelli, Universita' degli Studi di Milano, Italy), and was responsible for the development and operation of LFI. The HFI consortium is led by J.L. Puget, Institut d'Astrophysique Spatiale in Orsay, France (deputy PI: F. Bouchet, Institut d'Astrophysique de Paris, France), and was responsible for the development and operation of HFI.
For further information, please contact:
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
ESA Planck Project Scientist
Tel: +31 71 565 5342
(This article was originally published on ESA's Space Science Portal) | 0.877848 | 3.1634 |
Polar plots of the solar wind speed
These radial plots of the solar wind speed combine data from all three of Ulysses' polar orbits of the sun, each of which take six years to complete. The blue coloured lines represent the outward interplanetary magnetic field; the red coloured lines the inward IMF. The first orbit occurred during solar minimum and showed slow wind over the equator and a fast wind over the poles. The second orbit showed fast and slow winds at all latitudes, consistent with solar maximum activity. Ulysses has completed more than three quarters of the third orbit, occurring around the current solar minimum cycle. While much of the data gathered thus far is consistent with typical solar minimum activity, surprisingly, it also indicates that the solar wind is about 25 percent less powerful than it was in the previous solar minimum cycle. The Sun's magnetic field flips approximately every 11 years, which explains the reversal of the red and blue IMF lines in the third orbit. A timeline and line graphs showing sunspot frequency are shown at the bottom for comparison.
The images are from the ESA/NASA Solar and Heliospheric Observatory (SOHO) and High-Altitude Observatory at Mauna Loa. | 0.822664 | 3.512189 |
Sky watchers should be alert for fireballs in the nights ahead. Forecasters say Earth might be heading for a swarm of gravelly debris from comet Encke. If so, meteoroids the size of pebbles and small stones hitting Earth's atmosphere at 25 km/s would produce a slow drizzle of very bright fireballs flying out of the constellation Taurus--hence the name "Taurids." The display is expected to peak with a few fireballs every hour during the nights of Nov. 5-12.
NASA's network of all-sky meteor cameras is already picking up some Taurid fireballs--"7 in the past two nights and 11 altogether since Halloween," reports Bill Cooke of the Meteoroid Environment Office. Here are their orbits: In the orbital diagram, the location of Earth is denoted by a red splat. The orbits of the meteoroids (yellow) roughly match that of parent Comet Encke (orange), confirming their association with the Taurid debris swarm.
"What always strikes me about the Taurids," notes Cooke, "is how deeply they penetrate Earth's atmosphere. On average, they make it to an altitude of 44 miles. Contrast this to the recent Orionids, which burn up at an average altitude of 58 miles. Part of this is due to the speed difference: Taurids are slow (27 km/s) while Orionids are fast (66 km/s). In addition, many Taurids are made up of stronger stuff than the Orionids." http://www.spaceweather.com | 0.819565 | 3.071829 |
With the start of each New Year, astronomers everywhere look forward with anticipation to a variety of celestial events, everything from meteor showers, planetary conjunctions, and the occasional comet.
But nothing gets them quite so stirred up as does the prospect of seeing one of Nature’s greatest spectacles: a total solar eclipse of the Sun.
In terms of sheer awe and grandeur nothing rivals it, and that’s not just hyperbole on my part. If there is a total solar eclipse happening somewhere then you can bet that thousands of astronomers from all over the
world will begin making plans months (or even years) in advance to be within the path of totality. It’s been 26 years since America last saw a total solar eclipse and on August 21st of 2017 we will finally have another.
On that day, the moon’s shadow will race across the U.S. from the Pacific northwest to the southeastern Atlantic seaboard, most Americans will literally be within a day’s drive of the path of totality. But let’s backup for just a moment and talk about what an eclipse is.
Simply put, an eclipse is what happens when either the moon or the Earth blocks out some, or all, of the light from the Sun. In a lunar eclipse the Earth passes in front of the Sun and then casts its shadow upon the moon.
This always happens during a full moon phase when the Earth is positioned in between the Sun and moon.
A solar eclipse always happens at new moon, when the moon lies in between the Sun and the Earth and its shadow gets cast somewhere upon the Earth. Since we have a full and new moon each month you may well wonder why it is that we don’t see an eclipse of some sort each month as well. The reason we don’t has to do with the moon’s orbit around the Earth, which happens to be at an inclined angle of about 5 degrees relative to the Earth’s orbital plane around the Sun.
The upshot of all this is that to have an eclipse you must have the Sun, moon, and Earth all aligned in just the right way at just the right time. The points where the orbital planes of both the Earth and the moon intersect is called a “node”. To get a solar eclipse then, the moon must be at a node during new moon phase, something that doesn’t always happen each and every month. And it’s not just a matter of timing and position, it’s also a matter of distance. Especially in order to get a total solar eclipse.
You see, the moon’s orbit around the Earth is elliptical in shape and this means that sometimes it’s a little closer to us and at other times it’s a little bit further away. Why is this important? To answer that you must appreciate an incredible cosmic coincidence. Our Sun is some 864,000 miles in diameter, which is about 400 times the size of the moon’s 2,160-mile diameter. The Sun also happens to be 400 times further away from us than the moon is.
These two facts mean that the discs of the Sun and moon, from our perspective here on Earth, appear to be the same size and that’s why we can see the new moon cover up the disc of the Sun during a total solar eclipse. But note that the moon must be not only at a node and at new phase during a total solar eclipse- it also must be at just the right distance within its elliptical orbit to cover the Sun’s disc so precisely.
You and I are lucky to be living in just the right place and at just the right time to see eclipses of this sort because the odds of such cosmic coincidences happening with such precision in other solar systems are very low.
I mentioned at the beginning of the program that the moon’s shadow will race across the
United States on August 21st, so now might be a good time to talk about the anatomy of shadows. During an eclipse the moon casts a cone-shaped shadow out into space and then onto the Earth’s surface. This shadow consists of two parts. The narrow, darkest, and innermost part of the shadow is known as the “umbra”. If you want to see a total solar eclipse, then you must be somewhere within the umbra. The umbra may be as much as 167 miles wide during some eclipses but on August 21st it will only average about 65 miles in width.
The outermost part of the shadow, which is also quite broad and much lighter than the umbra, is called the “penumbra”. If you are viewing an eclipse from within the penumbra, then you will only see a partial solar eclipse. There is one other solar eclipse type besides a total and partial eclipse I want to mention and that’s an “annular” eclipse. With an annular eclipse the moon is at its furthest most distance from Earth so the lunar disc is not quite large enough to entirely cover the Sun’s disc.
This will leave a thin, but very bright, ring (or “annulus”) around the edges of the moon’s disc. During the early morning hours of August 21st, the moon’s shadow will first strike the Earth out in the North Pacific. At 10:15 AM PDT it will make landfall along the Oregon coast. From there the path of totality will cut a swath through Idaho, Montana, Wyoming, Nebraska, Kansas, Missouri, Illinois, Kentucky, Tennessee, North Carolina, Georgia, and then South Carolina before heading on out into the Atlantic by around 2:49 PM EDT.
The penumbra will cover almost all North America and here in Little Rock you will get to see a partial eclipse beginning at around 11:47 AM CDT when you will see the lunar disc make first contact with the Sun. Eclipse maximum will occur at around 1:18 PM when the new moon will have covered nearly 90% of the Sun. The show ends here in Little Rock by 2:46 PM when the moon’s edge finally clears the Sun’s disc. Now, here is the usual word of warning when it comes to looking at an eclipse: Do Not Look Directly At The Sun! Even if 99% of the solar disc is blocked, the remaining 1% is still 4,000 times brighter than a full moon.
And by no means should you observe the Sun through any kind of optical aid that lacks proper filters. If you are just observing with your eye then be aware that regular sunglasses will NOT be suitable. #14 grade welders glass is a good example of a safe solar viewing filter. And there are others that are available commercially online.
Special Mylar glasses such as these can be found online if you search the internet for “eclipse glasses”. Here is another safe and very cool way to observe the eclipse. Pay attention to the shadows around you, especially shadows under a tree or where the shadows from the tree are being cast upon any light-colored surface. You may notice hundreds of miniature eclipses being projected onto the ground, sidewalk, or the side of a house.
What the heck is happening here? Well the gaps in between the leaves are, in effect, acting as pinhole cameras. As the Sun’s light filters through the leaves it doesn’t just pass on through in a straight line, instead they become bent (or, “diffracted”) around the edges of the leaves that are creating the gaps and then projected as an image onto a surface.
Here’s the cool thing though, the physics of diffraction doesn’t demand that there be a round hole through which to project an image. Square-shaped openings will work just as well. If the gaps are sufficiently spaced the incoming light getting bent around the edges will all average out to create an image of the scene contained within the incident light. I wish that I could be here on the UALR campus to enjoy this spectacle with you but I am going for the REALLY big show, the Big Kahuna of eclipses – the total solar eclipse.
On August 21st I plan on being in Nebraska along the path of totality. If possible, I urge you to try and position yourself within the path of totality as well because this is where you will experience the true spectacle and majesty of a total solar eclipse. Moments before totality the ambient light becomes darker and somewhat eerie, it’s no wonder that for time immemorial humans have viewed these events with an impending sense of doom and disaster.
Animals begin to behave oddly: birds will start to roost and night time insects will begin to sing. During the last couple of minutes before totality, if you look to the northwest you may be able to see the moon’s shadow racing towards you. Thin, wavy lines of shadows known as shadow bands will appear on the ground and scientists
to this day do not yet fully understand how they are created. In the last seconds before totality the thin, crescent Sun suddenly breaks up into a series of reddish colored beads, known as Bailey’s Beads
This is the last of the Sun’s light breaking through valleys on the moon itself. This phenomenon will only last a moment and the very last bead to disappear creates a giant diamond ring in the sky. Then, in an instant, the moon’s shadow is upon you and totality has begun. The Sun now appears as a black disc in the sky and this is the only time during the eclipse that you are free to look at the Sun with your eyes or with binoculars. And believe me, you will want to.
During the next couple of minutes of totality, you can see a faint, pinkish ring encircling the Sun. This is the Sun’s chromosphere
, a thin layer forming a part of its atmosphere. With binoculars
, you will see what appears to be tongues of flame
flickering at the edges of the disc. These are solar prominence’s and they are super heated clouds of hydrogen gas
lifting off from the Sun. Stop to consider that any one of them is hundreds of thousands of miles long, many times longer than the Earth is wide.
Perhaps the most awesome sight of all will be the pearly white or pink colored halo
radiating out from the solar disc. This is the Sun’s outermost atmosphere, the corona, and it extends for millions of miles out into space. In fact, it is only during an eclipse that you will ever be able to see it naked eye
. But the show isn’t just restricted to what’s going on with the Sun.
If you look around the sky you will also see that a few bright stars such as Regulus in the constellation of Leo; planets such as Mercury, Mars, and Venus will also be on display. And then, after a couple of minutes the diamond ring makes another appearance, followed by the reappearance of Bailey’s Beads. You’ll need your solar glasses again at this point. But now the show is over and the new moon begins to work its way out from our line of sight to the Sun.
If you miss this show, fear not, because on April 8th, in the year 2024 the United States, Canada, and Mexico will be treated to another total solar eclipse. And guess what? The UALR campus will be within the path of totality. Okay, before I go here are a couple of suggested astronomy reads for the month.
The first is Sun, Moon, Earth: The History of Solar Eclipses, From Omens of Doom
to Einstein and Exoplanets by Tyler Nordgren
. This is your ideal guide for the upcoming eclipse. Nordgren packs in a lot of great historical information on how humans have perceived solar eclipses through time and how modern science has used them to confirm Einstein’s theory of relativity
. The content is informative while the prose is both breezy and lyrical.
Not bad for a book that comes in at just 264 pages long. The second book is Night Sky With the Naked Eye: How to Find Planets, Constellations, Satellites, and Other Night Sky Wonders Without a Telescope by Bob King. There are plenty of great astronomy blogs out there but if I had to recommend just one for the beginning stargazer it would have to be Bob King’s Astro Bob Blog. I have been in awe of Bob for many years with his ability to make accessible the wonders of the universe to the average person. His writing is always eloquent, funny, as well as informative and this book comes with a very high rating from me in terms of a book that you should have at your side whether you are just starting out in astronomy or even if you are a veteran stargazer.
As the title says, Night Sky With the Naked Eye is a guide to the many things you can see overhead without any kind of optical aid. Few people can make the magic of the night sky come alive to a reader like Bob King; get his book, read it, and, most importantly, use it.
Be sure and visit The Night Sky web page for all the latest happenings in your sky and, until next time, be sure and take a little time to step outside and look up in both awe and wonder. | 0.803684 | 3.674007 |
Humans have dreamed about living among the stars since we were first able to gaze upwards and hold abstract thoughts about the curious lights we saw. Astronomy and other knowledge systems about the celestial bodies have been ubiquitous around the world throughout history, and in some ways a reverence and awe for the heavens above seems to be one of the universal characteristics of humankind. Neat.
It comes as a shock and a huge buzzkill, then, to learn that humans just aren’t really cut out for living in space. Long-term exposure to the environment of outer space has been found to cause all sorts of serious health problems like damaged immune systems, mysterious space fevers, and even altered DNA. Yikes. One study out of Florida State University even found that former astronauts die as a result of cardiovascular ailments at a much higher rate than the general population. Is the chance to leave the Earth for a little while worth the health risks?
Yeah, I know. It’s totally worth it. Still, the health risks astronauts face are a huge barrier towards ever sustaining long-term space stations, colonies on the Moon or Mars, or perhaps someday sending generations of travelers away from the dying Earth to find a new home aboard interstellar ark starships. Perhaps someday sooner than we think…
NASA scientists this week identified one more threat that astronauts must face in the harsh, cold vacuum of space: herpes. Space herpes. Medical researchers at NASA’s Johnson Space Center found that herpes viruses reactivated in more than half of the crew members sent to the International Space Station as a direct result of their time in space. According to Dr. Satish K. Mehtahe who authored the new study of space herpes and other spaceflight-related virus reactivations, the phenomenon is thought to stem from the stress the human body faces during spaceflight and made worse by the discomfort of living aboard a cramped space station. Like any other stress Mehtahe says, this weakens astronauts’ immune responses and allows dormant viruses to flourish:
NASA astronauts endure weeks or even months exposed to microgravity and cosmic radiation—not to mention the extreme G forces of take-off and re-entry. This physical challenge is compounded by more familiar stressors like social separation, confinement and an altered sleep-wake cycle. During spaceflight there is a rise in secretion of stress hormones like cortisol and adrenaline, which are known to suppress the immune system. In keeping with this, we find that astronaut’s immune cells—particularly those that normally suppress and eliminate viruses—become less effective during spaceflight and sometimes for up to 60 days after.
Hopefully one day the people of the future will look back and laugh at the primitive 21st-century humans who had to launch flaming tubes of volatile gases into the air just to reach outer space. We’ll find a better way soon. EM Drive-powered craft? Space elevators? They’ve been discussed for years, and I’m sure we’re only a few decades away from Star Trek-like teleportation, right? All of that kooky quantum stuff has got to lead to something someday.
Ultimately, it will be more likely that we’ll find ways to genetically alter the human genome to make our squishy little bodies more conducive to space flight. Well, the bodies of those who can afford the treatment. As the first humans begin to flee the stink of the hot, dying Earth, it will be the mega-rich who will have access to the means to secure a ticket on the interstellar ark. The rest of us will be stuck here forever, doomed to only gaze longingly at the skies like so many Earthbound humans have done for eons. Look on the bright side, though: at least you won’t have space herpes to worry about. It’s gotta be, like, the second worst herpes there is. | 0.863687 | 3.258224 |
Last month, astronomers made big headlines when they announced they had successfully imaged a black hole for the first time ever. This is more than just a really cool picture, it has some very important scientific ramifications. Black holes were first suggested by Karl Schwarzchild about one hundred years ago when he realized they were mathematically predicted by Einstein’s general theory of relativity. Saying something exists only because the math tells you it exists, though, is a long way from actually observing it. The math could, after all, be wrong. Indeed, Einstein’s math in particular was seen at the time as being particularly suspect because of its bizarre predictions. Almost immediately after he published it physicists set about trying to disprove it. As early as 1919 astronomers showed that light is bent around the sun by observing the apparent positions of stars during a solar eclipse. This vindicated the more pedestrian claims in Einstein’s theory, but people were still rightly skeptical of Schwarzchild’s claim about the existence of black holes. They are really strange things and as Carl Sagan said, “extraordinary claims require extraordinary evidence”. Gradually the evidence began to accumulate and one by one physicists came to agree that yes, black holes probably do exist. But still, nobody had ever actually seen one. That all changed last month with this image.
There can now be no question that Einstein and Schwarzchild had their math right.
A Lesson for Utility Engineers
But when I look at this picture, I see more than just a great scientific discovery. The story behind this image – the story of how humans managed to see something so far away that it takes light 54 million years to get there – is a fantastic engineering story, as well as a scientific one. And, believe it or not, it actually teaches a lesson that utility engineers should take to heart. To explain why, though, I need to explain a few basic facts about how astronomers use radio waves to image objects in space.
This is something I have a little bit of experience in. Early in my career as a graduate student I was working as a research assistant in the astronomy department at the University of Illinois. I was actually a student in the electrical engineering department, but I wanted to work on image processing problems in astronomy (instead of compressing the same images every other EE was working on at that time). One of the problems I considered was data collected from the Very Large Array, or VLA.
This is an array of huge antennas, each one 82 feet in diameter, mounted on tracks in a Y configuration. The tracks make it possible to move the antennas around, which is important because the spacing between antennas drives the resolution of the image. The farther apart they are, the more resolved the image produced becomes. The tracks on the VLA are each about 13 miles long making it possible for the two most distant antennas to be 22 miles apart. This gives the overall array a resolution of 0.04 arcseconds, which takes up about the size a football field would take up on the moon if you were to look at it from the Earth.
Now, that red glowing disk around the black hole is about 0.011 light years in diameter (which is huge), but it’s 54 million light years away. That makes its angular size on the sky about the same as what an orange sitting on the surface of the moon would take up when viewed from Earth. You can fit a lot of oranges inside a football stadium, so a lot of black holes would fit inside just one pixel of an image created by the VLA. Obviously, we need to place the antennas farther apart if we’re going to have any chance of imaging this black hole. Very far apart… like on different continents.
Enter the Event Horizon Telescope: a planet-wide array of radio telescope arrays.
The EHT combines data from radio telescopes in Europe, North and South America, and Hawaii to produce an aperture as big as the planet Earth itself which has a combined resolution many orders of magnitude greater than the VLA. The idea is simple: point all these telescopes at the black hole at the center of M87, collect the signals from every antenna in every telescope array, and process that data as if it were from a single array.
The devil is in the details, however. The signal is very weak (it is 54 million light years away) and the antennas have to stare at it for a very long time. That makes the amount of data each array generates immense. Also, all the signals from each antenna have to be time stamped so they can be processed as if they were connected to the same electronics. The imaging team, using an algorithm written by computer scientists, saw to these details and solved the problem handsomely.
Fact: Arrays of Sensors are Better Than the Sum of Their Parts
All this demonstrates a fundamental fact in sensor signal processing. Generally speaking, it is better to have a lot of medium quality sensors than it is to have a few very high-quality sensors. It’s true that each of the composite radio telescopes in the Event Horizon Telescope are very high quality, but that isn’t what made this image possible. It was bringing together many sensors from around the planet to look at the black hole, and then process their data collectively, that sparked this innovation. So, what I see when I look at this image is a dramatic demonstration of something signal processing engineers have known for some time: sensor arrays are better than the sum of their parts.
There is no shortage of demonstrations of this. If you’ve used Google Maps to navigate your way around traffic jams you’ve benefited directly from it. When you use Google Maps, if you have your location services turned on, your phone reports back to Google your location and velocity. The same is true of everyone else in traffic that is using Google Maps. So, in any given traffic jam, it’s an almost sure bet that there are more than a few phones reporting back to Google that they are not moving as fast as they should. Google then surmises that traffic on that part of the highway is moving slowly and warns other users.
Essentially, they have turned all our phones into a gigantic traffic-sensing sensor array. What makes it work so well is the fact that so many people use Google Maps and are reporting that data. If the number of users were much fewer there wouldn’t be enough data to make the correct inferences.
How Can Utilities Benefit?
Some utilities are starting to take advantage of large sensor arrays too. If you think about it, the vast array of meters and monitors present on any electric, gas, or water distribution network can be considered a large sensor array.
A meter measures the flow of your product at a customer point and relays that information back to your computers. On a gas network, there may be sensors that measure the concentration of methane in the neighborhood of the sensor. On an electric network, feeder-level sensors measure real-time current and voltage waveforms at strategic choke points.
SCADA equipment measures the same, but at the substation. All of this data is available to utilities to draw from, but in most cases, the sensor data is still used independently of other sensors when drawing conclusions. Is there a gas leak at a given point? Check the methane sensor at that point (even though the many gas meters nearby may provide complementary information on the same leak).
Likewise, when a fault occurs on an electric network the SCADA equipment or feeder level sensors that recorded the current transient are examined. Nearly every meter on the network would have at least recorded a voltage dip if it didn’t lose power entirely. This data is generally ignored. And with good reason. There is a lot of it for one thing. Mining through all that data to find the one little thing you are looking for could rightly be compared to looking for a needle in a haystack.
A Sensor Array that Detects Water Leaks
Aclara’s acoustic leak detection technology – ZoneScan – is one example where water utilities are using large sensor arrays to detect water leaks before they become a problem. The idea is pretty simple: use microphones to listen for water leaks (because water leaks are noisy). Now, with just one microphone, you might be able to hear a leak, but you would have no idea where it is.
Try covering up one of your ears so you can only hear out of the other and you’ll see what I mean. With one ear you lose sense of which direction sounds are coming from. With ZoneScan we place sensors throughout the water network so that no matter where the leak is it’s pretty much a sure thing that several of the microphones are going to hear it. We time stamp that data and process it using an algorithm that isn’t that much different from the one used by radio telescopes to image black holes and you can tell where on the network the leak is.
Sensor Arrays for Electrical Distribution Networks
For electric utilities, we have the Aclara Fault Detection & Localization software package, which uses the TWACS communication system to detect power outages. Here, the sensor array consists of every meter on the entire network. Data is collected from each of the meters semi-randomly using a statistical algorithm developed in the Aclara R&D lab. The purpose of the algorithm is to quickly find meters that may be without power and verify the outage by pinging other meters in their vicinity.
This approach differs from many outage detection systems, which will designate a small subset of meters in a system as bellwether meters and ping those more frequently. The idea behind this is that if a recloser trips one of the bellwether meters will see it and since the number of meters sensed is fairly small, communications will not suffer. However, this introduces several other problems, such as causing confusion when one of the bellwether meters loses power for reasons other than an upstream recloser tripping (believe me, it happens!). Sometimes smaller outages are missed that are not the result of a recloser tripping because the outage did not affect a bellwether meter.
By comparison, Aclara’s algorithm looks at all the meters and considers all possibilities while using mathematics to minimize the impact to the communications bandwidth. The very first time we turned the system on at a customer site we almost immediately detected a downed power line that the utility’s existing outage management system had not seen.
Some of our customers are using their own versions of sensor array processing to solve problems using Aclara’s Grid Monitoring (AGM) solution. This uses line sensors and software to provide real-time data that alerts operators to potential problems on the network. The sensors easily clamp onto medium voltage feeders and provide voltage and current waveforms. Signal processing algorithms on board the sensor detect when a statistically anomalous event has occurred, say a transient that may have caused a recloser to open. When that occurs, the sampled waveforms are transmitted to the utility and an alert is sounded. By examining the data from even just one sensor it is possible to predict outages and locate major faults before they even occur. But if the utility has multiple smart grid sensors along the same feeder it is very likely that the same disturbance was recorded by several sensors. By examining the data from all the sensors collectively, it is possible to infer several things about the transient, such as where it occurred, how many customers it affected, and which, if any, protective devices were affected.
This is just a glimpse of what we believe is ultimately possible by bringing multi-sensor signal processing to bear on gas, water, and electric distribution problems. Many of the things I’ve mentioned here will be discussed at the upcoming #AclaraConnect 2019. While I don’t know exactly what he will talk about, I would be very surprised if Dr. Michio Kaku, as a theoretical physicist, didn’t at least mention black holes in his keynote.
There will be other talks about ZoneScan, fault detection, and AGM, as well as knowledgeable Aclara R&D engineers there to answer your technical questions. And if you’re up for hearing what the future might hold for utilities, I will be talking about that, too. So make sure to check out the agenda here and I’ll see you then! | 0.822206 | 3.485394 |
Researchers at Clemson University calculated the Hubble constant used to measure the expansion of the universe with a new technique. The team compared data from gamma rays and extragalactic backlight.
Using a state-of-the-art technology and techniques available today, a team of Clemson University astrophysicists developed a new approach to measuring one of the most fundamental laws of the universe. The team used to describe the expansion rate of the universe. Hubble constant Measured again.
Researchers published their research in The Astrophysical on November 8 in the form of an article. According to the article, the team analyzed data from telescopes in orbit and ground to find a new unit of measurement of how fast the universe is expanding.
How the team achieved the new measurement was also included in the article. The researchers compared the gamma ray data from the Fermi Gamma Ray Telescope and the Imaging Atmospheric Cherenkov Telescopes with the data from the gal extragalactic background light EB models.
This new strategy, used by the team of researchers, has revealed what the rate of expansion of the universe is. Accordingly, the universe, 67.5 kilometers per second per megaparsec Expanding. (One parsec is up to three light years and one megaparsec is 1 million parsecs.)
What is the relationship between gamma ray and extragalactic barley background light?
Gamma rays are the most energetic form of light. The extragalactic background light emits all the stars or dust Ultraviolet, visible and infrared light is a cosmic mist. When gamma rays and extragalactic backlight interact, they leave an observable mark that scientists can create and analyze their hypotheses.
The world of astronomy invests enormously in different parameters to accurately perform cosmological calculations, including the Hubble constant. According to the researchers, if these laws can become more precise new insights and new discoveries It will be released.
Alberto Dominguez, a member of the team of researchers, described their success as follows:
G It is remarkable that we use gamma rays to study cosmology. Our technique has allowed us to go beyond existing techniques to measure the important features of the universe. Our results show how far the new field of high-energy astrophysics can progress in 10 years. ’ | 0.836378 | 3.668813 |
Earth-Moon-Earth, also known as moon bounce, is a radio communications technique which relies on the propagation of radio waves from an earth-based transmitter directed via reflection from the surface of the moon back to an earth-based receiver.
The use of the Moon as a passive communications satellite was proposed by Mr. W.J. Bray of the British General Post Office in 1940. It was calculated that with the available microwave transmission powers and low noise receivers, it would be possible to beam microwave signals up from Earth and reflect off the Moon. It was thought that at least one voice channel would be possible. The “moon bounce” technique was developed by the United States Military in the years after World War II, with the first successful reception of echoes off the Moon being carried out at Fort Monmouth, New Jersey on January 10, 1946 by John H. DeWitt as part of Project Diana. The Communication Moon Relay project that followed led to more practical uses, including a teletype link between the naval base at Pearl Harbor, Hawaii and United States Navy headquarters in Washington, DC.
- The Moon is typically around 384.400 Kilometers away from Earth.
- The moon’s Diameter is 3.476 Kilometers.
- The Moon only takes up 0.52 of one degree out of the full 180 degrees of sky.
- The fact that the Moon appears larger at moonrise and moonset is only an optical illusion.
- The Moon rotates around the Earth every 27 days 7 hours 43 minutes.
- The Moon goes from New Moon to New Moon every 29 days 12 hours 44 minutes.
- With my antenna (22dBi and 16°/-3dB angle) only 0,1% of total radiated energy hit the Moon (99,9% pass beside the Moon and go to the Space)
- The Moon only reflects back about 7 % of the signal during a Moonbounce Contact
- The average loss in decibels for the Earth-Moon-Earth path is 252,5dB (assuming a Moon reflectivity of about 7%, and calculated for my 144MHz (2m) frequency band)
- The path loss will wary approximately ±1dB during each month (as range to the Moon changes).
- If the receiver antenna array is linearly polarized (like my – horizontally), due to rotation of polarization into upper layers of atmosphere (ionosphere; Faraday fading), addition of attenuation can be expected between 20 to 30db
- Below about 1000MHz, cosmic noise is the dominant factor and varies with the portion of the galaxy observed. For 2m band it is between 150 to 7000°K. For successful EME contact on 144MHz, sky noise in direction of the Moon has to be less or equal 500°K.
- It takes approximately 2.52 seconds for a radio wave to travel from Earth to the Moon and back to Earth again.
- The Phase of the Moon has little to no effect on the EME Signals.
Spatial Polarization Loss: The signal loss in dB’s as a result of polarization differences between two stations across the EME signal path. Imagine that you are on the Moon and you have a horizontal beam looking down at the Earth. If one station is on one side of the Earth and another station is on another side of the Earth, the signal polarizations of those stations will not be the same because of the curvature on the Earth. It is this difference of polarizations that will cause a loss of signal strength. This is the Spatial Polarization Loss. If both stations are at the same latitude, then the loss will be just about nothing.
Faraday Rotation: The rotation of the polarization of the signal path caused by the earth’s magnetic field. This normally is a great contributor to signal QSB on EME Signals. It is more pronounced on the lower EME Bands.
Libration Fading: Fading of EME Signals due to the reflected characteristics of the signal. This is due to the rough surface of the Moon. The Moon actually wabbles in its orbit so when signals are reflected off the Moon, they are reflected across the rough terrain on the moon’s surface causing the reflected signals to be inconsistent. This fading becomes extremely pronounced on the higher EME bands (like 1296MHz and above) and is barely noticeable on the lower bands.
Doppler Shift: The frequency offset from the transmitted signal due to velocity factor. The velocity factor is determined by the rate of change in the EME Signal Path Distance. The Earth and Moon are constantly moving, sometimes closer to each other and other times farther away from each other. The greater the change in distance rate, the greater the Doppler Shift will be. Also, the higher the EME Frequency Band is, the greater the Doppler Shift will be also. Another thing to keep in mind is that the Doppler Shift will be higher from the original frequency when the distance becomes closer and the will become lower when the distance becomes farther.
Antenna Temperature (Ta): The Noise Temperature of the signal being received from the antenna. This noise comes from not only the main front lobe of the antenna, but also all the minor lobes and rear of the antenna as well. The combined noise of all these sources becomes the total Noise Temperature of the antenna or Antenna Temperature. One example is that the Moon normally runs at a temperature of around 210 degrees Kelvin. If this is all the antenna was seeing, then 210 degrees would be the Antenna Temperature. This becomes a critical parameter when designing a good antenna for EME use. The idea is to design an antenna that will not contribute noise from other directions that will add to degradation of the signal received off the Moon.
G/T or (Antenna Gain over System Noise Temperature): This is the Ratio of Antenna Gain over System Noise Temperature. Signal to Noise Ratio is comparable to this ratio and are related. This is also a very important parameter when designing a good EME station. A simple way to describe this is to make the Antenna Gain as high as possible and the Noise figure as low as possible to increase the Signal to Noise Ratio. The higher the G/T is, the better. When looking at the G/T of an antenna by itself, it is the factors of Antenna Temperature, Gain, and the antenna pattern that make up the G/T of an antenna.
Declination: The term used to describe the moon’s position relative to the equator of the Earth. If the Declination is minus 8 degrees, then the Moon would be 90 degrees elevation overhead at 8 degrees south latitude on Earth.
GHA or Greenwich Hour Angle: The term to describe the moon’s Position in relations to earth’s Longitude. If the moon’s GHA was at 20 degrees, then the Moon would be located directly overhead 20 degrees West Longitude.
EME Degradation: Basically, it is the amount of degradation in dB’s due to the Sky Temperature, moon’s Distance and Declination. Typically from 0dB’s to -2.5dB’s maximum. Most would agree that the smallest degradation loss would be with the lowest Sky Noise, highest Declination and Moon at Perigee.
Moon Perigee: When the Moon is at its closest Distance from the Earth.
Moon Apogee: When the Moon is at its farthest Distance from the Earth.
Sky Noise: This is the term to describe the background noise behind the Moon or Noise Temperature at and around the Moon. It is measured in degrees Kelvin. If the Moon is located at or near a high noise area such as the Milky Way or the Sun, then the Sky Noise would be high compared to the area in the sky which has the lowest Noise Temperature which is known as “Cold Sky “.
Elevation of the Moon: The term used to describe the height of the Moon at the observer’s location relative to the horizon. An elevation of 10 degrees would mean that the Moon at the observer’s location is 10 degrees above the horizon. 90 degrees elevation would be directly overhead.
Phase of the Moon: The term used to describe the Illumination of the Moon by the Sun. A full Moon would mean that the entire disk of the Moon is illuminated at the observer’s location. A New Moon would mean that the moon’s disk is completely dark at the observers location. The Phase of the Moon DOES NOT have any effect on EME Propagation. | 0.876224 | 3.488354 |
Here’s a wonderful color mosaic of Saturn’s moon Hyperion, assembled by Gordan Ugarkovic from four Cassini narrow-angle camera images. The moon’s heavily cratered sponge-like surface can be seen in vivid detail due to the high phase angle of sunlight, making its rough texture even more pronounced.
At 255 x 163 x 137 miles in diameter, Hyperion is the largest of Saturn’s irregularly-shaped moons. Scientists think it may be the remains of a larger body that was blown apart by an impact…Hyperion’s craters have a “punched-in” look rather than appearing to have been excavated by collisions.
Hyperion orbits Saturn in an eccentric orbit at a distance of over 920,000 miles…that’s almost four times the distance our own moon is from us! This distance – as well as gravitational nudging from Titan – prevents Hyperion from becoming tidally locked with Saturn, like most other moons are…that is, it does not always face the same side to Saturn (like our moon does with Earth.)
Gordan Ugarkovic’s talent at assembling intriguing images from raw data from Cassini and other exploration spacecraft is simply amazing…check out more of his work on his Flickr site here.
Image: NASA/JPL/SSI/Gordan Ugarkovic. | 0.836525 | 3.06705 |
NGC 1589 - Spiral Galaxy
NGC 1589 is a Spiral Galaxy in the Taurus constellation. NGC 1589 is situated close to the celestial equator and, as such, it is at least partly visible from both hemispheres in certain times of the year.
Photometric information of NGC 1589
The following table lists the magnitude of NGC 1589 in different bands of the electomagnetic spectrum (when available), from the B band (445nm wavelength, corresponding to the Blue color), to the V band ( 551nm wavelength, corresponding to Green/Yellow color), to the J, H, K bands (corresponding to 1220nm, 1630nm, 2190nm wavelengths respectively, which are colors not visible to the human eye).
For more information about photometry in astronomy, check the photometric system article on Wikipedia.
The surface brightess reported below is an indication of the brightness per unit of angular area of NGC 1589.
Apparent size of NGC 1589The following table reports NGC 1589 apparent angular size. The green area displayed on top of the DSS2 image of NGC 1589 is a visual representation of it.
