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|Other names||Space Slug|
|Length||10 meters (average)|
Can grow up to 900 meters
|Diet||Carnivorous, lithotroph, phototroph|
|Behind the Scenes|
The Exogorth (a.k.a. Space Slug) is a colossal, non-sapient silicon-based lifeform that naturally inhabits asteroid fields in several planetary systems of the galaxy, being able to survive the space vacuum and freezing temperatures found in this unusual habitat.
Biology and ecologyEdit
Being silicon-based, rather than carbon-based, Exogorths have a very unusual metabolism, which enables them – and other, probably related, silicon creatures, like Mynocks – to survive unharmed in the vacuum of interplanetary space. Needing no air or water, they feed on the minerals of asteroids and also use stellar light to produce energy. They are also reported to eat Mynocks.
Size varies a lot in this species: while the average adult is 10 meters long, there are individuals that grow up to 900 meters. Oversized Exogorths can house an entire ecosystem inside themselves, where Mynocks and other creatures swallowed by the beast may become internal parasites and even create a breeding population of beings that spend their whole lives inside the cave-like esophagus of the Exogorth. In spite of their huge size, Exogorths normally reproduce by fission, not unlike Earth's planarians. They also need to molt periodically.
Because Exogorths live in asteroid fields, they are exposed to the danger of being hit by small asteroids. Besides being physically resistant, the beast has a highly sophisticated sense of spatial awareness, allowing it to calculate the speed and trajectory of all asteroids around, minimalizing the peril.
Exogorths live in burrows they dig in asteroids and other small, atmosphere-less, celestial bodies. Tendril-like structures on their tail are used to anchor themselves to the rock and to absorb nutrients from it. They are not permanently attached to their asteroids, though, and they change their burrow from time to time. They do it by pushing off the asteroid and floating to another one. It could be said that they jump from one rock to another.
Virtually nothing is known about the origins of Exogorths, which are found all over the galaxy. We don't even know if they evolved on a planet or in the vacuum of space. The later alternative sounds a bit more likely, given how Exogorths are well adapted to their extreme environment. However, there is a theory that says that Exogorths are descendents from some sort of organism native to the ancient planet of Oblis, a world which later exploded and generated the Cularin Asteroid Belt, which is one of the areas where Exogorths are found. An interesting fact is that the Exogorths of the Cularin System belong to a different species which is relatively easier to tame. | 0.843547 | 3.372922 |
This first images from NSF’s Inouye Solar Telescope show a close-up view of the sun’s surface, which can provide important detail for scientists. The image shows a pattern of turbulent “boiling” plasma that covers the entire sun. The cell-like structures—each about the size of Texas—are the signature of violent motions that transport heat from the inside of the sun to its surface. That hot solar plasma rises in the bright centers of “cells,” cools off and then sinks below the surface in dark lanes in a process known as convection. (See video available with this news release.)
Solar magnetic fields constantly get twisted and tangled by the motions of the sun’s plasma. Twisted magnetic fields can lead to solar storms that can negatively affect our technology-dependent modern lifestyles. During 2017’s Hurricane Irma, the National Oceanic and Atmospheric Administration reported that a simultaneous space weather event brought down radio communications used by first responders, aviation and maritime channels for eight hours on the day the hurricane made landfall.
Finally resolving these tiny magnetic features is central to what makes the Inouye Solar Telescope unique. It can measure and characterize the sun’s magnetic field in more detail than ever seen before and determine the causes of potentially harmful solar activity.
“It’s all about the magnetic field,” said Thomas Rimmele, director of the Inouye Solar Telescope. “To unravel the sun’s biggest mysteries, we have to not only be able to clearly see these tiny structures from 93 million miles away but very precisely measure their magnetic field strength and direction near the surface and trace the field as it extends out into the million-degree corona, the outer atmosphere of the sun.”
Better understanding the origins of potential disasters will enable governments and utilities to better prepare for inevitable future space weather events. It is expected that notification of potential impacts could occur earlier—as much as 48 hours ahead of time instead of the current standard, which is about 48 minutes. This would allow for more time to secure power grids and critical infrastructure and to put satellites into safe mode.
he Inouye Solar Telescope combines a 13-foot (4-meter) mirror—the world’s largest for a solar telescope—with unparalleled viewing conditions at the 10,000-foot Haleakalā summit.
Focusing 13 kilowatts of solar power generates enormous amounts of heat—heat that must be contained or removed. A specialized cooling system provides crucial heat protection for the telescope and its optics. More than seven miles of piping distribute coolant throughout the observatory, partially chilled by ice created on site during the night.00:0000:00
The dome enclosing the telescope is covered by thin cooling plates that stabilize the temperature around the telescope, helped by shutters within the dome that provide shade and air circulation. The “heat-stop” (a high-tech, liquid-cooled metal donut) blocks most of the sunlight’s energy from the main mirror, allowing scientists to study specific regions of the sun with unparalleled clarity.
“This image is just the beginning,” said David Boboltz, program director in NSF’s division of astronomical sciences and who oversees the facility’s construction and operations. “Over the next six months, the Inouye telescope’s team of scientists, engineers and technicians will continue testing and commissioning the telescope to make it ready for use by the international solar scientific community. The Inouye Solar Telescope will collect more information about our sun during the first 5 years of its lifetime than all the solar data gathered since Galileo first pointed a telescope at the sun in 1612.” | 0.804855 | 3.819823 |
It sounds like dark matter makes up one quarter of the universe's mass-energy. And it's density is fairly uniform. But could it be simultaneously both uniform and moving - like currents in a lake. Does it have a standing wave? A propagating wave? A rotation around some universal central point? Local rotations around massive objects like low pressure systems on a weather map?
Yes and no. In general, Dark Matter tends to exist in the same places as galaxies. It isn't really distributed throughout all of space uniformly. It has voids and filaments just like normal matter does. In fact, on the whole, normal matter is a pretty good tracer of where Dark Matter is. In some cases Dark Matter can separate from normal matter, and it's believed by some that Dark Matter can clump in areas where normal matter doesn't, but more or less, on a cosmological scale, it is distributed and acts like regular matter. On short timescales, Dark Matter most just sits there. There isn't mass motion or propagating waves. On long timescales and in very large views, you can see actual motion and interesting structures (e.g., Baryonic Acoustic Oscillations - technically we observe these in normal matter, but Dark Matter would be affected in the same way).
To give you an idea of this, check out the Millennium Simulation (that's a YouTube video which moves around and views the results of the simulation). This was a set of simulations of the universe as a whole, in an attempt to test out current theories about our universe and see if those theories could produce a universe that looks like ours. Suffice to say, they were pretty successful. An image of the results of the simulation is shown below. This represents the universe at a very very large scale and you can see all the dark matter and how it is distributed.
You might also want to check out the Aquarius Simulation which was very similar in nature to the Millennium Simulation. However, unlike the video for the Millennium Simulation, this video shows the evolution of the universe. This really gives you an idea of the flow and motion of dark matter over the entire history of the Universe.
Hypothesised, weakly interacting, cold dark matter is affected by gravity, but behaves differently to normal matter, in terms of its spatial distribution and kinematics, because it is dissipationless. That is, it cannot lose kinetic energy through interactions and radiate heat away.
The distribution and motion of dark matter can be looked at on a number of scales. On the scale of galaxy clusters and superclusters, dark matter is arranged into voids and filaments, as shown by Zephyr's answer. It is decidedly non-uniform.
On the scale of a galaxy, our Milky way galaxy for instance, dark matter is thought to be distributed in a smoothly spherical, centrally concentrated way, and extends well beyond where the normal matter is found. The dark matter is moving; it orbits in the overall Galactic gravitational potential like everything else, but the orbits will be much more radial, rather than the circular orbits followed by stars in the disk of our Galaxy.
What this means for dark matter on solar system scales, is that we expect there is a dark matter "wind", because the Sun is orbiting at around 200 km/s with respect to the Galaxy, and so the dark matter will have this large number superimposed on its relative velocity with respect to the solar system. The wind at the Earth will also get stronger and weaker by 30 km/s as the Earth travels in its orbit.
The spatial distribution of dark matter on solar system scales should be quite uniform, and be less than one hundredth the density of normal matter in interplanetary space. There should however be a small (of order 1% density contrast) gravitational focusing effect due to the Sun as the "wind" passes by it. | 0.831597 | 3.924552 |
The jagged shores of Pluto's highlands
This enhanced color view from NASA's New Horizons spacecraft zooms in on the southeastern portion of Pluto's great ice plains, where at lower right the plains border rugged, dark highlands informally named Krun Macula. (Krun is the lord of the underworld in the Mandaean religion, and a 'macula' is a dark feature on a planetary surface.)
Pluto is believed to get its dark red color from tholins, complex molecules found across much of the surface. Krun Macula rises 1.5 miles (2.5 kilometers) above the surrounding plain – informally named Sputnik Planum – and is scarred by clusters of connected, roughly circular pits that typically reach between 5 and 8 miles (8 and 13 kilometers) across, and up to 1.5 miles (2.5 kilometers) deep.
At the boundary with Sputnik Planum, these pits form deep valleys reaching more than 25 miles (40 kilometers) long, 12.5 miles (20 kilometers) wide and almost 2 miles (3 kilometers) deep – almost twice as deep as the Grand Canyon in Arizona – and have floors covered with nitrogen ice. New Horizons scientists think these pits may have formed through surface collapse, although what may have prompted such a collapse is a mystery.
This scene was created using three separate observations made by New Horizons in July 2015. The right half of the image is composed of 260 feet- (80 meter-) per-pixel data from the Long Range Reconnaissance Imager (LORRI), obtained at 9,850 miles (15,850 kilometers) from Pluto, about 23 minutes before New Horizons' closest approach. The left half is composed of 410 feet- (125 meter-) per-pixel LORRI data, obtained about six minutes earlier, with New Horizons 15,470 miles (24,900 kilometers) from Pluto.
These data respectively represent portions of the highest- and second-highest-resolution observations obtained by New Horizons in the Pluto system. The entire scene was then colorized using 2,230 feet- (680 meter-) per-pixel data from New Horizons' Ralph/Multispectral Visual Imaging Camera (MVIC), obtained at 21,100 miles (33,900 kilometers) from Pluto, about 45 minutes before closest approach. | 0.862424 | 3.671175 |
The natural causes of normal climate variations include changes in solar activity, volcanic activity, variations in Earth’s orbit, and the role of the oceans. Among these, the variations in Earth’s orbit is the major driver of glacial and interglacial periodicity. It is important to note that the climate change we are experiencing today is a level of variation that far exceeds the normal climate variations caused by these natural causes.
Learn more about the sun’s fascinating sunspots.
Solar activity determines the amount of solar radiation that the sun emits. Sunspots are storms on the sun’s surface that are accompanied by intense magnetic activity; the storms and magnetic activity affect the output of solar radiation. There is an 11- to 22-year cycle of sunspots, which causes the total solar irradiance to vary within the cycle, and affects Earth’s climate. However, the variation in solar radiation caused by sunspot cycles is relatively small compared to total solar output (~0.1%) and far too low to cause the temperature changes observed by climate scientists today.
Volcanoes emit large amounts of ash that can remain in the atmosphere for long time periods, blocking solar radiation and effectively lowering the solar input to Earth, which causes a cooling period. The long period of cooling between 1500 and the end of the 1800s known as the “Little Ice Age” is now considered to be the result of a sizable increase in world-wide volcanic activity. There is some evidence for at least four major volcanic eruptions that initiated this cooling period.
Milutin Milankovitch, a Serbian astronomer and mathematician, suggested that variations in Earth’s orbit affect both the amount and the distribution of sunlight received at the Earth’s surface, which directly impacts the warming of Earth. These variations are called the “Milankovitch Cycles” (Figure 12) and are caused by three forces;
- changes in the shape of Earth’s orbit around the sun (eccentricity),
- the tilt of Earth on its axis (obliquity), and
- the wobbling of the Earth’s axis (precession).
Milankovitch’s theory explains the timing of the past ice ages and major continental glaciations according to paleoclimatology studies, but these cycles occur over tens of thousands of years and longer, and cannot account for the rapid temperature changes observed in the last few decades.
The Role of the Oceans in Moderating the Climate
The oceans cover 70% of the earth’s surface and because of their great depth and the high specific heat capacity of water, oceans retain much more heat than land surfaces. The 2013 IPCC report indicates that 90% of the net energy increase in the climate system between 1971 and 2010 is stored in the Earth’s oceans; with 60% being stored in the upper ocean (0-700 meters depth), and 30% being stored in depths below 700 meters.
There is a natural interactive 3-6 year cycle that involves both the oceans and the atmosphere that has be termed the El Niño-Southern Oscillation (ENSO). ENSO has a major impact on regional climate, often with disastrous consequences. Every few years, it brings flooding to some areas and drought to others. It is believed that as more heat becomes stored in the waters of the ocean, the ENSO effect will become more extreme. This means that ocean storms, including typhoons and hurricanes, will become more intense and frequent. Read more about El Niño at the National Oceanic and Atmospheric Administration webpage. As the examples above demonstrate, natural factors do affect Earth’s climate. However, the changes in climate that have taken place since the 1900s do not fit the patterns of natural variability in climate as caused by these natural factors alone. | 0.813713 | 3.738367 |
Theory of General Relativity
Albert Einstein's theory of general relativity remains an important and essential discovery because it permanently altered how we look at the universe. Einstein's major breakthrough was to say that space and time are not absolutes and that gravity is not simply a force applied to an object or mass. Rather, the gravity associated with any mass curves the very space and time (often called space-time) around it.
To conceptualize this, imagine you're traveling across the Earth in a straight line, heading east, starting somewhere in the Northern Hemisphere. After a while, if someone were to pinpoint your position on a map, you'd actually be both east and far south of your original position. That's because Earth is curved. To travel directly east, you'd have to take into account the shape of Earth and angle yourself slightly north. (Think about the difference between a flat paper map and a spherical globe.)
Space is pretty much the same. For example, to the occupants of the shuttle orbiting Earth, it can look like they're traveling on a straight line through space. In reality, the space-time around them is being curved by Earth's gravity (as it would be with any large object with immense gravity such as a planet or a black hole), causing them to both move forward and to appear to orbit Earth.
Einstein's theory had tremendous implications for the future of astrophysics and cosmology. It explained a minor, unexpected anomaly in Mercury's orbit, showed how starlight bends and laid the theoretical foundations for black holes. | 0.864346 | 3.561166 |
Researchers have snapped the best-resolution view of the sun ever, courtesy of the Daniel K. Inouye 4-meter solar telescope. The image, which resolves features as small as 18 miles wide (30km), is an unprecedented glimpse of what the surface of the sun really looks like.
Typical images of the sun look like this, as captured by NASA’s Solar Dynamics Observatory (SDO), in geosynchronous orbit above Earth.
This sort of image shows us a certain amount of detail, but it’s missing a lot — partly as a consequence of being shot from 93 million miles away. Then again, the SDO is also in orbit, which we know typically allows for much better viewing conditions than any ground-based telescope.
What allows the Inouye Solar Telescope to see in such detail compared with the SDO? Adaptive optics, location, and sheer size. At four meters (technically 4.24), the Inouye is the largest solar telescope on Earth and its location at Hawaii is one of the best-known locations for clear-sky viewing during the day. The situation appears to be analogous to the relationship between Hubble and some of our largest ground-based telescopes. Hubble has a 2.4-meter lens, while the European Extremely Large Telescope currently under construction in Chile will have a 39.3-meter lens upon completion. Hubble isn’t important because it presents us with the largest window on the heavens, but because the specific characteristics of space-based observation give us an additional level of bit-depth in areas other than the additional light-gathering capability from scaling up a lens. The Inouye Solar Telescope is expected to cooperate on observations with the already in-orbit NASA Parker Solar Probe and the joint ESA/NASA Solar Orbiter (currently prepping for launch).
In this case, the 4-meter telescope was able to make out what looks a lot like peanut brittle.
Here’s how NASA/AURA/NSO describe the image:
The cell-like structures – each about the size of Texas – are the signature of violent motions that transport heat from the inside of the sun to its surface. Hot solar material (plasma) rises in the bright centers of “cells,” cools off and then sinks below the surface in dark lanes in a process known as convection. In these dark lanes we can also see the tiny, bright markers of magnetic fields. Never before seen to this clarity, these bright specks are thought to channel energy up into the outer layers of the solar atmosphere called the corona. These bright spots may be at the core of why the solar corona is more than a million degrees!
These images have been lightly processed to remove noise and enhance the shape of the structures; the full data set is still undergoing scientific analysis. Still, seeing the fine-scale structure of the sun is a reminder that it isn’t actually “just” a ball of burning gas. The science of how heat is theorized to move through a star and the large-scale structures we observe has implications for stellar theory. It could tell us something about how our own sun is evolving over its own lifespan, and might even have implications for our attempts to create sustainable fusion power generation on Earth. A better understanding of solar dynamics might also enable us to predict coronal mass ejections in the future — and that could be critically important, given the risk they pose.
I’m downright curious to see what kind of new data we’ll learn once the Parker Solar Probe, Solar Orbiter, and the Inouye Solar Telescope are online simultaneously. | 0.842763 | 3.872045 |
There has been lots of buzz in the Astro community about whether Betelgeuse will be supernova or not. Well, let’s catch you up quickly on the background.
Betelgeuse is a huge star that is about 11-20 times larger than our own Sun! In fact, if it was placed where our Sun is that it would reach as far as Jupiter, engulfing Mercury, Venus, Earth and Mars.
Now, when we think about the most fantastic and terrifying explosions in the universe you might hear or think of supernova. If you start asking the question what’s the nearest star to us that will go supernova next? Then you land on Betelgeuse. It’s a widely known fact but no cause for alarm. It takes tens of thousands of years for a star to go down this path of going supernova. There’s a wonderful simulation of how frantic this process is over a time period of 16 years. Check out the following video:
So where is this all coming from about it going supernova all of a sudden if it takes so long? Well, there have been observations of Betelgeuse dimming in October 2019. Astronomers found it odd and peculiar but nothing to raise alarms. However, Betelgeuse is one of the brightest stars in our night sky in the northern hemisphere. It’s also one of the main stars in the Orion constellation which is one of the easier constellations to point out when stargazing. Since so many people around the world see this that you start to compile more and reports about whether something was happening.
However, it’s been debunked by many scientists and authoritative figures like Phil Plait over at Bad Astronomy. Here’s what he has to say:
“Despite its heft it’s chewing through its nuclear fuel at an extremely rapid rate, far faster than the Sun does, making its lifetime far shorter. It’s already used up all the hydrogen in its core and is currently fusing helium. But even at the prodigious rates it’s going through helium, it’ll probably be about 100,000 years before it explodes.” – Phil Plait
What’s interesting to consider is how close does a star needs to be for Earth to be in any real danger? It turns out that 300 light-years is close enough. That is pretty scary considering a light-year is about 10 trillion kilometres. Thus, that is a long distance away to cause some damage.
Fear not, because Betelgeuse is 650 light-years away from Earth. That puts us in a very safe and comfortable position.
What did we learn today?