Digitized Sky Survey image of NGC 1589
The image below is a photograph of NGC 1589 from the Digitized Sky Survey 2 (DSS2 - see the credits section) taken in the red channel. The area of sky represented in the image is 0.5x0.5 degrees (30x30 arcmins).
NGC 1589 - Spiral Galaxy morphological classification
NGC 1589 - Spiral Galaxy is classified as Spiral (SAab) according to the Hubble and de Vaucouleurs galaxy morphological classification. The diagram below shows a visual representation of the position of NGC 1589 - Spiral Galaxy in the Hubble de Vaucouleurs sequence.
Celestial coordinates and finder chart of NGC 1589
Celestial coordinates for the J2000 equinox of NGC 1589 are provided in the following table:
The simplified sky charts below show the position of NGC 1589 in the sky. The first chart has a field of view of 60° while the second one has a field of view of 10°. | 0.839692 | 3.392166 |
By the end of this section, you will be able to:
- Describe the effects of gravity on objects in motion.
- Describe the motion of objects that are in free fall.
- Calculate the position and velocity of objects in free fall.
The information presented in this section supports the following AP® learning objectives and science practices:
- 3.A.1.1 The student is able to express the motion of an object using narrative, mathematical, or graphical representations. (S.P. 1.5, 2.1, 2.2)
- 3.A.1.2 The student is able to design an experimental investigation of the motion of an object. (S.P. 4.2)
- 3.A.1.3 The student is able to analyze experimental data describing the motion of an object and is able to express the results of the analysis using narrative, mathematical, and graphical representations. (S.P. 5.1)
Falling objects form an interesting class of motion problems. For example, we can estimate the depth of a vertical mine shaft by dropping a rock into it and listening for the rock to hit the bottom. By applying the kinematics developed so far to falling objects, we can examine some interesting situations and learn much about gravity in the process.
The most remarkable and unexpected fact about falling objects is that, if air resistance and friction are negligible, then in a given location all objects fall toward the center of Earth with the same constant acceleration, independent of their mass. This experimentally determined fact is unexpected, because we are so accustomed to the effects of air resistance and friction that we expect light objects to fall slower than heavy ones.
In the real world, air resistance can cause a lighter object to fall slower than a heavier object of the same size. A tennis ball will reach the ground after a hard baseball dropped at the same time. (It might be difficult to observe the difference if the height is not large.) Air resistance opposes the motion of an object through the air, while friction between objects—such as between clothes and a laundry chute or between a stone and a pool into which it is dropped—also opposes motion between them. For the ideal situations of these first few chapters, an object falling without air resistance or friction is defined to be in free-fall.
The force of gravity causes objects to fall toward the center of Earth. The acceleration of free-falling objects is therefore called the acceleration due to gravity. The acceleration due to gravity is constant, which means we can apply the kinematics equations to any falling object where air resistance and friction are negligible. This opens a broad class of interesting situations to us. The acceleration due to gravity is so important that its magnitude is given its own symbol, . It is constant at any given location on Earth and has the average value
Although varies from to , depending on latitude, altitude, underlying geological formations, and local topography, the average value of will be used in this text unless otherwise specified. The direction of the acceleration due to gravity is downward (towards the center of Earth). In fact, its direction defines what we call vertical. Note that whether the acceleration in the kinematic equations has the value or depends on how we define our coordinate system. If we define the upward direction as positive, then , and if we define the downward direction as positive, then .
One-Dimensional Motion Involving Gravity
The best way to see the basic features of motion involving gravity is to start with the simplest situations and then progress toward more complex ones. So we start by considering straight up and down motion with no air resistance or friction. These assumptions mean that the velocity (if there is any) is vertical. If the object is dropped, we know the initial velocity is zero. Once the object has left contact with whatever held or threw it, the object is in free-fall. Under these circumstances, the motion is one-dimensional and has constant acceleration of magnitude . We will also represent vertical displacement with the symbol and use for horizontal displacement.
A person standing on the edge of a high cliff throws a rock straight up with an initial velocity of 13.0 m/s. The rock misses the edge of the cliff as it falls back to Earth. Calculate the position and velocity of the rock 1.00 s, 2.00 s, and 3.00 s after it is thrown, neglecting the effects of air resistance.
Draw a sketch.
We are asked to determine the position at various times. It is reasonable to take the initial position to be zero. This problem involves one-dimensional motion in the vertical direction. We use plus and minus signs to indicate direction, with up being positive and down negative. Since up is positive, and the rock is thrown upward, the initial velocity must be positive too. The acceleration due to gravity is downward, so is negative. It is crucial that the initial velocity and the acceleration due to gravity have opposite signs. Opposite signs indicate that the acceleration due to gravity opposes the initial motion and will slow and eventually reverse it.
Since we are asked for values of position and velocity at three times, we will refer to these as and ; and ; and and .
Solution for Position
1. Identify the knowns. We know that ; ; ; and .
2. Identify the best equation to use. We will use because it includes only one unknown, (or , here), which is the value we want to find.
3. Plug in the known values and solve for .
The rock is 8.10 m above its starting point at s, since . It could be moving up or down; the only way to tell is to calculate and find out if it is positive or negative.
Solution for Velocity
1. Identify the knowns. We know that ; ; ; and . We also know from the solution above that .
2. Identify the best equation to use. The most straightforward is (from , where ).
3. Plug in the knowns and solve.
The positive value for means that the rock is still heading upward at . However, it has slowed from its original 13.0 m/s, as expected.
Solution for Remaining Times
|Time, t||Position, y||Velocity, v||Acceleration, a|
Graphing the data helps us understand it more clearly.
The interpretation of these results is important. At 1.00 s the rock is above its starting point and heading upward, since and are both positive. At 2.00 s, the rock is still above its starting point, but the negative velocity means it is moving downward. At 3.00 s, both and are negative, meaning the rock is below its starting point and continuing to move downward. Notice that when the rock is at its highest point (at 1.5 s), its velocity is zero, but its acceleration is still . Its acceleration is for the whole trip—while it is moving up and while it is moving down. Note that the values for are the positions (or displacements) of the rock, not the total distances traveled. Finally, note that free-fall applies to upward motion as well as downward. Both have the same acceleration—the acceleration due to gravity, which remains constant the entire time. Astronauts training in the famous Vomit Comet, for example, experience free-fall while arcing up as well as down, as we will discuss in more detail later.
A simple experiment can be done to determine your reaction time. Have a friend hold a ruler between your thumb and index finger, separated by about 1 cm. Note the mark on the ruler that is right between your fingers. Have your friend drop the ruler unexpectedly, and try to catch it between your two fingers. Note the new reading on the ruler. Assuming acceleration is that due to gravity, calculate your reaction time. How far would you travel in a car (moving at 30 m/s) if the time it took your foot to go from the gas pedal to the brake was twice this reaction time?
What happens if the person on the cliff throws the rock straight down, instead of straight up? To explore this question, calculate the velocity of the rock when it is 5.10 m below the starting point, and has been thrown downward with an initial speed of 13.0 m/s.
Draw a sketch.
Since up is positive, the final position of the rock will be negative because it finishes below the starting point at . Similarly, the initial velocity is downward and therefore negative, as is the acceleration due to gravity. We expect the final velocity to be negative since the rock will continue to move downward.
1. Identify the knowns. ; ; ; .
2. Choose the kinematic equation that makes it easiest to solve the problem. The equation works well because the only unknown in it is . (We will plug in for .)
3. Enter the known values
where we have retained extra significant figures because this is an intermediate result.
Taking the square root, and noting that a square root can be positive or negative, gives
The negative root is chosen to indicate that the rock is still heading down. Thus,
Note that this is exactly the same velocity the rock had at this position when it was thrown straight upward with the same initial speed. (See Example 2.14 and Figure 2.54(a).) This is not a coincidental result. Because we only consider the acceleration due to gravity in this problem, the speed of a falling object depends only on its initial speed and its vertical position relative to the starting point. For example, if the velocity of the rock is calculated at a height of 8.10 m above the starting point (using the method from Example 2.14) when the initial velocity is 13.0 m/s straight up, a result of is obtained. Here both signs are meaningful; the positive value occurs when the rock is at 8.10 m and heading up, and the negative value occurs when the rock is at 8.10 m and heading back down. It has the same speed but the opposite direction.
Another way to look at it is this: In Example 2.14, the rock is thrown up with an initial velocity of . It rises and then falls back down. When its position is on its way back down, its velocity is . That is, it has the same speed on its way down as on its way up. We would then expect its velocity at a position of to be the same whether we have thrown it upwards at or thrown it downwards at . The velocity of the rock on its way down from is the same whether we have thrown it up or down to start with, as long as the speed with which it was initially thrown is the same.
The acceleration due to gravity on Earth differs slightly from place to place, depending on topography (e.g., whether you are on a hill or in a valley) and subsurface geology (whether there is dense rock like iron ore as opposed to light rock like salt beneath you.) The precise acceleration due to gravity can be calculated from data taken in an introductory physics laboratory course. An object, usually a metal ball for which air resistance is negligible, is dropped and the time it takes to fall a known distance is measured. See, for example, Figure 2.55. Very precise results can be produced with this method if sufficient care is taken in measuring the distance fallen and the elapsed time.
Suppose the ball falls 1.0000 m in 0.45173 s. Assuming the ball is not affected by air resistance, what is the precise acceleration due to gravity at this location?
Draw a sketch.
We need to solve for acceleration . Note that in this case, displacement is downward and therefore negative, as is acceleration.
1. Identify the knowns. ; ; ; .
2. Choose the equation that allows you to solve for using the known values.
3. Substitute 0 for and rearrange the equation to solve for . Substituting 0 for yields
Solving for gives
4. Substitute known values yields
so, because with the directions we have chosen,
The negative value for indicates that the gravitational acceleration is downward, as expected. We expect the value to be somewhere around the average value of , so makes sense. Since the data going into the calculation are relatively precise, this value for is more precise than the average value of ; it represents the local value for the acceleration due to gravity.
While it is well established that the acceleration due to gravity is quite nearly 9.8 m/s2 at all locations on Earth, you can verify this for yourself with some basic materials.
Your task is to find the acceleration due to gravity at your location. Achieving an acceleration of precisely 9.8 m/s2 will be difficult. However, with good preparation and attention to detail, you should be able to get close. Before you begin working, consider the following questions.
What measurements will you need to take in order to find the acceleration due to gravity?
What relationships and equations found in this chapter may be useful in calculating the acceleration?
What variables will you need to hold constant?
What materials will you use to record your measurements?
Upon completing these four questions, record your procedure. Once recorded, you may carry out the experiment. If you find that your experiment cannot be carried out, you may revise your procedure.
Once you have found your experimental acceleration, compare it to the assumed value of 9.8 m/s2. If error exists, what were the likely sources of this error? How could you change your procedure in order to improve the accuracy of your findings?
A chunk of ice breaks off a glacier and falls 30.0 meters before it hits the water. Assuming it falls freely (there is no air resistance), how long does it take to hit the water?
We know that initial position , final position , and . We can then use the equation to solve for . Inserting , we obtain
where we take the positive value as the physically relevant answer. Thus, it takes about 2.5 seconds for the piece of ice to hit the water.
Learn about graphing polynomials. The shape of the curve changes as the constants are adjusted. View the curves for the individual terms (e.g. ) to see how they add to generate the polynomial curve. | 0.821225 | 3.563736 |
Dr. Stone, JPL's director since 1991, is stepping down on May 1. During his tenure, the Laboratory has overseen 15 missions for NASA.
Stone's exploration days began in 1961 with his first cosmic-ray experiments on Discoverer satellites. He has been a principal investigator on nine NASA spacecraft missions and a co-investigator on five other NASA missions. One of his most famous contributions to space exploration is his continuing role as project scientist for the Voyager mission, whose twin spacecraft studied Jupiter, Saturn, Uranus and Neptune between 1979 and 1989. The Voyagers are still traveling in space and are expected to continue returning scientific information as they reach the outer bounds of our solar system in the next few years.
Stone will return fulltime to Caltech as a professor and scientist, and a researcher still reaping the riches of Voyager data.
Q. For either Voyager or other JPL missions, what has surprised you the most in terms of scientific discoveries?
A. If I had to pick one surprise that stands out on Voyager, it would be the volcanoes on Io [one of Jupiter's moons]. Finding a moon that's 100 times more active volcanically than the entire Earth, it's really quite striking. And this was typical of what Voyager was going to do on the rest of its journey through the outer solar system. This was really beyond imagination.
But look at the surprises [the] Galileo [spacecraft] has given us at Jupiter, such as finding a magnetic field on Ganymede [a Jovian moon] and showing us up close that there's likely an ocean beneath the icy crust of Europa [another Jovian moon]. And Mars Global Surveyor has really rediscovered Mars for us, with the discovery of gullies on canyon walls, which was not expected at all since it was believed water was frozen kilometers beneath its crust.
I also expect there will be a lot to learn from the first digital topographic map of Earth that will be produced from the Shuttle Radar Topography Mission.
Q. What stands out for you when you think about the past decade?
A. It's hard to imagine a more exciting decade than we've had. We have had many successes, and the level and the pace of innovation at the Laboratory has dramatically increased.
The one thing I'm most pleased about is the fact that the Laboratory continues to be the leading innovator in space in this new era of going more often, landing and eventually bringing samples back to Earth. For example, we have samples coming back from a comet in 2006 from the Stardust mission; this summer, we'll launch Genesis, which will bring back a sample of the Sun.
Q. What were the lessons learned from the Mars '98 losses?
A. We were changing to a new era of missions, and we found the limit. We tried to do two missions for the price of Mars Pathfinder, and it was just too hard. We've learned a lot from this and have put in place new processes and a better safety net so that today's project teams won't face the same limitations as we had with Mars '98. We will continue doing missions more often in this new era, but do them in a robust way.
Q. How do you see JPL beyond the next 10 years into the future?
A. Well, the next era might be going and staying, building a permanent robotic base of operations elsewhere in the solar system, which through modern communications is as accessible as any place here on Earth. So what's out there becomes, effectively, back here. JPL could be a key factor in realizing such an era, which, I think, is a bridge to eventual human exploration of the bodies in the solar system. | 0.864911 | 3.225916 |
In a recent paper in Nature Astronomy, researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam and from the French Alternative Energies and Atomic Energy Commission (CEA) in Saclay, Paris suggest how the planned space-based gravitational-wave observatory LISA can detect exoplanets orbiting white dwarf binaries everywhere in our Milky Way and in the nearby Magellanic Clouds. This new method will overcome certain limitations of current electromagnetic detection techniques and might allow LISA to detect planets down to 50 Earth masses.
In a paper to be published in Nature Astronomy on monday, Dr. Nicola Tamanini, researcher at the AEI in Potsdam and his colleague Dr. Camilla Danielski, researcher at the CEA/Saclay (Paris) show how these limitations may be overcome by gravitational-wave astronomy. “We propose a method which uses gravitational waves to find exoplanets that orbit binary white dwarf stars”, says Nicola Tamanini. White dwarfs are very old and small remnants of stars once similar to our Sun. “LISA will measure gravitational waves from thousands of white dwarf binaries. When a planet is orbiting such a pair of white dwarfs, the observed gravitational-wave pattern will look different compared to the one of a binary without a planet. This characteristic change in the gravitational waveforms will enable us to discover exoplanets.”
Doppler-shifted gravitational waves
The new method exploits the Doppler shift modulation of the gravitational-wave signal caused by the gravitational attraction of the planet on the white dwarf binary. This technique is the gravitational-wave analogue of the radial velocity method, a well-known technique used to find exoplanets with standard electromagnetic telescopes. The advantage, however, of gravitational waves is that they are not affected by stellar activity, which can hamper electromagnetic discoveries.
In their paper, Tamanini and Danielski show that the upcoming ESA mission LISA (Laser Interferometer Space Antenna), scheduled for launch in 2034, can detect Jupiter-mass exoplanets around white dwarf binaries everywhere in our Galaxy, overcoming the limitations in distance of electromagnetic telescopes. Furthermore, they point out that LISA will have the potential to detect those exoplanets also in nearby galaxies, possibly leading to the discovery of the first extragalactic bound exoplanet.
“LISA is going to target an exoplanet population yet completely unprobed”, explains Tamanini. “From a theoretical perspective nothing prevents the presence of exoplanets around compact binary white dwarfs.” If these systems exist and are found by LISA, scientists will obtain new data to further develop planetary evolution theory. They will better understand the conditions under which a planet can survive the stellar red-giant phase(s) and will also test the existence of a second generation of planets, i.e., planets that form after the red-giant phase.
On the other hand, if LISA does not detect exoplanets orbiting white dwarf binaries, the scientists will be able to set constraints on the final stage of planetary evolution in the Milky Way.
N. Tamanini, C. Danielski: The gravitational-wave detection of exoplanets orbiting white dwarf binaries using LISA, Nature Astronomy, DOI: 10.1038/s41550-019-0807-y
Dr. Nicola Tamanini
Dr. Elke Müller | 0.84915 | 3.947684 |
The Martian landscape is otherworldly. The ground is twisted into ropelike coils, rippling waves and jagged spikes; sulfurous gases billow from vents in the ground, bits of volcanic glass glitter in faint sunlight that filters through the undulating fog.
Two astronauts clamber across the tortured terrain, encumbered by the heavy scientific instruments they carry on their backs and in their hands. They are looking for rocks that could tell us whether life ever existed on Mars.
At makeshift mission control inside a converted conference room several miles away, Darlene Lim surveys video from the scene. The NASA geobiologist has been planning this mission for months. She listens attentively to the chatter between the roving astronauts and their counterparts at “base camp” and watches as one of the scientists in the field points a handheld spectrometer at a rock and scans it, Star Trek-style. Data on the rock’s composition starts streaming onto Lim’s computer screen.
“This is super awesome,” Lim murmurs under her breath. Remembering a reporter is listening over the phone, she laughs at herself. “It is!”
This landscape, of course, is not actually Mars, and the people exploring it aren’t really astronauts. But the expedition to the Mauna Ulu volcano on the Big Island of Hawaii is a dry run for the distant day when NASA intends to send a real crewed mission to the Red Planet.
Though NASA has spent billions of dollars and countless hours trying to get people into space, what they actually do up there can be an afterthought. Lim wants to change that.
“You’re trying to keep people alive and trying to get them beyond low Earth orbit . . . there are experiments that are done, but the science isn’t really baked in,” Lim said. “But when we head out to somewhere like Mars, and we’re going to be there for a while . . . we’re going to have to look at designing these missions with an inherent component to science.”
With the exception of space suits – and the thin, oxygen-less atmosphere that necessitates them – it is as high-fidelity a mission to Mars as Lim can muster. The Hawaiian mountainside is similar to the landscape scientists think existed on Mars billions of years ago, when the atmosphere was thicker and the planet seethed with volcanic activity. The “astronauts” tasked with collecting rock samples use instruments that are being developed for real space missions; one heavy backpack contains a spectrometer that is destined to fly to the moon. Their time in the field is limited to the length of an average astronaut excursion outside the spacecraft: about four hours per day. Their communications to “mission control” (the conference room where Lim and her colleagues are set up) are subject to a five- to 15-minute delay that mimics the actual signal latency between Earth and Mars.
And the science is real. Unlike many other NASA analog missions, which test gear and operations design on safe, familiar terrain, Lim and her team are exploring a site they have never seen. They are collecting rocks not for practice, but for research – the samples will be studied to understand the relationship between rock types and the microbes that live in them. Some day, the scientists hope their findings will help guide the search for past or present Martian life.
NASA has been trudging toward its goal of launching a human Mars mission in the 2030s – though at the program’s current pace, it’s unlikely to meet that deadline. And about six weeks before the mission’s trip to Hawaii, SpaceX founder Elon Musk announced his conceptual plans for a powerful rocket and spacecraft that would help humans colonize the Red Planet. Discussing the news at NASA’s Ames Research Center in Moffett Field, Calif., engineer Amanda Cook shook her head.
“The rocket’s the easy part,” she said. “It’s people who really throw a monkey wrench into things.”
This is the guiding principle for the Hawaiian mission, called BASALT, which stands for Biologic Analog Science Associated with Lava Terrains and is also the name of a kind of volcanic rock. Robots, satellites and space telescopes have produced pioneering, Nobel Prize-winning science – and they don’t require food, oxygen or a return trip home. If NASA is going to put humans on Mars, it needs to be certain the discoveries made are worth the expense and risk of sending them there.
During the Apollo program, science goals were secondary to the sheer technical challenge of getting people to the moon, and most astronauts had backgrounds in the military rather than research. Though the astronauts got some training in geology, and landing sites were selected according to pre-mission surveys of the moon’s surface, the collection of rock samples was relatively haphazard. Subsequent research on board the International Space Station has yielded mostly minor discoveries, and it is conducted in the relative security of low Earth orbit, where every detail can be monitored by principal investigators on Earth.
On Mars the risks are more immense, and help from home is dependent on weak and sometimes erratic connection with mission control. That’s why BASALT takes place in an environment known to the researchers mostly through satellite images. Lim wants to make sure that the mission leaves room for the unknown.
“NASA has a lot of legacy of automation,” she explained. The space agency understandably prefers to minimize the potential for the unpredictable, given that lives are on the line. “But we’re trying to figure out how to not stamp the humanity from human exploration.”
With that goal in mind, Lim has recruited experts from a wide range of fields to help with her Mars analog mission. Engineers such as Cook are building instruments that astronauts can carry on their backs and in their hands. Computer programmers develop communications software that can inform astronauts without overwhelming them. Geologists establish protocols for quickly analyzing rock types and prioritizing which ones to sample. The team even includes an ethnographer whose job is to analyze members’ interactions and figure out better ways for them to collaborate – a necessity for future Mars astronauts, who will have spent months in cramped, inescapable quarters.
It’s the “unsexy” side of mission planning, planetary scientist Rick Elphic admitted during that meeting at Ames. “But if you don’t do it, you’ll design a mission that doesn’t work.”
A month and a half later, Elphic and his colleague Kara Beaton are standing on the side of the Hawaiian volcano, in the middle of finding out whether all that preparation paid off. Already, there have been hiccups, which is helpful. Better to find out now that a communication tool doesn’t work or a schedule needs to be rearranged. It’s the eighth day of the expedition and the second day at this particular site. The “astronauts” asked to return to the rugged expanse of black and red rock after not having sufficient time to explore it the day before – field work almost always takes longer than expected – and geologists at mission control acceded to their judgment.
The fog that cloaked the mountain at the beginning of the expedition has burned off, revealing the treacherous terrain. Most of the BASALT team has scraped palms and scratched knees from collisions with the craggy rock, and the scientists are wary of concealed lava tubes, whose thin crusts could crack under a person’s weight, dropping them into caverns below. Beaton spends several minutes trying to maneuver toward an intriguing rock formation before deciding it’s not safe. With little more than half the time left in their expedition, she and Elphic need to wrap in the pre-sampling phase, in which they measure rocks against the criteria drawn up for them by geologist colleagues to decide which are most worth bringing home.
They are looking for examples of alteration, volcanic rocks whose composition has been changed by water and weather. The samples they collect will be analyzed by colleagues such as Allyson Brady, an organic geochemist at McMaster University in Canada. Brady will be looking for biosignatures, traces left by organisms that once inhabited the rock. Ideally, these biosignatures will correspond with qualities that can be seen from satellites; then researchers studying data from Mars orbiters can look for the same features in the Martian landscape and identify spots of interest to the planet’s future explorers.
“Sitting back watching these video feeds coming back from people actually out in the field and trying to see what’s around them . . . it’s different, that’s for sure,” Brady said. Researchers like her are used to doing their own field work, spending days searching for just the right samples. It’s disconcerting to put those decisions in someone else’s hands.
“Oh, we absolutely could just apply to a grant to go check out basalts in Hawaii,” she acknowledged. But that’s not the point.
“You can do the science separately and the exploration separately. But that doesn’t really tell you very much about whether, from science perspective, the exploration concept you’re testing has actually done a good job. . . . I want to make sure that when someone does go to Mars, they have tested all the things that are going to give them the best possible science.”
(c) 2016, The Washington Post · Sarah Kaplan · Photo: Darlene Lim and NASA – JPL – CALTECH – Cornell | 0.814766 | 3.168959 |
Today, kids studying astronomy and the solar system benefit from modern technology, sophisticated telescopes, affordable solar astronomy tools, and centuries of observation to better understand the relationship between the entire solar system, the sun, and the earth.
But hundreds of years ago, there were only a few scientists who were bold enough to challenge the accepted theories of the solar system. Let’s take a look at three of the most important early solar astronomers –– Copernicus, Brahe, and Kepler –– and understand their contributions to our study of the stars!
Nicolaus Copernicus was a Prussian mathematician who lived during the Renaissance, from 1473-1543. Copernicus was one of the first astronomers to argue that the Earth revolved around the Sun –– and not the other way around! This heliocentric theory of the universe was extremely controversial at the time, especially because it threatened commonly accepted religious views that God had placed the Earth at the center of the universe.
Copernicus developed his theory using extensive sets of astronomical tables and scientific proofs, and built his theory on earlier theories proposed by Plato, Aristarchus of Samos, and the Pythagoreans. One of the most important clues was the movement of Venus and Mercury in relation to the Sun; astronomers of the time observed that these planets moved as if “tethered” to the Sun, with some movement ‘forwards’ and ‘backwards’ over time. This sparked the idea that it was the Sun, not the Earth, which controlled the movement of the planets in the solar system –– including our own.
Copernicus developed his ideas for decades, even working on his book in which he planned to publish them up until the day he died –– literally! It is rumored that, when Copernicus became ill in 1543, he eventually slipped into a coma, only to wake up and review the final pages of his book one last time before passing away. That book, De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres), was not exactly an astronomy book about the solar system written for kids, but it did eventually change the way future generations thought about the relationship between the Earth and the Sun. This fundamental shift in thinking is known as the Copernican Revolution!
While Nicolaus Copernicus devised his heliocentric theory based on existing studies of the solar system, most of his contribution to our understanding of astronomy was through re-examining that data.
Tycho Brahe, a Danish astronomer and contemporary of Copernicus, left his mark on the field of astronomy by conducting thousands of observations, studies, and experiments of his own. Brahe believed that more careful observations could lead to better data, and better data could lead to more accurate models of the solar system.
Among Brahe’s most significant breakthroughs was his observation and measurement of a new star within the Cassiopeia constellation. In 1572, Brahe was studying the constellation when he thought he noticed a new star –– a hunch he confirmed by using a measurement tool called a sextant. What was so extraordinary was that, at the time, it was believed that the realm of the stars was “perfect,” unable to be changed.
Brahe’s new belief that, in fact, new stars could appear within the celestial realm was validated with the appearance of a comet in 1577. Brahe tracked the movement of the comet and determined that it was soaring through the “spheres” of various planets and the Moon.
Brahe used these observations, and others, to develop his new model for the solar system. The Tycho Brahe solar system model suggested that all of the planets revolved around the Sun… but that the Sun and the Moon (and therefore all of the planets, as well) orbited the Earth. In other words, according to Brahe, the Earth was still the center of the universe, but the rest of the planets revolved around the Sun.
The fact that Brahe still believed the Earth to be at the center of the universe has opened him up to some retrospective scrutiny; some scientists say it was a step backwards for astronomy. However, other scientists appreciate that Brahe was accounting for something called ‘stellar parallax’. This is the phenomenon of the stars in the sky maintaining their position despite the Earth moving around the Sun and not the other way around. While it is true that Brahe wasn’t exactly correct in his theory of the solar system, he at least proposed another way of looking at it –– and at the time, that in and of itself was revolutionary thinking.
Johannes Kepler was a student of Brahe who became a famous astronomer in his own right. Kepler combined elements of astronomy, mathematics, science, and astrology. According to Kepler, Tycho Brahe’s solar system theories didn’t go far enough in accounting for what he saw as a harmony which connected all things in the universe. For Kepler, geometry and physics were just as important as astrology and mysticism.
In 1609, Kepler published Astronomie Nova, in which he laid out his observations of Mars and its orbital shape. This is one of the first accounts of an oblong planetary orbit versus a perfectly circular orbit. In addition to changing the thinking of how planets moved –– elliptical rather than circular –– Kepler also offered one of the first instances of a theory that a force of attraction helped organize celestial bodies. This work laid the groundwork for what would become a fundamental theory of physics and something that all kids studying astronomy and the solar system have heard of: gravity!
Continue Your Study of the Stars
Rainbow Symphony wants to encourage the next generation of famous solar astronomers! If you’re a kid interested in astronomy and the solar system, explore our collection of eclipse gear, diffraction glasses, and other educational tools designed to help you make discoveries of your own.
Who knows? You may even challenge some astronomical theories of your own! | 0.914209 | 3.31489 |
Scientists have made a surprising discovery about Mars by playing with muck in the laboratory.
An international team of researchers wondered how volcanoes that spew mud instead of molten rock might look on the Red Planet compared with their counterparts here on Earth.
In chamber experiments, simulated Martian mud flows were seen to behave a bit like boiling toothpaste.
Under certain conditions, the fluid even began to bounce.
The mucky gunge resembled a certain type of lava referred to as “pahoehoe”, which is observed at Hawaii’s famous Kīlauea volcano.
The research results could now complicate some investigations at the Red Planet, believes study lead Dr Petr Brož from the Czech Academy of Sciences’ Institute of Geophysics.
“You’ll look at some features [from space] and you won’t know for sure whether they are the result of lava flows or mud flows.
“Without a geologist on the ground to hit them with a hammer, it will be hard to tell,” he told BBC News.
For a long time, Dr Brož had a sceptical view about mud volcanoes on Mars.
The phenomena are well known here on Earth, but he’d actually spent several years trying to disprove an interpretation that large numbers of conical forms on the Red Planet might also be the same thing.
Eventually, he came around to the idea, and that led him to wonder how mud – if it really does spew from the ground on Mars – would behave in the extreme cold and low-pressure conditions that persist there.
This took him to Dr Manish Patel and his team at the UK’s Open University. They have a special chamber that can recreate the Martian environment.
It’s the kind of set-up in which equipment destined to go on a space agency rover would be tested.
And although ordinarily every effort would be made to keep the chamber spotlessly clean, the researchers soon found themselves tipping experimental muddy fluids down a sandy slope.
Under “Earth conditions”, these muddy mixes behave as you would expect: they’re smooth, like gravy poured on to a dinner plate. But under “Martian conditions”, the mud progresses via a series of ropy and jagged lobes.
It all comes down to how the low pressure – 150 times less than the pressure of Earth’s atmosphere – makes water rapidly evaporate, boil and ultimately freeze.
“The skin on the fluid freezes, but this flow is thick enough that the inside remains fluid,” explained Dr Patel. “So the skin will stop the flow for a bit, but then the momentum from the fluid inside breaks through at weak points in the skin, and the flow propagates forward. It’s just like pahoehoe, except that’s molten rock. But again, it’s a cooling skin that forms before hot material bursts through.”
The team reports its initial experiments in a paper in the journal Nature Geoscience. Not captured in this publication are subsequent experiments in which the flows were repeated for a “hot day” on Mars. There are places where it can get as high as 20C for short periods.
In this scenario, the mud boiled vigorously in the low pressure; “it was jumping over the surface as if levitating,” said Dr Brož.
The team’s work should be a reminder to scientists that when they look at planetary bodies, physical processes can sometimes produce unexpected outcomes, he added.
and follow me on Twitter: @BBCAmos
With SpaceX's first astronaut launch, a new era of human spaceflight has dawned – Space.com
We’ve gotten our hopes up before.
The success of NASA’s Apollo moon missions half a century ago, for example, made Mars seem very much within reach for human explorers. Indeed, the space agency drew up plans to put boots on the Red Planet by the early 1980s, but shifting political and societal winds killed that idea in the cradle.
In 1989, President George H.W. Bush announced the Space Exploration Initiative, which aimed to send astronauts back to the moon by the end of the 1990s and get people to Mars in the 2010s. His son, President George W. Bush, also aimed for a crewed lunar return, with a program called Constellation, whose contours were outlined in 2004. Each program was soon axed by the next administration to come into power.
Full coverage: SpaceX’s historic Demo-2 astronaut launch explained
So it’s natural for space fans to greet the grand pronouncements occasioned by SpaceX’s first crewed launch on Saturday (May 30) with a bit of skepticism. Yes, the Demo-2 mission to the International Space Station (ISS), the first orbital human spaceflight to depart from American soil since NASA retired its space shuttle fleet in 2011, is a big deal. But does it really show that “the commercial space industry is the future,” as President Donald Trump said shortly after liftoff?
Actually, it very well might.
Demo-2 is far from a one-off, after all. It’s a test flight designed to fully validate SpaceX’s Crew Dragon capsule and Falcon 9 rocket for crewed missions to the ISS. The company holds a $2.6 billion NASA contract to conduct six such operational flights, the first of which is targeted for late August, provided Demo-2 goes well.
SpaceX is a highly ambitious company that has already accomplished a great deal in the final frontier; it’s been flying robotic cargo flights to the ISS for NASA since 2012, for example. So, there’s little reason to doubt SpaceX’s ability to fulfill that contract, and to execute a variety of other missions in Earth orbit as well.
Elon Musk’s company has in fact already inked Crew Dragon deals with other customers. For example, Houston-based company Axiom Space, which aims to build a commercial space station in Earth orbit, has booked a Crew Dragon flight to the ISS, with liftoff targeted in late 2021. And the space tourism outfit Space Adventures plans to use the capsule at around the same time, to carry passengers on a mission to high Earth orbit, far above the ISS.
Then there’s Boeing. Like SpaceX, Boeing signed a contract with NASA’s Commercial Crew Program to fly six crewed missions to and from the ISS. Boeing will fulfill the deal with a capsule called CST-100 Starliner, which has made one uncrewed trip to orbit to date.
That flight, which launched this past December, didn’t go as planned; Starliner was supposed to meet up with the ISS but suffered a glitch with its onboard timing system and got trapped in the wrong orbit. But Boeing plans to refly the uncrewed ISS mission later this year and put astronauts on Starliner shortly thereafter, provided everything goes well.
Activity is heating up in the suborbital realm as well.
For example, Richard Branson’s Virgin Galactic has already flown two piloted missions to suborbital space with its newest SpaceShipTwo vehicle, VSS Unity. The company is in the final phases of its test campaign and looks poised to begin carrying space tourists aboard the six-passenger Unity soon.
And Blue Origin, the spaceflight company run by Amazon’s Jeff Bezos, has reached space numerous times with its suborbital vehicle, known as New Shepard. Those test flights have been uncrewed to date, but it probably won’t be long before New Shepard begins carrying customers as well.
The names on this list chip away at the skepticism even more. We aren’t talking about cash-strapped startups here; Bezos is the world’s richest man, and Musk and Branson are both billionaires. And Boeing is an aerospace giant with a long history of achievement in the human spaceflight realm. The company is the prime contractor for the ISS, for example, and it built the first stage of NASA’s huge Saturn V rocket, which launched the Apollo moon missions.
So there’s real reason to hope that an exciting new era of human spaceflight has dawned — perhaps one that will even see people riding private spaceships to the moon, Mars and other destinations in deep space.