- Betelgeuse is a red supergiant star
- People speculated the recent odd dimmings of the star indicates it may go supernova
- Debunked that if it were to go supernova it would happen in 10,000- 100,000 years
- Betelgeuse is 650 light-years away (300 light-years is the danger zone for supernova)
Latest posts by Zain Husain (see all)
- Astronomers Discover the Biggest Explosion Seen in the Universe in Ophiuchus Galaxy Cluster - March 1, 2020
- ESA Solar Orbiter Mission Successfully Launches to Study the Sun - February 10, 2020
- Stunning View of the Famous (M27) Dumbbell Nebula - February 9, 2020 | 0.815449 | 3.516778 |
I think I need someone far cleverer than me to explain this to me. Dark Matter [wiki]…
In astronomy and cosmology, dark matter is matter that is inferred to exist from gravitational effects on visible matter and background radiation, but is undetectable byemitted or scattered electromagnetic radiation. Its existence was hypothesized to account for discrepancies between measurements of the mass of galaxies, clusters of galaxies and the entire universe made through dynamical and general relativistic means, and measurements based on the mass of the visible “luminous” matter these objects contain: stars and the gas and dust of the interstellar and intergalactic medium.
According to observations of structures larger than galaxies, as well as Big Bang cosmology interpreted under the Friedmann equations and the FLRW metric, dark matter accounts for 23% of the mass-energy density of the observable universe. In comparison, ordinary matter accounts for only 4.6% of the mass-energy density of the observable universe, with the remainder being attributable to dark energy. From these figures, dark matter constitutes 80% of the matter in the universe, while ordinary matter makes up only 20%.
Dark matter was postulated by Fritz Zwicky in 1934 to account for evidence of “missing mass” in the orbital velocities of galaxies in clusters. Subsequently, other observations have indicated the presence of dark matter in the universe; these observations include the rotational speeds of galaxies, gravitational lensing of background objects by galaxy clusters such as the Bullet Cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies.
Dark matter plays a central role in state-of-the-art modeling of structure formation and galaxy evolution, and has measurable effects on the anisotropies observed in thecosmic microwave background. All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which interacts with electromagnetic radiation. The largest part of dark matter, which does not interact with electromagnetic radiation, is not only “dark” but also, by definition, utterly transparent.
As important as dark matter is believed to be in the cosmos, direct evidence of its existence and a concrete understanding of its nature have remained elusive. Though the theory of dark matter remains the most widely accepted theory to explain the anomalies in observed galactic rotation, some alternative theoretical approaches have been developed which broadly fall into the categories of modified gravitational laws, and quantum gravitational laws.
Look, I jut don't get it. I mean I do get it in that I understand the basic concept – when we look at the universe and see all the stuff that we can see we end up with a real problem, that all the observable material around us only accounts for 20% of the matter that should be there if our current understandings of gravity etc are correct.
Is it me, or does that not make you want to argue that either we're very bad at just looking for stuff or maybe our current theories just aren't up to scratch at all? The wiki article goes on to present that latter choice as one possible alternative:
One group of alternative theories to dark matter assume that the observed inconsistencies are due to an incomplete understanding of gravitation rather than invisible matter. These theories propose to modify the laws of gravity instead.
But again, is this just me or doesn't this just all boil down to the fact that really, for all our claims to cleverness and despite all the incredible discoveries we've made about the Universe, we just still don't have a clue?
I have an alternate explanation for why we're still nowhere near close to having anything like a Theory of Everything. Some of you aren't going to like it,
Hebrews 1:3 The Son is the radiance of God's glory and the exact representation of his being, sustaining all things by his powerful word.
Now that is really going to mess up any theory built on materialism.
Now, can someone let me know if I'm just getting this hopelessly messed up or is all of this dark matter stuff really an exercise in trying to explain away our ignorance?
(image from ScienceBlogs.com) | 0.833339 | 3.917993 |
AMES, Iowa - NASA's planet-hunting TESS Mission keeps giving astronomers new realities to examine and explain.
Case in point: astronomers using the tools of asteroseismology - the observations and measurements of a star's oscillations, or starquakes, that appear as changes in brightness - have learned more about two stars bright enough to be visible in a dark sky to the naked eye. These red-giant stars - older, "retired" stars no longer burning hydrogen in their cores - are known as HD 212771 and HD 203949.
Both stars are known to host their own planets. And the TESS data indicate one of those "exoplanets" (the general term for planets that orbit stars other than our sun) is so close to its host star it shouldn't have survived the star's expansion as a red giant - if, that is, the star is old enough to have expanded and retreated.
Steve Kawaler, an Iowa State University distinguished professor of physics and astronomy, and Miles Lucas, a recent Iowa State graduate and current doctoral student at the University of Hawaii at Manoa, are part of the TESS asteroseismology study team.
"We listened to the notes the stars were singing," Kawaler said. "We used that data to determine actual values - mass, radius and evolutionary stage - for these stars. Asteroseismology can tell us all these things - and more - about stars that are difficult to obtain with other tools."
The team of 48 astronomers describe their findings in a paper recently published by The Astrophysical Journal. The lead author is Tiago L. Campante of Portugal's Universidade do Porto.
The paper describes the first use of TESS data to detect oscillations of stars already known to host exoplanets. The new work, the authors wrote, is a way of "further showcasing the mission's potential to conduct asteroseismology of red-giant stars."
Kawaler said the study indicated star HD 203949 was less massive than previously thought. That meant for its planet to be moving as fast as the astronomers determined, it had to be much closer to the star than expected. So close, in fact, it would be engulfed by the star's expansion as a red giant.
The paper offers two possible explanations: The host star is early in its red giant expansion and has yet to engulf and destroy the planet. Or, computer simulations of star-planet tides indicate the planet could have been dragged from a wider orbit, where it avoided destruction by the star, and then settled into a closer orbit once the star retreated.
It's an interesting case of planetary evolution, said Kawaler, who's on the seven-member board leading the TESS Asteroseismic Science Consortium. Jørgen Christensen-Dalsgaard of Aarhus University in Denmark is the consortium's lead investigator.
"Tiago (the paper's lead author) has a knack for finding these planetary systems that expand our horizons on how nature makes planets and keeps them," Kawaler said.
As astronomers continue to analyze data for clues about how planets and stars evolve with each other, Kawaler said TESS is an important tool.
TESS - the Transiting Exoplanet Survey Satellite, led by astrophysicists from the Massachusetts Institute of Technology - launched in April 2018. The spacecraft and its four cameras are on a two-year mission to survey 85 percent of the sky, looking for planets by detecting tiny dips of light as they pass in front of their host stars.
Those cameras also collect star data that are useful for planetary studies, too.
"Characterization of host stars is a critical component of understanding their planets," the authors wrote. " ... The asteroseismology techniques described here are thus an important component of overall planetary system characterization." | 0.896414 | 3.832299 |
The Universe is Expanding
Without going into the math, we will simply note that the redshift (z) is measured by taking the change in the wavelength and dividing it by the normal wavelength.
z = change in wavelength / normal wavelength
What is truly remarkable is that the redshift (z) is also the proportion of the velocity (v) of recession to the speed of light (c). So to find the velocity v of recession of a galaxy, we need only multiply z by the speed of light c.
z = v / c
which is the same as
v = z c
As we will see later, the speed of light is always the same. No matter how we make the measurement, we will find light moving at about 300,000 km/s. Multiply z by this speed, and you'll have that the velocity at which the galaxy is moving away from us.
Example: For the supercluster of galaxies known as BAS11, the redshift (the change in the wavelength divided by the normal wavelength) was measured to be a tiny change of z = 0.07. Since v = z c then 0.07 = v / c, and the velocity of recession of the cluster of galaxies is a huge v = 0.07 c or 21,000 km/s .
Redshift for Supercluster of Galaxies BAS11
The pattern of the spectral lines remains the same, but their wavelengths are all increased, and the lines shift to the red.
Edwin Hubble compared redshifts with the distances of the nearby galaxies he could measure at the time, and he found that the farther the galaxy from us, the faster it was receding away. Today, using the inverse square law with Type Ia supernovae, the effect has been studied with high precision. We find that galaxies recede about 70 km/sec faster for each megaparsec more distant they are. This is written 70 km/s / Mpc. (Recall that a parsec is 3.26163 light years. "Mega " means a million, so 1 megaparsec is 3,261,630 light years. Megaparsecs are used to keep the math simple.)
This 70 km/s / Mpc is called the Hubble Constant, and is written simply as H. There is some uncertainty on the exact value of H, but about 71 km/s / Mpc is the best measurement we have to date. We use H = 70 km/s / Mpc to keep things simple.
Here it is at last! The great Hubble's law used to measure the universe!
v = H D
Example: For the supercluster of galaxies BAS11, we have already measured the velocity v of recession for the galaxy cluster to be 21,000 km/s. We use H = 70 km/s / Mpc, to find the distance in megaparsecs (Mpc). For BAS11 we get
v = H D
21000 km/s = 70 km/s / Mpc x D
300 Mpc = D
Comparing Distances of Galaxies with Hubble's Law
Below is a graph showing measured velocities and distances to galaxies compared to Hubble's Law. Each point on ths graph is the average distance and speed of a cluster of hundreds of galaxies. The Virgo Cluster is the closest one to us. Notice that not only is the universe expanding, but the more distant the galaxies the faster they are receding from us!
Examples of Hubble's Law
Redshifts for Clusters of Galaxies
You are now measuring the Universe
NO MATTER WHICH DIRECTION WE LOOK THE MORE DISTANT THE GALAXY THE FASTER IT IS RECEDING
In all directions the faster a galaxy is receding the more distant it is. Here is a map of galaxy distances and distributions. Galaxies group in clusters and filaments everywhere.
Panorama of 1.5 million galaxies as they appear on the sky, color coded by "redshift." Blue galaxies are the nearest sources (z less than 0.01); green are at moderate distances (z from 0.01 to 0.04) and red are the most distant ones seen in a survey using infrared light that covers z out to 0.1.
Credit: T. Jarrett and the 2MASS Redshift Catalog
We have looked at relatively nearby galaxies so far, with fairly small z, but when dealing with galaxies very far away, and receding from us at nearly the speed of light (close to 300,000 km/s ), we must take into account the effects of General Relativity. That will come later, for objects such as the young cluster around the radio galaxy known as TNJ1338-1942, that's at a remarkable z=4.11.
Think for a moment what that means about the wavelengths we would see from this galaxy, and the velocity we would get for it. Eek!
You might explore some of entries on the Wikipedia List of Galaxy Clusters to see the variety in the structure of the universe around us. The Sloan Survey is currently mapping the Universe in 3D by using the Hubble Law to find the distances to galaxies. | 0.840481 | 3.854041 |
Today’s announcement of the detection of primordial gravitational waves is huge. The Harvard-Smithsonian Center for Astrophysics gave a news conference in which it described the first ever detection of these waves which provides a window onto the very earliest stages of our universe. Gravitational waves were the last untested prediction of Einstein’s General Theory of Relativity. Using a specialized telescope, the research group on the BICEP2 (Background Imaging of Cosmic Extragalactic Polarization) project at the south pole gathered data which should only be observable from an event as massively violent as the Big Bang.
These primordial gravitational waves would’ve been generated a trillionth of a trillionth of a trillionth of a second after the Big Bang, during a period known as cosmological inflation. The inflation period would’ve expanded the nascent universe many, many times faster than the speed of light and led to an extremely, yet not perfectly, smooth and uniform cosmos.
This evidence isn’t only a direct window onto the very earliest stages of the formation of our universe, it gives us new tools for studying it. Additionally, it provides major support for what’s known in physics as the Standard Model. This indicates our understanding of the cosmos is very much on track, even though there is still much for us to learn.
So why is this important to futurists? After all, this all occurred an unfathomably distant time in the past. But because this evidence allows us to more accurately model our universe’s past, it will also let us better understand it’s most distant future. As a result of today’s discovery, the evolution and ultimately the fate of our universe can be far better anticipated than ever before. It’s a discovery that many consider worthy of a Nobel prize.
(I explore the BICEP2 project and cosmic inflation in greater detail in my upcoming article, “Making Waves in the Cosmos” in the July-August 2014 issue of The Futurist Magazine.) | 0.816445 | 3.745722 |
June 19, 2018
In Discovering Pluto historian William Sheehan along with his co-writer Dale P. Cruikshank uncover the behind-the-scenes history of the enigmatic and much discussed icy orb at the edge of our solar system. Today, William answers our questions about the outer Solar System.
Why do you think Pluto has so captured the public imagination since it was first identified by Clyde Tombaugh in the 1930s?
From times immemorial, there were five planets—wanderers—tracing movements across the starry background of the night sky. After the Copernican revolution, the Earth of course became a planet, like the others traveling around the Sun, but still Saturn marked the outer boundary of the Solar System, and the stars were at unfathomable distances beyond. This ancient picture changed in 1781, when William Herschel discovered Uranus. Suddenly the scale of the Solar System had doubled, and within a few short years other astronomers began to discover new planets, as they were then called; these were the asteroids between Mars and Jupiter. Inspired either by the discovery of Uranus itself or by the first asteroids, Keats wrote the stirring lines,
“Then felt I like some watcher of the skies/When a new planet swims into his ken.”
Uranus began after a few years to wander inexplicably off course, and this led two mathematical investigators—John Couch Adams in England and Urbain Jean Joseph Le Verrier in France—to use the discrepancies in its movements to calculate the position of an unseen planet beyond—Neptune—whose optical discovery was made on the basis of these calculations in Berlin in September 1846. This was seen at the time as the greatest achievement of Newtonian celestial mechanics—the discovery of a planet, “with the stroke of a pen.” Adams and Le Verrier were duly enshrined in the pantheon of astronomical greats. Few developments in astronomy were awarded greater accolades than this, literal discovery of a new world.
Le Verrier himself thought that there might be another planet inside the orbit of Mercury, and even gave it a name, Vulcan; it does not exist, and never did—the movements for which its existence was invoked were explained by Einstein on the basis of the General Theory of Relativity in 1915. However, Uranus continued, apparently, to be wandering off course, even after Neptune was entered into the equations. Several astronomers, of whom Percival Lowell was the most celebrated, developed an elaborate program to track down another putative planet—Planet X—which might be indicating its presence as Neptune had done for Adams and Le Verrier. Lowell was an extraordinarily colorful and interesting figure, who is best remembered for founding the Southwest’s (and Arizona’s) first major observatory in Flagstaff, and for his exciting and provocative theories about the canals of Mars, which won over the general public (and inspired science fiction writers like Wells and Burroughs) but were harshly criticized by many professional astronomers. Lowell’s motivations in searching (secretively for the most part) for “X” were complex, and included the hope that recapitulating the great feat of Adams and Le Verrier would restore his prestige in the eyes of other astronomers. Unfortunately, Planet X was undiscovered when he died in November 1916.
The story of how later the search was resurrected at his observatory, how a self-taught farm boy from Kansas (Clyde Tombaugh) was hired to carry out the mind-numbing and backbreaking work of searching for it on photographic plates exposed in all weather under the stars, and how Clyde found a planet that at first was hailed as the incarnation of the icy planet of Percival’s dreams in 1930 provided the perfect coda to the story of frustrated ambition redeemed by faith and hard work. The planet was also the first discovered by an American, and came just as the Great Depression—and the rise of Fascism in Europe—were getting underway, so that the world, and Americans in particular, were in need of “good news.” In the end, Pluto proved to be a most peculiar planet, and was shown—rather definitively by Dale Cruikshank and David Morrison who in 1976 discovered the presence of methane ice on the surface—to be smaller than the Earth’s moon, and has now been seen as a kind of dual object—planetary in some ways, including rotundity and having an active (if extraordinarily odd) geology, but also the largest of the Kuiper Belt Objects which roam the outer Solar System.
What was the most surprising thing you uncovered during your research for Discovering Pluto?
The most surprising thing was what the New Horizons probe found when it passed by Pluto in July 2015. Most people, including me, had probably expected a cold and inert world, not perhaps unlike that the celebrated British astronomy writer Patrick Moore had invoked in 1955, “Beyond all doubt, Pluto is the loneliest and most isolated world in the Solar System—cut off from its fellows, plunged in everlasting dusk, silent, barren, and touched with the chill of death.” Far from it; instead, areas of Pluto show evidence of quite recent geological activity, with changing “land” forms that consist of exotic ices—including recently, methane ice dunes in Sputnik Planitia. It is also exciting to see—on an actual body in the Solar System—examples of the behavior of these ices that has already been elucidated in the laboratory.
You have written many books about planetary science, including Planet Mars. What keeps you coming back to writing these histories?
I have been fortunate in having been born just before Sputnik went into orbit around the Earth, and being consciously aware as the first spacecraft set out for the Moon and planets. I acquired my first small telescope in the mid-1960s, at a time when visual observations by amateur astronomers were still often better than the most detailed photographs by professional astronomers at the great observatories, and when it still seemed that amateurs might contribute usefully to their study. When I started out, Mariner 4 had not yet passed by Mars (July 1965, fifty years to the day before New Horizons made its Pluto flyby!), and it was still possible—just—to believe in Percival Lowell’s canals of Mars! Mariner 4—which showed there were craters on Mars—brought what seemed at the time to be a Great Disillusionment; almost like finding out (and I was at that age, just ten or so) that Santa Claus didn’t exist.
Robert Burnham, Jr, who wrote the Celestial Handbook series, and used the Pluto telescope for the proper motion study at Lowell Observatory in the 1960s, was a mentor, and encouraged me to look at Comet Ikeya-Seki in October 1965—it remains the most spectacular comet I have ever seen. This shows how important an interest of a professional can be in encouraging a young person. After a number of years, I was invited (in the summer of 1982) to Lowell as a guest investigator with a somewhat tentative project of trying to understand how observers like Lowell could have seen canals on Mars when obviously there are no canals. Art Hoag was the director then, and Bill Hoyt, who had written the landmark book Lowell and Mars published by University of Arizona Press, was in-residence historian. While there—and coming into contact with the observing books of Lowell and his associates, and seeing how their visions of canals gradually unfolded and became elaborated over time—and also observing directly through the Clark telescope they had used, I had a flash of insight—I was in the NAU library at the time; I remember it as if it were yesterday–that the key aspect no one had recognized was that because of fluctuating seeing the canals were seen only in brief intervals of a fraction of a second or so. All the observers of the canals—including Clyde Tombaugh, who graciously corresponded with me on his experiences—described this. Thus the phenomena of the canals could be related to experimental psychology. I had always been drawn to interdisciplinary work—this has become the fashion now but at the time represented an aspiration that was more honored in the breach than the observance, simply because the various disciplines had become so developed and complex that it was difficult for anyone to master them at the same time. In any case, I came away from Lowell with the thesis of a book—Planets and Perception—which I drafted during the summer of 1983, while living in a small town in southern Minnesota, just across from the Iowa border, with no resources more than those I brought with me and the Carnegie library with a six-foot shelf of books on astronomy, physics, and math. In retrospect, I think I was crazy to tackle such an ambitious project more or less alone and unaided; had I been in a graduate program, I might have worked for ten years on it, but I finished the draft in several months and then—put it away in a desk drawer as I began my medical studies.
Eventually, I got around to submitting it—and did so only to one publisher, the University of Arizona Press. Though they quailed a bit at the cross-disciplinary nature of the thing—and had to send it out to three academic reviewers, two astronomers and one psychologist!—they graciously accepted it. It was published thirty years ago in November, and I didn’t know what to expect. I was in my internship then. In January, I got a good review from Richard Baum in the Journal of the British Astronomical Association, which I remember reading in the on-call room, and thought that I was lucky to get that. By early May, I was at morning rounds on the psych service the VA in Minneapolis; the attending physician, Charlie Dean, who subscribed to Nature, rather casually congratulated me on the review the book had received in Nature by the renowned historian of science, Albert Van Helden. I was over the Moon. Of course, the book had many faults which I see only too clearly now—how could it not?—but proved to be quite seminal in its small way, and I will always be grateful to the University of Arizona Press for taking a chance with an unknown scholar and a very experimental piece of work and believing in it.
But to get back to your question, this book has defined my lifelong career interest—and until recently, when I retired, I have been both a practicing psychiatrist, interested in the brain and the way we “know,” and a historian of astronomy—and have found the history of Solar System studies during this period of time to be perhaps the most important thing we as a species have done. It has been our Parthenon, our Cathedrals. Obviously there are a lot of writers who understand this, and have devoted themselves to the documentation of this wonderful era, including many of the scientists who have been in the forefront of research (like Dale Cruikshank, my co-author of Discovering Pluto). But I think my background in psychiatry has given me a somewhat unique perspective on the human angle of this story, and that story—the exploration of the Solar System—is, after all, passionately and irreducibly a human story, whose grandeur and magnificence far exceeds the explorations (and too often bloody) conquests of previous eras. It collectively represents some of the best aspects of human nature, Something, I would add, that we desperately need to affirm and reaffirm at the present time, when it is too easy to be disillusioned about our species in light of some of its more unsavory aspects. These are things that keep drawing me back to this subject.
With the New Horizons space probe back in action after a 6-month break, what do you think will be the next chapter in Pluto’s history?
We are looking forward to New Horizons’ close approach to another KBO, MU69, which most of us expect to show only an ancient battered landscape. But as with Pluto, we are foolish not to expect to be pleasantly surprised, and perhaps we will discover fresh patches of surface exposed by a recent collision with another KBO, in which case we may have an opportunity to see deeper into the interior where so much of the early history of the Solar System lies hidden.
What are you working on now?
I have been working on a series of books on each of the planets for Reaktion Press in Great Britain—so far I have finished Jupiter and Mercury, and am on to Saturn. I am also working on a book on Mars with Jim Bell for the University of Arizona Press, who is the PI on the camera system for the 2020 Mars rover (and sample return mission). As with the Pluto book written with Dale, I will be covering mostly the historical backgrounds, in this case how we came to know Mars (including our long tendency to see it as the image of the Earth, or even of Arizona!), while Jim will take over the torch and bring to it his unrivaled knowledge of the spacecraft era. I always prefer, by the way, if possible, to work in collaboration, as it not only provides an opportunity for me to greatly extend the range of my own knowledge but also is as much more enjoyable for the shared companionship.
William Sheehan is a historian of astronomy and psychiatrist. His many books include Planets and Perception, Worlds in the Sky, and The Planet Mars, also published by the University of Arizona Press. Asteroid No. 16037 was named in his honor. | 0.905077 | 3.790953 |
Crowdsourcing Discovery: Meet the Massive Binary System Detected by Einstein@Home
|An artist’s conception of binary pulsar PSR J0737-3039, shown not-to-scale. |
Image Credit: Michael Kramer (Jodrell Bank Observatory, University of Manchester).
The binary system featured in this story (PSR J1913+1102) may be a binary pulsar, but only one of the neutron stars in the system has been confirmed as a pulsar to-date.
Started in 2005 as part of the World Year of Physics program, Einstein@Home is a distributed computing project supported by the American Physical Society (which runs PhysicsCentral and Physics Buzz), along with the National Science Foundation and the Max Planck Society, among others. The idea is this: our observatories generate more data than scientists have the resources to comb through, even with the help of supercomputers. That's where you come in. Regular people can donate the idle time from their computer (or phone) to searching data from the LIGO gravitational-wave detectors, the Arecibo radio telescope, and the Fermi gamma-ray satellite for evidence of pulsars—fast-spinning neutron stars. Interesting objects are flagged for follow-up by project scientists. The ultimate goal? To directly detect gravitational waves emitted by pulsars.
A pulsar is a strange, extremely dense, highly magnetized object that forms when a large star violently explodes. The outer layers of the star shoot off into space, leaving behind a collapsing, spinning core that isn’t quite massive enough to become a black hole. Many neutron stars have a strong charge, so they emit beams of electromagnetic waves as they move. Since they are spinning, we detect these signals as eerily regular pulses. In fact, on discovering a pulsar signal in 1967, the first one ever detected, then-graduate student Jocelyn Bell Burnell and her advisor Antony Hewish nicknamed the signal “LGM” for “little green men.”
What’s the gravitational wave connection? When two neutron stars orbit one another, general relativity predicts that the orbit will slowly contract because gravitational waves are emitted, depleting the system's energy. By precisely tracking the signals from binary pulsar systems, we can look for these predicted changes in the orbit. An experimental observation of this earned Russell Huse and Joseph Taylor Jr. the 1993 Nobel Prize in Physics. The more we know about pulsars, their distribution, and how often they appear in binary systems, the better equipped we are to directly detect the gravitational waves they emit with LIGO and future gravitational wave detectors.
In a recent issue of The Astrophysical Journal, a team using the world's largest radio telescope at Arecibo Observatory in Puerto Rico to search for radio pulsars, known as the PALFA survey, published a paper introducing the most massive double neutron star system ever seen. The system was detected by Einstein@Home in 2012 from the pulsing signal emitted by of one of the stars. Follow-up observations at Arecibo Observatory led to the discovery of the second neutron star. The two stars orbit each other in less than five hours, and are each much smaller in diameter but much larger in mass than the sun. This is the fourteenth double neutron star system observed, and the most massive yet.
The system is most likely the result of two separate supernovae. The pulsar detected by Einstein@Home computers appears to have formed first. The companion neutron star may also be a pulsar, but PALFA scientists haven’t seen any evidence of a signal in the available data. Right now it’s impossible to determine the mass of each of the stars individually, but it seems that the mass of the pulsar may be larger than the mass of the companion star. If that’s the case, scientists could have the chance to test some previously impossible-to-verify predictions related to general relativity and the composition of our galaxy, in addition to gathering more information for the gravitational wave search.
With eleven years under its belt, Einstein@Home has put idle time to good use. The project has discovered more than 70 pulsars and you can see publications resulting from several discoveries on the Einstein@Home website. The project includes more than 500,000 volunteers contributing about 1.7 petaflops (1015) of computing power, making it one of the largest computing clusters in the world! If you’d like to contribute, check out the Einstein@Home website for the quick and easy directions. It doesn’t take long to download the software and once you’re done, you can pick up the remote guilt free. Thanks to Einstein@Home, you can be dozing on the couch and on the cutting edge of gravitational wave detection at the same time.
Heinz-Bernd Eggensetin said...
> An experimental observation of this earned Russell Huse and
> Joseph Taylor Jr. the 1993 Nobel Prize in Physics.
It is "Hulse", and actually they got the Nobel Prize for the discovery of the system, not for the observation of the orbit changes due to gravitational wave emission implied here (which were actually done by Taylor and Weisberg, when Hulse had already turned to different research fields AFAIK, e.g see http://adsabs.harvard.edu/doi/10.1086/159690 ).
Also this was the 13th double NS system known, not the 14th (but there are 14 pulsars in double-NS systems because there is one double pulsar system known).
Friday, January 6, 2017 at 11:25 AM | 0.874594 | 3.815767 |
Earlier today, I posted a poll about where life could exist in the solar system. It seems Mars is quite popular. You can still vote in the poll with your answer. But now, I’ll examine each of the worlds and you can see what I think. Keep in mind that I am an expert. Okay, not an expert, but I do have a degree in astronomy. So it is my area of expertise.
Mars is the best-known planet in the solar system other than Earth. We’ve had many probes go there, rovers explore the surface, and it’s one of the easiest to observe from Earth. It’s a cold, dry world with most of its water locked up in the polar ice caps or underground. There has been evidence of sudden outflows of liquid water, though it couldn’t last long on the surface, but maybe there are aquifers. There are underground glaciers. There’s a chance there is life in the aquifers. Maybe there isn’t life now, but there may have been early in Mars’ history, as it’s recently been estimated that an ocean covered 20% of the surface. We know it had a wet history. Chances of life now? Quite low. But much better in the past.
We’ve only been studying Ceres up close for a very short time. We don’t know much about it, but there’s a guess about the internal structure. There’s likely a rocky core with a thick ice mantle. That’s covered by a thin dusty crust. Liquid water could exist if it’s warm enough inside. Water vapour was seen in January 2014, so it’s possible there is some sort of icy volcanism or geysers. What we’ve seen of the surface so far shows that it’s rather dark, but a couple bright spots could be ice. Chances of life now? Probably quite low.
This icy moon of Jupiter has been of particular interest for a very long time. It’s almost completely smooth, covered with water ice, and it shows evidence of an active surface, similar to the Arctic polar ice cap of Earth. Thanks to tidal forces exerted on it by Jupiter and other moons of Jupiter, it’s kept warm. That means there’s most likely a vast liquid water ocean under its icy crust. It’s also very likely that there’s underwater volcanism, similar to what we find on the floor of the Earth’s oceans. Those hydrothermal vents are teeming with life, and may give Europa a wonderful chance of supporting simple life, or even some more complex marine life. Because of the thick icy crust, it’s difficult to see what’s beneath. NASA’s recently had a proposal to explore Europa approved, so we could have this chance soon. Chances of life now? Not unlikely, but there’s a decent chance.
The second largest moon in the solar system also happens to be the only moon in the solar system to support a significant atmosphere. In fact, it’s more dense than the Earth’s. The surface of Titan is water ice with liquid hydrocarbon lakes and rivers. It rains and snows ethane and methane. While Earth has a water cycle, Titan has a hydrocarbon cycle. Titan even has cryovolcanoes that may be active. The composition of the atmosphere is said to be similar to early Earth’s, which makes a lot of people excited. However, Titan is extremely cold. There’s also likely a subsurface liquid water ocean, so it could be similar to Europa in that aspect. But on the surface, it’s unlikely we’ll find any life similar to what’s on Earth. Chances of life now? Probably low, but if there is any, it’s probably unrecognisable.
This small moon of Saturn has made planetary scientists very excited. It may be small, but it’s active. It has liquid water under the surface. We know this almost for certain, because it has hundreds of cryovolcanoes in the south polar region spraying out water vapour and other substances such as salt (NaCl). It could have a large salty underground ocean. Organic compounds have also been detected, which makes it an even better candidate for life. Chances of life now? There’s a decent chance, quite similar to Europa.
So, which places have the best chances of life now? I think Europa is number one, though Enceladus may have a good chance, as well as Titan. All three likely have subsurface liquid water oceans. In the past, Mars could very well have had life. We just need to find the fossils if it did. However, in all cases, it’s quite possible that life is single cellular, though Europa’s got a remote chance of multicellular life.
So, with this said, what do you think now? Where do you think life could be hiding? Or do you disagree with me? Let me know in the comments. | 0.801557 | 3.301614 |
Amid the many challenges that will face humans as we reach out to the stars, the simple problem of dust could prove among the most difficult.
That is the view of Professor G. Kim Prisk, from the University of California, who in the latest Medical Journal of Australia says lung health is a major challenge for people who leave Earth.
Professor Prisk is regarded as an expert on lung health in zero gravity and works with NASA personnel who have spent time on space shuttles and the International Space Station.
He said conditions in space, including the lack of gravity and changes in air pressure, made dust even more of a problem than it is on Earth.
“Dust exposure is a significant health hazard in occupational settings such as mining, and exposure to extraterrestrial dust is an almost inevitable consequence of planetary exploration,” Professor Prisk wrote.
“The combination of altered pulmonary deposition of extraterrestrial dust and the potential for the dust to be highly toxic likely makes dust exposure the greatest threat to the lung in planetary exploration.”
He pointed to the experience of the Apollo missions, where crews reported significant amounts of moon dust sticking to their space suits, which was then tracked into the main areas of the spacecraft despite decontamination procedures.
With the moon considered to be one of the major off-world candidates for extended development by humans, the problem of dust-related diseases needed to be considered by any people staying there for an extended time.
“The crews of the Apollo landing missions have not presented evidence of dust-associated disease (eg, silicosis), but the population is small and the exposure times quite limited, with the longest surface stay being only about 72 hours,” Professor Prisk said.
The lower gravity of locations such as the moon or Mars, as well as the zero-gravity environment of a spaceship, also makes coughing up dust harder, he said.
Also of concern is that unlike Earth, which is protected by its atmosphere, dust on celestial bodies such as the moon is exposed to the full force of cosmic radiation, meaning it could also be toxic when breathed in, beyond just being an irritant.
“In the case of lunar dust, there is a significant concern that the lack of any atmosphere means that the dust generated by meteoric bombardment over millennia will remain highly reactive and will thus have a high toxicological potential,” Professor Prisk said.
“By comparison, Martian dust has been exposed to an atmosphere (albeit a rather thin atmosphere), although there remain other concerns, such as the presence of perchlorate [a carcinogen] in Martian dust.”
Concern over the risk of possible alien diseases meant the Apollo 11 astronauts were kept in quarantine for three weeks after they returned from the moon.
Professor Prisk has noted lung function in astronauts does change when they spend long periods in space.
However, their lungs appear to return to normal relatively quickly once they return to Earth.
More broadly, despite the many challenges which it is faced with, Professor Prisk said the human lung adapts remarkably well to life off-world.
“While there are changes in lung function in partial or zero gravity, the lung continues to function well in this novel environment,” he said. | 0.904556 | 3.618635 |
Explaining the Movements of the Planets With Newton's Laws
Hundreds of years ago, people could only guess at how the planets moved and wonder why the sun rose and set each day. In 1687, Sir Isaac Newton changed astronomy forever with a work titled "Philosophiae Naturalis Principia Mathematica," or "Mathematical Principles of Natural Philosophy." This work contains Newton's laws of motions and gravity, which astronomers use to accurately explain the movement of planets.
Johanne Kepler's Planetary Laws
Years before the birth of Isaac Newton, a man named Johannes Kepler set the foundation for planetary laws of motion. Kepler went to work for a famed astronomer, Tycho Brahe, when he was 27 years old. Brahe asked him to determine the movement of the planet Mars. Kepler originally believed that planets orbited in a perfect circle. Eventually, however, he observed that planets have an elliptical orbit with the sun as the focus point in the center. He also determined that a planet moves more quickly when it's close to the sun and slower as it gets further from the sun. Kepler realized that there is a mathematical relationship between a planet's orbit time and its distance from the sun. This discovery would later inspire Newton's laws of motion.
Newton's First Law of Motion
Most scientists and thinkers of Isaac Newton's day believed that different kinds of motion had different causes. Newton, however, studied the laws of Kepler and noted that all motion followed the same basic principles. He conceived his first law -- a body at rest will remain still and a body in motion will continue moving at a constant velocity unless an outside force acts on it. This is the law of inertia, which explains how a planet moves in an elliptical orbit. If no force acted upon the planet, Newton stated that it would fly off into space in a straight line.
Newton's Second and Third Laws
Newton's second law describes how motion changes when some force acts upon an object. This law deals with the velocity and acceleration of planets. Velocity is the direction an object moves plus the speed of the object. The law is depicted in the equation F = ma, which means that the strength of a force is equal to the mass of the object being acted upon times the acceleration of that object. The third law is the law of reciprocal actions. Newton deduced that when one object exerted force upon a second object, that second object exerted an equal and opposite force on the first one. This law explains how the sun pulls on planets with gravity, just as the planets pull on the sun.
The Law of Universal Gravitation
Newton's last law describes how gravity works. According to Newton, all objects exert a force that pulls other objects to its center. The mass of the object dictates the strength of the force. The force also weakens as objects get farther apart. This law explains how the ocean tides rise and fall -- this movement is caused by the moon's gravitational pull as it orbits around Earth.
- Goodshoot/Goodshoot/Getty Images | 0.852721 | 3.824032 |
For the first time, astronomers are able to accurately simulate galaxies from shortly after the big bang to today by including a realistic treatment of the effects stars have on their host galaxies.
For the past few decades astronomers have simulated galaxies by mixing the basic physical ingredients — gravity, gas chemistry and the evolution of the universe — into their models.
For years their simulations have shown that gas cools off quickly and falls to the center of the galaxy. Eventually all of the gas forms stars. But observations show only “10 percent of the gas in the universe actually does so,” CalTech astronomer Dr. Philip Hopkins explained. “And in very small or very large galaxies, the number can go down to well below a percent.”
Models of galaxies create far too many stars and as a result end up weighing more than real galaxies in the observable universe. But in theory the solution is simple: the missing physics is a process known as stellar feedback.
For that, astronomers have to look at how stars help shape the evolution of the galaxies in which they reside. And what they have found is that stars affect their environments drastically.
When stars are very young they are extremely hot and blast off a high amount of radiation into space. This radiation heats up and pushes on the nearby interstellar gas. Later on stellar winds – particles streaming from the surface of stars — also push on the gas, further disrupting nearby star formation. Finally, explosions as supernovae can push the gas to nearly sonic speeds.
While astronomers have understood the missing physics for quite a while, they have not been able to successfully incorporate it a priori into their models. Despite their efforts their simulated galaxies have always weighed more than observed galaxies actually weigh.
Understanding the missing physics is a completely different question than being able to incorporate the missing physics directly into their models.
Instead, astronomers made big assumptions based on what galaxies should look like. At some point in their simulations, they had to go in by hand and tune certain parameters. They would get rid of so much gas until the results roughly matched the galaxies we observe.
“Basically, they (astronomers) said ‘we need there to be winds to explain the observations, so we’re going to insert those winds by hand into our models, and adjust the parameters until it looks like what’s observed,’ ” Hopkins told Universe Today.
At the time tuning their models in this way was the best astronomers could do and their models did help improve our understanding of galaxy evolution. But Hopkins and a team of astronomers from across North America have found a way to incorporate the missing physics — stellar feedback — directly into their models.
The research team is creating simulations that draw from stellar feedback explicitly. The FIRE (Feedback in Realistic Environments) project is a multi-year, multi-institution effort.
While it was no easy task, they incorporated the necessary and dare I say messy physics into their models, allowing for unprecedented accuracy. They tracked the affects radiation and stellar winds have on their environments and included a realistic supernovae rate.
“The result is that we see these stars pushing on the gas, and supernovae explosions sweeping up and ‘blowing out’ large amounts of material from galaxies,” Hopkins explained. “When you follow all of this, the story holds together, and indeed we can explain the observed masses of galaxies just from the input of stars.”
The results have been rewarding — providing some pretty cool videos of galaxies forming across the observable universe — and surprising.
It has become clear that the different types of stellar feedback don’t work alone. While the energy given off by stellar winds can push away interstellar gas, it cannot launch the gas out of the galaxy entirely. The necessary propulsion occurs, instead, when a supernova explosion happens nearby.
But this isn’t to say that supernova explosions play a larger role than stellar winds. If the authors left out any stellar feedback mechanism (the radiation from hot young stars, stellar winds, or supernova explosions) the results were equally poor — with too many stars and masses much too large.