Musk has long stressed that he founded SpaceX back in 2002 primarily to help humanity colonize the Red Planet, and the company is already building and testing prototypes of Starship, the vehicle designed to make that happen. And Bezos has repeatedly said that his overarching vision for Blue Origin involves helping to get millions of people living and working in space.
This coming private boom isn’t booting NASA off the human-spaceflight block, of course. The space agency has deep space ambitions of its own. Its Artemis program aims to land two astronauts near the moon’s south pole in 2024 and establish a long-term human presence on and around the moon by 2028.
And the moon will be a stepping stone, if all goes according to NASA’s plan, teaching the agency the skills and techniques required to put boots on Mars.
NASA wants to make that giant leap in the 2030s. We’ll see if the political will and the funding hold long enough for the agency to do it.
Mike Wall is the author of “Out There” (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.
How to watch SpaceX’s Crew Dragon dock with the International Space Station live – The Verge
On Saturday afternoon, SpaceX launched its first human crew to space for NASA on the company’s new Crew Dragon spacecraft — but the mission isn’t over yet. After spending nearly a full day in orbit, the two passengers on board SpaceX’s vehicle, NASA astronauts Bob Behnken and Doug Hurley, will attempt to dock with the International Space Station this morning.
SpaceX’s Crew Dragon has an automatic docking system, which uses a series of sensors and cameras to help the vehicle approach the ISS and then grab on to an existing docking port. The Crew Dragon successfully tested out this technique last year when SpaceX launched a test version of the vehicle to the ISS without crew on board. But this time, the Crew Dragon will carry very precious cargo.
While the Crew Dragon is capable of getting Bob Behnken and Doug Hurley to the station on its own, the two astronauts do plan to do some manual flying when they get close to the ISS. Somewhere between 220 and 170 meters out from the station, the crew will practice flying the capsule manually, using the vehicle’s touchscreen interface inside. Once they’re done, the automatic system will take over again, and the Crew Dragon will do the rest of the work to get to the station.
NASA is providing round-the-clock coverage of the Crew Dragon’s mission right now, but things kick off this morning when Behnken and Hurley do a broadcast from inside the Crew Dragon. Docking will come about a few hours later at 10:29AM ET. All of the events will take place live on NASA’s TV stream above.
Trump Given False Credit For Bush- And Obama-Era Space Program
Today the Space X Dragon “Endeavor” launched. It was the first time since 2011 that the U.S. had launched humans into space. The Commercial Crew Development Program was started during the George W. Bush administration, and was expanded through the NASA Authorization Act of 2010, approved by Congress and signed by President Obama.
JimBridenstine, the Administrator of NASA, was nominated by President Trump in 2017 and the Senate confirmed him in 2018 with a party-line vote, 50-49. All previous NASA administrators have been scientists or engineers — Bridenstine is neither. He is the first politician to head NASA.
Bridenstine gave a speech after the launch where the focus was put on the accomplishments of Trump, and the previous administrations’ roles in this mission were never mentioned. Bridenstine made a point to mention that there were layoffs at NASA in 2010, a pointed jab at the Obama administration. The reason for the layoffs was that the space shuttle missions were wrapping up. As you read above, the NASA Authorization Act of 2010, signed by President Obama, expanded the crew development program. All contracts for today’s mission, including SpaceX’s, were completed during the Obama administration. Trump and Pence also spoke at the event. Space.com described Trump’s address after the launch as something that “sounded like a campaign speech.”
Later, Bridenstine gave an interview where the questions were focused on Trump. Bridenstine offered, “We now have an administration that is fully supportive of our spaceflight initiatives…but also from a Space Force perspective.” Keep in mind, again, that the crew development program was started during the George W. Bush administration, and expanded during the Obama administration.
The U.S. Air Force already had jurisdiction over space, so the creation of the Space Force was redundant. Astronaut Mark Kelly said of Space Force in a tweet, “This is a dumb idea. The Air Force does this already. That is their job. What’s next? We move submarines to the 7th branch and call it the under-the-sea force?”
Bridenstine added during the interview, “[Trump] also said were going to go to the moon by 2024. That means he’s putting himself at risk to say, ‘look, I’m going to be accountable, potentially, I’m going to be accountable to the initiatives that I put forward,’ and I think that’s, we have not had that kind of leadership for space in a long, long time and I’m so grateful for it.”
A plan to go to the moon, as you can expect, takes years of preparation. Much longer than Trump has been in office. It’s unclear what risk Bridenstine was referring to, as the initiatives for the crew development program were begun during the George W. Bush administration.
This speech and interview were a marked shift from statements Bridenstine made three days prior, a day before the initial planned Dragon launch. On May 27th, an interview with Elon Musk and Bridenstine had comments from Bridenstine that focused on the contributions of NASA and SpaceX to the Dragon mission and didn’t mention Trump at all.
Three days later, what appeared originally to be a NASA administrator that is a little out of his element but just really likes space turned into an administrator that rarely acknowledged the endless amount of manpower put into the crew development program. Bridenstine appeared to go from space enthusiast to Trump campaign manager.
Some space enthusiasts expressed dismay at Bridenstine’s speech and interview, including the constant focus on Trump. Journalist Henry Brean tweeted, “What better moment is there for the NASA administrator to talk about the big risk the president is taking than when two astronauts are riding a rocket into space?”
Edited By Harry Miller
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Heliophysics nuggets are a collection of early science results, new research techniques, and instrument updates that further our attempt to understand the sun and the dynamic space weather system that surrounds Earth.
Throughout the universe more than 99 percent of matter looks nothing like what's on Earth. Instead of materials we can touch and see, instead of motions we intuitively expect like a ball rolling down a hill, or a cup that sits still on a table, most of the universe is governed by rules that react more obviously to such things as magnetic force or electrical charge. It would be as if your cup was magnetized, perhaps attracted to a metal ceiling above, and instead of resting, it floats up, hovering somewhere in the air, balanced between the upward force and the pull of gravity below.
This material that pervades the universe, making up the stars and our sun, and also – far less densely, of course – the vast interstellar spaces in between, is called plasma. Plasmas are similar to gases, and indeed are made of familiar stuff such as hydrogen, helium, and even heavier elements like iron, but each particle carries electrical charge and the particles tend to move together as they do in a fluid. Understanding the way the plasma moves under the combined laws of motion we know on Earth and the less intuitive (to most Earthlings, at least) electromagnetic forces, lies at the heart of understanding the events that spur giant explosions on the sun as well as changes in Earth's own magnetic environment – the magnetosphere.
Understanding this mysterious world of plasma, however, is not easy. With its complex rules of motion, the study of plasmas is rife with minute details to be teased out.
"Which particles are moving, what is the source of energy for the motion, how does a moving wave interact with the particles themselves, do the wave fields rotate to the right or to the left – all of these get classified," says Lynn Wilson who is a space plasma physicist at NASA's Goddard Space Flight Center in Greenbelt, Md.
Wilson is the first author of a paper in Geophysical Research Letters that was published on April 25, 2012. Using data from the WAVES instrument on NASA's Wind mission, he and his colleagues have discovered evidence for a type of plasma wave moving faster than theory predicted it could move. The research suggests that a different process than expected, electrical instabilities in the plasma, may be driving the waves. This offers scientists another tool to understand how heat and energy can be transported through plasma.
For the study, Wilson examined coronal mass ejections (CMEs) – clouds of solar material that burst off the sun and travel through space -- that move so much faster than the background solar wind that they create shock waves. These shock waves are similar to those produced by a supersonic jet when it moves faster than the speed of sound in our atmosphere.
"A bow shock is a little like a snow plow," says Adam Szabo, a space scientist at Goddard who is a co-author on the paper and also the project scientist for Wind. "The wave picks up particles that are traveling more slowly and speeds them up, piling them up in front as it moves."
Of course, the snow plow is a non-magnetic analogy, and that's where things get sticky. With a snow plow one would never expect a cloud of snowflakes to magically lift up from the shock and begin to speed ahead, streaming down the street faster than the rest of the plow's pile. But in the magnetized gas ahead of the shock, Wind observed a large wave in the plasma – a wave moving faster than it should be able to travel if it had been made by the shock.
The wave in this case is called a Whistler wave. (Classification, for those who want the nitty gritty: an electromagnetic wave, carried by electrons, right polarized, propagates obliquely to the magnetic field.) Since the wave couldn't be created by the shock, the Wind observations suggest that perhaps the waves are created by instabilities out in front of the shock. This is not in itself surprising. The Wind data used by Wilson can measure magnetic field information at 1875 samples per second and new qualities of observations always produce new sights. But the team is surprised by how large the waves are.
"The waves are massive," says Wilson. "They are almost as big as the shock itself."
Such size means the waves may play a larger role than previously thought in the quest to understand the ways that different types of energy converts from one form to another. In this context, two kinds of energy are of interest: bulk kinetic energy, which relates to the collective movement of a bulk of particles, and random kinetic energy, which relates to the speeds at which particles move with respect to each other. Increased random kinetic energy is, in fact, the very definition of heating, since temperature measurements are a characterization of how fast particles are moving within any given material. Large amplitude Whistler waves are known to cause both bulk acceleration and an increase in random kinetic energy, that is, the very temperature of a material.
So, this suggests that shocks and the instabilities they create may play a larger role in transferring the energy from the plasma's bulk movement into heat, than previously thought. Wilson believes that the instabilities caused something called perpendicular ion heating – a process that increases the random kinetic energy of the positively-charged ions in a direction perpendicular to the background magnetic field. The waves also added energy to the negatively-charged electrons -- with the greatest effects observed not being heating, the random kinetic energy, but bulk acceleration in a direction parallel to the magnetic field.
"The same type of wave-particle interaction is thought to happen in solar flares, the heating of the sun's corona, and supernova blast waves," says Wilson. "All of these energizations have very similar properties. Now we have evidence that these Whistler-like fluctuations may be causing heating in all these places."
Understanding the mechanics behind all these events requires collating and categorizing an entire zoo of waves and processes. Wilson's work may be but one piece of a larger puzzle, but together, teasing out the motions of plasmas will help scientists describe the laws of motion that govern the entire universe. | 0.809364 | 4.070283 |
Dark energy… We’re still not exactly sure of what it is or where it comes from. Is it possible this mysterious force is what’s driving the expansion of the Universe? A group of astronomers from the universities in Warsaw and Naples, headed by Dr. Ester Piedipalumbo, are taking a closer look at a way to measure this energetic enigma and they’re doing it with one of the most intense sources they can find – gamma-ray bursts.
“We are able to determine the distance of an explosion on the basis of the properties of the radiation emitted during gamma-ray bursts. Given that some of these explosions are related to the most remote objects in space that we know about, we are able, for the first time, to assess the speed of space-time expansion even in the relatively early periods after the Big Bang,” says Prof. Marek Demianski (FUW).
What spawned this new method? In 1998, astronomers were measuring the energy given off by Type Ia supernovae events and realized the expelled forces were consistent. Much like the standard candle model, this release could be used to determine cosmic distances. But there was just one caveat… The more remote the event, the weaker the signature.
While these faint events weren’t lighting up the night, they were lighting up the way science thought about things. Perhaps these Type Ia supernovae were farther away than surmised… and if this were true, perhaps instead of slowing down the expansion of the Universe, maybe it was accelerating! In order to set the Universal model to rights, a new form of mass-energy needed to be introduced – dark energy – and it needed to be twenty times more than what we could perceive. “Overnight, dark energy became, quite literally, the greatest mystery of the Universe,” says Prof. Demianski. In a model put forward by Einstein it’s a property of the cosmological constant – and another model suggests accelerated expansion is caused by some unknown scalar field. “In other words, it is either-or: either space-time expands by itself or is expanded by a scalar physical field inside it,” says Prof. Demianski.
So what’s the point behind the studies? If it is possible to use a gamma-ray burst as a type of standard candle, then astronomers can better assess the density of dark energy, allowing them to further refine models. If it stays monophonic, it belongs to the cosmological constant and is a property of space-time. However, if the acceleration of the Universe is the property of a scalar field, the density of dark energy would differ. “This used to be a problem. In order to assess the changes in the density of dark energy immediately after the Big Bang, one needs to know how to measure the distance to very remote objects. So remote that even Type Ia supernovae connected to them are too faint to be observed,” says Demianski.
Now the real research begins. Gamma-ray bursts needed to have their energy levels measured and to do that accurately meant looking at previous studies which contained verified sources of distance, such as Type Ia supernovae. “We focused on those instances. We knew the distance to the galaxy and we also knew how much energy of the burst reached the Earth. This allowed us to calibrate the burst, that is to say, to calculate the total energy of the explosion,” explains Prof. Demianski. Then the next step was to find statistical dependencies between various properties of the radiation emitted during a gamma-ray burst and the total energy of the explosion. Such relations were discovered. “We cannot provide a physical explanation of why certain properties of gamma-ray bursts are correlated,” points out Prof. Demianski. “But we can say that if registered radiation has such and such properties, then the burst had such and such energy. This allows us to use bursts as standard candles, to measure distances.”
Dr. Ester Piedipalumbo and a team of researchers from the universities in Warsaw and Naples then took up the gauntlet. Despite this fascinating new concept, the reality is that distant gamma-ray bursts are unusual. Even with 95 candidates listed in the Amanti catalogue, there simply wasn’t enough information to pinpoint dark energy. “It is quite a disappointment. But what is important is the fact that we have in our hands a tool for verifying hypotheses about the structure of the Universe. All we need to do now is wait for the next cosmic fireworks,” concludes Prof. Demianski.
Let the games begin…
Original Story Source: University of Warsaw Press Release. For Further Reading: Cosmological models in scalar tensor theories of gravity and observations: a class of general solutions. | 0.805258 | 4.06673 |
The search for Earth-like planets continues, as astronomers scour the sky examining stars for telltale clues of orbiting worlds. Most of the exoplanets found are big, like Jupiter, because they’re the easiest to detect. But our technology has become better and more clever over the years, and smaller planets have been found, including many roughly the size of Earth.
That search took a cool turn this week … literally. A team of astronomers announced they have found not one but three Earth-size planets orbiting a red dwarf, a tiny and cool star just 40 light-years away!
This is very interesting for many reasons: This is the lowest mass full-fledged star ever seen to have planets, it’s relatively close by, and all three planets are (more or less) in the star’s “habitable zone,” where temperatures might—might—support the existence of liquid water on the planets’ surfaces.
The European Southern Observatory put together a nice video explaining this, so give it a view:
The planets were discovered using TRAPPIST (short for Transiting Planets and Planetesimals Small Telescope). This is a 60 cm (24”) telescope that takes images of a select group of 60 nearby red dwarf stars visible from the Southern Hemisphere. The team looks for dips in the stars’ light that are caused by any planets orbiting those stars periodically blocking their host star’s light; this is called the transit method, and most exoplanets have been discovered this way.
TRAPPIST found evidence of planets orbiting a star, called TRAPPIST-1, and follow-up observations were made with much larger telescopes. Three planets were found in total, which is remarkable all by itself. But it gets better.
TRAPPIST-1 is an M8 dwarf, only 0.08 times the mass of the Sun; just barely massive enough to fuse hydrogen into helium in its core. If it were much lower mass we wouldn’t call it a star at all (we’d say it’s a brown dwarf). Its surface temperature is only about 2,550 K—the Sun is literally more than twice as hot—so it’s informally called an “ultracool” star. And it’s tiny, only about 0.11 times the diameter of the Sun. That’s roughly the same size as Jupiter!
Yet this teeny star sports at least three planets. Called TRAPPIST-1b, c, and d, the exoplanets were detected as they blocked a small fraction of the star’s light. The sizes of the planets were found by seeing just how much of the starlight they blocked. The best measurements indicate they are 1.1, 1.05, and 1.2 times the size of Earth. We don’t know their masses, but if they have the same composition as our home world—rock and metal—then their surface gravities wouldn’t be all that different than ours.
So they’re Earth-size. But are they Earth-like? That is, nearly the same temperature and composition as Earth?
We have no idea what these planets are made of. They could be rock, metal, watery, airless … with our current technology we don’t know how to determine that. Finding the masses of these planets would be extremely difficult, so we’re out of luck there.
But we can estimate their temperatures. The temperature of a planet depends on its distance from the star and that star’s temperature, of course, but also on how reflective the planet is; a more reflective planet will be cooler than a dark, absorptive one.
Each of the planets orbits ridiculously close to the star compared with the planets in our solar system. In order, they’re 1.7 million, 2.3 million, and 3.3 million–22 million kilometers from the star (the observations of the third planet, d, don’t constrain its distance very well, so there’s a range of possible distances). Mind you, Mercury is 58 million kilometers from the Sun, so all three of these planets would easily fit inside Mercury’s orbit, with a tens of millions of kilometers to spare.
But remember, the star is very cool, so even at those distance the planets aren’t as hot as you might think.
Assuming very dark planets, the inner two would be about 125° and 70° C, far too hot for life as we know it. The outer planet’s distance from the star wasn’t as well determined, but it would likely have a temperature somewhere from -160° - +10° C depending on its distance. The warmer end of that range is close to Earth’s average temperature!
Remember, that’s assuming dark planets. If they’re more like Earth (which reflects about 40 percent of the light that hits it), they’ll be cooler. If they’re reflective enough, the inner two planets might be more like Earth, too (but the outer planet would be a frozen ball of ice).
That part is more speculative; we have no idea how reflective they are. It’s possible, though I’d think unlikely, that all three planets are somewhat clement.
Again, we don’t know much about them; they might be airless, or have thick atmospheres of carbon dioxide, or some other noxious combination, so don’t start looking into real estate on them just yet. And even if they are Earth-like, 40 light-years is 400 trillion kilometers. That’s a fairly long road trip. It would take 450 million years to drive there at highway speeds. Better pack a lunch.
But don’t be disappointed. The amazing thing to remember here is that these planets exist at all. Even dinky red dwarf stars manage to make planets, including ones the same size as ours. That’s incredibly exciting.
Another reason this is so exciting is because of the host star. Cool red dwarfs are faint and hard to detect, making these observations somewhat difficult, but they also make up the most populous class of star in the galaxy. If they have planets in the same proportion as more massive, hotter stars do, then planets orbiting red dwarfs will outnumber planets orbiting all other types of stars combined. And here we found three Earth-size planets orbiting one nearby.
It’s impossible not to ask, how many planets like Earth exist in the galaxy? We’re not sure, but various methods have been used to estimate that number, and even conservatively their numbers must be in the billions. Billions. In our galaxy alone.
And our tech is getting better. In the coming years we’ll have telescopes able to dissect the light from such planets, looking for the Earth-like conditions: oxygen in the atmosphere, say, and a temperature more like ours. We’ve found a few candidates for Earth-like exoplanets, but nothing yet that we can point to and confidently say, “Earth 2.” | 0.866458 | 3.901569 |
During the hot, steamy nights of July, the Milky Way is a recurrent sight stretching from horizon to horizon. Now’s the best time to view it with the naked eye, and to discover a host of celestial gems within it using a telescope or binoculars. As well, one should not neglect Venus and Saturn, which continue to dominate the evening sky…
The Milky way is our galaxy — a disk-shaped island of stars that measures about 120 000 light years across with an average thickness of 1000 light years. To visualize it, our galaxy has the same proportions as a thin crust pizza… Our Sun, is an average star among 200 billion others, that is situated in the middle of the disk’s thickness about 26 000 light years from the centre. Seen from our perspective, inside the Milky Way, our galaxy looks like a narrow luminous band that arches overhead. This “milky trail” (as it was known to the ancient Greeks) owes its glow to the cumulative light of hundreds of millions of stars spread throughout the Galaxy’s disk.
However, the stars are not distributed evenly: Some parts of the disk are thicker and brighter than others. Such is the case for the region delimited by Sagittarius and Scorpius, above the southern horizon. The centre of our galaxy lies beyond the stars of these constellations and is demarcated by a prominent galactic bulge, which explains the disk’s increased thickness. At its heart lies Sagittarius A* (pronounced A-star), our galaxy’s supermassive black hole. This cosmic colossus has a mass of about four million “Suns” contained in a volume smaller than our solar system… Lucky for us, we’re at a safe distance!
Other striking features that await observers who scan the Milky Way between Sagittarius and Cygnus (at the heart of the summer triangle), are the dark zones that seem devoid of stars: The Cygnus rift, in particular, seems to split the Milky Way in two, along its length. These are not “holes” in the Galaxy, but rather foreground clouds of dust and gas that block the light of the stars that lie behind them. We see these dust-lanes silhouetted against the Milky Way’s luminous disk.
Viewed with binoculars, the Milky Way has a “granular” texture, which indicates that it consists of individual stars. And scanning along the Milky Way, between Sagittarius and Cygnus, one can find many nebulae and star clusters, both open and globular, which makes this one of the richest fields for deep-sky objects. Telescopes offer an even more rewarding experience, revealing many unexpected details… An absolute must for your “bucket list.”
And speaking of telescopes, you’ll need one (a small one will do) to see Saturn’s rings. In July, the planet is located in Virgo and is visible in the south after twilight; it sets in the west after midnight. On July 16, the first quarter Moon will pass below Saturn.
The only other evening planet, visible in July, is so bright that it doesn’t require a telescope or the Moon to see it. Of course, we’re talking about Venus, which is visible in the west after sunset. On July 3, Venus will pass just above the Beehive star cluster, also known as M44 (its number in the Messier catalogue). However, observing Venus will still present a challenge, requiring good weather conditions and an unobstructed west-northwest horizon. Binoculars will prove indispensable. During the course of the month, Venus will slowly approach the horizon, and the bright star Regulus, in Leo: the two will be separated by about one degree on the evening of July 21. | 0.833192 | 3.953179 |
The search for extraterrestrial life is one that intrigues and inspires. Are we truly alone in the universe? Although the definition of extraterrestrial life is as vastly different as the planetary bodies which they may inhabit, the possibilities that could arise upon the discovery of life outside Earth are unlimited. If life can be sustained elsewhere, what new doors could this open? Could humanity branch out beyond our own backyard and even further than our planetary neighbor, Mars?
These questions and more are often the basis for launching spacecraft to various planets and moons in the solar system. These spacecrafts often engage in missions designed to search for microbes. Additional tools such as large radio telescopes are designed to listen for signals emitted throughout the galaxy, and scientists now aim to probe planets orbiting other stars for signs of life or the ability to sustain life.
NASA is set to launch its Transiting Exoplanet Survey Satellite (TESS) on Monday, April 16thon a SpaceX Falcon 9 rocket. TESS is a NASA Astrophysics Explorer mission. Led and operated by MIT, TESS is designed to scan and measure the brightness of stars within approximately 300 lightyears. It will observe these stars and any dimming that occurs as planets orbit. The mission is projected to increase the list of known exoplanets by upwards of 400 per cent.
Over 2,500 exoplanets were discovered via a similar method employed by the Kepler space telescope, and an additional 2,500-plus are awaiting confirmation. Of these, around 30 are rocky planets approximately the size of Earth and within the Goldilocks Zone, the distance at which liquid water can exist and sustainable life is possible. Kepler is reaching the end of its life cycle as it will soon run out of fuel following a mission lasting nearly a decade. Anticipating the end of this current mission, NASA set out to create and prepare Kepler’s replacement, TESS.
“TESS is really a finder scope,” says George Ricker, principal investigator of the TESS mission and director of MIT’s CCD Imaging Laboratory. “The main thing that we’re going to be able to do is find a large sample from which the follow-up observations can be carried out in decades, even centuries to come.”
Natalia Guerrero, deputy manager of TESS Objects of Interest, likened TESS to a scout. “We’re on this scenic tour of the whole sky; and in some ways, we have no idea what we will see,” she said. “It’s like we’re making a treasure map. Here are all these cool things. Now, go after them.”
The area which TESS will observe is roughly 350 times larger than that of Kepler. However, TESS will have less time to collect light in each part of the sky. For this reason, it will need to focus on stars which are closer and brighter. Ricker and his colleagues have comprised a list of 200,000 particularly bright stars which they would like to more closely observe. The satellite will create pixelated images of each star. The images will be taken every two minutes in order to capture the moment that a planet crosses its path. Full-frame images will also be taken every 30 minutes, capturing the stars in a specified strip of the sky.
“With the two-minute pictures, you can get a movie-like image of what the starlight is doing as the planet is crossing in front of its host star,” said Guerrero. “For the 30-minute images, people are excited about maybe seeing supernovae, asteroids, or counterparts to gravitational waves. We have no idea what we’re going to see at that timescale.”
Creating a larger map of nearby exoplanets will allow for vastly increased discoveries, as well as closer and more detailed observation.
“The TESS survey should be comprehensive enough that we should be well positioned to essentially find all of these candidates and certainly the ones that are most promising,” said Ricker.
Sara Seager, deputy director of science for TESS, will scour the images for dips in starlight which indicate that a planet may have passed in front of its star. Seager and her team will also use cues from the imagery to determine the mass of a potential planet.
“Mass is a defining planetary characteristic,” said Seager. “If you just know that a planet is twice the size of Earth, it could be a lot of things: a rocky world with a thin atmosphere or what we call a “mini-Neptune,” a rocky world with a giant gas envelope, where it would be a huge greenhouse blanket and there would be no life on the surface. So, mass and size together give us an average planet density, which tells us a huge amount about what the planet is.”
Seager also believes that continued observation may yield surprising results, including the existence of life. “There’s no science that will tell us life is out there right now, except that small, rocky planets appear to be incredibly common,” she said. “They appear to be everywhere we look, so it’s got to be there somewhere.” | 0.936261 | 3.460419 |
Spacecraft are great explorers, but they can be frustrating pen pals.
The farther from home a probe ventures, the longer its dispatches take to reach eager humans on Earth and the terser such reports must be. That's why computer scientists and planetary scientists are teaming up to develop an algorithm that could potentially identify the most intriguing data an icy moon explorer mission collects, sending those tidbits to receivers first.
"We're in this golden age of space exploration, and we have hundreds and hundreds of gigabytes of data flooding back from across the solar system," Ashley Davies, a planetary scientist at NASA's Jet Propulsion Laboratory in California, told Space.com. "It's not possible to return all the data that you ever collect."
Hence the interest in an algorithm to negotiate what to report first. A team based at JPL is developing a potential system to do just that for individual instruments on NASA's Europa Clipper mission.
That spacecraft is due to launch in the mid-2020s to explore Jupiter's icy moon Europa. The moon is one of the most intriguing worlds in our solar system for scientists interested in understanding whether life exists beyond Earth. An ocean hidden below Europa's icy shell could potentially host microbial life similar to that found near deep-sea vents on Earth, and Clipper could collect information that would give scientists a more detailed understanding of the moon.
Europa Clipper will carry nine different science instruments, and the algorithm team is already working with the teams behind three of them, with more partnerships under discussion. The instruments will look for features like warm patches in the icy shell and plumes of seawater bursting out into space.
The idea behind the algorithm project is that it should be possible to train the spacecraft to spot the most promising data it gathers, then bump that to the front of the communications queue. It wouldn't change what Europa Clipper does next, but it could mean scientists wouldn't need to be quite as patient.
There's just one problem: space-ready machines are … not the typical hardware computer scientists use. The system on board Europa Clipper will be able to run at speeds of up to 200 megahertz. "For comparison, that's about the equivalent of an early '90s desktop PC, if you took that and put that into orbit," Kiri Wagstaff, a computer scientist at JPL who is leading the project, told Space.com. "We don't really encounter machines that limited today in our day-to-day life."
The stunted processing capacity means any space-bound algorithm has to be lean, and extremely so. It's one of the two key challenges Wagstaff and her colleagues are facing in developing a system for Europa Clipper: The researchers have to come up with ways of flagging key data for the limited processor to execute in ways that are simple and quick. "We get questions about, well, 'Are you using deep learning to help these spacecraft make these decisions?'" Wagstaff said. "And the answer is emphatically no, it's simply not possible."
The team's other main challenge is that, after all, Europa Clipper itself doesn't exist yet and hasn't produced any data yet. Wagstaff and her colleagues are basing their current work on data gathered by other spacecraft and on simulations of what Clipper's data could look like, but it's not the same.
Right now, the algorithm isn't a formal part of Europa Clipper, and there's no guarantee it will be used during the mission. First, it needs to pass a series of tests designed to make sure the algorithm is trim enough to work in flight. "That's kind of a go, no-go point," Wagstaff said. "If it can't fit into the available resources, you can't use it."
Wagstaff and her colleagues are also checking whether the algorithm can withstand the harsh radiation environment around this frigid moon. The computer on the spacecraft will be sheathed to protect it from radiation, but some particles will still sneak through. Scientists need to know whether such hits can derail a calculation.
But if the team can get the algorithm right, it could make Europa Clipper a more powerful mission, encouraging scientists to gather too much data to send home in the allotted time, with the assurance that they'll see the most intriguing of it.
That's the first step in using such algorithms to actively shape outer solar system missions. The process has already begun at Mars on NASA's Curiosity rover, which can use its laser spectrometer to analyze rocks that meet current science priorities without waiting for instructions from Earth. "It all happens without any human in the loop," Wagstaff said. "The rover itself decides, 'This looks like an interesting rock, I will sample that,'" in time that it would otherwise spend twiddling its thumbs. "We're getting this bonus science basically for free."
Examples like that make a tempting lure for planetary scientists with more distant targets. But even if an algorithm doesn't fly on Clipper, there's plenty for scientists to look forward to, Davies said.
"Whatever happens, the data that we're going to get back from Europa Clipper is going to be of immeasurably higher quality than what was achievable from previous missions," he said. "We're going to see a lot of things that previous instruments simply couldn't have detected." They may just need a little more patience.
- Photos: Europa, Mysterious Icy Moon of Jupiter
- Life on Jupiter's Moon Europa? Lander Design Team Hopes to Be the Ones to Find It
- Europa's Buried Ocean Could Rise to the Surface (Video)
Editor's note: This story has been updated to clarify that the Mars Curiosity instrument that can operate autonomously is its laser spectrometer, not its drill. Email Meghan Bartels at [email protected] or follow her @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook. | 0.876207 | 3.193532 |
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You know what's really amazing? Despite all the technological innovations in TV, computers, the Internet and what not, the radio is still alive and well today. Some scholars believe it's because when we listen to the radio, we believe it's speaking directly to us, making us feel warm, fuzzy, and important deep down.
I don't know the real reason for why the radio has stuck around, but I do know that the radio waves used in radios aren't just for sound. They're for looks too. Telescopes, called radio telescopes, rely on radio waves as much as any radio you may have.
This lesson will go over what radio telescopes are, the basics of how they work, and some other key concepts related to their use.
Radio telescopes are instruments used to detect, collect, and analyze radio waves coming from cosmic sources. If you look at the electromagnetic spectrum, you can see that radio waves include a very large range of frequencies. As a result, radio telescopes vary a lot since different techniques must be used for different parts of this spectrum. Here's just one example of what I mean.
Radio telescopes are reflectors. This means they use metallic surfaces that act as mirrors. These mirrors reflect radio waves to a focus. In order to accomplish this task well, the surface of a radio telescope may need to be very smooth. How smooth? The imperfections on the telescope have to be smaller than 1/10 the wavelength the telescope is tuning into.
What this means is, radio telescopes that are designed for wavelengths that are longer than a meter can have tennis sized holes and bumps in them and still reflect really well. In fact, you can just use some chicken wire mesh for the longer-wavelength radio waves. Obviously, if the radio telescope is operating at millimeter-long wavelengths, then chicken wire won't work and the irregularities on the telescope's surface have to be very small.
I'm sure you can appreciate why this is the case with a much simpler example closer to home. If you want to catch a big and long fish in a net, you can have big holes, and you'll still catch it. But that won't work for shorter and smaller fish, which will slip right through. So, in that case your net will need to have holes that are a lot smaller to catch the smaller fish.
Radio astronomers, the poor fellows, have two big disadvantages when compared to optical astronomers. Another lesson would've taught you that the resolving power of a telescope depends on two key factors. One was the size of the primary mirror or lens and the other was the wavelength of radiation in question. The longer the wavelength, the more diffraction, and the worse the image.
Thus, when it comes to radio waves, the diffraction fringes will be large and the images produced by radio telescopes aren't as detailed as those produced by optical telescopes of a similar size.
Another problem radio astronomers face is the fact that longer wavelengths of radiation have lower energies. This means that radio signals arriving from the universe are very weak and radio astronomers need to either build humongous single dishes or combine lots of smaller dishes together before amplifying the signal further to be properly measured.
The largest single radio telescope has a diameter of 1,000 feet and a circumference of about 1,000 meters! And if you wanted to resolve the details of a galaxy as well as a much smaller optical telescope, you'd have to build a radio dish that's the size of Rhode Island.
So, to get a high angular resolution, radio astronomers have turned to interferometry. I sort of glossed over what this is just a second ago.
Interferometry is the use of more than one telescope, connected together and operating as one instrument, in order to achieve a higher angular resolution. Angular resolution is a telescope's ability to see two glowing objects as distinct and separate sources of light. In interferometry, widely spaced radio dishes produce a resolution that's like the resolution of one telescope that's as large as the distance between the two dishes in question.
As a real-world example of this, there are two telescopes, called Keck I and Keck II on top of Mauna Kea. They are 85 meters apart. When they are used as an interferometer (a radio telescope made of two or more separate antennas), the angular resolution is equivalent to one 85-meter telescope. If your eyes were this good, this would allow you to read the last row on an eye-chart 22 miles away!
Radio telescopes are instruments used to detect, collect, and analyze radio waves coming from cosmic sources. They are a kind of reflecting telescope, and therefore, use mirrors to reflect radio waves to a focus. Although you can technically build a radio telescope out of cheap chicken wire, radio astronomy does have some serious disadvantages compared to the expensive optics of optical astronomy.
Namely, this lesson went over the fact that longer wavelengths of radiation suffer from more diffraction, and that radio waves are of low energy. Thus, radio astronomers need to either build large dishes or combine several telescopes in a process called interferometry to try and compensate for these problems.
Interferometry is the use of more than one telescope, connected together and operating as one instrument, in order to achieve a higher angular resolution. Angular resolution is a telescope's ability to see two glowing objects as distinct and separate sources of light.
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Back To CourseBasics of Astronomy
28 chapters | 325 lessons | 0.826387 | 3.319836 |
Black holes have always been the great mystery objects of our universe, but lately theyve got even more mysterious. Its always been thought that black holes were the dead bodies of the cosmos. When a star dies, for example, it can turn into a black hole when a galaxy grows older a big black holes builds up at the centre, but new observations suggest that black holes might be the birth-givers of our cosmos.
Discoveries made from a new way of doing astronomy (Deep Field Survey Astronomy) have revealed that giant black holes were already present at the centres of the very first galaxies when they were being born.
Dr Graham Phillips: Black holes have always been the great mystery objects of our universe, but lately they've got even more mysterious. It's always been thought that black holes were the dead bodies of the cosmos. When a star dies, for example, it can turn into a black hole when a galaxy grows older a big black holes builds up at the centre, but new observations suggest that black holes might be the birth-givers of our cosmos.