“We’ve just begun to explore these new surprises, but we hope that these new tools will enable us to study a whole host of open questions in the field.”
The paper has been submitted for publication in the Monthly Notices of the Royal Astronomical Society and is available for download here.
Hopkins discusses the “Cosmological zoom-in simulation using new stellar feedback” at at workshop at the University of California, Santa Cruz earlier this year: | 0.848637 | 4.1267 |
Discovered in 1930, Pluto is the second closest dwarf planet to the Sun and was at one point classified as the ninth planet. Pluto is the largest dwarf planet but only the second most massive, with Eris being the most massive.
Facts about Pluto
- Pluto is named after the Roman god of the underworld.
This was proposed by Venetia Burney an eleven year old schoolgirl from Oxford, England.
- Pluto was reclassified from a planet to a dwarf planet in 2006.
This is when the IAU formalised the definition of a planet as “A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.”
- Pluto was discovered on February 18th, 1930 by the Lowell Observatory.
For the 76 years between Pluto being discovered and the time it was reclassified as a dwarf planet it completed under a third of its orbit around the Sun.
- Pluto has five known moons.
The moons are Charon (discovered in 1978,), Hydra and Nix (both discovered in 2005), Kerberos originally P4 (discovered 2011) and Styx originally P5 (discovered 2012) official designations S/2011 (134340) 1 and S/2012 (134340) 1.
- Pluto is the largest dwarf planet.
At one point it was thought this could be Eris. Currently the most accurate measurements give Eris an average diameter of 2,326km with a margin of error of 12km, while Pluto’s diameter is 2,372km with a 2km margin of error.
- Pluto is one third water.
This is in the form of water ice which is more than 3 times as much water as in all the Earth’s oceans, the remaining two thirds are rock. Pluto’s surface is covered with ices, and has several mountain ranges, light and dark regions, and a scattering of craters.
- Pluto is smaller than a number of moons.
These are Ganymede, Titan, Callisto, Io, Europa, Triton, and the Earth’s moon. Pluto has 66% of the diameter of the Earth’s moon and 18% of its mass. While it is now confirmed that Pluto is the largest dwarf planet for around 10 years it was thought that this was Eris.
- Pluto has a eccentric and inclined orbit.
This takes it between 4.4 and 7.3 billion km from the Sun meaning Pluto is periodically closer to the Sun than Neptune.
- Pluto has been visited by one spacecraft.
The New Horizons spacecraft, which was launched in 2006, flew by Pluto on the 14th of July 2015 and took a series of images and other measurements. New Horizons is now on its way to the Kuiper Belt to explore even more distant objects.
- Pluto’s location was predicted by Percival Lowell in 1915.
The prediction came from deviations he initially observed in 1905 in the orbits of Uranus and Neptune.
- Pluto sometimes has an atmosphere.
When Pluto elliptical orbit takes it closer to the Sun, its surface ice thaws and forms a thin atmosphere primarily of nitrogen which slowly escapes the planet. It also has a methane haze that overs about 161 kilometres above the surface. The methane is dissociated by sunlight into hydrocarbons that fall to the surface and coat the ice with a dark covering. When Pluto travels away from the Sun the atmosphere then freezes back to its solid state.
Pluto Image – www.nasa.gov/image-feature/global-mosaic-of-pluto-in-true-color | 0.816531 | 3.577553 |
Honoring the Fourth of July, NASA Tuesday released a striking new image of Herbig-Haro 110, a geyser of hot gas from a newborn star that looks remarkably like an Earth-bound skyrocket. HH 110 is a member of a family of Herbig-Haro objects that generally consist of two jets of hot gas ejected in opposite directions from a forming star. Astronomers think that the jets are fueled by gas falling into a young star from a surrounding disc of dust and gas. The gravitational heating causes jets of gas to be ejected at high speeds.
The jets slow down and cool off a bit, only to have pulses of gas emitted after them crash from behind. The friction of the collision heats the gas again, causing it to shine brightly. The result is a series of pulses that extend, in this case, over half a light-year.
HH 110, which is 1,300 light-years from Earth, has only one jet, and researchers have been unable to find its parent star. They now believe that this is because it is generated by another Herbig-Haro object. The team now believes that the nearby HH 279 jet grazes an immovable obstacle, a much denser, colder cloud core, and gets diverted off at about a 60-degree angle. The jet goes dark and then re-emerges, becoming HH 110.
The newly released image is a composite of data taken by the Hubble Orbiting Telescope Advanced Camera for Surveys in 2004 and 2005 and its Wide Field Camera 3 in 2011. | 0.825455 | 3.188647 |
The planet Mars will make a once-in-our-lifetimes, remarkably close approach to Earth on 27 August 2018.
Some things never go out of style, and the annual “Mars Spectacular” message announcing an evening when Mars will appear “as big as the moon in the sky” is one of them. It’s yet another example of a widely-circulated e-mail containing information that was once at least partly true but which continues to be forwarded around year after year in embellished form, long after whatever valid information it once contained has become outdated:
Two moons in the sky on August 27! The next time this cosmic event will happen again, will be 36,996 … Share this information as much as possible with your friends because NO human being alive today will be able to behold this incredible phenomenon a second time.
On August 27, around midnight, do not forget to raise your head and look into the sky: Mars will be the most brilliant star in the sky. This is because it will have an apparent diameter as big as the Full Moon! It will be possible to observe, with the naked eye, a cosmic phenomenon which will allow the inhabitants of the Earth to behold … two moons!
This is the first time that humanity will be able to observe this exceptional phenomenon. The last planet Mars proximity of such magnitude dates back to exactly 34,978 years, the Neolithic period during which Neanderthal and Homo habilis, the distant ancestors of Homo sapiens, coexisted together. Species to which the human race –- or more precisely, mankind –- belongs today.
This unique cosmic phenomenon called “two moons” is related, in part, to the proximity of the planet Mars with the Earth. As you must have seen on TV or read in the press, the planet Mars is now closer to the Earth, it is also possible to observe the orange star at night in the sky by looking towards the South. This phenomenon is quite common and appears about every 15 years.
Mars did make an extraordinarily close approach to Earth fifteen years ago, culminating on 27 August 2003, when the red planet came within 35 million miles (or 56 million kilometers) of Earth, its nearest approach to us in almost 60,000 years. At that time, Mars appeared approximately 6 times larger and 85 times brighter in the sky than it ordinarily does. (One version of the message was often reproduced with an unfortunate line break, leaving some readers with the mistaken impression that Mars would “look as large as the full moon to the naked eye” without realizing that that statement only applied to those viewing Mars through a telescope with 75-power magnification.)
Although Mars’ proximity to Earth in August 2003 (referred to as a perihelic opposition) was a rare occurrence, the red planet comes almost as near to us every 15 to 17 years. To the unaided observer, Mars’ appearance in August 2003 wasn’t significantly larger or brighter than it is during those much more common intervals of closeness.
Mars had another close encounter with Earth in 2005, but that occurrence took place in October (not August), and the red planet appeared about 20% smaller than it did during similar circumstances in 2003. Mars also made a close approach to Earth in December 2007, but even then it was still about 55 million miles away from us, not nearly as close as it was in 2003 or 2005.
The closest encounter between Mars and Earth since 2003 will occur on 27 July 2018, when the orbits of the two planets bring them to within 35.8 million miles of each other. Astronomers say Mars will appear twice as bright as usual around that time (though it will certainly not rival the brightness or size of the full moon).
The 2003 opposition will hang onto the record for the closest approach of Mars to Earth until 2287, when it is estimated the planets will be separated by 34.6 million miles.
Texas astronomer Torvald Hessel observed the following in a 2006 interview about the perennial “Mars Spectacular” message:
Q: What’s the truth?
A: Mars gets close to Earth every two years. So, last year, Mars was very close. Three years ago, it was spectacularly close … And right now, I’m sad to say, Mars is actually behind the Sun; we can’t see it at all.
Q: How wide spread is this falsehood?
A: People get excited about it, start to send e-mail … and every August we see this e-mail coming back and I get a lot of e-mails about it, of course.
The Smithsonian National Air and Space Museum also noted in 2010 that:
The e-mail in question is commonly referred to as the “Mars Hoax” or, more accurately, the “Mars Spectacular,” and is titled: “Two moons on 27 August or The Red Planet is about to be spectacular!”
It informs recipients that Mars will have an extremely close encounter with Earth during the month of August, culminating on August 27th when Mars is approximately 34 million miles away. The information in the previous sentence was only true during the month of August in 2003. This was a historic astronomical event. Mars was the closest it had been to Earth in 60,000 years. However, this already happened.
The web site of the Students for the Exploration and Development of Space (SEDS) provides a chart displaying data about Mars Oppositions (past, present, and future), and the web site of the Hubble Heritage Project offers some nice composite telescope images from previous Mars near oppositions. | 0.867105 | 3.297791 |
On Planet Earth, we revolve on our axis at 1000 mph, traveling around the Sun at 67,000 mph, whilst the Sun is traveling around the center of the Milky Way at a speed of 450,000 mph. Everything is revolving and spiraling through space, generating enormous gravitational and magnetic forces.
On Earth, we feel sheltered from these forces, wrapped up in the paper-thin cocoon of our oxygenated atmosphere, anchored on the even thinner crust of the Earth, which encases the molten center of the planet. Astronomy is the science which reveals these, our physical circumstances. Astrology is the art which shows how humans and the cosmos interact in this maelstrom of known and unknown forces.
In its travels, spiraling around the Sun through the Milky Way, Earth forges through thousands of tons of cosmic particles, of which tens of tons fall to the Earth each day as cosmic dust. The Sun itself, carries in its gravitational field an ecosystem of planets, comets, asteroids and moons, in what is known as the heliosphere – the Sun’s domain. When the heliosphere hits interstellar space Termination Shock is reached, which is when the solar wind can no longer compete against interstellar forces, and turns in on itself.
We know all this, because the spacecraft Voyager 1 left the heliosphere on August 25th, 2012. Meanwhile, its sister ship Voyager 2 is, here in 2018, also leaving the heliosphere, 40 years after its launch, carrying with it a Golden Record with digitally recorded music, pictures of human existence on Earth and other relevant information, so that – some time in the distant future – an alien species will know we are here. From India, the message was: “Hello to everyone. We are happy here, and you be happy there”.
This article tells the story of mankind’s longest journey. In the summer of 1977 both Voyager spacecraft were launched – first Voyager 2, then some weeks later, Voyager 1. For this journey to take place, launch could only take place at this time in history – not before. Why? Because Jupiter, Saturn, Uranus and Neptune had to be in alignment, and for that to take place, Jupiter has to be approaching Saturn, Saturn has to approach Uranus, and Uranus has to approach Neptune (which can only happen once ever 172 years). The whole point of this alignment for the Voyager program was that close flybys gave “gravity assist” accelerating the speed of the spacecraft to over one million miles a day and cutting over 20 years from travel time.
Thus, by an extraordinary stroke of “luck” Voyager could fly by all major planets (except Pluto) exactly at the time mankind had the technological capacity to do so.
Voyager 2 launch. August 20, 1977, 21.26 Cape Canaveral, Florida AS 13.38 Libra
The plan was to send Voyager 1 to Jupiter and Saturn and on a flyby of Saturn’s largest moon Titan, and from there off out of the heliosphere. Voyager 2 was to go to Jupiter and Saturn, and if all went well, on to Uranus and Neptune. In the mid-seventies computers were in their infancy. No flash drives, no hard disks – data was recorded on a tape recorder, and the calculations to time arrivals at each planet and turn the camera on the spacecraft to photograph each moon at an exact hour were extremely complex. For the mechanics to work there was a plutonium energy source which gave enough warmth to prevent breakdown in near absolute zero temperatures.
Voyager 2 horoscope
Perhaps all this can be seen in the launch horoscope, where Pluto conjoins the Ascendant (the plutonium?) and the North Node of the Moon. At the same time, the Moon in Scorpio exactly conjoins Uranus which is an extraordinarily explosive combination – something which was to be discovered in an unexpected way when Voyager 2 flew past Uranus. The Sun configures exactly with Moon/Uranus by quintile aspect (and Neptune/Venus by semi-quintile), and septile aspects – the 7th harmonic horoscope – show an amazing conjunction of Jupiter and Saturn with the Pluto/Ascendant and opposing Moon/Uranus on the Descendant. In other words, all the planets beyond Mars are configured in a tight pattern reflecting the qualities of 5, creative outreach, and 7, cosmic mystery.
What better signature for the Voyager Grand Tour than to see Jupiter itself just entering exaltation in Cancer at 0.00 degrees – a key degree for world events. together with Mars in the 9th house. Mars itself is square Mercury, symbolizing perhaps the transmission back to Earth of an unprecedented amount of data, and never-before seen images of the moons of Jupiter, Saturn, Uranus and Neptune. To crown the magic of this horoscope, Venus in Cancer is exactly sextile Mercury with an orb of 2 minutes of arc, reflecting, perhaps, the extraordinary beauty and detail of the digital photography.
Discovery of the Outer Planets
The discovery of Uranus, Neptune and Pluto in 1781, 1846 and 1930 respectively, clearly showed that outer exploration was synchronistic with transformative changes in society. The development of the telescope enable the discovery of Uranus, which at a stroke doubled the area of the solar system. This was the time when revolutions shook first the USA in 1776 and then France in 1789. The principles of freedom, equality and brotherhood were enshrined in constitutions in true Aquarian fashion. Mankind conquered the air, first with hot air balloons, later with jet aircraft and rockets. The discovery of Neptune coincided with the first use of anesthetics, the communist manifesto, and the development of the camera, which later found expression in film and the cinema. And the discovery of Pluto coincided with the Depression, dictatorial leadership, the splitting of the atom and later the threat of world destruction with the atomic bomb.
The same synchronicity affects every human exploration of our solar system. Pictures sent back by the Apollo spacecraft of the Earth rising over the horizon of the Moon, became the first cosmic Selfie. The first Earth Day in 1970 was inspired by this Apollo 8 Earthrise photo. It awakened ecological consciousness, and the Moon landing awakened a nurturing awareness of the vulnerability of our planet and, interestingly, attachment theory (Moon) became a predominant development in psychology. By the mid-1970’s spacecraft had made flybys of Venus (1962), Mercury, and landed a rover on Mars. The Pioneer 11 spacecraft had even flown by Jupiter and in 1979 Saturn, but they were unable to send back pictures of better quality than those acquired by telescopes on Earth.
The Euphoric Arrival at Jupiter
The Voyager Grand Tour opened a new dimension. In 1979 both Voyagers arrived at Jupiter sending a stream of fantastic pictures, and showing that water and volcanic activity existed on some of the moons, particularly Europa, which made them candidates for habitation. Voyager 1 arrived on March 5th, 1979 and Voyager 2 on July 9th, 1979. Back on Earth, this was the time the Islamic Republic of Iran was founded, with the return of Ayatollah Khomeini, which sparked decades of religious fundamentalism, as Middle-Eastern countries competed to be leaders in the Islamic world. With the election of Margaret Thatcher that year, another kind of idealism – Thatcherism – was to take hold. This was the theory of expansion without excessive state control – a philosophy which also took hold in the USA with the election of Reagan in 1980 and Reaganomics. In China, Deng Xiaoping introduced “Socialism with Chinese characteristics”, which gave rise to a burst of capitalist expansion.
The general mood back at NASA was euphoric, and as the Voyager spacecraft sent back previously unseen photographs of the Jupiter system in the rear-view mirror, the imaging teams, and trajectory calculation teams – hundreds of technicians, began their work on the impending Saturn flybys.
Saturn and the Prospect of Failure
The Voyager 1 and Voyager 2 encounters with Saturn took place nine months apart – the first in November 1980 and the second in August 1981, and by this time the Jupiter/Saturn conjunction was taking place – the first one in air signs for over 600 years, conjoining Pluto and the Ascendant of the launch horoscope. Reaganomics had another side, and apart from encouraging Wall Street excesses, there was a corresponding period of budget cutting, which was profoundly affecting NASA. The Voyager teams were drastically cut back, not least because five years would go by before Voyager 2 arrived at Uranus. And in Britain, Margaret Thatcher, who believed trade unions were a fossilized relic from the past, began to realize her long-term ambition to crush trade unions, not least in the coal industry.
Despite the initial success of the Saturn flyby, the atmosphere at NASA was depressed. When Voyager 2 flew into the shadow of Saturn the fall in temperature caused a malfunction on the camera scan platform. High hopes that new and amazing discoveries would be made about Saturn’s ring system from the dark side of the planet were crushed. No pictures at all were transmitted in this last phase of the Voyager 2 flyby. Conspiracy theorists suggested that NASA had discovered secret information that they would not reveal.
As Jim Bell related in his book about the mission (Note 1): “a sense of gloom pervaded the Imaging Science area… it was like watching each labored breath, waiting for the sick scan platform to expire”. This was NASA’s baby, and the future of the mission to Uranus and Neptune seemed compromised.
Bullseye on Uranus
After the gravity assist from Saturn, Voyager 2 sped on its way to Uranus, and technicians developed a workaround for the damaged camera platform. Meanwhile Voyager 1 sped away to the outer reaches of the solar system without further encounters. As Voyager 2 approached Uranus, an extraordinary sight greeted them. Unlike all other planets, Uranus revolved at a 180-degree angle to the plane of the ecliptic, and this meant that the moons of Uranus were arrayed like a bullseye.
As a result, unlike the leisurely exploration of the moons of Jupiter and Saturn, Voyager 2 would speed past Uranus and its 27 moons in less than one day. Most of these moons are very small, but there are five large moons: Miranda, Ariel, Umbriel, Titania, and Oberon. From an astrological point of view, it is possible that each of the many moons of the planets beyond Mars, represent a nuance in the expression of each planet. For example, it is interesting that the New Horizons spacecraft, which took detailed photographs of Pluto and its enormous satellite Charon, revealed Pluto with a massive heart etched onto its surface, whilst Charon was a cracked and cratered wreck, which with a little imagination could be seen to reflect a beautiful transformation on the one hand, and destruction on the other.
Explosion Over the Atlantic
Something incredible took place as Voyager 2 was relaying its last photographs of Uranus. Back in NASA, everyone was simultaneously following the launch of the Challenger space shuttle. A reporter for National Geographic described the scene:
“Tuesday, January 28. As Voyager scientists are preparing to sum up the mission to the press, the space shuttle Challenger explodes. Those clustered in the JPL’s press centre share a horrible irony. On one monitor we watch replay after replay of seven lives evaporating over the Atlantic, while on the adjacent TV screen, we see the latest triumphant pictures from Uranus.”
This explosion was probably witnessed by the largest number of people ever. Perhaps Uranus had a statement to make. This was the period when Reagan was pushing SDI – the Star Wars initiative which spooked the Soviet Union, because it would enable a first strike by USA. This was also the time of another massive explosion, which affected large areas of the world – the meltdown of Chernobyl on April 26th, 1986.
The Challenger explosion took place with Uranus exactly square Mercury and opposing Mars in the launch horoscope, whilst Mars exactly squared the launch Sun (and of course the 27 degree Aquarius position of the US Moon). Pluto, aptly, was one degree from the Moon/Uranus of launch – the aspect that presaged this disaster, and the explosion MC was on US Pluto.
Challenger explosion. April 26. 1986. 11.39 EST Cape Canaveral, Florida.
Neptune and a New World Order
Voyager 2 left Jupiter with euphoria amongst the NASA team; it left Saturn with gloom, and Uranus with shock. What would the encounter with Neptune reveal? The spacecraft’s closest approach to Neptune took place on August 26th, 1989 – a complete Jupiter cycle from launch, and now Uranus was exactly opposing the launch Jupiter.
Voyager closest approach. August 26, 1989 9.00 a.m. PDT Pasadena, California
What a year 1989 was! As the distant outer planets Saturn, Uranus and Neptune approached to make a grand conjunction in early Capricorn, the world was changing. The 172-year Uranus/Neptune cycle was soon to begin, bringing the New World Order with it. The seemingly invincible Soviet Union with its East European satellite states, was in the process of dissolving. The Chernobyl explosion led to Perestroika – openness – and this openness exposed the weaknesses of the creaking Soviet empire. One by one the its vassal states seceded from the “evil empire” as Reagan liked to call it. But none so dramatically as in East Germany, where, as Jupiter at 10 degrees Cancer went to oppose the Saturn/Neptune conjunction at 10 degrees Capricorn, hammers large and small broke down the Berlin Wall on November 9th and people streamed from East to West.
So, as Voyager 2 explored Neptune and its magic moons (none more magic than Triton, which, extraordinarily, orbits in the opposite direction to Neptune’s other main moons), the Iron Curtain itself dissolved. On August 23rd, 1989 – three days before Neptune’s closest approach, the populations of the Baltic countries – Latvia, Estonia and Lithuania – joined hands, forming a 400-mile human chain to protest the Soviet occupation. What could be a better symbol of the unifying principle of Neptune, which evokes humanity’s need to rise above material limitations and join against oppression and suffering, and for love and unity?
Now, both Voyager spacecraft have left our home – the solar system – in the direction of far-distant Sirius. When found by an alien civilization, they will be able to play the Golden Record on board and dance to the music of Chuck berry’s “Johnny B. Goode” and read instructions about how to get to Earth. Not everyone thought this was a good idea. As Stephen Hawking said: “Don’t tell the aliens we’re here, they might not be friendly”.
Adrian Ross Duncan
March 20th, 2018
1. “The Interstellar Age: Inside the Forty-Year Voyager Mission” – Jim Bell | 0.825983 | 3.368129 |
A team of astronomers at the University of Chicago and Grinnell College seeks to change the way scientists approach the search for Earth-like planets orbiting stars other than the sun. They favor taking a statistical comparative approach in seeking habitable planets and life beyond the solar system.
“The nature of proof should not be: ‘Can we point at a planet and say, yes or no, that’s the planet hosting alien life,” said Jacob Bean, associate professor of astronomy and astrophysics at UChicago. “It’s a statisical exercise. What can we say for an ensemble of planets about the frequency of the existence of habitable environments, or the frequency of the existence of life on those planets?”
The standard approach of researching exoplanets, or planets that orbit distant stars, has entailed studying small numbers of objects to determine if they have the right gases in the appropriate quantities and ratios to indicate the existence of life. But in a recent paper with co-authors Dorian Abbot and Eliza Kempton in the Astrophysical Journal Letters, Bean describes the need “to think about the techniques and approaches of astronomy in this game—not as planetary scientists studying exoplanets.”
“Nature has provided us with huge numbers of planetary systems,” said Kempton, an assistant professor of physics at Grinnell College in Iowa. “If we survey a large number of planets with less detailed measurements, we can still get a statistical sense for how prevalent habitable environments are in our galaxy. This would give us a basis for future, more detailed surveys.”
Kempton and Bean attest to the challenges of making detailed observations of a potentially Earth-like planet. Together they have previously studied the super-Earth known as GJ 1214b, an exoplanet with a mass greater than Earth’s but less than gas giants such as Neptune and Uranus. GJ 1214b turned out to be quite cloudy, which prevented them from determining the composition of its atmosphere.
“A large statistical study will allow us to look at many planets,” Kempton said. “If any single object proves to be particularly challenging to observe, like GJ 1214b, that won’t be a major loss to the observing program on the whole.”
Kepler observatory a game-changer
The inspiration for the paper stemmed from Bean’s membership on the Science and Technology Definition Team that is assessing the potential for a new space telescope, NASA’s proposed Large UV/Optical/Infrared Survey (LUVOIR).
One of LUVOIR’s scientific priorities is the search for Earth-like planets. During one team meeting, Bean and his colleagues listed all the properties of a potentially habitable exoplanet that they need to measure and how they would go about obtaining the data. Given the current state of technology, Bean concluded that it’s unlikely scientists will be able to confirm an individual exoplanet as suitable for life or whether life is actually there.
Nevertheless, astronomers have gathered an impressive haul of exoplanetary data from NASA’s Kepler space observatory, which has operated since 2009.
“Kepler completely changed the game,” Bean said. “Instead of talking about a few planets or a few tens of planets, all of a sudden we had a few thousand planet candidates. They were planet candidates because Kepler couldn’t definitely prove that the signal it was seeing was due to planets.”
The standard approach has been to take additional observations for each candidate to rule out possible false positive scenarios, or to detect the planet with a second technique.
“That’s very slow going. One planet at a time, a lot of different observations,” Bean noted. But an alternative is to make statistical calculations for the probability of false positives among these thousands of exoplanet candidates. That new approach led directly to a good understanding of the frequency of exoplanets of different sizes. For example, scientists now can say that the frequency of super-Earth-type planets is 15 percent, plus or minus 5 percent.
Role of spectroscopy
Spectroscopic studies play a key role in characterizing exoplanets. This involves determining the composition of a planetary atmosphere by measuring its spectra, the distinctive radiation that gases absorb at their own particular wavelengths. Bean and his co-authors suggest focusing on what can be learned from measuring the spectra of a large ensemble of terrestrial exoplanets.
Spectroscopy may, for example, help exoplanetary researchers verify a phenomenon called the silicate weathering feedback, which acts as a planetary thermostat. Through silicate weathering, the amount of atmospheric carbon dioxide varies according to geologic processes. Volcanoes emit carbon dioxide into the atmosphere, but rain and chemical reactions that occur in rocks and sediments also remove the gas from the atmosphere.
Rising temperatures would put more water vapor into the atmosphere, which then rains out, increasing the amount of dissolved carbon dioxide that chemically interacts with the rocks. This loss of carbon dioxide from the atmosphere has a cooling effect. But as a planet begins to cool, rock weathering slows and the amount of carbon dioxide gradually builds from its volcanic sources, which causes rising temperatures.
Global-scale observations suggest that Earth has experienced silicate-weathering feedback. But attempts to verify that the process is operating today on the scale of individual river basins has proven difficult.
“The results are very noisy. There’s no clear signal,” Abbot said. “It would be great to have another independent confirmation from exoplanets.”
All three co-authors are interested in fleshing out the details of experiments they proposed in their paper. Abbot plans to calculate how much carbon dioxide would be necessary to keep a planet habitable at a range of stellar radiation intensities while changing various planetary parameters. He also will assess how well a future instrument would be able to measure the gas.
“Then we will put this together to see how many planets we would need to observe to detect the trend indicating a silicate-weathering feedback,” Abbot explained.
Bean and Kempton, meanwhile, are interested in detailing what a statistical census of biologically significant gases such as oxygen, carbon dioxide and ozone could reveal about planetary habitability.
“I’d like to get a better understanding of how some of the next-generation telescopes will be able to distinguish statistical trends that indicate habitable—or inhabited—planets,” Kempton said.
Citation: “A statistical comparative planetology approach to the hunt for habitable exoplanets and life beyond the solar system,” by Jacob L. Bean, Dorian S. Abbot and Eliza M.-R. Kempton, Astrophysical Journal Letters. Doi: 10.3847/2041-8213/aa738a/.
Funding: David and Lucile Packard Foundation, National Aeronautics and Space Administration, Research Corporation for Science Advancement, and Grinnell College’s Harris Faculty Fellowship. | 0.927283 | 3.858599 |
A SNAPSHOT of a lonely planet rejected by its star system and hurtling
towards oblivion was released last week by NASA. The picture, taken in the
infrared by the Hubble Space Telescope, is the first convincing direct view of
an extrasolar planet, the space agency claims.
The latest announcement follows hard on the heels of a similar image,
released with little fanfare (This Week, 31 January, p 6). Doubts remain over
whether either picture really depicts an alien planet. But if they are what they
seem, astronomers have their hands on images that some thought would only be
taken by future generations of orbiting telescopes (“Searching for alien Earth”,
New Scientist, 13 May 1995, p 24).
Some 450 light years away in the constellation of Taurus, stars are being
born in a cloud of dust. Susan Terebey of the Extrasolar Research Corporation in
Pasadena, California, was looking at these stars when she noticed a streamer of
radiation in a binary star system. At its end was an object that Terebey and her
colleagues believe is a planet about twice the size of Jupiter. “It may be the
first picture ever taken of a planet outside the Solar System,” she says.
The object, dubbed TMR-1C, seems to have been thrown out of its star system
by the unstable gravitational influence of the two central stars. TMR-1C’s
distance from these stars is about 1400 times the gap between the Earth and the
Sun. As TMR-1C sped away, Terebey argues, it carved a tunnel in the dusty cloud,
creating the illuminated streamer.
The images come from NICMOS, the Near Infrared Camera and Multi-image
Spectrometer, installed on Hubble in February 1997. Infrared can penetrate
clouds of dust, so astronomers can see details that are hidden in the visible
Alan Boss, an astrophysicist at the Carnegie Institution in Washington DC, is
convinced by Terebey’s interpretation. “This is the first image of another
planet around its star,” he asserts.
The earlier claim, made by Al Schulz of the Space Telescope Science Institute
in Baltimore, didn’t impress Boss. Schulz’s team also used Hubble and spotted a
point of light on two occasions, three months apart. It seemed to be orbiting
the Sun’s nearest stellar neighbour, Proxima Centauri, 4.2 light years away. But
other researchers have since failed to spot the object.
Schultz argues that his object disappeared because its orbit brought it into
the glow produced by its parent star. He expects it to become visible again in
A question mark also hangs over Terebey’s planet. Although she estimates that
it is twice the size of Jupiter, it may be much larger. And if its mass is much
more than ten times that of Jupiter, it might not be a planet, but a brown
dwarf—a failed star, too puny to sustain thermonuclear reactions.
Terebey assumed the planet was the same age as its parent stars. She
determined its temperature from the spectrum of the radiation it emitted.
Because the temperature of a young planet depends on its age and its size, she
was then able to estimate its mass. However, other astronomers say there are
wide margins for error. “We just don’t know, frankly, that it’s two Jupiter
masses,” says Jonathan Lunine of the University of Arizona in Tucson.
If Terebey’s object is a planet, it is an interesting one. The two stars in
the binary system are only a few hundred thousand years old, but a popular
theory of how Jupiter-sized planets form implies that it would take a million
years for the dust orbiting a star to coalesce into a rocky planetary core, and
then 10 million years more for the core to acquire a gaseous envelope. Boss
argues that Terebey’s data support a rival “one step” theory for planetary
formation, which allows the material orbiting a star to form a planet in a
thousand years or less. | 0.909909 | 3.608428 |
As aptly observed by shuttle veteran Don Pettit, humans are distinctly disadvantaged in in search of to realize orbit. The trouble, colloquially acknowledged as the “tyranny of the rocket equation,” is that as payload mass improves, so does the total of propellant necessary to crack no cost of Earth’s gravitational grip. Even between spacecraft of radically unique structure, the ratios are strikingly related. The Saturn V rocket that took astronauts to the moon was eighty five per cent propellant by mass on the launchpad, virtually similar to the area shuttle. And the total of payload mass rarely ever exceeds four per cent of that of the entire rocket.
Thus, all launch vehicles suffer from Earth’s gravity with equivalent impact. Whilst new discoveries in resources science are yielding huge innovations in the structural integrity of spacecraft, only marginal improvements in the cargo-to-weight ratios have been uncovered. The more one particular does the math, the fewer advantageous Earth-dependent launch becomes.
Contemplate this: Irrespective of the generations of probes and robotic missions to Mars, some 34 million miles from Earth at its perigee, humans have in no way transited more than 1 per cent of that distance in area. And yet, back again in the 1960s, Wernher von Braun experienced dreamed of, and made, spacecraft to achieve that feat by the nineteen eighties.
Regretably, fairly than proceed to boost on the Saturn V, American political will atrophied and the country receded from its spacefaring ambitions. The subsequent yrs uncovered our get to limited to a quick shuttle vacation 250 miles upward. In truth, right until the advancement of the Space Start System (SLS), there was not even a auto able of returning astronauts to the moon, enable on your own Mars.
On the other hand, with SLS main motor stage screening underway at NASA’s Stennis Space Heart, America is fast approaching a return to deep area. And with the evolution of the SLS to its Block 2 variant with a payload capability of virtually one hundred,000 kilos per launch, the country will lastly understand the dream of a everlasting lunar outpost.
Whilst the reusability of reduced-Earth orbit launch vehicles and crew modules can boost cost efficiency, deep area missions need payloads on an inherently larger scale.
The lunar area is not simply just a location, it is more akin to a training and equipping station. With its gravity perfectly only one particular sixth of Earth’s and a abundant array of chemical things, the moon will be a staging floor for missions additional afield. On the other hand, for that to happen, early human explorers will need sizeable materiel support. That is wherever the SLS will make all the change.
Significantly, the previous several decades of deep area exploration have disclosed the omnipresent biological building blocks of oxygen, nitrogen, potassium and even calcium. So, we know humans can live off Earth. But we really don’t just want to survive we want to prosper. Luckily, metals critical for industrial software, such as aluminum, nickel, cobalt and titanium, materialize to be unbelievably plentiful all over the inner photo voltaic system. With SLS coming online, area exploration and habitation will shift from sole Earth dependency into an period of self-sustainment.
Whilst first settlement functions will certainly need prefabricated shelter and power generation modules, a sustained lunar existence will necessitate use of community sources. As deep area provide chains will generally be tenuous, scalable human occupation have to depend on lunar extraction and production functions with ever-expanding capability to guarantee ample provide of food, air, h2o, rocket propellant and construction resources. Certainly, the industrial learning curve will be steep, but the multinational and business enthusiasm currently underway demonstrates the shared commitment to recognize and get over obstacles as they crop up.
As U.S. Chamber of Commerce CEO Tom Donohue just lately wrote, “We are in the early levels of an financial revolution that could redefine the boundaries of humankind. Space is not an vacant void but a landscape of countless likelihood.”
Most likely we can not trick the legal guidelines of physics as witnessed on the Hollywood display screen, but SLS will decisively get over Earth’s gravity and established us on a training course to boldly go wherever no one particular has long gone ahead of. | 0.826644 | 3.337121 |
Using NASA’s Hubble and Kepler space telescopes, astronomers have uncovered tantalizing evidence of what could be the first discovery of a moon orbiting a planet outside our solar system.
This moon candidate, which is 8,000 light-years from Earth in the Cygnus constellation, orbits a gas-giant planet that, in turn, orbits a star called Kepler-1625. Researchers caution that the moon hypothesis is tentative and must be confirmed by follow-up Hubble observations.
“This intriguing finding shows how NASA’s missions work together to uncover incredible mysteries in our cosmos,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate at Headquarters, Washington. “If confirmed, this finding could completely shake up our understanding of how moons are formed and what they can be made of.”
Since moons outside our solar system – known as exomoons – cannot be imaged directly, their presence is inferred when they pass in front of a star, momentarily dimming its light. Such an event is called a transit, and has been used to detect many of the exoplanets cataloged to date.
However, exomoons are harder to detect than exoplanets because they are smaller than their companion planet, and so their transit signal is weaker when plotted on a light curve that measures the duration of the planet crossing and the amount of momentary dimming. Exomoons also shift position with each transit because the moon is orbiting the planet.
In search of exomoons, Alex Teachey and David Kipping, astronomers at Columbia University in New York, analyzed data from 284 Kepler-discovered planets that were in comparatively wide orbits, longer than 30 days, around their host star. The researchers found one instance in planet Kepler-1625b, of a transit signature with intriguing anomalies, suggesting the presence of a moon.
“We saw little deviations and wobbles in the light curve that caught our attention,” Kipping said.
NASA’s Hubble and Kepler space telescopes have uncovered what could be the first exomoon.
Based upon their findings, the team spent 40 hours making observations with Hubble to study the planet intensively – also using the transit method – obtaining more precise data on the dips of light. Scientists monitored the planet before and during its 19-hour transit across the face of the star. After the transit ended, Hubble detected a second, and much smaller, decrease in the star’s brightness approximately 3.5 hours later. This small decrease is consistent with a gravitationally-bound moon trailing the planet, much like a dog following after its owner. Unfortunately, the scheduled Hubble observations ended before the complete transit of the candidate moon could be measured and its existence confirmed.
In addition to this dip in light, Hubble provided supporting evidence for the moon hypothesis by finding the planet transit occurring more than an hour earlier than predicted. This is consistent with a planet and moon orbiting a common center of gravity that would cause the planet to wobble from its predicted location, much the way Earth wobbles as our Moon orbits it.
The researchers note the planetary wobble could be caused by the gravitational pull of a hypothetical second planet in the system, rather than a moon. While Kepler has not detected a second planet in the system, it could be that the planet is there, but not detectable using Kepler’s techniques.
“A companion moon is the simplest and most natural explanation for the second dip in the light curve and the orbit-timing deviation,” Kipping explained. “It was definitely a shocking moment to see that Hubble light curve, my heart started beating a little faster as I kept looking at that signature. But we knew our job was to keep a level head and essentially assume it was bogus, testing every conceivable way in which the data could be tricking us.”
In a paper published in the journal Science Advances, the scientists report the candidate moon is unusually large – potentially comparable to Neptune. Such large moons do not exist in our own solar system. The researchers say this may yield new insights into the development of planetary systems and may cause experts to revisit theories of how moons form around planets.
The moon candidate is estimated to be only 1.5 percent the mass of its companion planet, and the planet is estimated to be several times the mass of Jupiter. This mass-ratio is similar to the one between Earth and the Moon. In the case of the Earth-Moon system and the Pluto-Charon system, the moons are thought to be created through dust leftover after rocky planetary collisions. However, Kepler-1625b and its possible satellite are gaseous and not rocky, so the moon may have formed through a different process.
Researchers note that if this is indeed a moon, both it and its host planet lie within their star’s habitable zone, where moderate temperatures allow for the existence of liquid water on any solid planetary surface. However, both bodies are considered to be gaseous and, therefore, unsuitable for life as we know it.
Future searches for exomoons, in general, will target Jupiter-size planets that are farther from their star than Earth is from the Sun. The ideal candidate planets hosting moons are in wide orbits, with long and infrequent transit times. In this search, a moon would have been among the easiest to detect because of its large size. Currently, there are just a handful of such planets in the Kepler database. Whether future observations confirm the existence of the Kepler-1625b moon, NASA’s James Webb Space Telescope will be used to find candidate moons around other planets, with much greater detail than Kepler.
“We can expect to see really tiny moons with Webb,” Teachey said.
Space Telescope Science Institute, Baltimore
Ames Research Center, California’s Silicon Valley | 0.871297 | 3.972076 |
Content by James Whitby, with contributions from Leandro von Werra, Prof. Nicolas Thomas, Dr Veerle Sterken, Dr Frank Preusker, Dr Frank Scholten, and Dr Raphael Marschall.