Narration: When big stars explode one kind of black hole is created, the sun-sized ones we hear most about. But the mystery here is a different species...the supermassive black hole...it weighs millions of suns and lurks at the centre of a galaxy. And it's a weird object.
Professor Ray Norris: It's a hole in space-time. It sounds terribly Dr Who but it is actually. What's happened is a whole lot of mass has got together ...stars, mass whatever and it's actually collapsed into this object which keeps on falling for ever. And what happens is the gravitation pull of this is so strong that even light will get sucked into it. I mean your really don't want to go near a black hole. Because everything gets sucked into it. They're terrible places.
Narration: And yes, there is a supermassive black hole at the centre of our Milky Way galaxy.
Dr Graham Phillips: So is the black hole doing anything?
Professor Ray Norris: It's sucking in the odd star. If you're in a civilisation on one of those stars you'd say yes it certainly is. You'd be pretty upset about it - your civilisation has just been sucked into this black hole.
Dr Graham Phillips: But we're a safe distance from it.
Professor Ray Norris: Yeah that's right where we stand right out in the western suburbs of the Milky Way where we're pretty safe we say, yeah that's interesting.
Narration: Here's the mystery. Conventional wisdom says that giant black holes are created by matter slowly accumulating at the centres of ageing galaxies. But new research shows that's probably wrong.
That new research is actually a new way of doing astronomy, called deep field survey astronomy. It all started with an almost wacky experiment on the Hubble Space Telescope.
Professor Ray Norris: The guy who was the director of the space telescope, announced that he was going to spend ten days looking at a bit of black sky. And everyone says this is stupid what a waste of this fantastic resource. You're just going to find the blackest piece of sky and stare at it for 10 days! Yep, let's see what's out there. And he did that and that became the Hubble Deep Field and it turned out to be one of the most scientifically productive things ever to be done on the space telescope.
Narration: By opening Hubble's camera shutter for 10 days to gather the faintest light, the seeming dark patch of sky turned into a staggering array of very distant galaxies. The Hubble experiment inspired more deep field surveys.
With these, the galaxies' light takes so long to reach us we're seeing the galaxies as they were when they were extremely young.
And that's been the surprise. Those young galaxies already have fully formed giant black holes at their centres.
Professor Ray Norris: We don't expect that. How did they get there? They shouldn't be there. We've got something wrong. We know we've got something wrong.
Narration: Rather than supermassive holes being part of a galaxy's ageing process, it seems they might play a key role in the birth of galaxies.
Professor Ray Norris: And we don't know what that role is. Were' trying to look at these early galaxies, find out which ones have black holes. Is there anything different about the galaxies? Can we see a whole load of stars being born around the black holes are the black holes in some way the key to the formation of the galaxies we really don't know.
Narration: To find the answer we'll probably have wait for a new generation of radio telescopes - which are currently being planned.
Professor Ray Norris: Radio telescopes like the new generation we are building - they can see these big black holes right back at the beginning of the universe. We'll basically pick up every big black hole ever since the beginning of the universe.
Dr Graham Phillips: Really?
Professor Ray Norris: Yeah
Narration: And by studying all those black holes, we should find out if they are indeed the key to galaxies being born. If so we own our existence to the monster black holes in the middle of galaxies. | 0.855687 | 3.305883 |
As the sunsets on NASA?s Phoenix Mars Lander, both literally and figuratively, missionengineers are beginning to shut down some of the spacecraft?s instruments andheaters to conserve what little energy it has left.
The Phoenixlander, originally slated to run for 90 days after its May 25 touchdown onthe red planet, has completed its fifth month of exploring the surface of theMartian arctic. Over the course of its mission, the lander dug up samples ofdirt and the rock-hard ice layer underlying the surface of Mars' arctic plainsand analyzed them for signs of past potentialhabitability.
But as theMartian northern hemisphere transitions from summer to fall, the spacecraft isgenerating lessand less power as the days grow shorter, reducing the hours of sunlightreaching its solar panels.
To keepPhoenix chugging along for as long as possible, mission controllers willgradually shut down four survival heaters over the next few weeks, one at atime, to conserve power. The heaters keep the lander and its instruments withintheir tested operational temperature range.
"If wedid nothing, it wouldn't be long before the power needed to operate the spacecraftwould exceed the amount of power it generates on a daily basis," saidPhoenix Project Manager Barry Goldstein of NASA's Jet Propulsion Laboratory(JPL) in Pasadena, Calif. "By turning off some heaters and instruments, wecan extend the life of the lander by several weeks and still conduct somescience."
Engineerssent commands to disable the first heater on Tuesday. That heater warms Phoenix's robotic arm, robotic-arm camera and Thermal and Evolved-Gas Analyzer (TEGA),which bakes samples and "sniffs" the vapors given off to helpdetermine the samples' composition. Shutting down this heater is expected tosave 250 watt-hours of power per Martian day.
The Phoenix team has parked the robotic arm on the ground, with its thermal andelectrical-conductivity probe (TECP) ? located on the wrist of the arm ? stuckinto the dirt. The TECP will continue to measure soil temperature andconductivity (or how heat and electricity move through the surface dirt), aswell as atmospheric humidity near the surface. (The probe does not need a heaterto operate and should continue sending back data for weeks.)
The roboticarm won't be diggingup any more dirt samples though.
"Weturn off this workhorse with the knowledge that it has far exceededexpectations and conducted every operation asked of it," said the roboticarm's co-investigator Ray Arvidson, of Washington University in St. Louis.
Phoenix finished scooping up all itssamples last week and mission scientists were working to analyze them before Phoenix'stime is up.
As powerlevels continue to drop, Phoenix engineers will gradually turn off the otherthree heaters. The second heater serves the lander's pyrotechnic initiationunit and is expected to add four or five days to the mission's lifetime. Thethird warms the lander's main camera and meteorological instruments. Theelectronics that operate those instruments should generate enough heat to keepthem, and the camera, functioning for awhile.
The fourthheater ? one of two survival heaters that warm the spacecraft and its batteries? would be shut down in a final step. This would leave only one survival heaterto run out on its own.
"Atthat point, Phoenix will be at the mercy of Mars," said Chris Lewickie ofJPL and the lead mission manager.
Engineersare also preparing for solar conjunction, when the sun is directly between Earthand Mars. This will happen between Nov. 28 and Dec. 13 and will block radiotransmission between the spacecraft and Earth. No commands will be sent to Phoenix during that time, but downlinks from Phoenix will continue through NASA's Odysseyand Mars Reconnaissance orbiters.
For now,mission controllers are uncertain whether the fourth heater will be shut downbefore or after conjunction.
- Video - Phoenix: Digging on Mars
- Special Report: Phoenix Mars Lander
- Images: Phoenix on Mars! | 0.811185 | 3.032308 |
TRAPPIST-1 is only eight percent the mass of our sun, making it a cooler and less luminous star. It’s home to seven Earth-size planets, three of which orbit in their star’s habitable zone—the range of distances from a star where liquid water could pool on the surface of a rocky planet. The system is located about 40 light-years away in the constellation of Aquarius and is estimated to be between 3 billion and 8 billion years old.
Scientists announced that the system has seven Earth-sized planets at a NASA press conference on Feb. 22. NASA’s Spitzer Space Telescope, the TRAPPIST (Transiting Planets and Planetesimals Small Telescope) in Chile and other ground-based telescopes were used to detect and characterize the planets. But the collaboration only had an estimate for the period of TRAPPIST-1h.
According to NASA report, astronomers from the University of Washington have used data from the Kepler spacecraft to confirm that TRAPPIST-1h orbits its star every 19 days. At six million miles from its cool dwarf star, TRAPPIST-1h is located beyond the outer edge of the habitable zone, and is likely too cold for life as we know it. The amount of energy (per unit area) planet h receives from its star is comparable to what the dwarf planet Ceres, located in the asteroid belt between Mars and Jupiter, gets from our sun.
“It’s incredibly exciting that we’re learning more about this planetary system elsewhere, especially about planet h, which we barely had information on until now,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate at Headquarters in Washington. “This finding is a great example of how the scientific community is unleashing the power of complementary data from our different missions to make such fascinating discoveries.”
“It really pleased me that TRAPPIST-1h was exactly where our team predicted it to be. It had me worried for a while that we were seeing what we wanted to see — after all, things are almost never exactly what you expect them to be in this field,” said Rodrigo Luger, doctoral student at UW in Seattle, and lead author of the study published in the journal Nature Astronomy. “Nature usually surprises us at every turn, but, in this case, theory and observation matched perfectly.”
Orbital Resonance – Harmony Among Celestial Bodies
Using the prior Spitzer data, the team recognized a mathematical pattern in the frequency at which each of the six innermost planets orbits their star. This complex but predictable pattern, called an orbital resonance, occurs when planets exert a regular, periodic gravitational tug on each other as they orbit their star.
To understand the concept of resonance, consider Jupiter’s moons Io, Europa and Ganymede, which is the farthest out of the three. For every time Ganymede orbits Jupiter, Europa orbits twice and Io makes four trips around the planet. This 1:2:4 resonance is considered stable and if one moon were nudged off course, it would self-correct and lock back into a stable orbit. It is this harmonious influence between the seven TRAPPIST-1 siblings that keeps the system stable.
These relationships, said Luger, suggested that by studying the orbital velocities of its neighboring planets, scientists could predict the exact orbital velocity, and hence also orbital period, of planet h, even before the Kepler observations. The team calculated six possible resonant periods for planet h that would not disrupt the stability of the system, but only one was not ruled out by additional data. The other five possibilities could have been observed in the Spitzer and ground-based data collected by the TRAPPIST team.
“All of this”, Luger said, “indicates that these orbital relationships were forged early in the life of the TRAPPIST-1 system, during the planet formation process.”
“The resonant structure is no coincidence, and points to an interesting dynamical history in which the planets likely migrated inward in lock-step,” said Luger. “This makes the system a great laboratory for planet formation and migration theories.” | 0.932167 | 3.769454 |
The discovery of Proxima Centauri b in 2016 caused a flood excitement. We had found an extrasolar planet around our nearest star, making this the closest possible world outside of our solar system!
But despite its proximity, discovering more about this planet is difficult. Proxima Centauri b was found via the radial velocity technique, which measures the star’s wobble due to the gravity of the orbiting planet. This technique gives a minimum mass, the average distance between the star and planet and the time for one orbit, but no details about conditions on the planet surface.
If the planet had transited its star, we might have tried detecting starlight that passed through the planet’s atmosphere. This technique is known as transit spectroscopy, and reveals the composition of a planet’s atmosphere by detecting what wavelengths of light are absorbed by the molecules in the planet’s air. But searches for a transit proved fruitless, suggesting the planet’s orbit did not pass in front of the star from our viewpoint.
Another option for planet characterization is to capture a direct image of the planet. This is one of the most exciting observational techniques, as it reveals the planet itself, not its influence on the star. Temporal changes in the planet’s light could reveal surface features as the planet rotates, and if enough light is detected to analyze different wavelengths, then the atmospheric composition could be deduced.
But direct imaging requires that the planet’s light can be differentiated from the much brighter star. With our current instruments, Proxima Centauri b orbits too close to its star to be distinguished. This seemed to close the door on finding out more about our nearest neighbors, until the discovery of a second planet in the system was announced early this year.
Also identified via the radial velocity technique, Proxima Centauri c has a minimum mass of 5.8 Earth masses. It sits further out than its sibling, with a chilly orbit that takes 5.2… Read more | 0.838845 | 3.737588 |
A couple of weeks ago I wrote a (tongue in cheek) post about a very inert gas, nitrogen. Silliness aside though, nitrogen is a bit, well boring. I mean, we’ve known about it for nearly 250 years, it makes up nearly 80% of our atmosphere and it mostly just sits around doing nothing. Even plants, who’ve mastered the spectacular trick of making solid stuff out of sunlight and carbon dioxide, can’t do much with it in its gaseous form (with a few exceptions).
There are much more interesting inert gases. There’s one that wasn’t even discovered on Earth. In fact, it was first spotted on the Sun by Jules Janssen, an astronomer who was taking advantage of a total solar eclipse to study the Sun’s atmosphere. After some more experiments astronomer Norman Lockyer and chemist Edward Frankland named the element after the Greek word for the Sun. It was the first element to be discovered somewhere other than Earth.
As it turns out, this element is the second most abundant element in the universe (after hydrogen), but one of the least abundant elements on Earth – with a concentration of just 8 parts per billion in the Earth’s crust.
Today, almost all of us meet it as very young children. In balloons.
We all learnt what ‘non-renewable’ means in school: it refers to something we’re using up faster than we can ever replace it. Almost anyone can tell you that crude oil is non-renewable. But the thing is, there are alternatives to crude oil. We can use bioethanol, biodiesel and their cousins to power vehicles and provide power. Bioethanol can act as a route to plastics, too. Scientists are also investigating the potential of algae to produce oil substitutes. These alternatives may (at the moment) be relatively expensive, and come with certain disadvantages, but they do exist.
We have no way to make helium. At least, no way to make it in significant quantities (it’s a by-product in nuclear reactors, but there we’re talking tiny amounts). And because it’s so light, when helium escapes into the atmosphere it tends to float, well, up. Ultimately, it escapes from our atmosphere and is lost. Every time you get fed up with that helium balloon that’s started to look a bit sorry for itself and stick a pin in it (perhaps taking a few seconds to do the squeaky-voice trick first) you’re wasting a little bit of a helium.
But so what? We could all live without helium balloons right? If we run out, balloons will just have to be the sinking kind. What’s the problem?
The problem is that helium has a lot more uses than you might realise. Cool it to -269 oC – just 4 degrees warmer than absolute zero, the lowest termperature there is – and it turns into a liquid, and that liquid is very important stuff. It’s used to cool the superconducting magnets in MRI (magnetic resonance imaging) scanners in hospitals, which provide doctors with vital, non-invasive, information about what’s going on inside our bodies. MRI techniques have made diagnoses more accurate and allowed surgery to become far more precise. Nothing else (not even the lightest element, hydrogen) has a lower boiling point than helium, so nothing else is quite as good for this chilly job. Scientists are working hard on developing superconducting magnets that work at warmer temperatures, but this technology is still in its infancy.
There’s another technology called NMR (nuclear magnetic resonance) which chemists use all the time to help them identify unknown compounds. In fact, MRI was born out of NMR – they’re basically the same technique applied slightly differently – but the medical application was renamed because it was felt that patients wouldn’t understand that the ‘nuclear’ in NMR refers to the nuclei of atoms rather than nuclear energy or radiation, and would balk at the idea of a ‘nuclear’ treatment. Possibly imagining that they’d turn into the Hulk when they went into the scanner, who knows.
Since it works in essentially the same way, NMR also relies on superconducting magnets, also often cooled with liquid helium. Without NMR, whole swathes of chemical research, not to mention drug testing, would run into serious problems overnight.
It doesn’t stop there. Helium is also used in deep-sea diving, in airships, to cool nuclear reactors and certain other types of chemical detectors. NASA also uses massive amounts of helium to help clean out the fuel from its rockets. In summary, it’s important stuff.
But if we can’t make it, where does all this helium come from?
The Earth’s helium supplies have largely originated from the very slow radioactive alpha decay that occurs in rocks, and it’s taken 4.7 billion years to build them up. Helium is often found sitting above reserves of natural oil and gas. In fact that’s exactly how the first helium reserve was discovered: when, in 1903, an oil drilling operation in Kansas produced a gas geyser that wouldn’t burn. It turned out that although helium is relatively rare in the Earth overall, it was concentrated in large quantities under the American Great Plains.
Of course this meant that the United States quickly became the world’s leading supplier of helium. The US started stockpiling the gas during World War I, intending to use it in barrage balloons and later in airships. Helium, unlike the other lighter-than-air gas hydrogen, doesn’t burn. This made things filled with helium safer to handle and, of course, more difficult to shoot down or sabotage.
In 1925 the US government set up the National Helium Reserve in Amarillo, Texas. In 1927 the Helium Control Act came into force, which banned the export of the gas. At that point, the USA was the only country producing helium, so they had a complete monopoly (personally, I’d quite like to see a Monopoly board with ‘helium reserves’ on it, wouldn’t you?). And that’s why the Hindenburg, like all German Zeppelins, both famously and tragically had to use hydrogen as its lift gas.
Helium use dropped after World War II, but the reserve was expanded in the 1950s to supply liquid helium as a coolant to create hydrogen/oxygen rocket fuel during the Space Race and the Cold War. The US continued to stockpile helium until 1995. At which point, the reserve was $1.4 billion in debt. The government of the time pondered this and ended up passing the Helium Privatization Act of 1996, directing the United States Department of the Interior to empty the reserve and sell it off at a fixed rate to pay off the cost.
As a result cheap helium flooded the market and its price stayed fairly static for a number of years, although the price for very pure helium has recently risen sharply. This sell-off is why we think of helium as a cheap gas; the sort of thing you can cheerfully fill a balloon with and then throw away. Pop down to a large supermarket or your local high street and you might even be able to buy a canister of helium in the party section relatively cheaply.
The problem is that this situation isn’t going to last. The US reserves have been dramatically depleted, and at one point were expected to run out completely in 2018, although other reserves have since been discovered and other countries have set up extraction plants. It is also possible to extract helium from air by distillation, but it’s expensive – some 10,000 times more expensive. None of these alternatives are expected to really ease the shortage; they’ll just delay it by a few years.
So are helium party balloons truly an irresponsible waste of a precious resource? Well… the helium that’s used in balloons is fairly impure, about 98% helium (mixed with, guess what? Yep, we’re back to nitrogen again!) whereas the helium that’s needed for MRI and the like is what’s called ‘grade A’ helium, which is something like 99.997% pure, depending on whom you ask. Of course you can purify the low-grade helium to get the purer kind but this costs money, which is why grade A helium is so much more expensive.
The National Balloon Association (‘the voice of the balloon industry’ – you can’t help wondering whether that’s a very high-pitched voice, can you?) argues that balloons only account for 5-7% of helium use and that the helium that goes into balloons – which they prefer to call ‘balloon gas’ because of its impurities – is mainly recycled from from the gas that’s used in the medical industry, or is a by-product of supplying pure, liquid helium, and therefore using it in balloons isn’t really a problem.
On the other hand, more than one eminent physics professor has spoken out on the subject of helium wastage. It costs about 30-50p to fill a helium balloon, but Professor Robert Richardson of Cornell University argued (before his death in 2013) that a helium party balloon should cost £75 to more accurately reflect the true scarcity value of the gas. Dr Peter Wothers of Cambridge University has called for an outright ban of them, saying that in 50 years’ time our children will be amazed that we ever used such a precious material to fill balloons.
Is it time to call for a helium balloon boycott? Perhaps, although it will probably take more than one or two scientifically-minded consumers refusing to buy them before we see any difference. Realistically, the price will sky-rocket in the next few years and, as Peter Wothers suggests, filling balloons with helium will become a ridiculous notion because it’s far too expensive.
It’s strange to think though, that in maybe 50 years or so the idea of a floating balloon might simply disappear. Just think of all the artwork and drawings that will no longer make sense.
Perhaps this quotation by the late Sir Terry Pratchett is even more relevant than it first appears:
“There are times in life when people must know when not to let go. Balloons are designed to teach small children this.” | 0.823027 | 3.651577 |
The US-European Solar Orbiter probe launched Sunday night from Florida on a voyage to deepen our understanding of the Sun and how it shapes the space weather that impacts technology back on Earth.
The mission, a collaboration between ESA (the European Space Agency) and NASA, successfully blasted off from the Kennedy Space Center in Cape Canaveral at 11:03pm (0403 GMT Monday) and could last up to nine years or more.
At 12:24am Monday (0524 GMT) the European Space Operations Centre in Darmstadt, Germany, received a signal from the spacecraft indicating that its solar panels had successfully deployed.
Space Orbiter is expected to provide unprecedented insights into the Sun’s atmosphere, its winds and its magnetic fields, including how it shapes the heliosphere, the vast swath of space that encompasses our system.
By journeying out of the ecliptic plane — the belt of space roughly aligned with the Sun’s equator, through which the planets orbit — it will acquire the first-ever images of our star’s uncharted polar regions.
Drawing on gravity assists from Earth and Venus, Solar Orbiter will slingshot itself into a bird’s eye view of the Sun’s poles, reaching its primary science orbit in two years’ time.
“I think it was picture perfect, suddenly you really feel like you’re connected to the entire solar system,” said Daniel Muller, ESA project scientist, shortly after the launch.
“You’re here on Earth and you’re launching something that will go close to the Sun.”
“We have one common goal and that is to get the good science out of this mission. I think we’re going to succeed,” added Holly Gilbert, director of NASA’s heliophysics science division.
– Space weather –
Ten state-of-the-art instruments on board will record myriad observations to help scientists unlock clues about what drives solar winds and flares.
These emit billions of highly charged particles that impact the Earth, producing the spectacular Northern Lights. But they can also disrupt radar systems, radio networks and even, though rarely, render satellites useless.
The largest solar storm on record hit North America in September 1859, knocking out much of the continent’s telegraph network and bathing the skies in an aurora viewable as far away as the Caribbean.
“Imagine if just half of our satellites were destroyed,” said Matthieu Berthomier, a researcher at the Paris-based Plasma Physics Laboratory. “It would be a disaster for mankind.”
– Titanium heat shield –
At its closest approach, Solar Orbiter will be nearer to the Sun than Mercury, a mere 42 million kilometers (26 million miles) away.
With a custom-designed titanium heat shield, it is built to withstand temperatures as high as 500 Celsius (930 Fahrenheit). Its heat-resistant structure is coated in a thin, black layer of calcium phosphate, a charcoal-like powder that is similar to pigments used in prehistoric cave paintings.
The shield will protect the instruments from extreme particle radiation emitted from solar explosions.
All but one of the spacecraft’s telescopes will peep out through holes in the heat shield that open and close in a carefully orchestrated dance, while other instruments will work behind the shadow of the shield.
Just like Earth, the Sun’s poles are extreme regions quite different from the rest of the body. It is covered in coronal holes, cooler stretches where fast-gushing solar wind originates.
Scientists believe this region could be key to understanding what drives its magnetic activity.
Every 11 years, the Sun’s poles flip: north becoming south and vice versa. Just before this event, solar activity increases, sending powerful bursts of solar material into space.
Solar Orbiter will observe the surface as it explodes and record measurements as the material goes by the spacecraft.
The only spacecraft to previously fly over the Sun’s poles was another joint ESA/NASA venture, the Ulysses, launched in 1990. But it got no closer to the Sun than the Earth is.
“You can’t really get much closer than Solar Orbiter is going and still look at the Sun,” ESA’s Muller said.
Solar Orbiter will use three gravity assists to draw its orbit closer to the Sun: two past Venus in December 2020 and August 2021, and one past Earth in November 2021, leading up to its first close pass by the Sun in 2022.
It will work in concert with NASA’s Parker Solar Probe, which launched in 2018 and will fly much closer to the Sun, passing through the star’s inner atmosphere to see how energy flows through its corona.
Feb 10, 2020 | 0.810365 | 3.578553 |
6 November, 2017Scientific Paper ALMA Kids Publication
Astronomers found a rich molecular reservoir in the heart of an active star-forming galaxy with the Atacama Large Millimeter/submillimeter Array (ALMA). Among eight clouds identified at the center of the galaxy NGC 253, one exhibits very complex chemical composition, while in the other clouds many signals are missing. This chemical richness and diversity shed light on the nature of the baby boom galaxy.
Ryo Ando, a graduate student of the University of Tokyo, and his colleagues observed the galaxy NGC 253 and for the first time, they resolved the locations of star formation in this galaxy down to the scale of a molecular cloud, which is a star formation site with a size of about 30 light-years. As a result, they identified eight massive, dusty clouds aligned along the center of the galaxy.
“With its unprecedented resolution and sensitivity, ALMA showed us the detailed structure of the clouds,” said Ando, the lead author of the research paper published in the Astrophysical Journal. “To my surprise, the gas clouds have a strong chemical individuality despite their similarity in size and mass.”
Different molecules emit radio waves at different frequencies. Using this feature, the team investigated the chemical composition of the distant clouds by analyzing the radio signals precisely. They identified signals from various molecules including formaldehyde (H2CO), hydrogen cyanide (HCN), and many organic molecules.
One of the clouds stood out with its extremely rich chemical composition. The team identified footprints of 19 different molecules in the cloud, such as thioformaldehyde (H2CS), propyne (CH3CCH), and complex organic molecules including methanol (CH3OH) and acetic acid (CH3COOH). “The data are filled with the signals of various molecules,” said Ando. “It is like a forest of molecules.”
Many “molecular forests” have been found in our Milky Way Galaxy, but this is the first example outside the Milky Way. Researchers assume that the molecular jungle is an aggregate of dense and warm cocoons around bright baby stars. The cocoon gas is heated from inside by hundreds of young stars and a myriad of chemical reactions is driven to form various molecules.
Interestingly, the number of chemical signals is different in different clouds. For example, another cloud among the eight has a very sparse chemical composition, even though it is located within dozens of light-years of the chemically rich cloud. Such a diverse nature of star forming clouds has never been seen before and could be a key to understanding the starburst process in this galaxy.
NGC 253 is a prototypical active star forming galaxy, or starburst galaxy. It is located 11 million light-years away in the constellation Sculptor. Starburst, or baby boom, galaxies have been the major drivers of star formation and galaxy evolution throughout the whole history of the Universe. Therefore it is crucial to understand what exactly is going on in the heart of such galaxies.
These observation results were published as Ando et al. “Diverse nuclear star-forming activities in the heart of NGC 253 resolved with 10-pc-scale ALMA images” in the Astrophysical Journal in November 2017.
The research team members are:
Ryo Ando (The University of Tokyo), Kouichiro Nakanishi (National Astronomical Observatory of Japan/SOKENDAI), Kotaro Kohno (The University of Tokyo), Takuma Izumi (National Astronomical Observatory of Japan/The University of Tokyo), Sergio Martín (European Southern University/Joint ALMA Observatory), Nanase Harada (Academia Sinica Institute of Astronomy and Astrophysics), Shuro Takano (Nihon University), Nario Kuno (University of Tsukuba), Naomasa Nakai (University of Tsukuba), Hajime Sugai (The University of Tokyo), Kazuo Sorai (Hokkaido University), Tomoka Tosaki (Joetsu University of Education), Kazuya Matsubayashi (National Astronomical Observatory of Japan), Taku Nakajima (Nagoya University), Yuri Nishimura (The University of Tokyo/National Astronomical Observatory of Japan), and Yoichi Tamura (Nagoya University/The University of Tokyo)
This research was supported by the Japan Society for the Promotion of Science KAKENHI (Grant Number 15K05035 and 25247019).
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).
ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA. | 0.80105 | 3.829314 |
Fast show: Andrew Wade reports on an exciting new UK-led project to intercept a long-period comet for the first time.
There’s an assumption with space missions that they must be years in the planning before they’re approved for launch. In the case of Comet Interceptor, a new UK-led project to observe a long-period comet up close for the first time, that assumption couldn’t be more wrong.
The first in a new type of F-Class (the F stands for ‘fast’) mission, Comet Interceptor was selected by ESA in June 2019, with the request for proposals having gone out less than a year before. Rather than years in the making, the entire concept for the mission is barely 18 months old.
“We had the idea a few months before [ESA’s call for proposals in July 2018], but actually, no, we started then,” mission proposal lead Prof Geraint Jones told The Engineer, shattering those aforementioned assumptions.
Jones is head of the Planetary Science Group at UCL’s Mullard Space Science Laboratory. Together with deputy mission lead Dr Colin Snodgrass from the University of Edinburgh, he tailored a plan based on the parameters of ESA’s request. Those included a launch mass of less than 1,000kg and a budget of €150m.
The chosen entry would also be hitching a ride with ESA’s Ariel space telescope, set to launch in 2028 to the L2 Lagrange Point, 1.5-million kilometres from Earth in the opposite direction to the Sun. This was ideal for Comet Interceptor, as its final target is currently unknown. The spacecraft will lie in wait at L2 until a suitable long-period comet – or even an interstellar object such as Oumuamua – is identified from Earth. It will then travel to intercept its target, splitting into three separate craft that will help create a 3D profile of the celestial body.
“It’s part of the whole concept that we sit at L2 and wait for the right target”
“The really nice fit with our mission is the fact we’re being delivered to Lagrange point L2 and we can just sit there and wait,” Jones explained. “For almost every other mission to a small body you have to identify your target beforehand and then you’ve got launch windows where you can only launch at certain times of the year.
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“Other missions could be delivered to L2 and then just leave when they needed to go to their targets, but it’s not the most efficient way of doing it. For our proposal, it’s part of the whole concept that we sit there and wait for the right target to come along.”
The mission’s goal is to characterise the comet’s surface composition, shape and structure, as well as the make-up of its gas coma. Each of the three spacecraft will carry a unique sensor suite, comprising cameras, imagers and spectral analysers. When we spoke to Jones, the team was still in consultation with ESA over the exact payload, with the space agency due to make its final decisions at the end of October. According to the professor, this type of wrangling is typical as the costs and benefits of individual instruments are weighed up. What’s important is that the core scientific objectives of the mission are maintained.
“The whole point that we’re doing this for is ultimately for the science,” he said. “So, we do want to be assured that whatever does get descoped or removed potentially, that it doesn’t impact the science too much.
“We do have an input, but ultimately it’s ESA’s decision. We’re working closely with them. For the proposal, we had to provide a science traceability matrix showing all the scientific objectives and goals that we have, and which instruments would meet them. So, if any area looks like it might be reduced in terms of scientific return, we can point out the implication so that’s also taken into consideration.”
Most space missions tend to rely on tried-and-tested equipment where possible. For Comet Interceptor, the accelerated timeline makes this especially pertinent. Its instrumentation is influenced by previous ESA endeavours, including the Rosetta mission that captured the world’s attention back in 2014 when its Philae lander touched down on comet 67P/Churyumov–Gerasimenko. Comet Interceptor’s plasma package and mass spectrometer have taken cues from Rosetta, while echoes of other missions can be found throughout the payload.
“Every instrument has got strong heritage or is largely a re-flight of a previous instrument,” Jones explained.
“So the main camera, CoCa [Comet Camera], led from the University of Bern, large elements of that are actually based on the CaSSIS [Colour and Stereo Surface Imaging System] camera that is on the ExoMars Trace Gas Orbiter that’s orbiting Mars now: another ESA mission.”
It’s not just ESA’s experience that the mission will be tapping into. One of Comet Interceptor’s three spacecraft will be developed by JAXA (Japan Aerospace Exploration Agency) and is set to carry a Lyman-alpha hydrogen imager, as well as a wide-angle camera and plasma suite. Members of Jones’s team had already been working with the Japanese agency on imaging hydrogen around comets, so the collaboration was a natural fit.
“Although it’s a much reduced-cost mission compared to the usual-sized missions that ESA launches, it still has to reach a minimum threshold of design maturity and JAXA clearly has the expertise to do that,” said Jones. “It has flown a small satellite in deep space arguably before anyone…it’s fantastic to have them on board.”
As well as liaising with JAXA, ESA and numerous space scientists around the world, Jones himself is heading up development of the EnVisS (Entire Visible Sky coma mapper) instrument. Based on the JANUS camera that will fly on board ESA’s JUICE (JUpiter ICy moons Explorer) mission in 2022, EnVisS will map the entire sky around the comet’s head and near tail, revealing changes in the structure of its dust and gases.
Comet Interceptor’s multinational team includes scientists from the length and breadth of Europe, as well as India, Japan, the US, Canada, Russia and Chile. The last of those countries is likely to play a pivotal role in the mission’s outcome, as Chile is home to the Large Synoptic Survey Telescope (LSST). Currently under construction high in the Andes, the LSST will use three primary mirrors and the world’s largest digital camera (3.2 gigapixel) to photograph the entire visible sky anew every three nights or so. When it’s fully operational in 2023 it will be the most likely source of targets for Comet Interceptor.
“LSST in particular is expected to basically revolutionise things,” said Jones. “So, we probably will find more comets, but what’s most important for us is that they’re found further out.”
With Comet Interceptor not launching until 2028, it’s entirely possible that the mission’s target may already be identified by then, either by the LSST or other comet-hunting telescopes such as Hawaii’s Pan-STARRS.
“That’s what we’re hoping for,” said Jones. “We’re preparing a plan for choosing targets as well. We may have – if we’re lucky – two or three and have to decide between them. If there’s an interstellar object, for example, I would expect that to trump all the others.”
Intercepting an interstellar object is particularly enticing, as astronomers have only recently confirmed their existence. Two years ago, the oblong-shaped Oumuamua set pulses racing when it was detected by Pan-STARRS, with suggestions it may even have alien origins. Although that theory has been debunked, the mysterious tumbling asteroid has raised a whole host of new questions for astronomical science.
On 14 October 2019, a second interstellar object, Borisov, was confirmed. Its shape and behaviour align with conventional comets, with only its hyperbolic speed indicating origin outside our solar system. This only serves to highlight the strangeness of Oumuamua, as well as how little we know about these interstellar visitors. Whether Comet Interceptor gets to observe one up close remains to be seen, but the possibility is certain to keep stargazers excited over the coming years | 0.858806 | 3.12323 |
November 17, 2016 – Sputnik Planitia, a 1,000-kilometer wide basin within the iconic heart-shaped region observed on Pluto’s surface, could be in its present location because accumulation of ice made the dwarf planet roll over, creating cracks and tensions in the crust that point towards the presence of a subsurface ocean.
Published in the November 17 issue of Nature, these are the conclusions of research by James Keane, a doctoral student at the University of Arizona’s Lunar and Planetary Laboratory, and his adviser, assistant professor Isamu Matsuyama. They propose evidence of frozen nitrogen pileup throwing the entire planet off kilter, much like a spinning top with a wad of gum stuck to it, in a process called true polar wander.
“There are two ways to change the spin of a planet,” Keane said. “The first — and the one we’re all most familiar with — is a change in the planet is a change in the planet’s obliquity, where the spin axis of the planet is reorienting with respect to the rest of the solar system. The second way is through true polar wander, where the spin axis remains fixed with respect to the rest of the solar system, but the planet reorients beneath it.”
Planets like to spin in such a way that minimizes energy. In short, this means that planets like to reorient to place any extra mass closer to the equator, and any mass deficits closer to the pole. For example, if a giant volcano were to grow on Los Angeles, the earth would reorient itself to place L.A. on the equator.
To understand polar wander on Pluto, one first has to realize that unlike Earth, whose spin axis is only slightly tilted so that the regions around the equator receive the most sunlight, Pluto is like a spinning top lying on its side. Therefore, the planet’s poles get the most sunlight. Depending on the season, it’s either one or the other, while Pluto’s equatorial regions are extremely cold, all the time.
Because Pluto is almost 40 times farther from the sun than we are, it takes the little ball of rock and ice 248 Earth years to complete one of its own years. At Pluto’s lower latitudes near the equator, temperatures are almost as cold as minus 400 degrees Fahrenheit, cold enough to turn nitrogen into a frozen solid.