- 1 Science themes addressed by the MiARD project
- 1.1 Mapping
- 1.2 Cometary outgassing and material loss i.e. ‘activity’
- 1.3 Dust
- 1.4 What have we learnt from the Rosetta mission?
- 1.5 A future sample return mission?
- 1.6 Links to further information:
Science themes addressed by the MiARD project
The LOMID project seeks to combine two different techniques which can be used to generate a digital terrain model or relief map from a set of images. The two techniques are
- SPG = stereophotogrammetry. This is the use of stereo pairs of images of the same area taken from two slightly different locations to deduce heights (essentially the same way our brain infers depth from our two eyes), and is the ‘classical’ technique used by cartographers to generate relief maps from aerial or satellite photography.
- SPC = stereo photoclinometry. Instead of using images taken from two different locations (angles) this uses images of the same area under different illumination angles. All other things being equal, the brightness is then related to the slope.
SPC is better than SPG for determining relief due to rather subtle slopes, whereas SPG gives better results for rough areas. SPC can give a higher resolution model than SPG because information even for single pixels is obtained, but the SPC approach needs additional constraints which in our approach come from a lower resolution SPG model. The MiARD project will create the most accurate possible three dimensional representation of the comet’s surface by combining results from both the SPC and SPG techniques, using the thousands of images taken of the comet during the ROSETA mission. Accurate maps of the surface, from different locations (times) in the comet’s orbit around the sun will show the changes in the surface due to the loss of material as the comet heats up and evaporates when it approaches the sun. The particular approach to SPC taken by the MiARD project is known as Multi-resolution Stereo-PhotoClinometry by Deformation (MSPCD).
There are several challenges to be overcome by the project members in creating the digital terrain model (sometimes also simply known as a shape model of the comet).
- The comets surface is changing all of the time. This makes it difficult to use image pairs consisting of images taken at different times, and, together with a lack of many images of some areas such as the southern hemisphere, makes it difficult to simply define pre- and post-helion shape models.
- Because of the rotation of the comet and the Rosetta spacecraft, overlapping images are often taken from different distances, with different orientations and illuminations. This makes the stereo reconstruction process much more difficult than for say an aerial survey on Earth.
- The coordinate system of the comet is complicated because it’s surface is not well approximated by a sphere or even an ellipsoide.
- There is a huge amount of data to process – there are tens of thousands of pictures of the surface, and the resulting final shape models have fifty million points (intermediate calculations use over a billion points!)
- Assessing the quality (accuracy) of the shape model
Using the nature of the surface (smooth or rough, craters or cracks…) and spectroscopic information about the composition, ‘geological’ maps of the comets surface will be made, grouping characteristic surface types together.
Cometary outgassing and material loss i.e. ‘activity’
In order to interpret measurements of the cometary surface and tail, we need to understand the processes that occur at the surface that result in the comet losing material each time it approaches the sun and is heated. Even before we had close-up views of comets, we knew that they could not be pure ‘snowballs’ of frozen water and frozen carbon dioxide – a simple but robust model of such a snowball predicts mass loss rates at least an order of magnitude higher than those actually observed. There must therefore be some ‘dirt’ on the surface that reduces the evaporation rate of the ices. Several possible hypotheses for mass loss from a ‘dirty’ comet follow:
- The simplest is that mass loss is uniform over the cometary surface. This would result in a roughly uniform spherical cloud of dust and gas around the comet as the comet rotates. Comparing the predictions of such a model to pressure data measured by the COPS sensor in the ROSINA instrument suite on the Rosetta space craft suggests that this simple picture explains the data only moderately well (80% correlation coefficient).
- A more sophisticated approach (but one that needs additional parameters) is that of localised activity, in which only a small fraction of the surface is active as ‘hot spots’. The numerical model is agnostic as to what the cause of such hot spots might be. This model does indeed give a better fit to the data, but this might be expected since it adds a parameter. However, such a model makes testable predictions about the velocity of dust particles entrained by the gas flows (higher than for uniform mass loss). A paper from the University of Bern group in Astronomy and Astrophysics (A&A 589 A90, 2016 – no open access) describes such a model and comparison to data.
Low-pressure gas flow and dust entrainment
When pressures are low enough, gas molecules no longer collide with each other very frequently, and the physics of gas flows changes from the regime we are familiar with (described by the Navier-Stokes equations for non-turbulent flows) to that of rarefied gas dynamics which requires a different numerical approach. Which flow regime is relevant is determined by the Knudsen number, a ratio which essentially describes if a gas molecule is more likely to hit another gas molecule before it hits a surface or is lost. Such rarefied gas flows occur not only on and in comets, but also within vacuum systems and for rocket or engine exhausts in the upper atmosphere or space.
The numerical approach adopted by the MiARD project is that of Direct Simulation Monte Carlo. The experience of the University of Bern in using this technique for space science problems is complemented by Heriot-Watt University’s experience in applying the technique to flow problems arising in the oil industry. The project will use this numerical approach to flows with a high Knudsen number in two different situations:
- For flows from the cometary surface into space
- For flows through the cometary soil to the surface, in particular to help set initial conditions for the flows from the comet (e.g. velocity distribution functions). For background, see e.g. “Predicting enhanced mass flow rates in gas microchannels using nonkinetic models” (not open access).
Further details from the University of Bern’s DRAG team.
The dust particles emitted by comets are moving at high velocities compared to some other solar system objects, and so pose a potential hazard to satellites and spacecraft (e.g. the Perseid meteor shower is thought to be due to debris from the comet Swift-Tuttle which has a period of 135 years). At the moment, the exact nature of the dust and so the forces acting upon dust particles are not known accurately and so trajectories are not certain. Although dust particles such as those responsible for the Perseid meteor storm are usually much less than 1 gram in weight, they are moving at about 58 km/s with respect to the Earth, so they have a lot of energy – comparable to that of a rifle bullet. When Perseids hit the moon, they cause an explosion at the surface that can be seen from Earth.
Although meteorite or dust induced damage to satellites is rare, it is likely that the OLYMPUS communications satellite was badly damaged by a Perseid (due to a temporary electronics problem that used up too much fuel for attitude control) during the unusually intense 1993 pass. It is known from measurements that other satellites (Pegasus satellites equipped to measure such impacts) have been impacted. The risk to satellites from meteor storms is discussed in this peer-reviewed paper from 1997 (no open access), in which it is estimated that for every 50 meters-squared of surface, there is a less than 1% risk of being struck during an average meteor storm.
When we see the ‘tail’ of a comet, we are mostly seeing sunlight scattered by dust particles. If you look closely at a comet from Earth, you will see that the visible tail is split into two – one of these consists of dust particles (made visible by scattered sunlight) and the other consists of ionised gas molecules (also made visible by sunlight, but by resonant scattering at certain wavelengths only).
Effects on comet’s trajectory
As gas and particles are lost from the comet, there is a momentum transfer. This gives rise to ‘non-gravitational’ forces which can significantly perturb the orbit of the comet compared to predictions that don’t take account of this (i.e. the comet slows down or speeds up in a way that wouldn’t happen if it was just affected by gravitational forces). Such changes in comets’ orbits were first noticed by Johann Franz Encke in the early 19th century, but not correctly explained until 1950 by the astronomer Fred Whipple. The data products and models created by the MiARD project have allowed us to accurately explain the non-gravitational forces acting on Comet 67P, and to estimate a value for the important ‘momentum transfer coefficient’. A paper describing this work will be submitted for publication to a journal in October 2018 .
Dust particle trajectories
Dust particles from comets can be a hazard to spacecraft and terrestrial satellites. The results of such particles meeting the Earth’s atmosphere at high relative velocities are seen as meteor storms (also known as shooting stars). In order to better model the trajectories of these dust particles through the solar system, and thus to better be able to take precautionary action for terrestrial satellites and interplanetary spacecraft, it is important to understand not only the forces acting on such dust particles (mostly tiny) but also their initial trajectories when they are ejected from their parent comet. The activity models developed by the MiARD project can be used to better constrain the intial velocities of dust particles when leaving comet 67P, and in future also other comets for which we have some information to constrain the activity.
What have we learnt from the Rosetta mission?
The shape and surface structure of 67P/Churyuomv-Gerasimenko were a big surprise. The comet is sometimes described as ‘duck shaped’, consisting of two lobes which probably have different densities, leading to speculation that this shape has a collisional origin. (Cracks at the neck of the comet between the lobes have been seen to increase during perihelion, and it could be that the comet will break into two parts eventually).
A future sample return mission?
The Rosetta mission and subsequent scientific work have not answered all of our questions about comets and the origin of the solar system. Although we have learnt a lot, we have also been faced by unexpected behaviour and data. In order to further our understanding of the universe, we will need to design future missions to comets perhaps returning material to the Earth for a more sophisticated analysis than can be performed in space. Documents describing the remaining questions, and suggestions as to how to address them, will be produced by the MiARD project. | 0.874111 | 3.732563 |
Note: This is a 360° Video — press and hold to explore it!
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid
These are organized by a classification scheme developed exclusively for Cosma. More…
Ceres is the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter, slightly closer to Mars’ orbit. Its diameter is approximately 945 kilometers (587 miles), making it the largest of the minor planets within the orbit of Neptune. It is the 33rd-largest known body in the Solar System and the only dwarf planet within the orbit of Neptune. Ceres is composed of rock and ice and is estimated to comprise approximately one third of the mass of the entire asteroid belt. Ceres is the only object in the asteroid belt known to be rounded by its own gravity (though detailed analysis was required to exclude 4 Vesta). From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, peaking once every 15 to 16 months, hence even at its brightest it is too dim to be seen with the naked eye except under extremely dark skies.
Ceres was the first asteroid to be discovered (by Giuseppe Piazzi at Palermo Astronomical Observatory on 1 January 1801). It was originally considered a planet, but was reclassified as an asteroid in the 1850s after many other objects in similar orbits were discovered.
Ceres appears to be differentiated into a rocky core and an icy mantle, and may have a remnant internal ocean of liquid water under the layer of ice. The surface is a mixture of water ice and various hydrated minerals such as carbonates and clay. In January 2014, emissions of water vapor were detected from several regions of Ceres. This was unexpected because large bodies in the asteroid belt typically do not emit vapor, a hallmark of comets.
The robotic NASA spacecraft Dawn entered orbit around Ceres on 6 March 2015. Pictures with a resolution previously unattained were taken during imaging sessions starting in January 2015 as Dawn approached Ceres, showing a cratered surface. — Wikipedia
Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.
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NASA has selected a new space-based instrument as an innovative and cost-effective approach to maintaining the 40-year data record of the balance between the solar radiation entering Earth's atmosphere and the amount absorbed, reflected, and emitted. This radiation balance is a key factor in determining our climate: if Earth absorbs more heat than it emits, it warms up; if it emits more than it absorbs, it cools down.
Study reveals details of 'golf ball asteroid'
on February 11, 2020 at 2:54 pm
Asteroids come in all shapes and sizes, and now astronomers at MIT and elsewhere have observed an asteroid so heavily cratered that they are dubbing it the "golf ball asteroid." | 0.853728 | 3.338168 |
The Catalina Comet returns this month with naked-eye potential. Follow its every move with our guide and finder charts.
Get ready to lose some sleep — The Catalina Comet (C/2013 US10) will be arriving soon! After making a hairpin turn around the Sun at perihelion on November 15th, the comet will surge into the dawn sky for Northern Hemisphere skywatchers and put on a great show by month's end. Early on, binoculars will show the comet's small, bright coma with a whisper of a tail. Naked-eye sightings may be possible by mid-December.
There's been a lot of buzz about the Catalina Comet, since many of us expected Comet Catalina to depart the solar glare pumped up to magnitude 3, making it the brightest expected fuzzball of the year. Maybe it will still. But in September, the comet's rate of brightening began to flag. Revised estimates now call for it to top out between magnitude 5 and 6 by year's end.
From late March through mid-October, Catalina's path confined its visibility to southern eyes only. Chris Wyatt of New South Wales, Australia, made one of the last visual observations on October 16th before the comet disappeared in the solar glare. Using 10×70 binoculars, he estimated a magnitude of 7 with a 7′-wide, well-condensed, greenish coma, and short ion tail pointing southeast.
Through his 10-inch Dobsonian reflector, the coma expanded to 8.2′ with a longer 35′ tail. Wyatt noted that Catalina responded well to a Swan Band filter, a narrow bandpass filter tuned to oxygen and carbon emissions that enhances the view of gassy (versus dusty) comets. With the filter in place he saw significant brightening in the inner coma.
Discovered by the Catalina Sky Survey on Halloween 2013, the Catalina Comet received the "US10" designation because it was initially thought to be an asteroid in a short period orbit. After more observations to refine its path and additional photographs that revealed telltale comet fuzz, astronomers realized they'd run into a denizen from the Oort Cloud, knocked our way by the close passage of some nameless star long ago. At the time of discovery, Catalina glowed at only 19th magnitude some 7.7 a.u. from Earth. Typical of new arrivals, it dove into the inner solar system on a steeply inclined orbit.
The comet pursues a northerly track through Virgo when it returns at dawn around November 24th, appearing 8° high in the southeastern sky 70 minutes before sunrise. By the 28th, it will have climbed to 10° in a dark sky shortly before the start of dawn.
Now for the bad news. A bright Moon will put a temporary damper on the comet's rise to fame from November 24th through December 3rd. From there on out, though, it's smooth sailing until the Moon returns for Round 2 at the winter solstice.
Catalina Comet glides northward at nearly 1° per day in late December as it crosses from Virgo into Boötes on a beeline for Arcturus. On the morning of January 1st, the comet skims ½° southwest of that orange luminary in a remarkable conjunction highlighting the arrival of the new year. Photo anyone?
The comet passes closest to Earth at 0.72 a.u. on January 12th, then buzzes Mizar in the Big Dipper's handle on January 14–15, hurrying along at the rate of 2° per day or 5′ an hour — fast enough to easily detect motion in 30 minutes or less. After mid-month, it's expected to fade quickly.
In this dark time of year, when the Sun bows low in the south, we welcome a potentially bright comet to lift our spirits and add celestial pizzazz to the seasonal holidays of Thanksgiving, Christmas, and New Year's.
Who really knows how bright Comet Catalina will get? Will it break into multiple comets after perihelion? First-time visitors from the Oort Cloud often do surprising things. No matter what Catalina has up its sleeve, its tour will be be a brief one.
After several million years of inbound travel, perturbations induced by the planets will boot it out of the solar system and into interstellar space. We're glad for the chance to share our table with a visitor who spent so much time getting here but can only stay a short while.
Catalina Comet Highlights:
- November 24 — Approximate date of first visibility in the dawn sky
- December 7 — Catalina gets company! The comet pairs up with the planet Venus and the waning crescent Moon this morning. From the central United States, Venus shines 4° southwest and the Moon 5° southwest of the comet.
- December 23–24 — Comet crosses into Boötes
- January 1, 2016 — Close pass (0.5°) of Arcturus on the first day of 2016
- January 9 — Comet crosses into Canes Venatici
- January 12 — Closest to Earth at 66.9 million miles
- January 14 — Comet crosses into Ursa Major
- January 14–15 — Passes just 1° north of Alkaid, the star at the end of the Big Dipper's handle
- January 16 — Passes 2° southwest of the 8th-magnitude galaxy, M101
- January 17 — Passes 3.4° northeast of the double star Mizar in the bend of the Big Dipper's handle
- January 21 — Comet crosses into Draco
- January 25 — Comet crosses into Camelopardalis | 0.819951 | 3.716596 |
With the nights of late summer upon us, and the constellation Cygnus the swan flying high overhead, it is a good time to become acquainted with one of the most fascinating stars in the sky. This star is normally a faint, nondescript point of light about 12th magnitude (easily within reach of a 4-inch telescope)-literally one among hundreds in a medium powered field. However, every now and then, on a somewhat regular schedule of about 52 days, it brightens suddenly in the course of a night by about 40 times (4 magnitudes). It stays bright for several nights, then begins it decline back to quiescence. For the next 20-50 days or so, it remains there, perhaps flickering slightly. Then all of a sudden it explodes again-becoming one of the brightest stars in the field. This star is one of my favorites, and it has captivated me on many summer nights. This star is non other than the famous prototype of the cataclysmic variables — SS Cygni.
SS Cygni is a binary star; however, both components are much too close to be resolved from earth in any telescope. In fact, they have one of the quickest rotation periods known-just 6.5 HOURS! This means the stars must be nearly in contact. It is this binary nature that accounts for this stars unusual behavior. According to theory, one component is a solar type star and the other a white dwarf. The gravitational field of the white dwarf pulls material off the outer atmosphere of the larger star. This material spirals down onto the surface of the white dwarf, and when certain conditions of temperature and pressure are met- BANG-the star explodes. Here on earth we see the star brighten suddenly. There are two general types of maxima-one lasting about 8 days and the other about 18 days. These two types usually alternate, but sometimes similar maxima types can reoccur.
SS Cygni is located in northern Cygnus at RA 21h41m Dec +43.3 degrees There is a quaint asterism of about 10-12 stars arranged in a multisided figure with a small triangle attached that catches the eye 20 arc-minutes to the northeast of SS Cygni. This group has always reminded me of a duck floating on some celestial sea, and I never fail to give it a look when making magnitude estimates of SS. If you are interested in observing this star, and have trouble finding it, just track me down at a future star party and I would be happy to show you where it is. If we get some magnitude estimates from club members, I will forward them to the AAVSO, which is always interested in your observations of variable stars!
Contributed by Myron Wasiuta | 0.906002 | 3.850037 |
Inside Iowa State
Apr. 03, 1998
In search of a big diamond
by Skip Derra
Steve Kawaler aims his telescopesnot to the far reaches of the universe, but to objects much closer and much more interesting. From April 20 to May 2, Kawaler, a professor of physics and astronomy, will lead a group of about 50 astronomers in an observation of a "particularly interesting" pulsating white dwarf.
The white dwarf star, designated BPM37093, is the slowly cooling remnant of a star once nearly the size of our Sun. It resides only 17 light-years from Earth in the constellation of Centaurus. Astronomers are interested in BPM37093 for several reasons.
Learning more about white dwarfs could help them better determine the age of our galaxy and the universe. Understanding the properties of white dwarf stars is important because all stars, depending on their size, will become either eternally cooling dwarf stars or fiery exploding supernovas.
Being a white dwarf star, Kawaler said, BPM37093 has burned its gaseous fuel and all that remains is ash of carbon and oxygen. By measuring the frequency of pulsations emanating from BPM37093, astronomers can sneak a peak into its interior. Kawaler thinks what they'll find could be a gemologist's dream.
"We think it's primarily made up of crystallized carbon with an oxygen impurity," he said. "That would make it a diamond with a blue-green tint. Its estimated carat weight is 1034, or 10 billion trillion trillion. This could truly be a diamond in the sky."
Scientists have theorized the existence of crystallized stars for 30 years. But there has never been direct proof. To make the first direct measurements of the star, Kawaler's group will use a modern-day armada of Earth-based telescopes coupled with highly sensitive measurements from the orbiting Hubble space telescope.