Over the course of a Pluto year, nitrogen and other exotic gases condense on the permanently shadowed regions, and eventually, as Pluto goes around the sun, those frozen gases heat up, become gaseous again and re-condense on the other side of the planet, resulting in seasonal “snowfall” on Sputnik Planitia.
“Each time Pluto goes around the sun, a bit of nitrogen accumulates in the heart,” Keane said. “And once enough ice has piled up, maybe a hundred meters thick, it starts to overwhelm the planet’s shape, which dictates the planet’s orientation. And if you have an excess of mass in one spot on the planet, it wants to go to the equator. Eventually, over millions of years, it will drag the whole planet over.”
In a sense, Pluto is a (dwarf) planet whose shape and position in space are controlled by its weather.
“I think this idea of a whole planet being dragged around by the cycling of volatiles is not something many people had really thought about before,” Keane said.
The two researchers used observations made during New Horizons’ flyby and combined them with computer models that allowed them to take a surface feature such as Sputnik Planitia, shift it around on the planet’s surface and see what that does to the planet’s spin axis. And sure enough, in the models, the geographic location of Sputnik Planitia ended up suspiciously close to where one would expect it to be.
If Sputnik Planitia were a large positive mass anomaly–perhaps due to loading of nitrogen ice–it would naturally migrate to Pluto’s tidal axis with regard to Charon, Pluto’s largest moon, as it approaches a minimum energy state, according to Keane and Matsuyama. In other words, the massive accumulation of ice would end up where it causes the least wobble in Pluto’s spin axis.
This phenomenon of polar wander is something that was discovered with the Earth’s moon and with Mars, as well, but in those cases it happened in the distant past, billions of years ago.
“On Pluto, those processes are currently active,” Keane said. “Its entire geology–glaciers, mountains, valleys–seems to be linked to volatile processes. That’s different from most other planets and moons in our solar system.”
And not only that, the simulations and calculations also predicted that the accumulation of frozen volatiles in Pluto’s heart would cause cracks and faults in the planet’s surface in the exact same locations where New Horizons saw them.
The presence of tectonic faults on Pluto hint at the existence of a subsurface ocean at some point in Pluto’s history, Keane explained.
“It’s like freezing ice cubes,” he said. “As the water turns to ice, it expands. On a planetary scale, this process breaks the surface around the planet and creates the faults we see today.”
The paper is published alongside a report by Francis Nimmo of the University of California Santa Cruz and colleagues, who also consider the implications for Pluto’s apparent reorientation. The authors of that paper agree with the idea that tidal forces could explain the current location of Sputnik Planitia, but in order for their model to work, a subsurface ocean would have to be present on Pluto today.
Both publications underscore the notion of a surprisingly active Pluto.
“Before New Horizons, people usually only thought of volatiles in terms of a thin frost veneer, a surface effect that might change the color, or affect local or regional geology,” Keane said. “That the movement of volatiles and shifting ice around a planet could have a dramatic, planet-moving effect is not something anyone would have predicted.” | 0.832361 | 3.825978 |
An enormous black hole one hundred thousand times more massive than the sun has been found hiding in a toxic gas cloud wafting around near the heart of the Milky Way.
If the discovery is confirmed, the invisible behemoth will rank as the second largest black hole ever seen in the Milky Way after the supermassive black hole known as Sagittarius A* that is anchored at the very centre of the galaxy.
Astronomers in Japan found evidence for the new object when they turned a powerful telescope in the Atacama desert in Chile towards the gas cloud in the hope of understanding the strange movement of its gases. Unlike those that make up other interstellar clouds, the gases in this cloud – including hydrogen cyanide and carbon monoxide – move at wildly different speeds.
Observations from the Alma telescope in Chile showed that molecules in the elliptical cloud, which is 200 light years from the centre of the Milky Way and 150 trillion kilometres wide, were being pulled around by immense gravitational forces. The most likely cause, according to computer models, was a black hole no more than 1.4 trillion km across.
The scientists’ suspicion that a black hole lay in the midst of the gas cloud received a boost when further observations picked up radio waves indicative of a black hole coming from the centre of the cloud, said Tomoharu Oka, an astronomer at Keio University in Tokyo. “This is the first detection of an intermediate-mass black hole candidate in the Milky Way galaxy,” he said.
So-called intermediate-mass black holes fill a gap in astronomer’s knowledge of the most massive objects in the universe. The smallest black holes form when particular types of stars explode at the end of their lives. According to scientists’ calculations, the Milky Way is home to about 100m of these smaller black holes, though only about 60 have been spotted.
But astronomers also know that much larger, supermassive black holes lie at the heart of large galaxies including the Milky Way, where Sagittarius A* weighs as much as 4 million suns. What is unknown is how these supermassive black holes form.
Click here to read more.
SOURCE: The Guardian, Ian Sample | 0.897294 | 3.687163 |
May 25, 2012
Problematic black hole physics is in the news again.
In a recent press release from the Galaxy Evolution Explorer and the Pan-STARRS1 telescope in Hawaii, astronomers announced “direct evidence” for the existence of a supermassive black hole (SMBH) in another galaxy. The high frequency ultraviolet spectrum, as well as the infrared light from the two detectors, seems to indicate the “shredding” of a star near the center of a galaxy 2.7 billion light-years away.
Black holes have been discussed many times in previous Picture of the Day articles. They owe their existence to mathematical legerdemain, and can have nothing to do with the substantive Universe because they are said to occupy a region where the laws of space and time break down.
Black holes are said to cause space and time itself to twist and warp so that the past becomes the future and velocity calculations yield impossible solutions. According to standard theories, matter inside of a black hole occupies no volume at all, yet retains gravitational acceleration so great that not even light can escape its attraction—thus they are “black” holes because they cannot be detected with optical telescopes. Although they are impossible to observe directly, over 90% of galaxies in the Universe are supposed to harbor these perilous maws
The terminology used by astrophysicists to describe black holes is highly problematic, relying on “explanations” derived from loose interpretations. Ambiguous labels such as space/time, singularities, infinite density, and other ideas that are not quantifiable have introduced irony into what should be a realistic investigation into the nature of the Universe.
According to Suvi Gezari, an astronomer from Johns Hopkins University, “When the star is ripped apart by the gravitational forces of the black hole, some part of the star’s remains falls into the black hole, while the rest is ejected at high speeds. We are seeing the glow from the stellar gas falling into the black hole over time.”
NASA’s Chandra X-ray Observatory also looked at the hot material in order to see if it matched the emissions normally seen in an “active galactic nucleus”. Their results indicated that the spectrum observed by Gezari’s group did not conform to those prior observations.
Flares and X-ray jets spewing from galaxies are thought to be caused by stars traveling too close to their central supermassive black holes where they are torn apart by tidal forces. Most of the star’s gas escapes the black hole, but a small quantity is captured by the immense gravity and forms a rotating disk. Closer to the black hole, heat generated by molecular collisions tears the atoms apart and the disk of gas glows in extreme ultraviolet and X-rays. When matter eventually falls into the black hole, gamma rays can also explosively burst out.
X-rays in space are not created in gravity fields. Laboratory experiments most easily produce them by accelerating charged particles through an electric field. No gigantic masses compressed into tiny volumes are necessary and they are easily generated with the proper experimental models.
To say that gas can be heated by gravity until it emits X-rays indicates a serious lapse on the part of the GALEX research team. Molecules of gas cannot remain intact at million degree temperatures because electrons are stripped from the atomic nuclei, causing them to become ionized. Instead of hot gas, the galactic radiation should be referred to by its proper name: plasma.
An electric current in plasma generates a magnetic field that constricts the flow of charge. The constricted channel is known as a Bennett pinch, or z-pinch. The “pinched” filaments of electric current remain coherent over large distances, spiraling around each other, forming helical structures that can transmit power through space.
As we have noted in the past, Hannes Alfvén identified the “exploding double layer” as a new class of celestial object. It is double layers in space plasmas that form most of the unusual structures we see. Stellar explosions, jets, rings, and glowing clouds—these are all examples of electricity flowing through dusty plasma confined within Birkeland currents that stretch across the light years.
Retired Professor of Electrical Engineering Donald Scott, author of The Electric Sky, wrote about the way plasma acts in the Universe: “Plasma phenomena are scalable. Their electrical and physical properties remain the same, independent of the size of the plasma. In a laboratory plasma, of course, things happen much more quickly than on, say, galaxy scales, but the phenomena are identical—they obey the same laws of physics. In other words we can make accurate models of cosmic scale plasma behavior in the lab, and generate effects that mimic those observed in space. It has been demonstrated that plasma phenomena can be scaled to fourteen orders of magnitude. (Alfvén hypothesized that they can be scaled to 28 orders or more!) Electric currents flowing in plasmas produce most of the observed astronomical phenomena that remain inexplicable if we assume gravity and magnetism to be the only forces at work.”
Irrespective of their source, X-rays in space are not created by gravitational fields regardless of how strong they are theorized to be. Since plasma is composed of charged particles, the particles are accelerated by electric currents and spiral in the resulting magnetic fields, creating synchrotron radiation that can shine in all high energy frequencies, including extreme ultraviolet, X-rays, and gamma rays.
Hat tip to Larry White | 0.882903 | 3.810614 |
A star catalogue, or star catalog, is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some of the more frequently quoted ones. Star catalogues were compiled by many different ancient peoples, including the Babylonians, Greeks, Chinese, Persians and Arabs. Most modern catalogues are available in electronic format and can be freely downloaded from NASA's Astronomical Data Center.
Ancient Egypt and Mesopotamia
From their existing records, it is known that the ancient Egyptians recorded the names of only a few identifiable constellations and a list of thirty-six decans that were used as a star clock. The Egyptians called the circumpolar star 'the star that cannot perish' and, although they made no known formal star catalogues, they nonetheless created extensive star charts of the night sky which adorn the coffins and ceilings of tomb chambers.
Although the ancient Sumerians were the first to record the names of constellations on clay tablets, the earliest known star catalogues were compiled by the ancient Babylonians of Mesopotamia in the late 2nd millennium BC, during the Kassite Period (ca. 1531 BC to ca. 1155 BC). They are better known by their Assyrian-era name 'Three Stars Each'. These star catalogues, written on clay tablets, listed thirty-six stars: twelve for 'Anu' along the celestial equator, twelve for 'Ea' south of that, and twelve for 'Enlil' to the north. The Mul.Apin lists, dated to sometime before the Neo-Babylonian Empire (626-539 BC), are direct textual descendants of the 'Three Stars Each' lists and their constellation patterns show similarities to those of later Greek civilization.
Hellenistic world and Roman Empire
In Ancient Greece, the astronomer and mathematician Eudoxus laid down a full set of the classical constellations around 370 BC. His catalogue Phaenomena, rewritten by Aratus of Soli between 275 and 250 BC as a didactic poem, became one of the most consulted astronomical texts in antiquity and beyond. It contains descriptions of the positions of the stars, the shapes of the constellations and provided information on their relative times of rising and setting.
Approximately in the 3rd century BC, the Greek astronomers Timocharis of Alexandria and Aristillus created another star catalogue. Hipparchus (c. 190 – c. 120 BC) completed his star catalogue in 129 BC, which he compared to Timocharis' and discovered that the longitude of the stars had changed over time. This led him to determine the first value of the precession of the equinoxes. In the 2nd century, Ptolemy (c. 90 - c. 186 AD) of Roman Egypt published a star catalogue as part of his Almagest, which listed 1,022 stars visible from Alexandria. It was the standard star catalogue in the Western and Arab worlds for over a thousand years. Ptolemy's catalogue was based almost entirely on an earlier one by Hipparchus (Newton 1977; Rawlins 1982).
Although the ancient Vedas of India specified how the ecliptic was to be divided into twenty-eight nakshatra, Indian constellation patterns were ultimately borrowed from Greek ones sometime after Alexander's conquests in Asia in the 4th century BC.
The earliest known inscriptions for Chinese star names were written on oracle bones and date to the Shang Dynasty (c. 1600 - c. 1050 BC). Sources dating from the Zhou Dynasty (c. 1050 - 256 BC) which provide star names include the Zuo Zhuan, the Shi Jing, and the "Canon of Yao" (堯典) in the Book of Documents. The Lüshi Chunqiu written by the Qin statesman Lü Buwei (d. 235 BC) provides most of the names for the twenty-eight mansions (i.e. asterisms across the ecliptic belt of the celestial sphere used for constructing the calendar). An earlier lacquerware chest found in the Tomb of Marquis Yi of Zeng (interred in 433 BC) contains a complete list of the names of the twenty-eight mansions. Star catalogues are traditionally attributed to Shi Shen and Gan De, two rather obscure Chinese astronomers who may have been active in the 4th century BC of the Warring States Period (403-221 BC). The Shi Shen astronomy (石申天文, Shi Shen tienwen) is attributed to Shi Shen, and the Astronomic star observation (天文星占, Tianwen xingzhan) to Gan De.
It was not until the Han Dynasty (202 BC - 220 AD) that astronomers started to observe and record names for all the stars that were apparent (to the naked eye) in the night sky, not just those around the ecliptic. A star catalogue is featured in one of the chapters of the late 2nd-century-BC history work Records of the Grand Historian by Sima Qian (145-86 BC) and contains the "schools" of Shi Shen and Gan De's work (i.e. the different constellations they allegedly focused on for astrological purposes). Sima's catalogue—the Book of Celestial Offices (天官書 Tianguan shu)—includes some 90 constellations, the stars therein named after temples, ideas in philosophy, locations such as markets and shops, and different people such as farmers and soldiers. For his Spiritual Constitution of the Universe (靈憲, Ling Xian) of 120 AD, the astronomer Zhang Heng (78-139 AD) compiled a star catalogue comprising 124 constellations. Chinese constellation names were later adopted by the Koreans and Japanese.
A large number of star catalogues were published by Muslim astronomers in the medieval Islamic world. These were mainly Zij treatises, including Arzachel's Tables of Toledo (1087), the Maragheh observatory's Zij-i Ilkhani (1272) and Ulugh Beg's Zij-i-Sultani (1437). Other famous Arabic star catalogues include Alfraganus' A compendium of the science of stars (850) which corrected Ptolemy's Almagest; and Azophi's Book of Fixed Stars (964) which described observations of the stars, their positions, magnitudes, brightness and colour, drawings for each constellation, and the first descriptions of Andromeda Galaxy and the Large Magellanic Cloud. Many stars are still known by their Arabic names (see List of Arabic star names).
The Motul Dictionary, compiled in the 16th century by an anonymous author (although attributed to Fray Antonio de Ciudad Real), contains a list of stars originally observed by the ancient Mayas. The Maya Paris Codex also contain symbols for different constellations which were represented by mythological beings.
Bayer and Flamsteed catalogues
Two systems introduced in historical catalogues remain in use to the present day. The first system comes from the German astronomer Johann Bayer's (1572–1625) Uranometria published in 1603 and is for bright stars. These are given a Greek letter followed by the genitive case of the constellation in which they are located; examples are Alpha Centauri or Gamma Cygni. The major problem with Bayer's naming system was the number of letters in the Greek alphabet (24). It was easy to run out of letters before running out of stars needing names, particularly for large constellations such as Argo Navis. Bayer extended his lists up to 67 stars by using lower-case Roman letters ("a" through "z") then upper-case ones ("A" through "Q"). Few of those designations have survived. It is worth mentioning, however, as it served as the starting point for variable star designations, which start with "R" through "Z", then "RR", "RS", "RT"..."RZ", "SS", "ST"..."ZZ" and beyond.
The second system comes from the English astronomer John Flamsteed's (1646–1719) Historia coelestis Britannica. It kept the genitive-of-the-constellation rule for the back end of his catalog names, but used numbers instead of the Greek alphabet for the front half. Examples include 61 Cygni and 47 Ursae Majoris.
Bayer and Flamsteed covered only a few thousand stars between them. In theory, full-sky catalogues try to list every star in the sky. There are, however, literally hundreds of millions, even billions of stars resolvable by telescopes, so this is an impossible goal; these kind of catalogs generally try to get every star brighter than a given magnitude.
Jérôme Lalande published the Histoire Céleste Française in 1801, which contained an extensive star catalog, among other things. The observations made were made from the Paris Observatory and so it describes mostly northern stars. This catalog contained the positions and magnitudes of 47,390 stars, out to magnitude 9, and was the most complete catalog up to that time. A significant reworking of this catalog in 1846 added reference numbers to the stars that are used to refer to some of these stars to this day. The decent accuracy of this catalog kept it in common use as a reference by observatories around the world throughout the 19th century.
The Henry Draper Catalogue was published in the period 1918–1924. It covers the whole sky down to about ninth or tenth magnitude, and is notable as the first large-scale attempt to catalogue spectral types of stars. The catalogue was compiled by Annie Jump Cannon and her co-workers at Harvard College Observatory under the supervision of Edward Charles Pickering, and was named in honour of Henry Draper, whose widow donated the money required to finance it.
HD numbers are widely used today for stars which have no Bayer or Flamsteed designation. Stars numbered 1–225300 are from the original catalogue and are numbered in order of right ascension for the 1900.0 epoch. Stars in the range 225301–359083 are from the 1949 extension of the catalogue. The notation HDE can be used for stars in this extension, but they are usually denoted HD as the numbering ensures that there can be no ambiguity.
The Smithsonian Astrophysical Observatory catalogue was compiled in 1966 from various previous astrometric catalogues, and contains only the stars to about ninth magnitude for which accurate proper motions were known. There is considerable overlap with the Henry Draper catalogue, but any star lacking motion data is omitted. The epoch for the position measurements in the latest edition is J2000.0. The SAO catalogue contains this major piece of information not in Draper, the proper motion of the stars, so it is often used when that fact is of importance. The cross-references with the Draper and Durchmusterung catalogue numbers in the latest edition are also useful.
Names in the SAO catalogue start with the letters SAO, followed by a number. The numbers are assigned following 18 ten-degree bands in the sky, with stars sorted by right ascension within each band.
The Bonner Durchmusterung (German: Bonn sampling) and follow-ups were the most complete of the pre-photographic star catalogues.
The Bonner Durchmusterung itself was published by Friedrich Wilhelm Argelander, Adalbert Krüger, and Eduard Schönfeld between 1852 and 1859. It covered 320,000 stars in epoch 1855.0.
As it covered only the northern sky and some of the south (being compiled from the Bonn observatory), this was then supplemented by the Südliche Durchmusterung (SD), which covers stars between declinations -1 and -23 degrees (1886, 120,000 stars). It was further supplemented by the Cordoba Durchmusterung (580,000 stars), which began to be compiled at Córdoba, Argentina in 1892 under the initiative of John M. Thome and covers declinations -22 to -90. Lastly, the Cape Photographic Durchmusterung (450,000 stars, 1896), compiled at the Cape, South Africa, covers declinations -18 to -90.
Astronomers preferentially use the HD designation of a star, as that catalogue also gives spectroscopic information, but as the Durchmusterungs cover more stars they occasionally fall back on the older designations when dealing with one not found in Draper. Unfortunately, a lot of catalogues cross-reference the Durchmusterungs without specifying which one is used in the zones of overlap, so some confusion often remains.
Star names from these catalogues include the initials of which of the four catalogues they are from (though the Southern follows the example of the Bonner and uses BD; CPD is often shortened to CP), followed by the angle of declination of the star (rounded towards zero, and thus ranging from +00 to +89 and -00 to -89), followed by an arbitrary number as there are always thousands of stars at each angle. Examples include BD+50°1725 or CD-45°13677.
The Catalogue astrographique (Astrographic Catalogue) was part of the international Carte du Ciel programme designed to photograph and measure the positions of all stars brighter than magnitude 11.0. In total, over 4.6 million stars were observed, many as faint as 13th magnitude. This project was started in the late 19th century. The observations were made between 1891 and 1950. To observe the entire celestial sphere without burdening too many institutions, the sky was divided among 20 observatories, by declination zones. Each observatory exposed and measured the plates of its zone, using a standardized telescope (a "normal astrograph") so each plate photographed had a similar scale of approximately 60 arcsecs/mm. The U.S. Naval Observatory took over custody of the catalogue, now in its 2000.2 edition.
USNO-B1.0 is an all-sky catalog created by research and operations astrophysicists at the U.S. Naval Observatory (as developed at the United States Naval Observatory Flagstaff Station), that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations. The data was obtained from scans of 7,435 Schmidt plates taken for the various sky surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at J2000.0, 0.3 magnitude photometric accuracy in up to five colors, and 85% accuracy for distinguishing stars from non-stellar objects. USNO-B is now followed by NOMAD; both can be found on the Naval Observatory server.
The Guide Star Catalog is an online catalog of stars produced for the purpose of accurately positioning and identifying stars satisfactory for use as guide stars by the Hubble Space Telescope program. The first version of the catalog was produced in the late 1980s by digitizing photographic plates and contained about 20 million stars, out to about magnitude 15. The latest version of this catalog contains information for 945,592,683 stars, out to magnitude 21. The latest version continues to be used to accurately position the Hubble Space Telescope.
Specialized catalogs make no effort to list all the stars in the sky, working instead to highlight a particular type of star, such as variables or nearby stars.
Aitken's double star catalogue
New general catalogue of double stars within 120 deg of the North Pole (1932, R. G. Aitken).
This lists 17,180 double stars north of declination -30 degrees.
BS, BSC, HR
First published in 1930 as the Yale Catalog of Bright Stars, this catalog contained information on all stars brighter than visual magnitude 6.5 in the Harvard Revised Photometry Catalogue. The list was revised in 1983 with the publication of a supplement that listed additional stars down to magnitude 7.1. The catalog detailed each star's coordinates, proper motions, photometric data, spectral types, and other useful information.
The last printed version of the Bright Star Catalogue was the 4th revised edition, released in 1982. The 5th edition is in electronic form and is available online.
Stephenson's General Catalogue of galactic Carbon stars is a catalogue of 7000+ carbon stars.
Gl, GJ, Wo
The Gliese (later Gliese-Jahreiß) catalogue attempts to list all stars within 20 parsecs of Earth ordered by right ascension (see the List of nearest stars). Later editions expanded the coverage to 25 parsecs. Numbers in the range 1.0–965.0 (Gl numbers) are from the second edition, which was
Catalogue of Nearby Stars (1969, W. Gliese).
The integers up to 915 represent stars which were in the first edition. Numbers with a decimal point were used to insert new stars for the second edition without destroying the desired order (by right ascension). This catalogue is referred to as CNS2, although this name is never used in catalogue numbers.
Numbers in the range 9001–9850 (Wo numbers) are from the supplement
Extension of the Gliese catalogue (1970, R. Woolley, E. A. Epps, M. J. Penston and S. B. Pocock).
Numbers in the ranges 1000–1294 and 2001–2159 (GJ numbers) are from the supplement
Nearby Star Data Published 1969–1978 (1979, W. Gliese and H. Jahreiß).
The range 1000–1294 represents nearby stars, while 2001–2159 represents suspected nearby stars. In the literature, the GJ numbers are sometimes retroactively extended to the Gl numbers (since there is no overlap). For example, Gliese 436 can be interchangeably referred to as either Gl 436 or GJ 436.
Numbers in the range 3001–4388 are from
Preliminary Version of the Third Catalogue of Nearby Stars (1991, W. Gliese and H. Jahreiß).
Although this version of the catalogue was termed "preliminary", it is still the current one as of March 2006[update], and is referred to as CNS3. It lists a total of 3,803 stars. Most of these stars already had GJ numbers, but there were also 1,388 which were not numbered. The need to give these 1,388 some name has resulted in them being numbered 3001–4388 (NN numbers, for "no name"), and data files of this catalogue now usually include these numbers. An example of a star which is often referred to by one of these unofficial GJ numbers is GJ 3021.
The General Catalogue of Trigonometric Parallaxes, first published in 1952 and later superseded by the New GCTP (now in its fourth edition), covers nearly 9,000 stars. Unlike the Gliese, it does not cut off at a given distance from the Sun; rather it attempts to catalogue all known measured parallaxes. It gives the co-ordinates in 1900 epoch, the secular variation, the proper motion, the weighted average absolute parallax and its standard error, the number of parallax observations, quality of interagreement of the different values, the visual magnitude and various cross-identifications with other catalogues. Auxiliary information, including UBV photometry, MK spectral types, data on the variability and binary nature of the stars, orbits when available, and miscellaneous information to aid in determining the reliability of the data are also listed.
William F. van Altena, John Truen-liang Lee and Ellen Dorrit Hoffleit, Yale University Observatory, 1995.
The Hipparcos catalogue was compiled from the data gathered by the European Space Agency's astrometric satellite Hipparcos, which was operational from 1989 to 1993. The catalogue was published in June 1997 and contains 118,218 stars. It is particularly notable for its parallax measurements, which are considerably more accurate than those produced by ground-based observations. See Stellar parallax and List of stars in the Hipparcos Catalogue.
The PPM Star Catalogue is one of best, both in the proper motion and star position till 1999. Not as precise as Hipparcos catalogue but with many more stars. The PPM was built from BD, SAO, HD and more, with sophisticated algorithm and is a extension for the Fifth Fundamental Catalogue, "Catalogues of Fundamental Stars".
Proper motion catalogues
A common way of detecting nearby stars is to look for relatively high proper motions. Several catalogues exist, of which we'll mention a few. The Ross and Wolf catalogues pioneered the domain:
Ross, Frank Elmore, New Proper Motion Stars, eight successive lists, The Astronomical Journal, Vol. 36 to 48, 1925-1939
Wolf, Max, "Katalog von 1053 stärker bewegten Fixsternen", Veröff. d. Badischen Sternwarte zu Heidelberg (Königstuhl), Bd. 7, No. 10, 1919; and numerous lists in Astronomische Nachrichten 209 to 236, 1919-1929
Willem Jacob Luyten later produced a series of catalogues:
L - Luyten, Proper motion stars and White dwarfs
Luyten, W. J., Proper Motion Survey with the forty-eight inch Schmidt Telescope, University of Minnesota, 1941 (General Catalogue of the Bruce Proper-Motion Survey)
LFT - Luyten Five-Tenths catalogue
Luyten, W. J., A Catalog of 1849 Stars with Proper Motion exceeding 0.5" annually, Lund Press, Minneapolis (Mn), 1955 ()
LHS - Luyten Half-Second catalogue
Luyten, W. J., Catalogue of stars with proper motions exceeding 0"5 annually, University of Minnesota, 1979 ()
LTT - Luyten Two-Tenths catalogue
Luyten, W. J. Luyten's Two Tenths. A catalogue of 9867 stars in the Southern Hemisphere with proper motions exceeding 0".2 annually, Minneapolis, 1957; also supplements 1961–1962. ()
NLTT - New Luyten Two-Tenths catalogue
Luyten, W. J., New Luyten Catalogue of stars with proper motions larger than two tenths of an arcsecond (NLTT), Univ. of Minnesota, 1979, supplement 1980 ()
LPM - Luyten Proper-Motion catalogue
Luyten, W. J., Proper Motion Survey with the 48 inch Schmidt Telescope, University of Minnesota, 1963-1981
Later, Henry Lee Giclas took over, again with a series of catalogues:
Giclas, H. L., et al., Lowell Proper Motion Survey, Lowell Observatory Bulletins, 1971-1979 ()
* Gaia mission
* Newton, Robert R. (1977). The Crime of Claudius Ptolemy. Baltimore: Johns Hopkins University Press.
1. ^ Chadwick, Robert. (2005). First Civilizations: Ancient Mesopotamia and Ancient Egypt (Second Edition). London and Oakville: Equinox Publishing Ltd. ISBN 1904768776. Page 115. | 0.861274 | 3.669641 |
An Earth-like planet with an atmosphere, existing outside our solar system—new findings published in The Astronomical Journal is a step forward in the search for life beyond our world.
An atmosphere around an Earth-like planet outside our solar system is a big deal in the world of astronomy—an atmosphere could mean the existence of life. This is also the first time such a detection has been made; a tremendous step for the search for life in outer space.
The planet, dubbed a super-Earth, is named GJ 1132b. It orbits the star GJ 1132, and the system was viewed by the ESO/MPG telescope based in Chile by a team of researchers from Keele University led by Dr John Southworth. While life has not actually been found on the planet, Dr Southworth believes it is a “step in the right direction”.
Super-Earth GJ 1132b is a transiting planet, that is, its pathway is such that it passes directly between Earth and its host star—an event that happens every 1.6 days. It was viewed simultaneously at 7 different wavelengths at its transit during which a small of light from the star was blocked. The team measured the decrease in brightness that indicated the absorption of some of the star’s light by the planet and its atmosphere. The amount of light lost was, then, used to calculate the size of the planet. The results show that it is 1.4 times Earth’s size. Another finding from the new observations is that the planet appears to be bigger in one of the 7 wavelengths: this suggests that it is surrounded by an atmosphere opaque only to the particular light wavelength (it is not actually larger).
Dr Southworth and his team launched several simulations, trying to test possible atmosphere types for the planet. They found that those rich in water and/or methane might explain their findings. According to the researcher, GJ 1132b is much hotter than Earth; it could be a “water world” shrouded in a hot-steam atmosphere.
The study has a number of implications for the search of life in outer space, mainly because the star of the planet is a low-mass one, something very common in the universe. Normally, low-mass stars, which have lots of planets orbiting them, display high levels of X-rays and UV-light that should cause the evaporation of the atmospheres of planets. However, our super-Earth seems to have an atmosphere that can protect itself from this for centuries on end. If this is true, and given that low-mass stars are common, it could indicate that conditions conducive to life might be common elsewhere in the Universe. | 0.834206 | 3.919832 |
Have you ever been on a really long trip, and it felt like it took forever to get where
Well, how would you like to take a long trip into space?
That might sound like something you’ve read about in a book or seen in a movie, but for
a select few people, it’s real life!
I’m talking about the astronauts who live in space for months at a time, on the Internationals
The International Space Station — or ISS for short — is in orbit above Earth.
Astronauts live and work up there doing science experiments and learning about life in space.
To get there, astronauts are carried up into space by rockets. And when they go home, they
ride in space capsules that fall back to Earth.
Let’s take a closer look.
Those big, flat shiny things are solar panels, and they provide energy for the space station.
They capture sunlight and they turn it into electricity. The space station uses that electricity
to power lights and computers and everything else that makes the ISS go.
This is a robot arm. Astronauts inside the station use this arm, by remote control, to
fix things on the outside of the ISS.
Although it might not look like it, the space station is kind of like a big house.
It has 5 bedrooms, 2 bathrooms, a kitchen — which astronauts call a galley — and they
even have a laboratory, just like we do at the fort.
But as you can imagine, life on the space station is a lot different than it is back
home on Earth.
For one thing, all of the water that astronauts use has to be flown up by rockets. Since it’s
so hard to get up there, water is only used for drinking and eating.
So astronauts don’t take baths or showers with water. Instead, they wash up with special
But probably the biggest difference is that there’s much less gravity up in the space
station than there is here on Earth. Instead of sticking to the ground like we do at home,
astronauts up there just float around!
So, in a way, it’s a lot easier for the astronauts to move around, because there’s
less gravity. But after a couple of days in space, their muscles actually get weak. So
astronauts on the space station have to exercise at least two hours every day to give their
muscles a workout.
But the rest of the time, the astronauts are conducting experiments!
They’ll study plants to see how they grow in space, and they’ll study small animals,
like fish, to see how their muscles do in low gravity.
They even study how robots work in space.
Say hello to Robonaut 2. He’s a robot, like Squeaks, who lives on the space station full
time — He’s on board so astronauts can see if robots work as well in space as they
do on Earth.
R2, as his friends call him, can use tools, and even go on a spacewalk by himself.
Spacewalks are when astronauts leave the space station in a spacesuit, to do work on the
outside of the station.
But they don’t do them very often. Spacewalks are only for when astronauts need to fix things
on the ISS or to gather information for experiments.
So life on the International Space Station is hard work, and it’s really different
than life at home. But if you ask me, the astronauts who get to go there are pretty
lucky — because they actually get to live in space!
Thanks for joining us on SciShow Kids. Maybe one day, if you work really hard, you can
go to the ISS! See you next time. | 0.825618 | 3.341622 |
Major volcanic activity on the planet Mercury was ended about 3.5 billion years ago, according to a new research from a team of scientists lead by a planetary geologist. The study states that there aren’t any major volcanic eruptions on the surface of Mercury since millions of years.
The findings by NC State assistant professor and planetary geologist Paul Byrne and colleagues, studied the planet Mercury’s geological evolution in particular, and tried to find the results when rocky planets cool and contract in general.
The lead author of the study Paul Byrne said:
“There is a huge geological difference between Mercury and Earth, Mars or Venus. Mercury has a much smaller mantle, where radioactive decay produces heat, than those other planets, and so it lost its heat much earlier. As a result, Mercury began to contract, and the crust essentially sealed off any conduits by which magma could reach the surface.”
There are two common types of volcanic activities – explosive volcanism and effusive volcanism. In the first activity, the eruption of the volcano is more violent and it blasts ash and debris to more areas over larger areas. In the latter volcanic activity, the volcano erupts slowly and steadily spreads the lava flow out of the core area over the landscapes, which is believed as a key process in the formation of any planet’s crusts.
Effusive volcanism always helped researchers to learn about the geological history of many planets. Some examples are: From a study, scientists proved that an effusive volcanism was active on Mars a few million years ago, Venus witnessed it a few hundred million years ago and on Earth, it still takes place in many places. Have you seen photographers taking pictures near slowly flowing lavas?
Until now, the duration of effusive volcanic activity on Mercury, made of the same materials as these other planets, had not been known. The researchers from North Carolina State University used the Mercury’s surface images from NASA’s MESSENGER spacecraft to determine the period of the bulk of crust-forming volcanism on the planet.
They used a different technique to analyze the volcanism as there are no physical samples available from Mercury for radiometric dating. Researchers calculated absolute ages for these activities on the planet by using the images. They analyzed the number of craters and its size and placed it into the established mathematical models to determine that “the major volcanic activity on a planet – effusive volcanism” ended on Mercury about 3.5 billion years ago.
“These new results validate 40-year-old predictions about global cooling and contraction shutting off volcanism,” Byrne continues. “Now that we can account for observations of the volcanic and tectonic properties of Mercury, we have a consistent story for its geological formation and evolution, as well as new insight into what happens when planetary bodies cool and contract.”
The research was published in Geophysical Research Letters, with co-authors from the Carnegie Institution of Washington, Mount Holyoke College, the University of Georgia, Southwest Research Institute and Brown University.
[ Image credit: NASA ] | 0.855042 | 3.602554 |
Looking up at the silvery orb of the Moon, you might recognize familiar shadows and shapes on its face from one night to the next. You see the same view of the Moon our early ancestors did as it lighted their way after sundown.
Only one side of the spherical Moon is ever visible from Earth – it wasn’t until 1959 when the Soviet Spacecraft Luna 3 orbited the Moon and sent pictures home that human beings were able to see the “far side” of the Moon for the first time.
A phenomenon called tidal locking is responsible for the consistent view. The Earth and its Moon are in close proximity and thus exert significant gravitational forces on each other. These tidal forces slow the rotations of both bodies. They locked the Moon’s rotation in sync with its orbital period relatively soon after it formed – as a product of a collision between a Mars-sized object and the proto-Earth, 100 million years after the solar system coalesced.