The astronomers will use some observatories of the Whole Earth Telescope (WET) to monitor BPM37093 from Earth. WET telescopes in South Africa, Brazil, Chile, New Zealand and Australia will be used in the observation.
Kawaler is the director of WET, which includes a total of 22 observatories around Earth and allows 24-hour monitoring of objects. WET is headquartered at Iowa State and is a program of the International Institute for Theoretical and Applied Physics.
The core observation will be run April 20-29. During this time, the Hubble space telescope will turn its attention to BPM37093 and provide the astronomers with measurements in ultraviolet and optical wavelengths. Kawaler said the Hubble measurements will allow the astronomers to actually see BPM37093 as it pulsates.
The astronomers will continue to monitor the dwarf star periodically for several years. What they'd like to obtain is the first direct evidence of a star that shines, or in this case, pulsates, like a diamond.
While the astronomers want to know what BPM37093 is made of, they also hope to pin down how the crystallization happens and determine if it is "a solid diamond or a diamond shell," Kawaler said.
"The material that is crystallizing is a mixture of different elements," he explained. "Different elements crystallize at different temperatures. Heavier elements like oxygen crystallize first, then the carbon will crystallize. If oxygen crystallizes in a gas of carbon, then those crystalline nuggets will sink to the inside of the star -- as if it were snowing."
The snowing effect would create additional energy not accounted for in current white dwarf star models, Kawaler said. "But if the oxygen crystallizes and stays suspended, then you're getting crystallization without an additional energy source. If it snows, you'll have an oxygen crystal core and a carbon crystal mantle. Sort of a diamond shell."
And if they detect a shell with snow, then cool white dwarf stars (the oldest stars in this part of the galaxy) are older than previously thought.
A pulsating white dwarf star that is snowing inside will be roughly 11 to 12 billion years old, rather than the currently estimated 9 billion years, Kawaler said. This finding will extend the lower limit of the age of the galaxy, and in turn extend the estimated age of the universe.
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Primary mirror cell for Daniel K. Inouye Solar Telescope (DKIST)
The Daniel K. Inouye Solar Telescope (DKIST) is the world’s next largest solar telescope. It is currently under construction by AURA, the Association of Universities for Research in Astronomy on top of the Haleakala mountain on the Maui island in Hawaii, and is expected to start its operations in 2019.
With a primary mirror of 4.2 m in diameter, DKIST – formerly called Advanced Technology Solar Telescope (ATST) – will dwarf by its size previous solar telescopes. It is packed with complex technologies in order to capture very detailed images of the sun’s constantly-changing surface with a resolution twice better than former solar observatories. It is an off-axis telescope, equipped with an active and thermally-controlled primary mirror and adaptive optics.
AMOS was contracted the design and manufacturing of the primary mirror cell. The cell is an active cell carrying a thin mirror: 10cm thick for a diameter of 4.2m. It uses 142 hydraulic and pneumatic actuators to keep the mirror in the proper shape. More challenging was the thermal control of the heat, as the mirror is directly exposed to solar radiation. The cell has thus to keep the mirror at ambient temperature and avoid any thermal gradient across the mirror.
A key element of the telescope, the primary mirror cell has been completely designed and manufactured by AMOS in Belgium. It consists ina 9-ton high-precision electro-mechanical subsystem which guarantees that the 4.2 m primary mirror keeps its exact position and shape in all circumstances, despite continuously changing orientations and temperatures.
The performances of this system are mind-blowing:
- The 3-ton mirror will be positioned with a precision of a few micrometers, i.e. 40 times better than the thickness of a human hair, in all positions of the constantly moving telescope.
- 142 pneumatic and hydraulic actuators will continuously correct the shape of the thin primary mirror to an accuracy better than 45 nm RMS. As a comparison, if the mirror was the size of the Atlantic Ocean, the perfectness of the surface would be equivalent to removing all waves higher than a few centimeters.
- The temperature uniformity will be controlled within half a degree Celsius, from early morning to late evening, including at noon when the mirror is fully exposed to the sun heat.
After a successful Factory Acceptance Test in January 2017, AURA formally accepted the mirror cell and its handling equipment in the AMOS facilities, and authorized their shipment to Hawaii where they arrived at the end of June 2017. The cell is now integrated and tested in the telescope. | 0.822039 | 3.213306 |
25 August 2015
A Cosmic Perspective:
Four Centuries of Expanding Horizons
Professor Lord Rees of Ludlow FRS
Astronomy is a fundamental science. It is also the grandest of the environmental sciences, and the most universal – indeed the starry sky is the one feature of our environment that has been shared, and wondered at, by all cultures throughout human history. Today, it is an enterprise that involves a huge range of disciplines: mathematics, physics and engineering, of course; but others too.
We want to understand the exotic objects that our telescopes have revealed. But also to understand how the cosmic panorama, of which we are a part, emerged from our universe’s hot dense beginning.
The good news, for students or postdocs in the audience, is that today is a brilliant time for young researchers. The pace of advance has crescendoed rather than slackened; instrumentation and computer power have improved hugely.
OUR SOLAR SYSTEM, SPACE EXPLORATION
I will start with a flashback to Isaac Newton. He must have thought about space travel. Indeed, there is a famous picture, in the English edition of his 'Principia', which depicts the trajectory of cannon balls being fired from a mountaintop. If they are fired fast enough, their paths curves downward no more sharply than the Earth’s surface curves away underneath them: the cannon-balls go into orbit. This is still the neatest way to teach the concept of orbital flight.
Newton knew that, for a cannon-ball to achieve an orbital trajectory, its speed must be 25000 km /hour. But that speed was not achieved until 1957 with the launch of Sputnik 1. Four years later, Yuri Gagarin went into orbit. Eight years after that we had the moon landings. The Apollo programme was a heroic episode. But it was all over more than 40 years ago—you have got to be middle-aged to remember when men walked on the Moon; it is ancient history to the younger generation. If the momentum had been maintained there would be footprints on Mars by now. But actually people have done no more than circle the Earth in low orbit – more recently, in the international space station.
But space technology has burgeoned -- for communication, environmental monitoring, satnav and so forth. We depend on it every day. For astronomers, it is revealed the far infrared, the UV, X-ray, gamma ray sky.
And unmanned probes to other planets have beamed back pictures of varied and distinctive worlds. The most recent has been ESA’s Rosetta comet mission, which landed a small probe on the comet itself, to check, for instance, if isotopic ratios in the cometary ice are the same as in the Earth’s water – crucial for deciding where that water came from. NASA’s ‘New Horizons’ probe has passed Pluto, and is now heading into the Kuiper Belt.
Rosetta was launched 10 years ago; its design was frozen five years before that. It is robotic technology dates from the 1990s – that is the greatest frustration for the team that has been dedicated to it for so long because present-day designs would have far greater capabilities.
I hope that, during this century, the entire solar system will be explored and mapped by flotillas of tiny robotic craft. And, on a larger scale, robotic fabricators may build vast lightweight structures floating in space (solar energy collectors, for instance), perhaps mining raw materials from asteroids or the Moon.
But will people follow them? Robotic advances will erode the practical case for human spaceflight. Nonetheless, I hope people will follow the robots, though it will be as risk-seeking adventurers rather than for practical goals. The most promising developments are spearheaded by private companies. For instance SpaceX, led by Elon Musk, who also makes Tesla electric cars, has launched unmanned payloads and docked with the Space Station.He hopes soon to offer orbital flights to paying customers. Wealthy adventurers are already signing up for a week-long trip round the far side of the Moon – voyaging further from Earth than anyone has been before (but avoiding the greater challenge of a Moon landing and blast-off). I am told they have sold a ticket for the second flight but not for the first flight. We should surely cheer on these private enterprise efforts in space – they can tolerate higher risks than a western government could impose on publicly-funded civilians, and thereby cut costs.
I hope some people now living will walk on Mars – as an adventure, and as a step towards the stars. They may be Chinese. Indeed, if China wishes to assert its super-power status by a ‘space spectacular’it would need to aim for Mars. Just going to the Moon, in a re-run of what the US achieved 50 years earlier, would not proclaim parity.
But perhaps the future of manned spaceflight, even to Mars, lies with privately-funded adventurers, prepared to participate in a cut-price programme far riskier than any government would countenance when civilians were involved – perhaps even one-way trips. (The phrase ‘space tourism’ should however, be avoided. It lulls people into believing that such ventures are routine and low-risk. And if that is the perception, the inevitable accidents will be as traumatic as those of the US Space Shuttle were. Instead, these cut-price ventures must be ‘sold’ as dangerous sports, or intrepid exploration).
By 2100, groups of pioneers may have established bases independent from the Earth – on Mars, or maybe on asteroids. But do not ever expect mass emigration from Earth. Nowhere in our Solar System offers an environment even as clement as the Antarctic or the top of Everest. Space does not offer an escape from Earth's problems.
What are the long-term hopes for space travel? The most crucial impediment today stems from the intrinsic inefficiency of chemical fuel, and the consequent requirement to carry a weight of fuel far exceeding that of the payload. Launchers will get cheaper when they can be designed to be more fully reusable. But so long as we are dependent on chemical fuels, interplanetary travel will remain a challenge. A space elevator would help. Nuclear power could be transformative. By allowing much higher in-course speeds, it would drastically cut the transit times to Mars or the asteroids (reducing not only astronauts’ boredom, but their exposure to damaging radiation).
Another question we are all asked is – is there life out there already?Prospects look bleak in our Solar System, though the discovery of even the most vestigial life-forms – on Mars, or in oceans under the ice of Europa or Enceladus – would be of crucial importance, especially if we could show they had an independent origin. But prospects brighten if we widen our horizons to other stars – far beyond the scale of any probe we can now envisage.
EXOPLANETS AND STARS
Perhaps the hottest current topic in astronomy is the realization that many other stars -- perhaps even most of them -are orbited by retinues of planets, like the Sun is. The planets are not detected directly but inferred by precise measurement of their parent star. There are two methods:
(A) If a star is orbited by a planet, then both planet and star move around their centre of mass -- the barycentre. The star, being more massive, moves slower. But the tiny periodic changes in the star’s Doppler Effect can be detected by very precise spectroscopy. By now, more than 500 exo-solar planets have been inferred in this way. We can infer their mass, the length of their ‘year’, and the shape of their orbit. This evidence pertains mainly to 'giant' planets -- objects the size of Saturn or Jupiter. Detecting Earthlike planets -- hundreds of times less massive -- is a real challenge. They induce motions of merely centimeters per second in their parent star.
(B) But there is a second technique that works better for smaller planets. A star would dim slightly when a planet was 'in transit' in front of it. An earth-like planet transiting a sun-like star causes a fractional dimming, recurring once per orbit, of about one part in 10,000. The Kepler spacecraft pointed steadily at a 7-degree-across area of sky for more than three years -- monitoring the brightness of over 150000 stars, at least twice every hour, with precision of one part in 100,000. It has already found more than 2000 planets, many no bigger than the Earth. And of course it only detects transits of those whose orbital plane is nearly aligned with our line of sight. We are especially interested in possible 'twins' of our Earth -- planets the same size as ours, on orbits with temperatures such that water neither boils nor stays frozen. Some of these have already been identified in the sample, suggesting that there are billions of earth-like planets in the Galaxy.
The real goal, of course, is to see these planets directly -- not just their shadows. But that is hard. To realise just how hard, suppose an alien astronomer with a powerful telescope was viewing the Earth from (say) 30 light years away -- the distance of a nearby star. Our planet would seem, in Carl Sagan's phrase, a 'pale blue dot', very close to a star (our Sun) that outshines it by many billions: a firefly next to a searchlight. But if it could be detected, even just as a ‘dot’, several features could be inferred. The shade of blue would be slightly different, depending on whether the Pacific Ocean or the Eurasian land mass was facing them. The alien astronomers could infer the length of our 'day', the seasons, the gross topography, and the climate. By analysing the faint light, they could infer that it had a biosphere.
Within 20 years, the huge E-ELT telescope planned to be built by the European Southern Observatory on a mountain in Chile (where the site has already been leveled) – with a mosaic mirror 39 metres across - will be drawing inferences like this about planets the size of our Earth, orbiting other Sun-like stars. But what most people want to know is: Could there be life on them – even intelligent life? Here we are still in the realm of science fiction.
We know too little about how life began on Earth to lay confident odds. What triggered the transition from complex molecules to entities that can metabolise and reproduce? It might have involved a fluke so rare that it happened only once in the entire Galaxy. On the other hand, this crucial transition might have been almost inevitable given the ‘right’ environment. We just do not know - nor do we know if the DNA/RNA chemistry of terrestrial life is the only possibility, or just one chemical basis among many options that could be realized elsewhere
Moreover, even if simple life is widespread, we cannot assess the odds that it evolves into a complex biosphere. And, even it did, it might anyway be unrecognizably different. I will not hold my breath, but the SETI programme is a worthwhile gamble - because success in the search would carry the momentous message that concepts of logic and physics are not limited to the hardware in human skulls.
And, by the way, it is too anthropocentric to limit attention to Earth-like planets even though it is prudent strategy to start with them. Science fiction writers have other ideas - balloon-like creatures floating in the dense atmospheres of Jupiter-like planets, swarms of intelligent insects, etc. Perhaps life can flourish even on a planet flung into the frozen darkness of interstellar space, whose main warmth comes from internal radioactivity (the process that heats the Earth's core).
We should also be mindful that seemingly artificial signals could come from super-intelligent (though not necessarily conscious) computers, created by a race of alien beings that had already died out. Indeed I think this is the most likely possibility, we may learn this century whether biological evolution is unique to our Earth, or whether the entire cosmos that teems with life - even with intelligence.
Even if simple life is common, it is a separate question whether it is likely to evolve into anything we might recognize as intelligent or complex. Perhaps the cosmos teems even with complex life; on the other hand, our Earth could be unique among the billions of planets that surely exist. That would be depressing for the searchers. But it would allow us to be less cosmically modest: Earth, though tiny, could be the most complex and interesting entity in the entire Galaxy.
Back now to the physics, far simpler than biology. What has surprised people about the newly-discovered planetary systems is their great variety. But the ubiquity of such systems was not surprising. We have learnt that stars form, via the contraction of clouds of dusty gas; and if the cloud has any angular momentum, it will rotate faster as it contracts, and spin off a dusty disc around the protostar. In such a disc, gas condenses in the cooler outer parts; closer in less volatile dust agglomerates into rocks and planets - this should be a generic process in all protostars.
In the rest of my talk I will outline how the cosmogonic causal chain has been pushed back further – to the formation of galaxies, stars, atoms, and right back to the first nanosecond of the big bang.
First, what about stars and atoms? We see stars forming, in places like the Eagle Nebula, 7000 light-years away. And we see many star dying - as the Sun will in around 6 billion years, when it exhausts its hydrogen fuel, blows off its outer layers, and settles down to a quiet demise as a white dwarf.
More massive stars die explosively as supernovae, generally leaving behind a neutron star or black hole. The most famous is the Crab Nebula, the expanding debris from a supernova recorded by oriental astronomers in 1054 AD, with, at its centre, a neutron star spinning at 30 revs/second (and these fascinating objects, natural ‘laboratories’ for the study of extreme physics, could be the topic for a separate lecture).
Supernovae are important for us: if it was not for them we would not be here. By the end of a massive star’s life, nuclear fusion has led to an onion skin structure - with hotter inner shells processed further up the periodic table. This material is then flung out in the supernova explosion. The debris then mixes into the interstellar medium and re-condenses into new stars, orbited by planets.
The concept was developed primarily by Hoyle and his associates. They analysed the specific nuclear reactions involved, and were able to understand how most atoms of the periodic table came to exist and why oxygen and carbon (for instance) are common, whereas gold and uranium are rare.
Our Galaxy is a huge ecological system where gas is being recycled through successive generations of stars. Each of us contains atoms forged in dozens of different stars spread across the Milky Way, which lived and died more than 4.5 billion years ago, polluting the interstellar cloud in which the Solar System condensed.
BEYOND OUR GALAXY – COSMIC HORIZONS
Let us now enlarge our spatial horizons to the extragalactic realm.We know that galaxies – some disc-like, resembling our Milky Way or Andromeda; others amorphous ‘ellipticals’ - are the basic constituents of our expanding universe. But how much can we actually understand about galaxies? Physicists who study particles can probe them, and crash them together in accelerators at CERN. Astronomers cannot crash real galaxies together. And galaxies change so slowly that in a human lifetime we only see a snapshot of each. But we can do experiments in a 'virtual universe': computer simulations, incorporating gravity and gas dynamics.
We can redo such simulations making different assumptions about the mass of stars and gas in each galaxy, and so forth, and see which matches the data best. Importantly, we find, by this method and others, that all galaxies are held together by the gravity not just of what we see. They are embedded in a swarm of particles that are invisible, but which collectively contribute about five times as much mass as the ordinary atom – the dark matter.
And we can test ideas on how galaxies evolve by observing eras when they were young. The Hubble Telescope has been used to study ‘deep fields’, each encompassing a tiny patch of sky - just a few arc minutes across. You can see hundreds of smudges – these are galaxies, some fully the equal of our own, but they are so far away that their light set out more than 10 billion years ago – they are being viewed when they have recently formed.
But what happened before there were galaxies? The key evidence here, dating back to Penzias and Wilson 50 years ago, is that intergalactic space is not completely cold. It is warmed to three degrees above absolute zero by weak microwaves, known to have an almost exact black body spectrum. This is the ‘afterglow of creation’ – the adiabatically cooled and diluted relic of an era when everything was squeezed hot and dense. It is one of several lines of evidence that have allowed us to firm up the ‘hot big bang’ model.
The background radiation was last scattered when the temperature was 3000 degrees and the free electrons combined with nuclei to mainly H and He atoms. This was after about 300,000 years of expansion. The He and D abundance was determined by nuclear reactions in the first few minutes, at temperatures of a few billion degrees.
More about this later.
But first, let us address an issue that might seem puzzling. Our present complex cosmos manifests a huge range of temperature and density - from blazingly hot stars, to the dark night sky. People sometimes worry about how this intricate complexity emerged from an amorphous fireball. It might seem to violate the second law of thermodynamics - which describes an inexorable tendency for patterns and structure to decay or disperse.
The answer to this seeming paradox lies in the force of gravity. Gravity enhances density contrasts rather than wiping them out. Any patch that starts off slightly denser than average would decelerate more, because it feels extra gravity; its expansion lags further and further behind, until it eventually stops expanding and separates out. Many simulations have been made of parts of a 'virtual universe' – modelling a domain large enough to make thousands of galaxies. The calculations, when displayed as a movie, clearly display how incipient structures unfold and evolve. Within each galaxy-scale clump, gravity enhances the contrasts still further; gas is pulled in, and compressed into stars.
There is one very important point. The initial fluctuations fed into the computer models are not arbitrary – they are derived from the observed fluctuations in the temperature of the microwave background, which have been beautifully and precisely delineated over the whole sky by ESA’s Planck Spacecraft. The amplitude of the temperature fluctuations is only one part in 100000, but computing forward, they are amplified by gravity into the conspicuous structures in the present universe.