Now the Moon takes one trip around the Earth in the same amount of time it takes to make one rotation around its own axis: about 28 days. From Earth, we always see the same face of the Moon; from the Moon, the Earth stands still in the sky.
The near side of the Moon is well studied because we can see it. The astronauts landed on the near side of the Moon so they could communicate with NASA here on Earth. All of the samples from the Apollo missions are from the near side.
Although the far side of the Moon isn’t visible from our vantage point, and with all due respect to Pink Floyd, it is not accurate to call it the dark side of the Moon. All sides of the moon experience night and day just like we do here on Earth. All sides have equal amounts of day and night over the course of a single month. A lunar day lasts about two Earth weeks.
With modern satellites, astronomers have completely mapped the lunar surface. A Chinese mission, Chang’e 4, is currently exploring the Aitken Basin on the far side of the Moon — the first such mission ever landed there. Researchers hope Chang’e 4 will help answer questions about the crater’s surface features and test whether things can grow in lunar soil. A privately funded Israeli mission, Beresheet, started as a mission to compete for the Google Lunar X Prize. Despite crashing during an attempted landing earlier this month, the Beresheet team still won the Moon Shot Award.
Being shielded from civilization means the far side of the moon is “radio dark.” There, researchers can measure weak signals from the universe that would otherwise be drowned out. Chang’e 4, for instance, will be able to observe low-frequency radio light coming from the Sun or beyond that’s impossible to detect here on the Earth due to human activity, such as TV and radio broadcasts and other forms of communication signals. Low-frequency radio peers back in time to the very first stars and the very first black holes, giving astronomers a greater understanding of how the structures of the universe began forming.
Rover missions also investigate all sides of the Moon as space scientists prepare for future human missions, looking to the Moon’s resources to help humanity get to Mars. For instance, water – discovered by NASA’s LCROSS satellite beneath the Moon’s north and south poles in 2009 – can be broken up into hydrogen and oxygen and used for fuel and breathing.
Researchers are getting closer to exploring the Moon’s polar craters, some of which have never seen the light of day – literally. They are deep and in just the right place to never have the Sun shine onto the crater floor. There are certainly dark parts of the Moon, but the whole far side isn’t one of them.
Saint Paul police chief condemns tactics used on George Floyd: ‘We’re here to serve — not choke people!’
Saint Paul Police Chief Todd Axtell told CNN's Jim Sciutto and Poppy Harlow on Thursday that he's showing his officers footage from George Floyd's death as an example of how not to handle a suspect.
In particular, Axtell told the CNN hosts that all of the officers in his department said that the actions of the officers in Minneapolis to Floyd were completely unacceptable.
"Every police officer that I know that I interacted with yesterday in the city of Saint Paul, there was not one who felt that what they observed on that video in Minneapolis was in any way, shape, or form acceptable police behavior," he said. "It is disgusting, it is dehumanizing, it is something that absolutely has to stop."
WATCH: Man holds black DoorDash driver at gunpoint for delivering food to an Arizona apartment complex
A man in Mesa, Arizona, is facing assault and weapons charges after he allegedly held a delivery driver at gunpoint this Sunday, 12News reports.
Police say Valentino Tejeda pulled a gun on 24-year-old Dimitri Mills in the parking lot of Tejeda's apartment complex, and when Mills and his girlfriend tried to explain they were making a food delivery to a neighbor, Tejeda still insisted that Mills, who is black, was somehow a threat.
Trump became enthralled with presidency while watching balloons drop on 1988 GOP convention stage
Donald Trump became enthralled with the presidency while watching balloons drop for George H.W. Bush at the 1988 Republican National Convention.
The celebrity real estate developer had been taken to New Orleans by his longtime pal Roger Stone, a Republican political operative hoping to spark an interest in Trump to run for the presidency, reported Politico.
“I got the definite impression that Roger Stone was preparing Donald Trump to run for president,” said Michael Caputo, a Stone associate who worked for Trump's 2016 campaign. “I didn’t know when it would be — but it was very clear to me that he wasn’t there for the cocktails.” | 0.857052 | 3.780686 |
Black hole shredding star caught on camera
Scientists have captured a view of a colossal black hole violently ripping apart a doomed star, illustrating an extraordinary and chaotic cosmic event from beginning to end for the first time using NASA's planet-hunting telescope.
The U.S. space agency's orbiting Transiting Exoplanet Survey Satellite, better known as TESS, revealed the detailed timeline of a star 375 million light-years away warping and spiraling into the unrelenting gravitational pull of a supermassive black hole, researchers said on Thursday.
The star, roughly the same size as our sun, was eventually sucked into oblivion in a rare cosmic occurrence that astronomers call a tidal disruption event, they added.
Astronomers used an international network of telescopes to detect the phenomenon before turning to TESS, whose permanent viewing zones designed to hunt distant planets caught the beginning of the violent event, proving effective its unique method of surveilling the cosmos.
"This was really a combination of both being good and being lucky, and sometimes that's what you need to push the science forward," said astronomer Thomas Holoien of the Carnegie Institution for Science, who led the research published in the Astrophysical Journal.
Such phenomena happen when a star ventures too close to a supermassive black hole, objects that reside at the center of most large galaxies including our Milky Way. The black hole's tremendous gravitational forces tear the star to shreds, with some of its material tossed into space and the rest plunging into the black hole, forming a disk of hot, bright gas as it is swallowed.
"Specifically, we are able to measure the rate at which it gets brighter after it starts brightening, and we also observed a drop in its temperature and brightness that is unique," Holoien said.
Observing the oscillation of light as the black hole gobbles the star and spews stellar material in an outward spiral could help astronomers understand the black hole's behavior, a scientific mystery since physicist Albert Einstein's work more than a century ago examined gravity's influence on light in motion. | 0.898523 | 3.652071 |
ESO’s Very Large Telescope (VLT) have observed an extreme planet where they suspect it rains iron. The ultra-hot giant exoplanet has a day side where temperatures climb above 2400 degrees Celsius, high enough to vaporise metals. Strong winds carry iron vapour to the cooler night side where it condenses into iron droplets.
This strange phenomenon happens because the ‘iron rain’ planet only ever shows one face, its day side, to its parent star, its cooler night side remaining in perpetual darkness. Like the Moon on its orbit around the Earth, WASP-76b is ‘tidally locked’: it takes as long to rotate around its axis as it does to go around the star.
On its day side, it receives thousands of times more radiation from its parent star than the Earth does from the Sun. It’s so hot that molecules separate into atoms, and metals like iron evaporate into the atmosphere. The extreme temperature difference between the day and night sides results in vigorous winds that bring the iron vapour from the ultra-hot day side to the cooler night side, where temperatures decrease to around 1500 degrees Celsius.
The observations show that iron vapour is abundant in the atmosphere of the hot day side of WASP-76b.This result was obtained from the very first science observations done with ESPRESSO, in September 2018, by the scientific consortium who built the instrument: a team from Portugal, Italy, Switzerland, Spain and ESO.
ESPRESSO the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations was originally designed to hunt for Earth-like planets around Sun-like stars. However, it has proven to be much more versatile. | 0.860468 | 3.52503 |
Specific Orbital Energy
In the gravitational two-body problem, the specific orbital energy (or vis-viva energy) of two orbiting bodies is the constant sum of their mutual potential energy and their total kinetic energy , divided by the reduced mass. According to the orbital energy conservation equation (also referred to as vis-viva equation), it does not vary with time.
For an elliptical orbit the specific orbital energy is the negative of the additional energy required to accelerate a mass of one kilogram to escape velocity (parabolic orbit). For a hyperbolic orbit, it is equal to the excess energy compared to that of a parabolic orbit. In this case the specific orbital energy is also referred to as characteristic energy.
|ϵ||specific orbital energy (J/kg)|
|μ||sum of the standard gravitational parameters of the bodies (m3/s2)|
|a||semi-major axis (m)| | 0.824791 | 3.324543 |
Al Osborne doesn't have much of an accent anymore, but there's still a bit of the Texas drawl left over from his youth in College Station. And even a few decades in Italy hasn't erased the easy-going attitude and low-key charm that are the hallmarks of a Texas gentleman. When Osborne talks about physics, he tends to drop in an Italian word here or there, along with American colloquialisms like "loaded for bear" when he means "prepared for anything." It's a style that can make Osborne's explanation of the non-linear Schrodinger equation sound more like a cosmopolitan folktale.
Osborne is a leading researcher studying nonlinear dynamics in water - from monster waves, to tidal bores, to unusual ocean currents. His status in the field stems in part from his groundbreaking discovery of enormous, subsurface ocean waves, which turned out to be the largest solitons ever found. "The evidence for the solitons was there all along in a number of satellite observations,"says Osborne, "but nobody understood them until the proper in situ measurements were made." It was a career-changing event for the physicist who started out studying cosmic rays.
Converging Oceaniac Internal Waves, Somalia, Africa
(Nasa Image eXchange)
A soliton is an example of a wave in nonlinear physics. Small waves in many media add linearly - that is, a one meter wave passing through another one meter wave will combine to briefly form a two meter peak. When waves grow large, they no longer add linearly, and the resulting height can be substantially different than the sum of the component waves. Solitons are special solutions of nonlinear wave equations. These robust structures behave more like particles than waves, traveling long distances and scattering off other solitons and waves.
Osborne explains that his own breakthrough echoes the original discovery of solitons by a young naval architect who happened to be riding his horse along Edinburgh's Union Canal in August 1834. John Scott Russell had set out to learn why the water was perpetually draining from the canal when he noticed an odd wave produced at the bow of a barge as it came to a halt. Unlike the waves Russell had studied in school, a single hump of water traveled along the canal "without change of form or diminution of speed." Russell's waves, which were the first solitons ever described, continued to the end of the canal, where they jumped the final containing wall and dumped some of the water out. The discovery simultaneously solved Russell's canal-draining mystery and presaged the modern study of nonlinear physics.
As was the case for Russell, luck and insight were key to Osborne's discovery of ocean solitons. While living in Houston in 1962, Osborne was eager to aid the nation in the space race, and offered his talents to NASA engineers in Houston. He worked on the Apollo program part-time while attending graduate school at the University of Houston. Despite completing a PhD dissertation on cosmic ray physics, Osborne was lured away from aerospace by the oil industry, where he concentrated on oceanographic research for Exxon Production Research Co.
Osborne and oceanographer Terrence Burch discovered oceanic solitons while investigating mysterious currents that were battering an oil drilling vessel off the coast of Sumatra. They studied ocean images taken from the 1975 Apollo-Soyuz space station, which revealed striations over one hundred miles long in the waters surrounding the vessel. Osborne and Burch deployed sensors in the water and discovered subsurface waves of warm water extending a hundred meters down, propagating along the "thermocline" between layers of cooler and warmer water. The waves' temperature profiles resembled the surface profile of Russell's wave. They also maintained their shape and speed over long distances, just as the traveling hump of water had in the Edinburgh canal. Indeed, the waves were simply enormous solitons.
Osborne's seminal paper on oceanic solitons was significant enough to be assigned to the cover of Science magazine. It also inspired Osborne's passion for nonlinear physics, and garnered him a guest spot on the Tonight Show with Johnny Carson. Although Osborne says that so much success and notoriety so early in his career was a generally positive experience, he admits that his subsequent choice to join the faculty of an Italian university was in part a reaction to the excitement that followed his soliton discovery. "I felt like I needed the change to regroup," says Osborne.
These days, Osborne divides his time between the University of Torino (in the Italian city that is home to the Shroud of Turin) and the Office of Naval Research in Arlington, Virginia. Although he studies a range of nonlinear phenomena, much of his work concentrates on surface ocean waves known as rogues that would give a brave sailor nightmares. Rogue waves are surface manifestations similar to solitons that tower over normal waves by a factor of two or more. Occasionally, rogues may be taller than a ten-story office building, or cause equally impressive troughs in the ocean that can swallow a ship. The faces of rogues are steeper than normal waves, leading to walls of water that can split open tankers, blow out bulkheads, or rip the bridge clean off of a ship's decks.
Fortunately for sailors, such enormous rogues are rare. Nevertheless, Osborne has found that significant rogue waves are much more common than was once thought. Marine engineers often design structures to withstand the largest wave likely to come along in a hundred years. "Our measurements show that oil drilling platforms are sometimes experiencing these 'hundred-year waves' several times each year," says Osborne, suggesting that true hundred-year waves must be much larger than anyone expected.
A possible reason for the discrepancy in wave height predictions is the mathematical difficulty of nonlinear computations. Physicists often make their calculations simpler by throwing out everything but the linear terms in their equations, and leaving the nonlinear mathematics to computer simulations. Osborne believes that he has better ways to deal with nonlinear terms, allowing him to keep them in his equations. He says that his techniques provide enhanced insight into a range of nonlinear phenomena, including solitons. And when he explains his ideas in that faded Texas drawl peppered with the occasional Italian, the math doesn't seem so bad - at least until he sketches something on a napkin that looks almost like, but isn't exactly, a phase-space diagram. Clearly, Osborne's work is no mere cosmopolitan folktale. | 0.806103 | 3.237667 |
Observational astronomy/Extrasolar planet
This learning project will study extrasolar planets. It is very difficult to directly detect planets orbiting distant stars. There are, however, a number of indirect methods. The first activity here will focus on the radial velocity method. Later, another activity will be created that uses the transit method.
In this activity you will use a computer program called the Systemic Console to examine radial velocity data for stars known to have one or more planets. The goal is to figure out the planetary configuration that best fits the observational data and look for additional planets. The Systemic website contains detailed instructions on how to participate. Here is an overview of the steps involved:
- Then, follow the instructions to install the Downloadable Console.
- After the software is installed, start the program and go through the steps described in the three part tutorial:
- At this point you should pick a few different stars and try to find the planetary system that is the best fit to the data. A good fit will have a low ChiSq value in the console.
Uploading your results is an end in itself and will help the Systemic project progress. Here at Wikiversity we will concentrate on trying to find the best fit for a small number of the stars in the database. Later, we will be studying exoplanets that are known to transit. So, we'll begin by looking at a few of these systems. If you are going to continue, please sign your name under Active Participants at the talk page.
- Choose HD189733 from the Real Star pulldown menu in the Systemic Console. Try to find a planetary system that best fits the data. Some other systems to try are:
- w:Extrasolar planet
- w:Methods of detecting extrasolar planets
- w:Systemic (amateur extrasolar planet search project)
- The Extrasolar Planets Encyclopaedia
- Catalog of Nearby Exoplanets
- Exoplanet Transit Search Observing Program
- The Transiting Exoplanets HD 209458 and TrES-1
- XO-1 Transit Observations
- Summary Table of parameters for transiting planets | 0.843268 | 3.062784 |
MENCA observed the evening exosphere of Mars
The Mars Exospheric Neutral Composition Analyser (MENCA), onboard Indian Mars Orbiter Mission (MOM) is a mass spectrometer, provides in-situ measurements of the neutral composition of the exosphere of the Mars. MENCA is capable of measuring relative abundances of neutral constituents in the mass range 1 to 300 atomic mass unit (amu); the major gases in the Martian atmosphere fall in this range. In addition to acquiring the mass spectra in a specified mass range, the instrument has a provision to track the time variation of the abundances of a set of selectable species. The observation from MENCA will help in understanding the escape of the Martian atmosphere.
At the surface of Mars, the atmosphere is rich in Carbon Dioxide (CO2) and very thin (~6 millbar), about 1% of that of Earth. In the upper part of the Martian atmosphere, at around 100 km, the ultraviolet (UV) rays of sunlight breaks CO2 molecule into Carbon Monoxide (CO) molecule and Oxygen (O) atom. The CO also can be broken by solar UV radiation into C and O atoms. The oxygen atoms are about three times lighter than the CO2 molecules and two times lighter than CO molecules. Hence, oxygen atoms have larger scale height, which means it's density at higher heights falls-off slower compared to that of CO and CO2. Hence, there comes a region in Martian upper atmosphere where the number of O atoms exceeds the number of CO2 molecules. The altitude at which this change-over (CO2 dominance to O dominance) happens depends on how deep the solar UV rays penetrate the Mars atmosphere.
The figure below shows the MENCA-measured abundances of the major gases, namely, atomic Oxygen (O, 16 amu), Nitrogen molecule (N2) plus Carbon Monoxide (CO, 28 amu), and Carbon Dioxide (CO2, 44 amu), in the exosphere of Mars on 21 December 2014, during Martian evening (around sunset in the sky of Mars), from 265 km to 400 km altitude. These observations correspond to moderate solar activity conditions and when MOM’s periapsis altitude was the lowest (~265 km).
MENCA observations have shown that the abundance of Oxygen exceeds that of Carbon Dioxide at an altitude of 270 ±10 km during Martian evening. From the variation of the abundances of different gases with the altitude, the temperature of the Martian exosphere was found to be about 271 ±5 K (-7 to +3 °C). These measurements were conducted when Mars was closer to the Sun in its elliptical orbit (i.e., at perihelion); it is still cooler when Mars is farthest from the Sun.
These are the first in-situ measurements of composition during the local dusk sector on Mars, which would help in setting up the boundary conditions for models dealing with thermal escape processes. The models are basically used to understand the evolution of atmospheres to its present state and its response to various forces.
It is important to note that the CO2-to-O dominance transition altitude differs in day and night, and also varies with different seasons of Mars (due to similar tilt of rotation axis as on Earth, Mars has seasons similar to that on Earth), as well as depends on how active is the Sun.
MENCA has provided several measurements of the composition of the key species of the Martian neutral exosphere.
The above results are published in American journal, Geophysical Research Letters. vol. 43, pp. 1862–1867, (2016).
Abundances of the major gases measured by MENCA
Specifications of MENCA | 0.80436 | 4.025234 |
Gravitational waves squash and stretch space as they travel through the universe. Current attempts to spot them involve monitoring a region of space several kilometres across on Earth for the tell tale signs of this squeezing. Although great things are expcted, these experiments have so far thrown up precisely nothing.
But there’s another way. Gravitational waves should also stretch and squeeze pulsars as they pass by, subtly changing the radio pulses they produce. So by monitoring an array of pulsars throughout the galaxy, astronomers should be able to see the effects of nanohertz to microhertz gravitational waves passing by. The array of pulsars should effectively shimmer as the waves wash over it, like a grid of buoys bobbing on the ocean.
So the plan is to keep a beedy eye on an array of carefully chosen pulsars. It’s called the North American Nanohertz Observatory for Gravitational Waves or NANOGrav and it’s part of an international effort to spot gravitational waves in this way.
Of course, these kinds of observations are hard to make. First, astronomers need well-characterised millisecond pulsars to observe. They’re not easy to find and there appears to be a particular dearth of them in the northern hemisphere. And measuring them with the required accuracy isn’t easy either, say Fredrick Jenet at the University of Texas, Brownsville, and a few buddies.
But there’s hope on the horizon. These guys say the next generation of radio telescope arrays such as the Allen Telescope Array in California and the Square Kilometer Array in Australia or South Africa, should be capable of making the required measurements. And the scientific potential of the data is huge.
The team says the observations should help them understand how galaxies and supermassive black holes evolve together, shed light on the physics of the early universe such as inflation as well as probing the nature of space-time, perhaps revealing quantum gravity corrections to classical gravity. It may even throw up some new sources of gravitational waves.
Of course, many of those things are also the goals of the Earth-based gravitational wave observatories, which have cost hundreds of millions of dollars to build and more to maintain and upgrade. By contrast, the NANOGrav team estimates the cost of its project over ten years to be a mere $66 million.
It expects to be up and running by 2020 and at that price looks remarkably good value.
Ref: arxiv.org/abs/0909.1058: The North American Nanohertz Observatory for Gravitational Waves | 0.814616 | 4.004285 |
With exoplanet discoveries coming at us several times a month, finding these worlds is a hot field of research. Once the planets are found and confirmed, however, there’s a lot more that has to be done to understand them. What are they made of? How habitable are they? What are their atmospheres like? These are questions we are only beginning to understand.
One long-standing exoplanet researcher argues that we don’t know very much about about alien planet atmospheres, as an example. Princeton University’s Adam Burrows says that not only is our understanding at an infancy, but the media and scientists overhype information based on very little data.
“Exoplanet research is in a period of productive fermentation that implies we’re doing something new that will indeed mature,” Burrows stated in a story posted on Princeton Journal Watch. “Our observations just aren’t yet of a quality that is good enough to draw the conclusions we want to draw.”
Burrow’s skepticism comes from how information on exoplanet atmospheres is collected. That uses a method called low-resolution photometry, which shows changes in light and radiation emitted from an object such as a planet. This could be affected by things such as a planet’s rotation and cloud cover.
Burrows’ solution is to use spectrometry, which can glean physical information through looking at light spectra, but that would be a challenge given the existing exoplanet-seeking infrastructure in space and on Earth uses telescopes that generally rely on other methods.
Despite a horrendous weather forecast, the clouds parted – at least partially – just in the nick of time for a massive crowd of astronomy and space enthusiasts gathered at Princeton University to see for themselves the dramatic start of the Transit of Venus shortly after 6 p.m. EDT as it arrived at and crossed the limb of the Sun.
And what a glorious view it was for the well over 500 kids, teenagers and adults who descended on the campus of Princeton University in Princeton, New Jersey for a viewing event jointly organized by the Astrophysics Dept and the Amateur Astronomers Association of Princeton (AAAP), the local astronomy club to which I belong.
See Transit of Venus astrophotos snapped from Princeton, above and below by Astrophotographer and Prof. Bob Vanderbei of Princeton U and a AAAP club member.
It was gratifying to see so many children and whole families come out at dinner time to witness this ultra rare celestial event with their own eyes – almost certainly a last-in-a-lifetime experience that won’t occur again for another 105 years until 2117. The crowd gathered on the roof of Princeton’s Engineering Dept. parking deck – see photos
For the next two and a half hours until sunset at around 8:30 p.m. EDT, we enjoyed spectacular glimpses as Venus slowly and methodically moved across the northern face of the sun as the racing clouds came and went on numerous occasions, delighting everyone up to the very end when Venus was a bit more than a third of the way through the solar transit.
Indeed the flittering clouds passing by in front of Venus and the Sun’s active disk made for an especially eerie, otherworldly and constantly changing scene for all who observed through about a dozen AAAP provided telescopes properly outfitted with special solar filters for safely viewing the sun.
As part of this public outreach program, NASA also sent me special solar glasses to hand out as a safe and alternative way to directly view the sun during all solar eclipses and transits through your very own eyes – but not optical aids such as cameras or telescopes.
Altogether the Transit lasted 6 hours and 40 minutes for those in the prime viewing locations such as Hawaii – from where NASA was streaming a live Transit of Venus webcast.
You should NEVER look directly at the sun through any telescopes or binoculars not equipped with special eye protection – because that can result in severe eye injury or permanent blindness!
We in Princeton were quite lucky to observe anything because other astro friends and fans in nearby areas such as Philadelphia, PA and Brooklyn, NY reported seeing absolutely nothing for this last-in-a-lifetime celestial event.
Princeton’s Astrophysics Department organized a series of lectures prior to the observing sessions about the Transit of Venus and how NASA’s Kepler Space Telescope currently uses the transit method to detect and discover well over a thousand exoplanet and planet candidates – a few of which are the size of Earth and even as small as Mars, the Red Planet.
NASA’s Curiosity rover is currently speeding towards Mars for an August 6 landing in search of signs of life. Astronomers goal with Kepler’s transit detection method is to search for Earth-sized planets in the habitable zone that could potentially harbor life !
So, NASA and astronomers worldwide are using the Transit of Venus in a scientifically valuable way – beyond mere enjoyment – to help refine their planet hunting techniques.
Historically, scientists used the Transit of Venus over the past few centuries to help determine the size of our Solar System.
See more event photos from the local daily – The Trenton Times – here
And those who stayed late after sunset – and while the Transit of Venus was still visibly ongoing elsewhere – were treated to an extra astronomical bonus – at 10:07 p.m. EDT the International Space Station (ISS) coincidentally flew overhead and was visible between more break in the clouds.
Of course clouds are no issue if you’re watching the Transit of Venus from the ISS or the Hinode spacecraft. See this Hinode Transit image published on APOD on June 9 and enhanced by Marco Di Lorenzo. | 0.90489 | 3.655185 |
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Close your eyes and imagine you are standing in a wide open field. In the field you see a gigantic white rocket reaching far up into the sky. As you walk up to the rocket, the door opens and you climb inside and find a seat and buckle up. Next you hear the countdown – 5, 4, 3, 2, 1. Suddenly the rocket rumbles as it lifts of the ground and shoots through the sky, past the clouds, and up, up, up into space. When you look out the window you see the round blue ball of earth far below.
The rocket is going faster and faster. You zoom past the moon as the rocket picks up speed. Soon the other planets of our solar system pass you by. You look back and notice the earth has grown smaller and smaller until it has disappeared from view. Then suddenly you are traveling at the speed of light, and before long you have left the solar system and are deep into outer space. All is black. You travel further and further until suddenly you look out your window and see a beautiful cloud of dust and gas all swirling together. You have arrived at the place where stars are born. It is called a stellar nursery, which means a star birthing place.
Stars are sort of like people in that they are born, and they grow until they are bigger, and then eventually get old and die. But unlike people stars live for millions or even trillions of years. Our own sun is a star, it’s just a lot closer than the stars we see twinkling in the sky at night that appear so small.
For millions of years clouds of dust and gas in space swirl around each other in what is called a nebula. Over time these clouds slowly group together into clumps that eventually become baby stars — or protostars. Some stars grow bigger and bigger until they become as large as our own sun. And often they have their very own planets, just like our sun has its own planets. These stars become very hot and bright, which is why when you look up at the sky at night you can see them even though they are sooo far away. To travel to many of these stars would take thousands of years.
The reason we know a lot about how stars are born is because of a space telescope. A space telescope is a telescope that is launched into space and can see better because it is above the earth. The Herschel Space Observatory was built by the European Space Agency and watched where stars were born for 4 years. Because of the hard work of the engineers and astronomers working on this space telescope, we know a lot more about the life of stars.
After changing from clouds of gas and dust many of these baby stars eventually become “main sequence” stars, then sub-giant stars and then red giant stars. Many of these very large stars are thousands of times bigger than our own sun. And our own sun is very, very big.
After millions of years even stars grow old and die. Eventually they begin to collapse in on themselves and then suddenly explode in what is called a supernova. During a supernova they shoot gas and dust for millions of miles around them. Supernovas happen in the universe all the time but often it’s hard for us to see them happening because there are so many stars and they are so far away. The people who study stars are called astronomers. Most astronomers thought the only way to see supernovae would be to use a large telescope run by many astronomers. In Australia there was an amateur astronomer named Robert Evans. He had a normal job during the day, but at night his favorite thing to do was to go on his back porch and use his little telescope to watch the stars. Robert was interested in supernovas, when stars explode, but decided he didn’t need all of the big telescopes to see them. So he started watching for supernovas on his own. For many nights Robert didn’t see anything. But he kept watching and kept waiting, until he saw his first supernova. He was so excited. Over the years Robert has seen 42 supernovae! Which is an amazing achievement. Because Robert is very patient and very diligent he has been able to see when these gigantic stars explode all the way across the galaxy.
When we look out in the night sky we see many stars, but they are very far away. After the sun, the closest star is called Alpha Centauri. Alpha Centauri is 25 trillion miles away! This gives you a little bit of an idea of how large our galaxy is.
Stars like our sun are very important because they are like huge factories which give off energy and heat. They send this energy in the form of waves that travel all the way across space to Earth. There are many reasons our sun is important. First off, without it would always be night. If it was always night, it would be very hard to see! Also, trees would never grow, because trees need the sun’s energy to grow. Without trees and other plants we wouldn’t have oxygen to breath and animals wouldn’t have food. And without animals and plants we wouldn’t be able to eat either. We would all be in very big trouble! Also, the earth would become very very cold and everything would freeze. Even on hot days, we should be very grateful we have a sun that keeps planet Earth running smoothly.
Next time when you go outside and feel the warm sun on your skin, think about how the sun rays travelled 100 million miles to to make you warm. That’s pretty amazing that an object sooo far away can make its way all the way to you and keep you warm and keep us all alive.
When we learn about how stars and our own sun it makes us grateful for nature and the world around us. And when we understand how important they are it reminds us to respect and take care of what we have.
Tonight think of some ways you can better take care of the Earth, whether it means picking up trash outside or not wasting water or planting flowers or a tree. There are many things around us in nature that we can be curious about and appreciate if we just take the time to notice them.
- Have you ever heard of a comet? A comet is a gigantic piece of ice and rock and dirt that flies through outer space at incredible speeds. Many comets are the size of mountains and when they speed around space have a tail of gasses that can be hundreds of thousands feet long.
- For a long time humans have seen comets in the sky and wondered what they are. some very smart scientists decided they wanted to learn more about comets so they decided to create a spaceship that would find a comet and land on it. This had never been done before but they knew if they build the spaceship right and worked out all of the math correctly they could make it happen.
- Many different countries in Europe, designed and started working on the spacecraft they would call Rosetta. It took many different engineers and scientists studying space and spaceships to know how Rosetta should work.
- Astronomers, scientists who know a lot about space also had to follow the comet Rosetta would land on. They had to use math to figure out how fast Rosetta should go and where it should go to land on the large rocky comet flying around space.
- When Rosetta was ready they blasted the ship into outer space and someone gave it directions to fly. No one was actually on Rosetta because it would be gone for a very long time and might be a very dangerous mission. They flew it sort of like you might fly a remote controlled helicopter or car.
- For 10 years Rosetta flew through outer space. It had many adventures there such as passing planets like Mars and asteroids, other rocks in space, many places a spacecraft had never been. After 10 years it finally was close enough to the icy comet speeding through space. All of the engineers and scientists at mission control were very nervous. They had worked very hard for this day and had been very patient waiting 10 years until they could land their ship. When the day finally came they watched in anticipation as Rosetta came into the orbit of the gigantic comet. This comet was as big as a mountain.
- Attached to Rosetta was a robot that would land on the comet and do experiments to learn more about the comet. When the time was right the lander shot out of Rosetta and raced toward the massive comet below. For a moment it seemed as thought it wouldn’t work, the lander was off track, then suddenly it shot spears out of its side and stuck into the comets ground. It used these hooks and ropes to pull itself down to the ground. When it hit the ground it tumbled and was broken in some places but eventually came to rest. Everyone at mission control cheered. The robot had landed, Rosetta had completed its mission. This was the first time a robot had ever landed on a comet flying through space! The mission was a success!
- Once the lander, which they had called Phillae had time to recharge its batteries it was able to do a few experiments and send the data back to earth. They learned about the water on comets and some of its metals.
- Like the scientists and engineers who designed and built Rosetta you can learn all you can about science and other subjects. They had to listen closely and study and do their homework to become skilled at what they do.
- Astronomers also helped by learning about the stars. You can go out at night and look at the stars and watch shows and read about all of the amazing things happening in the sky above you.
- Waiting for Rosetta to finally reach the comment also took patience. They had to wait many years until it arrived.
- Over 2000 people worked on this project. This shows that teamwork is important to make great things happen.
- What would you like to do when you grow up? Think about it tonight, use your imagination and make a list of the things you can do now to improve yourself, then, pick one of them and start right away. | 0.905217 | 3.19443 |
The Moon and Mercury will share the same right ascension, with the Moon passing 6°40' to the north of Mercury. The Moon will be 1 days old.
The Moon will be at mag -9.0, and Mercury at mag 0.2, both in the constellation Libra.
The pair will be too widely separated to fit within the field of view of a telescope or pair of binoculars, but will be visible to the naked eye.
A graph of the angular separation between the Moon and Mercury around the time of closest approach is available here.
The positions of the two objects at the moment of conjunction will be as follows:
|Object||Right Ascension||Declination||Constellation||Magnitude||Angular Size|
The coordinates above are given in J2000.0. The pair will be at an angular separation of 20° from the Sun, which is in Virgo at this time of year.
|The sky on 29 October 2019|
1 day old
All times shown in EDT.
The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.
|25 Oct 2019||– Mercury at dichotomy|
|11 Nov 2019||– Mercury at inferior solar conjunction|
|11 Nov 2019||– Transit of Mercury|
|16 Nov 2019||– Mercury at perihelion| | 0.898291 | 3.077821 |
New findings could help keep satellites and space debris from colliding
Half a million objects, including debris, satellites, and the International Space Station, orbit the planet in the thermosphere, the largest layer of Earth's atmosphere. To predict the orbits—and potential collisions—of all this stuff, scientists must forecast the weather in the thermosphere.
Researchers who analyzed the role that gravitational effects of the Moon have on the thermosphere found that satellites taking different paths around the planet—circling over the poles, around the equator, or any route in between—will experience different levels of lunar-induced drag. Incorporating these results in current atmospheric models can refine the accuracy of orbital predictions, thus keeping satellites and space junk on separate paths.
"We continue to be surprised and fascinated by the different pathways that connect the lower atmosphere to space weather," said Jesse Zhang, lead author of the Space Weather paper. | 0.861194 | 3.564697 |
An eclipse is an astronomical event that occurs when one celestial object moves into the shadow of another. When an eclipse occurs in a stellar system such as the Solar System, the celestial bodies directly involved in the eclipse form what is known as a syzygy—that is, three or more celestial bodies in the same gravitational system are aligned along a straight line. The object closest to the star is called the occulting object, as it blocks the light of the star as seen from the more distant object.
The term "eclipse" is most often used to describe either a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse, when the Moon moves into Earth's shadow. However, an eclipse can also refer to similar events beyond the Earth-Moon system. Examples include (a) a planet moving into the shadow cast by one of its moons, (b) a moon passing into the shadow cast by its parent planet, or (c) a moon passing into the shadow of another moon. A binary star system can also produce eclipses if the plane of their orbit intersects the position of the observer.
Eclipses have helped people visualize the relative movements of the celestial bodies involved. In addition, they have provided great opportunities to check theories and gather useful information. For example, the dates of eclipses have been used for the chronological dating of historical records. Also, solar eclipses are opportunities to learn more about the Sun's structure and to observe how the Sun's gravity bends light coming from distant stars, as predicted by the theory of general relativity. Moreover, the timings of eclipses involving the moons of Jupiter have been used to calculate an observer's longitude on Earth.
The term eclipse is derived from the ancient Greek noun έκλειψις (ékleipsis), from the verb εκλείπω (ekleípō), meaning "I cease to exist." It is a combination of the preposition εκ, εξ (ek, ex), meaning "out," and the verb λείπω (leípō), meaning "I am absent."
Forming a syzygy
An eclipse occurs when there is a linear arrangement (syzygy) involving a star and two celestial bodies, such as a planet and a moon. The shadow cast by the object closest to the star intersects the more distant body, lowering the amount of luminosity reaching the latter's surface. The shadow cast by the occulting body is divided into two types of regions:
- An umbra, where the radiation from the star's photosphere is completely blocked
- A penumbra, where only a portion of the radiation is blocked.
An observer located within the umbra of the occulting object will see a total eclipse, whereas someone in the penumbra will see a partial eclipse. Totality occurs at the point of maximum phase during a total eclipse, when the occulted object is the most completely covered. Outside the umbra, the occulting object covers the light source only partially, and this produces a partial eclipse.
The part of the occulting object's shadow that extends beyond the umbra is called the antumbra. Like the penumbra, the antumbra is a region where only part of the star's radiation is blocked by the occulting body. During a solar eclipse, an observer on Earth located inside the antumbra will see an annular eclipse, in which the Moon appears smaller than the Sun and in complete silhouette.
For spherical bodies, when the occulting object is smaller than the star, the umbra forms a cone whose length L is calculated by the formula:
where Rs is the radius of the star, Ro is the occulting object's radius, and r is the distance from the star to the occulting object. For Earth, on average L is equal to 1.384×106 km, which is much larger than the Moon's semimajor axis of 3.844×105 km. Hence, the umbral cone of the Earth can completely envelop the Moon during a lunar eclipse. If the occulting object has an atmosphere, however, some of the luminosity of the star can be refracted into the volume of the umbra. This occurs, for example, during an eclipse of the Moon by the Earth—producing a faint, ruddy illumination of the Moon even at totality.
An astronomical transit is also a type of syzygy, but is used to describe the situation where the nearer object is considerably smaller in apparent size than the more distant object. Likewise, an occultation is a syzygy where the apparent size of the nearer object appears much larger than the distant object, and the distant object becomes completely hidden during the event.
An eclipse cycle takes place when a series of eclipses are separated by a certain interval of time. This happens when the orbital motions of the bodies form repeating harmonic patterns. A particular instance is the Saros cycle, which results in a repetition of a solar or lunar eclipse every 6,585.3 days, or a little over 18 years. However, because this cycle has an odd number of days, a successive eclipse is viewed from a different part of the world.
An eclipse involving the Sun, Earth, and Moon can occur only when they are nearly in a straight line, allowing the shadow cast by the Sun to fall upon the eclipsed body. Because the orbital plane of the Moon is tilted with respect to the orbital plane of the Earth (the ecliptic), eclipses can occur only when the Moon is close to the intersection of these two planes (the nodes). The Sun, Earth, and nodes are aligned twice a year, and eclipses can occur during a period of about two months around these times. There can be from four to seven eclipses in a calendar year, which repeat according to various eclipse cycles, such as the Saros cycle.
An eclipse of the Sun by the Moon is termed a solar eclipse. This term is actually a misnomer. The phenomenon is more correctly described as an occultation of the Sun by the Moon, or an eclipse of the Earth by the Moon.
Records of solar eclipses have been kept since ancient times. A Syrian clay tablet records a solar eclipse on March 5, 1223 B.C.E., while Paul Griffin argues that a stone in Ireland records an eclipse on November 30, 3340 B.C.E. Chinese historical records of solar eclipses date back over 4,000 years and have been used to measure changes in the Earth's rate of spin. Eclipse dates can also be used for chronological dating of historical records.
The type of solar eclipse event depends on the distance of the Moon from the Earth during the event. A total solar eclipse occurs when the Earth intersects the umbra portion of the Moon's shadow. When the umbra does not reach the surface of the Earth, the Sun is only partially occulted, resulting in an annular eclipse. Partial solar eclipses occur when the viewer is inside the penumbra.
Solar eclipses are relatively brief events that can only be viewed in totality along a relatively narrow track. Under the most favorable circumstances, a total solar eclipse can last for 7 minutes, 40 seconds, and can be viewed along a track that is up to 250 km wide. However, the region where partial totality can be observed is much larger. The Moon's umbra will advance eastward at a rate of 1,700 km/h, until it no longer intersects the Earth.
Lunar eclipses occur when the Moon passes through the Earth's shadow. Since this occurs only when the Moon is on the far side of the Earth from the Sun, lunar eclipses only occur when there is a full moon. Unlike a solar eclipse, an eclipse of the Moon can be observed from nearly an entire hemisphere. For this reason it is much more common to observe a lunar eclipse from a given location. A lunar eclipse also lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour.
There are three types of lunar eclipses:
- Penumbral, when the Moon crosses only the Earth's penumbra
- Partial, when the Moon crosses partially into the Earth's umbra
- Total, when the Moon circles entirely within the Earth's umbra
Total lunar eclipses pass through all three phases. Even during a total lunar eclipse, however, the Moon is not completely dark. Sunlight refracted through the Earth's atmosphere intersects the umbra and provides a faint illumination. Much as in a sunset, the atmosphere tends to scatter light with shorter wavelengths, so the illumination of the Moon by refracted light has a red hue.
Eclipses are impossible on Mercury and Venus, which have no moons. However, both have been observed to transit across the face of the Sun. There are on average 13 transits of Mercury each century. Transits of Venus occur in pairs separated by an interval of eight years, but each pair of events happen less than once a century.
On Mars, only partial solar eclipses are possible, because neither of its moons is large enough, at their respective orbital radii, to cover the Sun's disc as seen from the surface of the planet. Eclipses of the moons by Mars are not only possible, but commonplace, with hundreds occurring each Earth year. On rare occasions, Deimos is eclipsed by Phobos. Martian eclipses have been photographed from both the surface of Mars and from orbit.
The gas giant planets (Jupiter, Saturn, Uranus, and Neptune) have many moons and are thus frequently involved in eclipses. The most striking eclipses involve Jupiter, which has four large moons and a low axial tilt, making eclipses more frequent as these bodies pass through the shadow of the larger planet. Transits occur with equal frequency. It is common to see the larger moons casting circular shadows on Jupiter's cloudtops.
The eclipses of the Galilean moons by Jupiter became accurately predictable once their orbital elements were known. During the 1670s, it was discovered that these events were occurring about 17 minutes later than expected when Jupiter was on the far side of the Sun. Ole Rømer deduced that the delay was caused by the time needed for light to travel from Jupiter to the Earth. This understanding was used to obtain the first estimate of the speed of light.
With the other three gas giants, eclipses occur only at certain periods during the planet's orbit, due to the higher inclination between the orbits of the moons and the orbital plane of the planet. The moon Titan, for example, has an orbital plane tilted about 1.6° to Saturn's equatorial plane. But Saturn has an axial tilt of nearly 27°. The orbital plane of Titan crosses the line of sight to the Sun at only two points along Saturn's orbit. As the orbital period of Saturn is 29.7 years, an eclipse is possible only about every 15 years.
The timing of the Jovian satellite eclipses was also used to calculate an observer's longitude on the Earth. By knowing the expected time when an eclipse would be observed at a standard longitude (such as Greenwich), the time difference could be computed by accurately observing the local time of the eclipse. The time difference gives the longitude of the observer because every hour of difference corresponded to 15° around the Earth's equator. This technique was used, for example, by Giovanni D. Cassini in 1679, to re-map France.
Pluto, with its proportionately large moon Charon, is also the site of many eclipses. A series of such mutual eclipses occurred between 1985 and 1990. These daily events led to the first accurate measurements of the physical parameters of both objects.
A binary star system consists of two stars that orbit around their common center of mass. The movements of both stars lie on a common orbital plane in space. When this plane is very closely aligned with the location of an observer, the stars can be seen to pass in front of each other. The result is a type of extrinsic variable star system called an eclipsing binary.
The maximum luminosity of an eclipsing binary system is equal to the sum of the luminosity contributions from the individual stars. When one star passes in front of the other, the luminosity of the system is seen to decrease. The luminosity returns to normal once the two stars are no longer in alignment.
The first eclipsing binary star system to be discovered was Algol, a star system in the constellation Perseus. Normally this star system has a visual magnitude of 2.1. However, every 20.867 days, the magnitude decreases to 3.4 for more than 9 hours. This is caused by the passage of the dimmer member of the pair in front of the brighter star. The concept that an eclipsing body caused these luminosity variations was introduced by John Goodricke in 1783.
- New York Times, Science Watch: A Really Big Syzygy. Retrieved August 4, 2017.
- Henry George Liddell and Robert Scott, A Greek-English Lexicon, The National Science Foundation. Retrieved August 4, 2017.
- Fred Espenak, Glossary of Solar Eclipse Terms, NASA. Retrieved August 4, 2017.
- Robin M. Green, Spherical Astronomy (Oxford: Oxford University Press, 1985, ISBN 0521317797).
- Fred Espenak, Eclipses and the Saros, NASA. Retrieved August 4, 2017.
- T. de Jong and W.H. van Soldt, The earliest known solar eclipse record redated, Nature, 338:238–240. Retrieved August 4, 2017.
- Paul Griffin, Confirmation of World's Oldest Solar Eclipse Recorded in Stone, The Digital Universe. Retrieved August 4, 2017.
- Bibliotheca Alexandria, Solar Eclipses in History and Mythology. Retrieved August 4, 2017.
- Matt Williams, What is a Total Eclipse? Universe Today, September 27, 2016. Retrieved August 4, 2017.
- Fred Espenak, Planetary Transits Across the Sun, NASA. Retrieved August 4, 2017.
- Norman Davidson, Astronomy and the Imagination: A New Approach to Man's Experience of the Stars (London: Routledge, 1985, ISBN 0710203713).
- JPL Solar Systems Simulator, Start eclipse of the Sun by Callisto from the center of Jupiter. Retrieved August 4, 2017.
- JPL Solar Systems Simulator, Eclipse of the Sun by Titan from the center of Saturn. Retrieved August 4, 2017.
- JPL Solar Systems Simulator, Brief Eclipse of the Sun by Miranda from the center of Uranus. Retrieved August 4, 2017.
- JPL Solar Systems Simulator, Transit of the Sun by Nereid from the center of Neptune. Retrieved August 4, 2017.
- Math Pages, Roemer's Hypothesis. Retrieved August 4, 2017.
- Giovanni D. Cassini, Monsieur Cassini His New and Exact Tables for the Eclipses of the First Satellite of Jupiter, Reduced to the Julian Stile, and Meridian of London, Philosophical Transactions. 18: 237–256. Retrieved August 4, 2017.
- M.W. Buie and K.S. Polk, Polarization of the Pluto-Charon System During a Satellite Eclipse, Bulletin of the American Astronomical Society, 20:806. Retrieved August 4, 2017.
- D.J. Tholen, et al., Improved Orbital and Physical Parameters for the Pluto-Charon System, Science. 237(4814): 512–514. Retrieved August 4, 2017.
- Dan Bruton, Eclipsing binary stars, Midnightkite Solutions. Retrieved August 4, 2017.
- Glenn Chaple, Beta Persei (Algol, the "Demon Star") Skyscrapers, Inc., November, 2009. Retrieved August 4, 2017.
- John Goodricke, Observations of a New Variable Star, Philosophical Transactions of the Royal Society of London. 75: 153–164. Retrieved August 4, 2017.
- Davidson, Norman. Astronomy and the Imagination: A New Approach to Man's Experience of the Stars. London: Routledge, 1985. ISBN 0710203713.
- Espenek, Fred. NASA Eclipse Web site. NASA. Retrieved August 4, 2017.
- Green, Robin M. Spherical Astronomy. Oxford: Oxford University Press, 1985. ISBN 0521317797.
- Littmann, Mark, Fred Espenak, and Ken Willcox. Totality: Eclipses of the Sun. New York: Oxford University Press, 2008. ISBN 0199532095.
All links retrieved August 4, 2017.
- A Catalogue of Eclipse Cycles.
- Search 5,000 years of eclipses (notice: loads slowly).
- International Astronomical Union's Working Group on Solar Eclipses.
- Mark's eclipse chasing website.
- Interactive eclipse maps site.
- Dan McGlaun's Total Eclipse web site.
- May 18, 1920 5:22-5:33 eclipse John Paul II.
- Solar and Lunar Eclipse Image Gallery.
- Williams College eclipse collection of images.
- Prof. Druckmüller's eclipse photography site.
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December 7th, 2017
Engineers at the University of Bern are developing the CHEOPS space telescope. From Earth´s orbit, this telescope is supposed to measure the diameter of exoplanets which are light-years away from us and pass in front of their host star. Swiss astronomers had the idea for CHEOPS back in 2008. [caption id="attachment_8349" align="alignright" width="700"]1 Testing CHEOPS in the thermal vacuum chamber at the University of Bern. (Photo UniBern)[/caption] Willy Benz, professor at the Physics Institute at the University of Bern, actually wanted to travel during a semester-long sabbatical in 2008. Instead of spending this sabbatical at foreign universities, the astrophysicist sat at his desk at home and worked on a research proposal. The Swiss National Science Foundation had announced that they would be appointing new National Centres of Competence in Research (NCCR) and Willy Benz wanted to submit a proposal for planetary research together with his colleague in Geneva, Didier Queloz. In 1995 the former doctoral student Queloz and his supervising professor Michel Mayor discovered the first exoplanet orbiting a sun-like star. Benz also received his doctorate from Mayor at the University of Geneva nine years earlier. Already in 2000, Benz submitted a proposal for a National Centre of Competence in Research on exoplanetary research to the National Science Foundation, but his proposal was rejected. “That's science fiction, they told me in an interview back then," recalls the astrophysicist. In the year 2000, dozens of exoplanets had already been identified, in 2008 there were 300, today there are more than 3,000. The first of these distant planets orbiting sun-like stars were discovered by astronomers who were able to demonstrate that the host stars move periodically towards and away from us because both star and planet rotate around their common centre of mass under the influence of gravity. This technique is called the radial velocity method. It works well with bright stars (at least 11 mag) and provides measurements to calculate the mass of the planet. Soon astronomers also used a second method: If a planet passes directly in front of its star, it causes a kind of mini-eclipse; the brightness of the star periodically decreases by a tiny fraction. Thanks to these so-called transits, the diameter of the planet can be determined. The French satellite COROT, which was launched in 2006, and later NASA's Kepler mission, used the transit method with great success. Progress thanks to new instruments “In the field of astrophysics today, progress is mostly made thanks to new instruments," explains Benz. "When we worked on our second NCCR proposal in 2008, we wanted to propose not only scientific research projects but also the construction of hardware, including a Swiss exoplanetary satellite." This satellite was supposed to be unique because of a new observation strategy. “Transit measurement is a great method," explains the expert, “but, unfortunately, it has almost only identified planets whose stars are not very bright.” Their average magnitude is only 14 to 15. The explanation for this is that only a very small percentage of the stars are orbited by planets whose orbits lie exactly in our line of sight. If you really want to discover transits, you have to target a large number of stars. COROT and Kepler targeted about 100,000, but this was only possible because the satellites were limited to a narrow region. The bright stars, however, are spread all over the sky. “At the time, we thought it would be possible to build a small satellite that would not focus on a narrow area, but would observe bright stars everywhere in the sky, stars that are already known to possess a planet because of the radial velocity method," Benz explains. The combination of the two detection methods is particularly interesting. If the mass is known on the basis of the radial velocity and the diameter of a planet is known due to the transit, its density can be calculated. “We then know whether the planet is mainly composed of rock or gas," says Benz - a particularly important result in the context of the search for Earth-like planets. [caption id="attachment_8350" align="alignleft" width="600"]2 Professor Willy Benz with a 1:2 scale model of CHEOPS. (Photo Alessandro Della Bella)[/caption] In 2009, Benz and Queloz submitted their applications for a National Centre of Competence in Research, including a feasibility study for a space telescope. When searching for the name of the satellite, the astrophysicists knew that "CH" for Switzerland would come at the beginning and that the abbreviation should be catchy. This is how they came up with "CH ExOPlanet Satellite" or CHEOPS for short. The application for planetary research was one of 13 projects that the National Science Foundation rated as excellent with a grade of A. “Unfortunately, the project was not chosen in the end," Benz says, "I was very disappointed, having sacrificed my entire sabbatical.” Persistence pays off The astrophysicist did not give up and was later able to negotiate with the rector of the University of Berne and the State Secretary for Education and Research on how the dream of a Swiss satellite could still be pursued. As a result of his persistence, the federal government and RUAG financed the feasibility report as industrial representatives, and the University of Bern founded the "Center for Space and Habitability" (CSH). “In the feasibility report, we quickly realized that the satellite project alone would be too expensive for Switzerland," Benz says. Sweden and Austria, where RUAG operated its branches, were the first European partners, and others soon followed. While the Swiss were still working on the CHEOPS feasibility study, the European Space Agency (ESA) was discussing the possibility of a new satellite programme. In addition to the existing large and medium-sized (L- and M-class) missions, the smaller ESA member states in particular wanted to launch an S-class mission. The development time for these missions should not exceed four years and the cost should not exceed a prescribed limit set by ESA. The ESA Member States agreed on an experiment and issued a first S-mission call in March 2012. As chairman of the scientific committee advising ESA, Benz was well informed about the discussions and decisions of the ESA delegates - and was prepared to participate in the call for proposals with the CHEOPS study. While most of the others had only three months to work out their proposals, the Swiss could rely on the extensive preparatory work done in the feasibility study and benefit from Benz's ‘insider’ knowledge. "I knew the objections and doubts that some ESA delegates had previously put forward, and I made sure that we went in the right direction in our proposal and, for example, prevented cost explosions.” Although they originally wanted to use CHEOPS to observe the transits in two different wavelengths, they decided against an infrared instrument for cost reasons. [caption id="attachment_8351" align="alignright" width="700"]3 The CHEOPS team at the University of Bern assembles the flight model in the clean room. (Photo PlanetS)[/caption] No holiday plans In June 2012, Benz submitted the proposal for the CHEOPS mission, now called ‘CHaracterizing ExOPlanets Satellite’. It was one of 26 proposed projects submitted. When the ESA Scientific Panel met in Madrid in October 2012 to select the winner, Chairman Benz stayed away from the conference because of his conflict of interest and waited in his Bern office for a call from the committee's secretary. "I remember his first sentence very well," Benz says. “He said, ‘you shouldn’t make any plans for holidays in the next four years’." CHEOPS started as a joint project between Switzerland and ESA. The University of Bern is responsible for the construction of the space telescope and heads the consortium of 11 ESA member states participating in the mission. The satellite platform will be built in Spain. The mission's operations centre is also located there, while the research centre is being set up at the University of Geneva. The launch is scheduled for the end of 2018 with a Soyuz rocket from Kourou. ESA will bear half of the total costs of around 100 million Euros. Switzerland will contribute around 30 million Euros, while the other partners involved will contribute the remainder of the finances needed for this undertaking. “Although we were not selected by the National Science Foundation in 2009, everything worked out very nicely in the end,” concludes Benz. "Despite the additional stress and a lot of work, we were able to start our projects and are now close to the launch!" In addition, The National Research Centre was also awarded to the planetary scientists on their third attempt. In June 2014, Willy Benz and co-director Stéphane Udry, professor at the University of Geneva, launched the NCCR PlanetS, in which the ETH Zurich and ETH Lausanne, as well as the University of Zurich are also involved. “This shows that you should never give up," says Willy Benz. (bva) For more information please visit http://cheops.unibe.ch This article was published in the magazin ORION of the Swiss Astronomical Society, August 2017. | 0.81208 | 3.580045 |
Hera – named after the Greek goddess of marriage – will be humankind’s first probe to rendezvous with a binary asteroid system, a little understood class making up around 15% of all known asteroids.
Hera is the European contribution to an international double-spacecraft collaboration. NASA will first perform a kinetic impact on the smaller of the two bodies, then Hera will follow-up with a detailed post-impact survey that will turn this grand-scale experiment into a well-understood and repeatable planetary defence technique.
While doing so, Hera will also demonstrate multiple novel technologies, such as autonomous navigation around the asteroid – like modern driverless cars on Earth, and gather crucial scientific data, to help scientists and future mission planners better understand asteroid compositions and structures.
Due to launch in 2024, Hera would travel to a binary asteroid system – the Didymos pair of near-Earth asteroids. The 780 m-diameter mountain-sized main body is orbited by a 160 m moon, informally called ‘Didymoon’, about the same size as the Great Pyramid of Giza.
This smaller body is Hera’s focus: the spacecraft would perform high-resolution visual, laser and radio science mapping of the moon, which will be the smallest asteroid visited so far, to build detailed maps of its surface and interior structure.
By the time Hera reaches Didymos, in 2026, Didymoon will have achieved historic significance: the first object in the Solar System to have its orbit shifted by human effort in a measurable way.
The NASA mission called the Double Asteroid Redirection Test, or DART, is due to collide with it in 2022. The impact will lead to a change in the duration of Didymoon’s orbit around the main body. But ground observatories will be watching from a minimum distance of 10 million km, and the immediate aftermath may well be hidden by an expected dust cloud. The observatories’ measurements of Didymoon’s altered orbit are expected to be stuck with a 10% residual uncertainty and the actual transferred momentum – that is, by how much was it deflected? – will not be measured directly, missing a vital piece of information: the mass of Didymoon and the crater shape.
By actually venturing to Didymoon, measuring its mass as well as its shifted orbit from up close and performing its own ‘crash scene investigation’ of the asteroid moon’s impact crater and surrounding surface in great detail, Hera will hone our understanding of this grand-scale space experiment. Its data will allow, for the first time, the validation or refinement of numerical models of the impact process at asteroid scale, rendering this deflection technique for planetary defence ready for operational use if ever needed to safeguard our home world, Earth.
DART and Hera were conceived together as part of the international ‘Asteroid Impact Deflection Assessment’ experiment. The two missions are valuable individually, but if flown in concert their overall scientific and technological return is significantly boosted. They will contribute to the important and positive message that international cooperation is key for the achievement of a planetary defence initiative.
Hera, a further optimisation of ESA’s earlier Asteroid Impact Mission, is currently in Phase B1 of mission development in preparation to the Agency’s Space19+ Council of Ministers at European Level in November 2019. | 0.839563 | 3.856214 |
Neomi Lewis ‘21
The glaring image of the Milky Way is the rotating galaxy that usually comes to mind when individuals think about outer space. However, this typical image is no longer useful in studying bodies within the galaxy. Images of the Milky Way captured in visible light are obscured by dust and clouds. To remedy the situation, astronomers have used a 45 m radio telescope at the Nobeyama Radio Observatory to create the largest survey of the Milky Way to date.
The group worked for 1,100 hours from 2014 to 2017 to create an area as wide as 520 full moons with about three times the spatial resolution of previous maps. This is particularly difficult because good spatial resolution and wide-framed telescopes are generally mutually exclusive characteristics. Before maps like Nobeyama’s, it has been difficult to capture large-scale and small-scale data at the same time, leaving astronomers the task of filling in the gaps.
A map of this scale definitely gives astronomers insight into the larger structure of the Milky Way, including objects that we have little information about. At the same time, the telescope was able to obtain data on 3 different isotopes of carbon monoxide: 12CO, 13CO, and 18CO, which included details about the physical characteristics of the gas, such as temperature and density, as well as the distribution of the molecular gas and its motions. Studies of molecule gases like CO and molecular cloud cores provide further insight into star formation and the evolution of gases during processes like the birth of stars. Other analysis of data from galactic longitudes from 12 to 22 degrees led to the uncovering of giant molecular filaments, many of which were found around star-forming regions such as M17 and W51, suggesting an important role in star formation also.
The radio map obtained from this endeavor will be released in June 2018. The map will provide valuable data for future studies of the Milky Way and act as a road map for other radio telescope and related objects perhaps even ultimately also for observations in infrared and other wavelengths, leading possibly to a variety of diverse, unique maps of the Milky Way in the future.
- The most detailed radio map of the milky way. Phys.org, (2018).
- Image retrieved from: https://commons.wikimedia.org/wiki/File:The_Milky_Way_and_Andromeda_Galaxies.jpg | 0.83641 | 3.6895 |
[On June 15, NASA’s Swift caught the onset of a rare X-ray outburst from a stellar-mass black hole in the binary system V404 Cygni. Astronomers around the world are watching the event. In this system, a stream of gas from a star much like the sun flows toward a 10 solar mass black hole. Instead of spiraling toward the black hole, the gas accumulates for decades in an accretion disk around it. Every couple of decades, the disk switches into a state that sends the gas rushing inward, starting a new outburst. Credit: NASA’s Goddard Space Flight Center]
A black hole that has been quiet since 1989 has been caught burping.
A NASA satellite monitored and controlled by Penn State University detected a black hole erupting high-energy flares called an X-ray nova from a black hole 8,000 light-years away from Earth in a system named V404 Cygni. This black hole has been known to burp up once in a while, but it had been dormant since 1989. Until NASA’s Swift Gamma-ray Burst Explorer caught it belching again on June 15.
This system is in the constellation Cygnus. V404 Cygni has a star slightly smaller than the Sun orbiting a black hole 10 times its mass in 6.5 days. Astronomers classify this system as a low-mass X-ray binary. The tight orbit and strong gravity of the black hole pulls a stream of gas from its companion star. The gas travels to a storage disk around the black hole and heats up to millions of degrees. When this super hot gas falls inward into the black hole, it produces a stream of X-rays causing the flares.
Relative to the lifetime of space observatories, these black-hole eruptions are quite rare,” said Neil Gehrels, Swift’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “So when we see one of them flare up, we try to throw everything we have at it, monitoring across the spectrum, from radio waves to gamma rays.”
V404 Cygni has flared many times since the eruption began. “It repeatedly becomes the brightest object in the X-ray sky — up to 50 times brighter than the Crab Nebula, which is normally one of the brightest sources,” said Erik Kuulkers, the INTEGRAL project scientist at ESA’s European Space Astronomy Centre in Madrid. “It is definitely a ‘once in a professional lifetime’ opportunity.” | 0.893911 | 3.889895 |
No one was necessarily counting on the objects around KIC 8462852 being alien megastructures, but a handful of researchers weren't necessarily ruling it out. Or, at the very least, the SETI Institute and SETI Berkeley were taking a look, just in case. But the most prevailing idea was that it was either a swarm of comets or a swarm of asteroids.
Now, it seems all-but-certain that it's just comets, as published in the Astrophysical Journal Letters. SETI's search turned up no strange radio signals, all but ruling out the alien megastructures, and the absence of infrared signatures from solar energy striking an asteroid seemed to rule out that hypothesis. That lack of infrared leaves out asteroids, dwarf planets, and other similar objects, meaning that the star is likely swarmed with icy comets.
Here's how the whole thing started: KIC 8462852 was discovered by Kepler, a space telescope which spots "transit events" of stars. That is to say, when something passes in front of a star and causes just enough of a blip of light to indicate an object passing across the surface from the point of view of an observer. Most of the time, this is planets, blocking out a small fraction of the light of a star. Even the largest planets, those Jupiter size or larger, only block out a small amount of their star's light, something on the order of 1 percent.
So astronomers and amateur planet hunters (people who sift through Kepler data) were perplexed when KIC 8462852 had something blocking out 22 percent of its light. The leading candidate was some sort of cosmic catastrophe that sent in a swarm of comets, dwarf planets, asteroids, or other small stellar objects in a tight orbit around the star.
But SETI was intrigued enough to say, "This is probably not, but maybe, just maybe, could be giant solar power plants orbiting in space, feasting on the energy from the star to power a huge civilization." Despite the line of work seeming a little unusual, SETI researchers are still scientists, through and through, who work with studying unusual hypotheses for stellar events and signals that may indicate intelligent life. They didn't go in thinking they'd find it – the weird transits just seemed to line up with what you might see if there were a "Dyson swarm" around the star.
But there were no weird radio waves. There wasn't enough heat for larger, rocky objects. It's just comets or some similar swarm of icy bodies. Which is intriguing enough, as we've never seen a massive swarm of comets or cometary debris act like this, meaning something flung it in. But, unfortunately, that was probably a planet or a passing star.
Or aliens. Comet flinging aliens. | 0.940666 | 3.807795 |
Mystery Plumes: Did the Sun Bruise Mars?
Strange plumes have been spotted high in the Martian atmosphere that have, so far, defied explanation. Now scientists think space weather is to blame.
In recent years, the Red Planet has been doing something quite weird and scientist are stumped.
On a handful of occasions bizarre "plumes" have been observed protruding from Mars' upper atmosphere. A 2012 event was spotted by amateur astronomers and the phenomenon persisted for several days. Even the Hubble Space Telescope has been witness to a plume.
At first it was assumed some form of high-altitude cloud may be to blame, or maybe a storm kicked up dust into the upper atmosphere. But each hypothesis had its flaws and planetary scientists were left confused.
Now, European Space Agency scientists heading the Mars Express mission have studied this Martian oddity and found pretty strong evidence that the plumes aren't produced by the planet's weather; they're likely sparked by space weather.
Interactions between the sun and planetary environments are well known. As highly energized particles from the solar wind hit Earth's global magnetic field, for example, they can get trapped in the magnetosphere and funneled to high latitude regions. This influx of solar wind ions will collide with high-altitude atmospheric gases, causing them to glow, creating auroras. Where ever there's a magnetic field and an atmosphere, the sun can kick off a dazzling lightshow and we've seen auroras throughout the solar system, including Jupiter, Saturn and even Venus.
But solar interactions are not limited to auroras. When Earth is hit by coronal mass ejections - basically bubbles of magnetized plasma ejected from the sun's lower atmosphere - the entire planet's magnetic configuration can feel its effects, setting up powerful electrical currents through the atmosphere and energizing our ionosphere.
Mars, however, does not possess a global magnetic field to deflect the worst the sun can throw at it. When a CME hits Earth, the magnetosphere protects the atmosphere, but on Mars, lacking this magnetic shield, it suffers atmospheric erosion. Though it is thought Mars once had a thicker atmosphere, over billions of years, the constant flow of solar wind particles have stripped it away. Mars' atmosphere is, literally, leaking into space.
If space weather has such a powerful influence on Mars' atmospher loss, could it also be to blame for these odd plumes? Mars Express scientists have turned to their veteran Mars orbiter for answers.
The 2012 Mars plume made world headlines and Mars Express was there collecting data of the local space environment. Did a space weather event occur around the time the plume was observed?
"Our plasma observations tell us that there was a space weather event large enough to impact Mars and increase the escape of plasma from the planet's atmosphere," said David Andrews of the Swedish Institute of Space Physics in an ESA news release. "But we were not able to see any signatures in the ionosphere that we can categorically say were due to the presence of this plume."
There is circumstantial evidence that Mars' ionosphere - an upper layer of the atmosphere filled with charged particles, or ions - was in some way influenced by a space weather event, such as the impact of a CME. But because of the plume's location, it is a challenge acquire additional observations of the event, so just because there is some evidence a CME-triggered event is at play, it's circumstantial at best.
Now scientists are looking over archival data in the hope of finding occasions when a plume occurred during a CME hit. In 1997, for example, a Mars plume was spotted by Hubble and at around the same time, a fast CME was recorded as hitting Earth. Unfortunately there was no information from any Mars mission as to how that CME impacted the Red Planet's atmosphere, if it affected it at all.
"The jury is still out as to what physics is at play here, but given the altitude of the plume, we think that plasma interactions must be important," said Andrews. "One idea is that a fast-travelling CME causes a significant perturbation in the ionosphere resulting in dust and ice grains residing at high altitudes in the upper atmosphere being pushed around by the ionospheric plasma and magnetic fields, and then lofted to even higher altitudes by electrical charging."
This, argues Andrews, could produce an obvious plume in the upper atmosphere that can be seen from Earth. It's basically an atmospheric bruise cased by CME impact. But like all good mysteries, more data is needed, but it looks like we may finally be closing in on a possible explanation for these bizarre Martian plumes.
The realism of "The Martian" is getting the attention of NASA -- and not only because of what fictional NASA astronaut Mark Watney (Matt Damon) does on the surface. The agency has released several photographs showing real-life locations related to Watney's journey as he tries to get home to Earth. Also, the European Space Agency put out a map showing where Watney moved around on the surface (which we have put last in case you are worried about any spoilers.) Read on to see some of the places Watney had to think about when surviving on Mars.
Watney's journey begins in Acidalia Planitia, the landing site for his mission (Ares 3). Inside the crater you can see deposits that were blown there by the wind. Think about it -- as Watney and his crew moved around the crater, every place they went to, they were the first to put bootprints in that sand. The University of Arizona's HiRISE camera aboard the Mars Reconnaissance Orbiter helped gather data for this picture. "We can’t see the Ares 3 habitat because it arrives sometime in the future, so this is the 'before' image,"
earlier this year.
While we think of Mars as a place devoid of humans, we've sent several landing missions over the years. It turns out that Ares 3 is not so far away from the landing site of
and its rover, Sojourner -- the first rover to explore Mars in 1997. This image shows portions of the craft after it was deployed, such as the airbags and possibly parts of the heat shield. Since Pathfinder, NASA has sent three more rovers to the surface:
(2012). Opportunity and Curiosity are still working on the surface. The European Space Agency plans to send its first rover to Mars as part of the
As the name "Ares 3" implies, the Ares program is just one of a series of missions to Mars. Ares 4 is the next one, targeting a famous crater on the Martian surface: Schiaparelli Crater. Nearly 300 miles (500 kilometers) across, it's hard to get the entire thing into one high-resolution image, so this is just a portion of it taken with HiRISE. According to NASA, the agency has
like this for two reasons: the dust gets very warm during the day and cold at night (hard on equipment) and it's hard to know if there's anything interesting geologically in the bedrock underneath.
Here's a challenge about moving around on Mars: it's really hard to judge distance, because there are no familiar human markings to help us find our way around. Astronauts faced this challenge on the moon, and as Watney uses his rover on the surface, he has to be similarly careful not to go in the wrong direction or overstretch his rover's battery. Mawrth Crater is one of the landmarks Watney plots. "The crater rim is not very distinct, and from the Martian surface it would be quite difficult to tell that you are even on the rim of a crater,"
The Opportunity rover (which landed in 2004) is somewhat close to where Watney is moving around. It's possible that Watney draws inspiration from the plucky machine, which is still working well on Mars long past its original 90-Martian-day expiry date. Among Opportunity's major milestones: driving
finding extensive evidence of water around its landing site and beyond, and
While we initially could imagine craters as simple excavations of the surface, the Martian weather makes them far more complex than that. This is a
, somewhat near where Watney was moving on the surface. These thick deposits would be made either by water (in the ancient past, when Mars was wetter) or wind, based on what we know of similar processes on Earth. You don't see a lot of craters here because the deposits are so thin that the wind can easily erase any craters in the surface.
Here you can see Watney's journey across the surface of Mars, as mapped by the European Space Agency (and German Space Agency, DLR) based on imagery from the Mars Express spacecraft. The colors represent different heights of features on the Martian surface, with blue being lowest and red being highest. You can see how Watney had to carefully make his way between craters to reach his destination, the Ares 4 landing site. | 0.86661 | 3.853284 |
The New Moon marks the beginning of a tidal month, and it’s an unassuming start at that – because the moon is directly between the sun and earth, sunlight is on the face we can’t see so it appears completely invisible in the sky. The New Moon can even hide the sun, but for this to happen there must be a rare synchronisation of orbits where the sun appears especially small and the moon exceptionally large. This is the famous solar eclipse, but less known is the accompanying ‘Perigean Spring Tide’, named because it only happens when the moon is at Perigee [the closest point to earth on its elliptical orbit]. This makes the New Moon appear large enough to block out the sun, and the increased gravitational pull creates exceptionally powerful tides.
Although Perigean Spring Tides are rare, the standard Spring Tide is much more common. Contrary to popular belief, springs don’t only happen in spring. Instead, we experience them every fortnight when the sun, moon and earth are aligned at the Full Moon and New Moon. The effect is higher highs and lower lows than the weeks either side, and this is because the gravitational pulls from the sun and moon are working together. On these days the transformation of our coastlines every six hours is awe-inspiring, but even more so is the phenomena that creates this change; a set of long-period waves flowing along our shores with high tide at their peaks and low tide at their troughs. If magic seaweed were to summarise the tide wave of my local beach in Kent during the New Moon it would be 36ft@6hrs, much more fearsome than the 3ft@6secs we get in the winter after a good blow.
These enormous tide waves power currents racing along the coast and they have a massive effect on anyone swimming, sailing, paddleboarding, scuba diving – literally every activity. To understand the connection between the waves and currents, think of the phenomena of water draining from a beach just before a tsunami. This is the trough of the tidal wave, and all the water is being sucked towards the peak – when it arrives, the water then surges towards the shore. Now take this concept but change a tidal wave into a tide wave, spin it 90 degrees so instead of the wave heading towards the shore it’s running along it, and you’ll understand how tidal currents work. Following this theory, if you’re on Britain’s east coast [where the tide wave travels south] at low tide you’ll be sucked north, and at high tide you’ll be pushed south with the peak of the wave. In essence, you’ll be riding the tide wave.
On an open coast at Spring Tides, the fastest currents might flow around 4 knots, so it takes a little imagination to truly ride the wave. However, in some places the powerful tides at New Moon can create intense surfing waves. And unlike beach waves that are over in seconds, these waves can be ridden for hours at a time. A perfect example is The Bitches in Wales, not named because of the bitchin’ rides but because that’s what the reef they break on is called. When the tide is rising, it pours over the reef and the tidal currents flow down a series of ramps, rising into standing waves that stay in one place while the water flows through at 10 knots [accelerated by the construction in the coastline around St Davids, Pembrokeshire]. At the New Moon this is not an environment for beginners, and even experienced surfers should wear helmets and buoyancy aids because when you come off the wave you’ll be catapulted into a cacophony of whitewater, with a few whirlpools thrown in for good measure.
The best feature of tide waves is that they appear like clockwork, directly synchronised with the moon phase. At every New Moon, the peak of the tide wave will pass your beach at the same time – in Lands End it’s around 6am/6pm and where I live in Deal high tide is around 12am/12pm [this is because it takes 6 hours for the wave to travel up the English Channel from Lands End to Deal]. It will then be 50 minutes later every day, a result of the simultaneous orbit of the moon as the earth rotates. The effect is that a week after New Moon tides are 6 hours later, two weeks after they are 12 hours later, three weeks after they are 18 hours later and a month after they are 24 hours later. Because New Moon happens once a month, this explains how tides essentially ‘reset’ themselves. Using this knowledge, and an understanding of the tide waves around the world, you could predict the tide anywhere on the planet, any day, by simply observing how many days after New Moon it is. And to do that, all you need to do is look at which side of the moon is illuminated, and how much.
Next week is the First Quarter moon phase with the right side lit up, and William will explore the effects this will have on our saltwater adventures. For more tidal information, visit tidalcompass.com or follow Tidal Compass on Instagram. | 0.878095 | 3.809766 |
Study resolves discrepancy in Greenland temperatures during end of last ice age
A new study of three ice cores from Greenland documents the warming of the large ice sheet at the end of the last ice age – resolving a long-standing paradox over when that warming occurred.
Large ice sheets covered North America and northern Europe some 20,000 years ago during the coldest part of the ice age, when global average temperatures were about four degrees Celsius (or seven degrees Fahrenheit) colder than during pre-industrial times. And then changes in the Earth’s orbit around the sun increased the solar energy reaching Greenland. Beginning some 18,000 years ago, release of carbon from the deep ocean led to a graduate rise in atmospheric carbon dioxide (CO2).
Yet past analysis of ice cores from Greenland did not show any warming response as would be expected from an increase in CO2 and solar energy flux, the researchers note.
In this new study, funded by the National Science Foundation and published this week in the journal Science, scientists reconstructed air temperatures by examining ratios of nitrogen isotopes in air trapped within the ice instead of isotopes in the ice itself, which had been used in past studies.
Not only did the new analysis detect significant warming in response to increasing atmospheric CO2, it documents a warming trend at a rate closely matching what climate change models predict should have happened as the Earth shifted out of its ice age, according to lead author Christo Buizert, a postdoctoral researcher at Oregon State University and lead author on the Science article.
“The Greenland isotope records from the ice itself suggest that temperatures 12,000 years ago during the so-called Younger Dryas period near the end of the ice age were virtually the same in Greenland as they were 18,000 years ago when much of the northern hemisphere was still covered in ice,” Buizert said. “That never made much sense because between 18,000 and 12,000 years ago atmospheric CO2 levels rose quite a bit.”
“But when you reconstruct the temperature history using nitrogen isotope ratios as a proxy for temperature, you get a much different picture,” Buizert pointed out. “The nitrogen-based temperature record shows that by 12,000 years ago, Greenland temperatures had already warmed by about five degrees (Celsius), very close to what climate models predict should have happened, given the conditions.”
Reconstructing temperatures by using water isotopes provides useful information about when temperatures shift but can be difficult to calibrate because of changes in the water cycle, according to Edward Brook, an Oregon State paleoclimatologist and co-author on the Science study.
“The water isotopes are delivered in Greenland through snowfall and during an ice age, snowfall patterns change,” Brook noted. “It may be that the presence of the giant ice sheet made snow more likely to fall in the summer instead of winter, which can account for the warmer-than-expected temperatures because the snow records the temperature at the time it fell.”
In addition to the gradual warming of five degrees (C) over a 6,000-year period beginning 18,000 years ago the study investigated two periods of abrupt warming and one period of abrupt cooling documented in the new ice cores. The researchers say their leading hypothesis is that all three episodes are tied to changes in the Atlantic meridional overturning circulation (AMOC), which brings warm water from the tropics into the high northern latitudes.
The first episode caused a jump in Greenland’s air temperatures of 10-15 degrees (C) in just a few decades beginning about 14,700 years ago. An apparent shutdown of the AMOC about 12,800 years ago caused an abrupt cooling of some 5-9 degrees (C), also over a matter of decades.
When the AMOC was reinvigorated again about 11,600 years ago, it caused a jump in temperatures of 8-, 11 degrees (C), which heralded the end of the ice age and the beginning of the climatically warm and stable Holocene period, which allowed human civilization to develop.
“For these extremely abrupt transitions, our data show a clear fingerprint of AMOC variations, which had not yet been established in the ice core studies,” noted Buizert, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Other evidence for AMOC changes exists in the marine sediment record and our work confirms those findings.”
In their study, the scientists examined three ice cores from Greenland and looked at the gases trapped inside the ice for changes in the isotopic ration of nitrogen, which is very sensitive to temperature change. They found that temperatures in northwest Greenland did not change nearly as much as those in southeastern Greenland – closest to the North Atlantic – clearly suggesting the influence of the AMOC.
“The last deglaciation is a natural example of global warming and climate change,” Buizert said. “It is very important to study this period because it can help us better understand the climate system and how sensitive the surface temperature is to atmospheric CO2.”
“The warming that we observed in Greenland at the end of the ice age had already been predicted correctly by climate models several years ago,” Buizert added. “This gives us more confidence that these models also predict future temperatures correctly.” | 0.806537 | 3.275248 |
Scientists have found exoplanets and protoplanets during their search for worlds beyond Earth, but here's a new first: A young planet still in the end stages of formation has been spotted by the Very Large Telescope in Chile. Best of all, it's been directly imaged – not discovered indirectly or inferred by seeing its star's light dip as the planet passes in front. The planet is believed to be between 1 and 10 million years old.
Located about 320 light years from Earth, the planet orbits star HD 100546. The existence of a companion planet for this star has long been suspected, but never confirmed until now. The star has a ring of gas and dust extending about 300 astronomical units out. In terms of our solar system, that would be far past the Kuiper Belt (where Pluto, Eris, and other dwarf planets reside) and the scattered disc, into the area full of detached objects (but not quite to the Oort Cloud.)
HD 100546b is far larger than Jupiter, and orbits its host star at about 68 AU. The giant planet is shown to be still gathering dust. The National Centre of Competence in Research Planets scientists who confirmed the planet suggest there's a second planetary candidate at around 13 AU, also believed to be a gas giant. The results were published in The Astrophysical Journal. | 0.876039 | 3.165438 |
The surface of Jupiter’s moon Europa features a widely varied landscape, including ridges, bands, small rounded domes and disrupted spaces that geologists call “chaos terrain.” Three newly reprocessed images, taken by NASA’s Galileo spacecraft in the late 1990s, reveal details in diverse surface features on Europa.
Although the data captured by Galileo is more than two decades old, scientists are using modern image processing techniques to create new views of the moon’s surface in preparation for the arrival of the Europa Clipper spacecraft. The orbiter of Jupiter will conduct dozens of flybys of Europa to learn more about the ocean beneath the moon’s thick icy crust and how it interacts with the surface. The mission, set to launch in the next several years, will be the first return to Europa since Galileo.
Planetary scientists study high-resolution images of Europa for clues about how the surface formed. At an average of 40 million to 90 million years old, the surface we see today is much younger than Europa itself, which formed along with the solar system 4.6 billion years ago. In fact, Europa has among the youngest surfaces in the solar system, one of its many intriguing oddities. | 0.859363 | 3.338912 |
Precise measurement using a continent-wide collection of National Science Foundation (NSF) radio telescopes has revealed that a narrow jet of particles moving at nearly the speed of light broke out into interstellar space after a pair of neutron stars merged in a galaxy 130 million light-years from Earth. The merger, which occurred in August of 2017, sent gravitational waves rippling through space. It was the first event ever to be detected both by gravitational waves and electromagnetic waves, including gamma rays, X-rays, visible light, and radio waves.
The aftermath of the merger, called GW170817, was observed by orbiting and ground-based telescopes around the world. Scientists watched as the characteristics of the received waves changed with time, and used the changes as clues to reveal the nature of the phenomena that followed the merger.
One question that stood out, even months after the merger, was whether or not the event had produced a narrow, fast-moving jet of material that made its way into interstellar space. That was important, because such jets are required to produce the type of gamma ray bursts that theorists had said should be caused by the merger of neutron-star pairs.
The answer came when astronomers used a combination of the NSF’s Very Long Baseline Array (VLBA), the Karl G. Jansky Very Large Array (VLA), and the Robert C. Byrd Green Bank Telescope (GBT) and discovered that a region of radio emission from the merger had moved, and the motion was so fast that only a jet could explain its speed.
“We measured an apparent motion that is four times faster than light. That illusion, called superluminal motion, results when the jet is pointed nearly toward Earth and the material in the jet is moving close to the speed of light,” said Kunal Mooley, of the National Radio Astronomy Observatory (NRAO) and Caltech.
The astronomers observed the object 75 days after the merger, then again 230 days after.
“Based on our analysis, this jet most likely is very narrow, at most 5 degrees wide, and was pointed only 20 degrees away from the Earth’s direction,” said Adam Deller, of the Swinburne University of Technology and formerly of the NRAO. “But to match our observations, the material in the jet also has to be blasting outwards at over 97 percent of the speed of light.” he added.
The scenario that emerged is that the initial merger of the two superdense neutron stars caused an explosion that propelled a spherical shell of debris outward. The neutron stars collapsed into a black hole whose powerful gravity began pulling material toward it. That material formed a rapidly-spinning disk that generated a pair of jets moving outward from its poles.
As the event unfolded, the question became whether the jets would break out of the shell of debris from the original explosion. Data from observations indicated that a jet had interacted with the debris, forming a broad “cocoon” of material expanding outward. Such a cocoon would expand more slowly than a jet.
“Our interpretation is that the cocoon dominated the radio emission until about 60 days after the merger, and at later times the emission was jet dominated,” said Ore Gottlieb, of the Tel Aviv University, a leading theorist on the study.
“We were lucky to be able to observe this event, because if the jet had been pointed much farther away from Earth, the radio emission would have been too faint for us to detect,” said Gregg Hallinan of Caltech.
The detection of a fast-moving jet in GW170817 greatly strengthens the connection between neutron star mergers and short-duration gamma-ray bursts, the scientists said. They added that the jets need to be pointed relatively closely toward the Earth for the gamma ray burst to be detected.
“Our study demonstrates that combining observations from the VLBA, the VLA and the GBT is a powerful means of studying the jets and physics associated with gravitational wave events,” Mooley said.
“The merger event was important for a number of reasons, and it continues to surprise astronomers with more information,” said Joe Pesce, NSF Program Director for NRAO. “Jets are enigmatic phenomena seen in a number of environments, and now these exquisite observations in the radio part of the electromagnetic spectrum are providing fascinating insight into them, helping us understand how they work.”
Mooley and his colleagues reported their findings in the September 5 online version of the journal Nature.
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. | 0.902695 | 4.1092 |
Pulsars in binary systems are affected by relativistic effects, causing the spin axes of each pulsar to change their direction with time. An MPIfR-led research team has used radio observations of the source PSR J1906+0746 to reconstruct the polarised emission over the pulsar’s magnetic pole and to predict the disappearance of the detectable emission by 2028. The experiment is the most challenging test to date of the important effect of relativistic spin precession for strongly self-gravitating bodies. The reconstructed radio beam shape has implications for the population of neutron stars and the expected rate of neutron star mergers as observed by gravitational wave detectors such as LIGO.
Pulsars are fast-spinning neutron stars that concentrate 40% more mass than the Sun – or more! – into a small sphere of only about 20 km diameter. They have extremely strong magnetic fields and emit a beam of radio waves along their magnetic axes above each of their opposite magnetic poles.
Due to their stable rotation, a lighthouse effect produces pulsed signals that arrive on Earth with the accuracy of an atomic clock. The large mass, the compactness of the source, and the clock-like properties allows astronomers to use them as laboratories to test Einstein’s theory of general relativity.
The theory predicts that spacetime is curved by massive bodies such as pulsars. One expected consequence is the effect of relativistic spin precession in binary pulsars. The effect arises from a misalignment of the spin vector of each pulsar with respect to the total angular momentum vector of the binary system, and is most likely caused by an asymmetric supernova explosion.
This precession causes the viewing geometry to vary, which can be tested observationally by monitoring systematic changes in the observed pulse profile.
Evidence for a variable pulse profile attributed to changes in the viewing geometry caused by spin precession have been observed and modelled in the Nobel-prize winning Hulse-Taylor binary pulsar B1913+16. Other binary pulsars also show the effect, but none of them has allowed studies at the precision and level of detail obtainable with PSR J1906+0746.
The target is a young pulsar with a spin period of 144 milliseconds in a 4-hour orbit around another neutron star in the direction of the constellation Aquila (the Eagle), pretty close to the plane of our Galaxy, the Milky Way.
“PSR J1906+0746 is a unique laboratory in which we can simultaneously constrain the radio pulsar emission physics and test Einstein’s theory of general relativity”, says Gregory Desvignes from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, the first author of the study.
The research team monitored the pulsar from 2012 to 2018 with the 305-m Arecibo radio telescope at a frequency of 1.4 GHz. Those observations were supplemented with archival data from the Nançay and Arecibo radio telescopes recorded between 2005 and 2009. In total, the available dataset comprises 47 epochs spanning from July 2005 to June 2018.
The team noticed that initially it was possible to observe the pulsar’s opposite magnetic poles, when both “Northern” and “Southern” beams (referred to as “main pulse” and “interpulse” in the study) were pointed to Earth once per rotation. With time, the Northern beam disappeared and only the Southern beam remained visible.
Based on a detailed study of the polarisation information of the received emission, it was possible to apply a 50-year old model, predicting that the polarisation properties encoded information about the geometry of the pulsar. The pulsar data validated the model and also allowed the team to measure the rate of precession with only 5% uncertainty level, tighter than the precession rate measurement in the Double Pulsar system, a reference system for such tests so far. The measured value agrees perfectly with the prediction of Einstein’s theory.
“Pulsars can provide tests of gravity that cannot be done in any other way”, adds Ingrid Stairs from the University of British Columbia in Vancouver, a co-author of the study. “This is one more beautiful example of such a test.”
Moreover, the team can predict the disappearance and reappearance of both, Northern and Southern beam of PSR J1906+0746. The Southern beam will disappear from the line of sight around 2028 and reappear between 2070 to 2090. The Northern beam should reappear around 2085–2105.
The 14-year-long experiment also provided exciting insight into the little-understood workings of pulsars themselves. The team realised that our Earth’s line of sight had crossed the magnetic pole in a North-South direction, allowing not only a map of the pulsar beam, but also a study of the conditions for radio emission right above the magnetic pole.
“ It is very gratifying that, after several decades, our line of sight is crossing a pulsar’s magnetic pole for the first time, demonstrating the validity of a model proposed in 1969”, explains Kejia Lee from the Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, another co-author of the paper. “In contrast, the beam shape is really irregular and unexpected.”
The beam map reveals the true extent of the pulsar beam which determines the portion of sky illuminated by the beam. This parameter affects the predicted number of the Galactic double neutron stars population and, hence, the expected gravitational wave detection rate for neutron star mergers.
“The experiment took us a long time to complete”, concludes Michael Kramer, director and head of MPIfR’s “Fundamental Physics in Radio Astronomy” research department. “These days, sadly, results have to be often quick and fast, whereas this pulsar teaches us so much. Being patient and diligent has really paid off.”
Authors of the original paper in “Science” are Gregory Desvignes, Michael Kramer, Kejia Lee, Joeri van Leeuwen, Ingrid Stairs, Axel Jessner, Ismaël Cognard, Laura Kasian, Andrew Lyne and Ben W. Stappers; authors from MPIfR include Gregory Desvignes, the first author, and also Michael Kramer and Axel Jessner.
Besides MPIfR, affiliations of the authors include the Laboratoire d'études spatiales et d'instrumentation en astrophysique, Observatoire de Paris, Université Paris-Sciences-et-Lettres, Centre National de la Recherche Scientifique, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France, the Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK, the Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of China, ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands, the Astronomical Institute Anton Pannekoek, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands, the Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada, the Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, Centre National de la Recherche Scientifique-Université d’Orléans, F-45071 Orléans, France, and the Station de radioastronomie de Nançay, Observatoire de Paris, Centre National de la Recherche Scientifique, Institut national des sciences de l’Univers, F-18330 Nançay, France.
Dr. Gregory Desvignes
Max-Planck-Institut für Radioastronomie, Bonn.
Fon: +33 1 4507-7101
Prof. Dr. Michael Kramer
Head of Research Department „Fundamental Physics in Radio Astronomy“
Max-Planck-Institut für Radioastronomie, Bonn.
Fon: +49 228 525-278
Gregory Desvignes et al.: Radio emission from a pulsar’s magnetic pole revealed by general relativity, in: Science, 6 September 2019 (Embargoed until 5 September 2019, 20:00 CEST / 14:00 US Eastern time).
https://www.sciencemag.org/ (after the embargo expires)
Requests for the original paper before the embargo expires:
+1-202-326-6440 or [email protected]
https://www.mpifr-bonn.mpg.de/4743618/desvignes-sep2019 (until the embargo expires)
https://www.mpifr-bonn.mpg.de/pressreleases/2019/7 (after the embargo expires)
Norbert Junkes | Max-Planck-Institut für Radioastronomie
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05.06.2020 | Life Sciences | 0.851354 | 4.079037 |
From: University of Hawaii
Posted: Tuesday, October 8, 2002
Astronomers at the University of Hawaii Institute for Astronomy (IfA) have been awarded a $3.4 million grant by the Air Force Research Laboratories to design a new observatory to survey the entire sky and detect very faint objects. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is currently conceived of as an array of small telescopes, and sites on either the Big Island or on Maui are being considered. Planned to become operational in 2006, Pan-STARRS will be more powerful for survey work than all existing telescopes combined. A major goal of the project is to identify and track asteroids that might collide with Earth.
Commenting on the project, IfA Director Rolf Kudritzki said, "I am pleased that the Institute will be able to play an important role in finding these hazardous asteroids that threaten humanity."
Exploiting recent advances in electronic detector technology, Pan-STARRS will have revolutionary optical sensors with billions of pixels, or picture elements. The IfA is collaborating with Lincoln Laboratories of the Massachusetts Institute of Technology (MIT) to develop the advanced detectors.
The telescopes will have a very large field of view, allowing them to image an area about 30-40 times that of the full moon in a single exposure. The system will rapidly survey large areas of the sky, making it uniquely powerful for detecting transient objects such as supernovae, and for detecting moving objects, such as asteroids.
Once operational, Pan-STARRS will generate huge quantities of data. To process these, the IfA astronomers have teamed up with the Maui High Performance Computer Center (MHPCC), and with Science Applications International Corporation (SAIC), a leader in the field of massive databases.
The huge database generated by Pan-STARRS will be made available over the Internet so that others may use it for education and research. Kudritzki commented that the Pan-STARRS database will be "a unique opportunity for education."
The currently favored design is an array of four relatively small telescopes. This would permit rapid construction, and would have a small environmental impact, because the system would be very compact. In fact, one possibility being explored is to house the system within the university's existing telescope building on Mauna Kea.
The IfA is working closely with the Office of Mauna Kea Management, and in accord with the design review process set out in the Mauna Kea Science Reserve Master Plan, to develop a design that minimizes environmental and cultural impacts.
The data from Pan-STARRS will be used to address many scientific questions, ranging from the origin of the Solar System to the properties of the Universe on the largest scales. However, a major goal of the project is to make an inventory of potentially dangerous asteroids.
It is now widely recognized that a collision with a large asteroid was responsible for the mass extinction of the dinosaurs 65 million years ago, and that more frequent collisions with smaller asteroids present a real hazard. Fatal asteroid collisions are rare, but when they happen they can be very destructive. In fact, experts have determined that, averaged over time, the risk of dying from an asteroid strike is approximately that of dying in a plane crash. A number of recent widely publicized close encounters with asteroids have highlighted the risk.
Congress has charged NASA to support searches for "killer asteroids." These surveys determine the orbits of the asteroids that they discover, and then project them forward to see if they will impact Earth. Pan-STARRS principal investigator Nick Kaiser comments that "current surveys have detected roughly half of the objects bigger than a mile in diameter. Impacts of this size cause global-scale catastrophes. Pan-STARRS will help complete this task and will extend the search to much smaller objects."
Images and relevant links are available at http://www.ifa.hawaii.edu/~kaiser/pan-starrs/pressrelease
The Institute for Astronomy at the University of Hawaii conducts research into galaxies, cosmology, stars, planets, and the Sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea. Refer to http://www.ifa.hawaii.edu/ for more information about the Institute.
// end // | 0.880799 | 3.024158 |
Binary pulsars are one of the few objects which allow physicists to test general relativity in the case of a strong gravitational field. Although the binary companion to the pulsar is usually difficult or impossible to observe, the timing of the pulses from the pulsar can be measured with extraordinary accuracy by radio telescopes. Binary pulsar timing has indirectly confirmed the existence of gravitational radiation and verified Einstein's general theory of relativity.
Relativity[change | change source]
Two objects orbiting do not do so in absolutely circular paths. the paths are virtually always elliptical. So twice a circuit they are closest, and twice a circuit they are furthest away. This is obvious for the Earth and Sun, but the idea applies much more widely.
When the two bodies are close, the gravitational field is stronger, and the passage of time is slowed. With pulsars, the time between pulses (or ticks) is lengthened. As the pulsar clock travels more slowly through the weakest part of the field it regains time. This is a relativistic time delay. It is the difference between what one would expect to see if the pulsar were moving at a constant distance and speed around its companion, and what is actually observed.
Binary pulsars are one of the few tools scientists have to detect evidence of gravitational waves. Einstein’s theory of general relativity predicts that two neutron stars would emit gravitational waves as they orbit a common center of mass, which would carry away orbital energy, and cause the two stars to draw closer together. As the two stellar bodies draw closer to one another, often one pulsar will absorb matter from the other, causing a violent accretion process. This interaction can heat the gas being exchanged between the bodies and produce X-ray light which can appear to pulsate, causing binary pulsars to occasionally be referred to as X-ray binaries. This flow of matter from one stellar body to another is known as an accretion disk. Millisecond pulsars (or MSP's) create a sort of "wind", which in the case of binary pulsars can blow away the magnetosphere of the neutron stars and have a dramatic effect on the pulse emission.
History[change | change source]
The first binary pulsar, PSR B1913+16 or the "Hulse-Taylor binary pulsar" was discovered in 1974 at Arecibo by Joseph Taylor and Russell Hulse, for which they won the 1993 Nobel Prize in Physics. Pulses from this system have been tracked, without glitches, to within 15 μs since its discovery.
The 1993 Nobel Prize was awarded to Joseph Taylor and Russell Hulse after they discovered two such stars. While Hulse was observing a new pulsar, named PSR B1913+16, he noticed that the frequency with which it pulsed fluctuated. It was concluded that the simplest explanation was that the pulsar was orbiting another star very closely at a high velocity. Hulse and Taylor determined that the stars were equally heavy by observing these pulse fluctuations, which led them to believe the other spacial object was also a neutron star.
The observations made of the orbital decay of this star system was a near perfect match to Einstein’s equations. Relativity predicts that over time a binary system’s orbital energy will be converted to gravitational radiation. Data collected by Taylor and his colleagues of the orbital period of PRS B1913+16 supported this relativistic prediction. They reported in 1983 that there was a difference in the observed minimum separation of the two pulsars compared to that expected if the orbital separation had remained constant. In the decade following its discovery the system’s orbital period had decreased by about 76 millionths of a second per year. This means the pulsar was approaching its maximum separation more than a second earlier than it would have if the orbit had remained the same. Subsequent observations continue to show this decrease.
References[change | change source]
- Weisberg J.M. Taylor J.H. and Fowler L.A. 1981. Gravitational waves from an orbiting pulsar. Scientific American, October.
- periastron = period of shortest distance in orbit
- Weisberg J.M. & Taylor J.H. 2004. Relativistic binary pulsar B1913+16: thirty years of observations and analysis. | 0.80375 | 4.202039 |
After nearly 16 years of exploring the cosmos in infrared light, NASA's Spitzer Space Telescope will be switched off permanently on January 30, 2020. The news was confirmed by the Jet Propulsion Laboratory (JPL), which said the spacecraft, by then will have operated for more than 11 years beyond its prime mission.
Managed and operated by JPL, Spitzer is a small but transformational observatory. It captures infrared light, which is often emitted by "warm" objects that are not quite hot enough to radiate visible light.
Spitzer has lifted the veil on hidden objects in nearly every corner of the universe, from a new ring around Saturn to observations of some of the most distant galaxies known.
"It has spied stars in every stage of life, mapped our home galaxy, captured gorgeous images of nebulas and probed newly discovered planets orbiting distant stars," the statement said.
Lasting more than twice as long as the primary mission, Spitzer's extended mission has yielded some of the observatory's most transformational results, said JPL.
The telescope had revealed the presence of seven rocky planets around the TRAPPIST-1 star in 2017.
In many cases, Spitzer's exoplanet observations were combined with observations by other missions, including NASA's Kepler and Hubble space telescopes.
According to JPL, Spitzer's final year and a half of science operations include a number of exoplanet-related investigations. One programme will investigate 15 dwarf stars likely to host exoplanets.
An additional 650 hours are dedicated to follow-up observations of planets discovered by NASA's Transiting Exoplanet Survey Satellite, which launched just over a year ago.
"There have been times when the Spitzer mission could have ended in a way we didn't plan for," said Spitzer's mission manager Bolinda Kahr. "I'm glad that in January we'll be able to retire the spacecraft deliberately, the way we want to do it."
While Spitzer's mission is ending, it has helped set the stage for NASA's James Webb Space Telescope, set to launch in 2021, which will study the universe in many of the same wave-lengths observed by Spitzer. | 0.887133 | 3.232988 |
10 most difficult time riddlesTime quiz
What is the highest time zone?
Time zones range from UTC-12 to UTC+14. UTC+14 stretches as far as 30° east of the 180° longitude line and creates a large fold in the International Date Line. In Kiribati (UTC+14), the local time is the same as in Hawaiʻi (UTC−10:00), but the date is one day ahead. It is also 26 hours ahead of Baker Island (UTC−12:00).
What does not include, Unix time?
of leap years
of leap hours
of leap minutes
of leap seconds
Unix time is a date-time format used to express the number of milliseconds that have elapsed since January 1, 1970 00:00:00 (UTC). Unix time does not handle the extra seconds that occur on the extra day of leap years. Currently, the difference is about 2 to 3 milliseconds a day and is adjusted on average once a year.
In what period of time does the Sun make a full turn around the center of the Milky Way?
within every 225 million years
within 250 million years
within 300 million years
within 350 million years
The sun performs a full turn around the center of our galaxy during 225 million years.
What was the exposure time of this photo?
about 10 seconds
about 10 minutes
about 1 hour
about 8 hours
The length of stars trails is pretty much the same as the distance travelled by an hour hand of clock during 30 minutes. But the Earth rotates twice as slow compared to the hour hand of a clock (one rotation per day, while clock's hour hand makes two).
What are the most luminous objects in the universe?
A quasar is an extremely energetic source of radiation powered by accretion disc around galaxy's central supermassive black hole. Quasars were much more common in the early universe, as all known quasars are extremely distant.
Who first proposed the need to use summer time?
The idea of daylight saving was first conceived by Benjamin Franklin during his sojourn as an American delegate in Paris in 1784. Sometimes, the creator of this solution is George Vernon Hudson, who wanted to "make better use of the long days of summer. The pioneers in the introduction of summer time were Germans during the First World War.
Which planet’s day lasts longer than its year?
Venus year (the time it takes it to rotate around the Sun) is equal to 225 Earth days, and its day (the time it takes it to rotate on its axis) equals 243 Earth days.
World's fastest high-speed cameras were built to take photos of specific objects. What kind of objects?
nuclear bomb explosions
The rapatronic cameras are capable of recording a still image with an exposure time as brief as 10 nanoseconds (that would give 100 million frames per second if the camera was capable to do multiple pictures). The camera uses two polarizing filters mounted with their polarization angles at 90° to each other and a Faraday cell which briefly changes the polarization plane of light passing through it, acting as a shutter.
What does the AM acronym stand for in time notation, ex. 11:40 AM?
“Ante meridiem” is Latin for “before noon”. Although “AM/PM” is especially common in English-speaking countries, these acronyms come actually from Latin. | 0.800799 | 3.042011 |
From Centauri Dreams:
The assumptions we bring to interstellar flight shape the futures we can imagine. It’s useful, then, to question those assumptions at every turn, particularly the one that says the reason we will go to the stars is to find other planets like the Earth. The thought is natural enough, and it’s built into the exoplanet enterprise, for the one thing we get excited about more than any other is the prospect of finding small, rocky worlds at about Earth’s distance from a Sun-like star. This is what Kepler is all about. From an astrobiological perspective, this focus makes sense, as we want to know whether there is other life — particularly intelligent life — in the universe.
But interstellar expansion may not involve terrestrial-class worlds at all, though they would still remain the subject of intense study. Let’s assume for a moment that a future human civilization expands to the stars in worldships that take hundreds or even thousands of years to reach their destination. The occupants of these enormous vessels might travel in a tightly packed urban environment or perhaps in a much more ‘rural’ setting with Earth-like amenities. Many of them would live out their lives in transit, without the ability to be there at journey’s end. We can only speculate what kind of social structures might emerge around the ultimate mission imperative.
Moving Beyond a Planetary Surface
Humans who have grown up in a place that has effectively become their world are going to find its norms prevail, and the idea of living on a planetary surface may hold little interest. Isaac Asimov once wrote about what he called ‘planetary chauvinism,’ which falls back on something Eric M. Jones wrote back in the 1980s. Jones believed that people traveling to another star will be far more intent on mining asteroids and the moons of planets to help them build new habitats for their own expanding population. Stephen Ashworth, a familiar figure on Centauri Dreams, writes about what he calls ‘astro-civilizations,’ space-based cultures that focus on the material and energy resources of whatever system they are in rather than planets.
Ashworth’s twin essays appear in a 2012 issue of the Journal of the British Interplanetary Society (citation below) that grew out of a worldship symposium held in 2011 at BIS headquarters in London. The entire issue is a wonderful contribution to the growing body of research on worldships and their uses. Ashworth points out that a planetary civilization like our own thinks in terms of planetary resources and, when looking toward interstellar options, naturally assumes the primary goal will be to locate new ‘Earths.’ A corollary is the assumption of rapid transport that mirrors the kind of missions used to explore our own Solar System.
Image: A worldship kilometers in length as envisioned by space artist Adrian Mann.
An astro-civilization is built on different premises, and evolves naturally enough from the space efforts of its forebears. Let me quote Ashworth on this:
“A space-based or astro-civilisation…is based on technologies which are an extension of those required on planetary surfaces, most importantly the design of structures which provide artificial gravity by rotation, and the ability to mine and process raw materials in microgravity conditions. In fact a hierarchical progression of technology development can be traced, in which each new departure depends upon all the previous ones, which leads ultimately to an astro-civilisation.
The technology development Ashworth is talking about is a natural extension of planetary methods, moving through agriculture and industrialization into a focus on the recovery of materials that have not been concentrated on a planetary surface, and on human adaptation not only to lower levels of gravity but to life in pressurized structures beginning with outposts on the Moon, Mars and out into the system. Assume sufficient expertise with microgravity environments — and this will come in due course — and the human reliance upon 1 g, and for that matter upon planetary surfaces, begins to diminish. Power sources move away from fossil fuels and gravitate toward nuclear and solar power sources usable anywhere in the galaxy.
Agriculture likewise moves from industrialized methods on planetary surfaces to hydroponic agriculture in artificial environments. Ashworth sees this as a progression taking our adaptable species from the African Savannah to the land surface of the entire Earth and on to the planets, from which we begin, as we master the wide range of new habitats becoming available, to adapt to living in space itself. He sees a continuation in the increase of population densities that took us from nomadic life to villages to cities, finally being extended into a fully urbanized existence that will flourish inside large space colonies and, eventually, worldships.
An interstellar worldship is, after all, a simple extension from a colony world that remains in orbit around our own star. That colony world, within which people can sustain their lives over generations, is itself an outgrowth of earlier technologies like the Space Station, where residence is temporary but within which new skills for adapting to space are gradually learned. Where I might disagree with Ashworth is on a point he himself raises, that the kind of habitats Gerard O’Neill envisioned didn’t assume high population densities at all, but rather an abundance of energy and resources that would make life far more comfortable than on a planet.
This reminds me of an old Analog article I read back in the 1970s by Larry Niven titled “Bigger Than Worlds” in which Niven gave several examples of structures that evolved into massive structures from interstellar vessels to Ringworlds and Dyson Sphere, all of which were safer than natural planets.
Of course this goes by the assumption if human goes by the “expansion” route, or the “evo devo” route proposed by Jon Smart. | 0.892873 | 3.364954 |
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