What about the far future of our universe? In 1998 cosmologists had a big surprise.It was by then well known that the gravity of dark matter dominated that of ordinary stuff – but also that dark matter plus baryons contributed only about 30 percent of the critical density. This was thought to imply that we were in a universe whose expansion was slowing down, but not enough to eventually be halted. But, rather than slowly decelerating, the Hubble diagram of Type 1a supernovae famously revealed that the expansion was speeding up. Gravitational attraction was seemingly overwhelmed by a mysterious new force latent in empty space which pushes galaxies away from each other.
Moreover there was independent evidence supporting this. According to Einstein’s theory, a straightforward low-density universe would have negative curvature – the three angles of a big triangle would add up to less than 180 degrees. This can be tested from microwave background measurements. That is because there is a straightforward effect that makes the temperature ripples more conspicuous for a particular wavelength – about 300,000 light years. This so-called ‘doppler peak’ was first revealed by a balloon-borne experiment called Boomerang, and has been confirmed by the Planck data. It is on an angular scale that is consistent with a flat universe.
If we had just had the supernova Hubble diagram, some of us would not have been convinced. But these two interlinked and almost simultaneous discoveries together clinched the case. The issue now is the nature of the dark energy – is it time-independent, like Einstein’s cosmological constant, or was it different in the past?
Long-range forecasts are seldom reliable, but the best and most ‘conservative’ bet is that we have almost an eternity ahead – an ever colder and ever emptier cosmos. Galaxies accelerate away and disappear over an ‘event horizon’ – rather like an inside out version of what happens when things fall into a black hole. All that is left will be the remnants of our Galaxy, Andromeda, and smaller neighbours. Protons may decay, dark matter particles annihilate, occasional flashes when black holes evaporate – and then silence.
THE VERY EARLY UNIVERSE – MORE SPECULATIVE THOUGHTS
We can trace back to 1 second after the initial instant. Indeed we can probably be confident back to a nanosecond: that is when each particle had about 50 Gev of energy - as much as can be achieved in the LHC – and the entire visible universe was squeezed to the size of our solar system. But questions like 'where did the fluctuations come from?' and "why did the early universe contain the actual mix we observe of protons, photons and dark matter?" take us back to the even briefer instants when our universe was hugely more compressed still - when energies were 10^16Gev, where experiments offer no direct guide to the relevant physics.
At this point, I should insert a ‘health warning’ because the discourse hereafter becomes much more speculative. According to a popular theory, the entire volume we can see with our telescopes was at 10^16 Gev, a hyper-dense blob no bigger than an apple. And it had inflated from something at least a trillion times smaller than an atomic nucleus.
The so-called ‘inflationary universe’ model is supported already by much evidence. But it may be useful to summarisethe essential requirements for the emergence of our complex and structured cosmos from simple amorphous beginnings.
(i) The first prerequisite is of course the existence of the force of gravity – which (as explained earlier) enhances density contrasts as the universe expands, allowing bound structures to condense out from initially small-amplitude irregularities. It is a very weak force. On the atomic scale, it is about 40 powers of ten weaker than the electric force between electron and proton. But in any large object, positive and negative charges almost exactly cancel, in contrast, everything has the same 'sign' of gravitational charge so when sufficiently many atoms are packed together, gravity wins. But stars and planets are so big because gravity is weak. Were gravity stronger, objects as large as asteroids (or even sugar-lumps) would be crushed. So, though gravity is crucial, it is also crucial that it should be very weak.
(ii) There must be an excess of matter over antimatter.
(iii) Another requirement for stars, planets and biospheres is that chemistry should be non-trivial. If hydrogen were the only element, chemistry would be dull. A periodic table of stable elements requires a balance between the two most important forces in the micro-world: the nuclear binding force (the 'strong interactions') and the electric repulsive force that drives protons apart.
(iv) There must be stars – enough ordinary atoms relative to dark matter. (Indeed there must be at least two generations of stars: one to generate the chemical elements, and a second able to be surrounded by planets).
(v) The universe must expand at the ‘right’ rate - not collapse too soon, nor expand so fast that gravity cannot pull together the structures.
(vi) There must be some fluctuations for gravity to feed on – sufficient in amplitude to permit the emergence of structures. Otherwise the universe would now be cold ultra-diffuse hydrogen - no stars, no heavy elements, no planets and no people. In our actual universe, the initial fluctuations in the cosmic curvature have amplitude of 0.00001. According to inflationary models, this amplitude is determined by quantum fluctuations. Its actual value depends on the details of the model.
Here is another fundamental question: How large is physical reality? We can only see a finite volume -- a finite number of galaxies. That is essentially because there is a horizon: a shell around us, delineating the distance light can have travelled since the Big Bang. But that shell has no more physical significance than the circle that delineates your horizon if you are in the middle of the ocean. We would expect far more galaxies beyond the horizon.
There is no perceptible gradient in temperature or density across the visible universe: this suggests that, even if it is of finite extent, it stretches thousands of times further. But that is just a minimum. If space stretched far enough, then all combinatorial possibilities would be repeated. Far beyond the horizon, we could all have avatars. Be that as it may, even conservative astronomers are confident that the volume of space-time within range of our telescopes - what astronomers have traditionally called 'the universe' – is only a tiny fraction of the aftermath of our Big Bang.
And there is something else. Plausible models for the physics at the ultra-high energies where inflation could have occurred lead to so-called 'eternal inflation'. ‘Our’ Big Bang could be just one island of space-time in a vast cosmic archipelago – a multiverse..
Key questions then are:
(i) Is there one big bang, or many?
(ii) If there are many, are they all replicas of each other, or do they ‘ring the changes’ on the laws and constants of physics, so that most are ‘stillborn’ and we find ourselves in one of the subset that allow complexity to emerge (so called ‘anthropic selection’) ?
This is speculative physics – but it is physics, not metaphysics. There is hope of firming it up. Further study of the fluctuations in the background radiation will reveal clues. But, more important, if physicists developed a unified theory of strong and electromagnetic forces – and that theory is tested or corroborated in our low-energy world – we would then take seriously what it predicts about an inflationary phase and what the answers to the two questions above actually are.
If the answer to (ii) is ‘yes’, then what we call 'laws of nature' may in the grandest perspective be mere local bylaws governing our cosmic patch. Many patches could be still-born or sterile – the laws prevailing in them might not allow any kind of complexity. We therefore would not expect to find ourselves in a typical universe – rather, we would be in a typical member of the subset where an observer could evolve. This is anthropic selection.
I started this talk by describing newly-discovered planets orbiting other stars. I would like to give a flashback to planetary science 400 years ago - even before Newton. At that time, Kepler thought that the Solar System was unique, and Earth’s orbit was related to the other planets by beautiful mathematical ratios involving the Platonic regular solids. We now realise that there are billions of stars, each with planetary systems. Earth's orbit is special only insofar as it is in the range of radii and eccentricities compatible with life (e.g. not too cold and not too hot to allow liquid water to exist).
Maybe we are due for an analogous conceptual shift, on a far grander scale. Our Big Bang may not be unique, any more than planetary systems are. Its parameters may be 'environmental accidents', like the details of the Earth's orbit. The hope for neat explanations in cosmology may be as vain as Kepler's numerological quest.
If there is a multiverse, it will take our Copernican demotion one stage further – our solar system is one of billions of planetary systems in our Galaxy, which is one of billions of galaxies accessible to our telescopes - but this entire panorama may be a tiny part of the aftermath of ‘our’ Big Bang – which itself may be one among billions. It may disappoint some physicists if some of the key numbers they are trying to explain turn out to be mere environmental contingencies -- no more ‘fundamental’ than the parameters of the Earth’s orbit round the Sun. But in compensation, we would realize space and time were richly textured-- but on scales so vast that astronomers are they not directly aware of it - any more than plankton whose ‘universe’ was a spoonful of water, would be aware of the world’s topography and biosphere.
At a conference in Stanford there was a panel discussion where the panelists were asked how strongly they would bet on the multiverse concept. I said that, on the scale would you bet your goldfish, your dog or yourself, I was almost at the dog level. Andre Linde said he was far more confident – after all he had devoted 25 years of his life to the eternal inflation idea. And the great theorist Steven Weinberg later said that he would happily bet Martin Rees’s dog and Andre Linde’s life.
We have made astonishing progress. Fifty years ago, cosmologists did not know if there was a Big Bang. Now, we can draw quite precise inferences back to a nanosecond. So in fifty years, debates that now seem flaky speculation may have been firmed up. But it is important to emphasise that progress will continue to depend, as it has up till now, 95 percent on advancing instruments and technology – less than 5 percent on armchair theory.
General relativity and quantum theory are the twin pillars of 20th century physics. But they have not yet been meshed together into a single unified theory. In most contexts, this does not impede us because the domains of relevance do not overlap. Astronomers can ignore quantum fuzziness when calculating the motions of planets and stars (right hand side). Conversely, chemists can safely ignore gravitational forces between individual atoms in a molecule because they are nearly 40 powers of ten feebler than electrical forces. But at the very beginning, everything was squeezed so small that quantum fluctuations could, as it were, ‘shake’ the entire universe.
We ourselves - are midway - on a log scale - between atoms and stars: large enough compared to atoms, to have layer upon layer of intricate structure; but not so large that we are crushed by our planet's gravity. (The geometric mean of a proton mass and the Sun's mass is 50 kilograms). To understand ourselves, we must understand the atoms we are made of, and the stars that made those atoms. Even an insect, with its layer upon later of complexity is harder to understand than a star, where intense heat and compression by gravity precludes complex chemistry.
And that is why 99 percent of scientists are neither particle physicists nor astronomers: they work neither on the very small nor on the very large, but, instead, on the very complex, which presents the greatest challenges of all.
The sciences are sometimes likened to different levels of a tall building - particle physics on the ground floor, then the rest of physics, then chemistry, and so forth: all the way up to psychology – and the economists in the penthouse. There is a corresponding hierarchy of complexity - atoms, molecules, cells, organisms, and so forth.
But the analogy with a building is poor. The 'higher level' sciences dealing with complex systems aren't imperiled by an insecure base, as a building is. Each level has its own autonomous concepts and theories. To understand why flows go turbulent, or why waves break, subatomic details are irrelevant. We treat the fluid as a continuum. An albatross returns predictably to its nest after wandering ten thousand miles in the southern oceans. But this is not the same kind of prediction as astronomers make of celestial orbits and eclipses.
Everything however complicated - breaking waves, migrating birds, and tropical forests - is made of atoms and obeys the equations of quantum physics. But even if Schrodinger’s equation could be solved, its solution would not offer the enlightenment that scientists seek. Reductionism is true in a sense. But it is seldom true in a useful sense. Each science has its own autonomous concepts and laws.
Phenomena with different levels of complexity are understood in terms of different irreducible concepts – turbulence, survival, alertness, and so forth. The brain is an assemblage of cells; a painting is an assemblage of chemical pigment. But in both cases what is important and interesting is the pattern and structure – the emergent complexity.
That was a digression to highlight the unity of science – plus gestures of deferential modesty towards the 99 percent of scientists are neither particle physicists nor cosmologists.
Finally, I want to draw back from the cosmos – even from what may be a vast array of cosmoses, governed by quite different laws - and focus back closer to the here and now. I am often asked - is there a special perspective that astronomers can offer to science and philosophy? We view our home planet in a vast cosmic context. And in coming decades we will know whether there is life out there. But, more significantly, astronomers can offer an awareness of an immense future.
The stupendous timespans of the evolutionary past are now part of common culture (maybe not in Kentucky, or in parts of the Muslim world). Darwinism tells us how our present biosphere is the outcome of more than four billion years of evolution.
But most people still somehow think we humans are necessarily the culmination of the evolutionary tree. That hardly seems credible to an astronomer – indeed, we are probably still nearer the beginning than the end. Our Sun formed 4.5 billion years ago, but it has got 6 billion more before the fuel runs out. It then flares up, engulfing the inner planets. And the expanding universe will continue -- perhaps forever - destined to become ever colder, ever emptier. To quote Woody Allen, eternity is very long, especially towards the end.
Any creatures witnessing the Sun's demise 6 billion years hence will not be human – they will be as different from us as we are from a bug. Post human evolution - here on Earth and far beyond - could be as prolonged as the Darwinian evolution that has led to us - and even more wonderful. Of course, this evolution is even faster now – it happens on a technological timescale, operating far faster than natural selection and driven by advances in genetics and in artificial intelligence (AI). We do not know whether the long term future lies with organic or silicon-based life.
But my final thought is this. Even in this ‘concertinaed’ timeline -- extending billions of years into the future, as well as into the past - this century may be a defining moment. Over most of history, threats to humanity have come from nature – disease, earthquakes, floods, and so forth. But this century is special. It is the first where one species – ours – has Earth's future in its hands, and could jeopardise life's immense potential. We have entered a geological era called the anthropocene.
Our Earth, this ‘pale blue dot’ in the cosmos, is a special place. It may be a unique place. And we are its stewards at an especially crucial era. That is an important message for us all, whether we are interested in astronomy or not.
© Professor Lord Rees of Ludlow, 2015 | 0.928637 | 3.5601 |
Just before he passed in 2018, famed physicist Stephen Hawking gave some last precious insights into some of the universe's greatest mysteries with his posthumously published book "Brief Answers to the Big Questions." In response to "What is the greatest threat to the future of this planet?" Hawking listed both man-made climate change and a catastrophic strike from a near-Earth object.
While Hawking thought humanity could still offer a response to fight climate change, he was less bullish on our species surviving a direct hit from above.
"An asteroid collision would be a threat against which we have no defense," he wrote.
In 2022, NASA and the European Space Agency (ESA) hope to craft the beginning of an answer to Hawking's challenge with the launch of the DART (Double Asteroid Redirection Test) mission. As shown in the brief animation below, the DART probe is intended as a proof-of-concept demonstration to see if a man-made "interstellar bullet" can create enough force to nudge an asteroid off-course.
"DART would be NASA's first mission to demonstrate what's known as the kinetic impactor technique — striking the asteroid to shift its orbit — to defend against a potential future asteroid impact," planetary defense officer Lindley Johnson said in a statement.
Throwing a punch at 'Didymoon'
In 2020, NASA intends to launch DART on a two-year, 6.8-million-mile mission to a binary asteroid system called Didymos. Instead of aiming for its parent body, a large asteroid measuring nearly 2,600 feet across, NASA will direct DART on a collision course with an orbiting satellite, a 500-foot-wide object nicknamed "Didymoon." If successful, the 1,100-pound probe will slam into Didymoon at a speed of 13,500 mph and create a very small velocity change (estimated at less than a fraction of 1 percent) that, over a long period of time, will have a much larger impact on the moonlet's orbit.
"With DART, we want to understand the nature of asteroids by seeing how a representative body reacts when impacted, with an eye toward applying that knowledge if we are faced with the need to deflect an incoming object," Andrew Rivkin, a researcher at Johns Hopkins Applied Physics Laboratory in Laurel, Maryland and a co-leader on the DART investigation, said in a statement. "In addition, DART will be the first planned visit to a binary asteroid system, which is an important subset of near-Earth asteroids and one we have yet to fully understand."
Despite all of this celestial drama taking place millions of miles away, ground-based telescopes and planetary radar on Earth will be utilized to measure any changes in momentum by the moonlet.
Autopsy of an asteroid collision
After DART completes its collision course with the moonlet, an event expected to take place in October 2022, the next mission phase will involve a visit some four years later by the ESA's Hera spacecraft. Its primary objective will be to use its array of high-resolution instruments to build detailed maps of Didymoon, the crater created by DART, and any dynamical changes present since the collision. It's hoped that the information gathered will better inform future versions of the DART weapon, in particular for deflecting much larger objects.
"This key data gathered by Hera will turn a grand but one-off experiment into a well-understood planetary defense technique: one that could in principle be repeated if we ever need to stop an incoming asteroid," Hera manager Ian Carnelli said in a statement.
Should DART prove successful, it could lead the way for what's expected to be a wide range of planetary defense options –– from nuclear explosive devices to solar sails that might attach and "pull" a near-Earth-object off-course. Either way, most astronomers agree that we'll need plenty of warning in the form of several years to even have a chance at altering a doomsday-sized object from colliding with Earth. With the last known major impact occurring roughly 35 million years ago, researchers are hopeful we'll still have time to plan accordingly.
As Danica Remy, president of the B612 Foundation's Asteroid Institute program, said last year: "It's 100 percent certain we'll be hit, but we're not 100 percent certain when." | 0.864208 | 3.424442 |
From Ashburn, it will be visible between 21:17 and 05:12. It will become accessible around 21:17, when it rises to an altitude of 10° above your south-eastern horizon. It will reach its highest point in the sky at 01:17, 32° above your southern horizon. It will become inaccessible around 05:12 when it sinks below 10° above your south-western horizon.
Saturn opposite the Sun
This optimal positioning occurs when Saturn is almost directly opposite the Sun in the sky. Since the Sun reaches its greatest distance below the horizon at midnight, the point opposite to it is highest in the sky at the same time.
At around the same time that Saturn passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest and largest.
This happens because when Saturn lies opposite the Sun in the sky, the solar system is lined up so that Saturn, the Earth and the Sun form a straight line with the Earth in the middle, on the same side of the Sun as Saturn.
In practice, however, Saturn orbits much further out in the solar system than the Earth – at an average distance from the Sun of 9.54 times that of the Earth, and so its angular size does not vary much as it cycles between opposition and solar conjunction.
On this occasion, Saturn will lie at a distance of 8.94 AU, and its disk will measure 18.6 arcsec in diameter, shining at magnitude 0.2. Even at its closest approach to the Earth, however, it is not possible to distinguish it as more than a star-like point of light without the aid of a telescope.
The rings of Saturn
Saturn will be angled to show its northern hemisphere at this opposition, and the rings will inclined at an angle of 18° to our line of sight, making them very well presented.
The graph below shows the changing inclination of Saturn's rings over time. The black line indicates their inclination to our line of sight from the Earth. A negative angle indicates that the north pole is tipped towards us, while a positive angle indicates that we see the south pole. A angle close to zero means that Saturn's rings appear close to edge on.
The red line indicates the inclination of the rings to the Sun's line of sight to the planet. Interesting phenomena can occur when the rings are very close to edge-on, if the Sun illuminates one side of the rings, while we see the other. At such times, we see the unilluminated side of the rings.
The Seeliger Effect
For a few hours around the exact moment of opposition, it may be possible to discern a marked brightening of Saturn's rings in comparison to the planet's disk, known as the Seeliger Effect.
This occurs because Saturn's rings are made of a fine sea of ice particles which are normally illuminated by the Sun at a slightly different angle from our viewing angle, so that we see some illuminated particles and some which are in the shadow of others.
At around the time of opposition, however, the ice particles are illuminated from almost exactly the same direction from which we view them, meaning that we see very few which are in shadow.
Saturn in coming weeks
Over the weeks following its opposition, Saturn will reach its highest point in the sky four minutes earlier each night, gradually receding from the pre-dawn morning sky while remaining visible in the evening sky for a few months.
The position of Saturn at the moment it passes opposition will be:
|Object||Right Ascension||Declination||Constellation||Magnitude||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 02 August 2021|
23 days 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.
|02 Aug 2021||– Saturn at opposition|
|04 Feb 2022||– Saturn at solar conjunction|
|14 Aug 2022||– Saturn at opposition|
|16 Feb 2023||– Saturn at solar conjunction| | 0.845699 | 3.769272 |
It's a great honor today to share with you The Digital Universe, which was created for humanity to really see where we are in the universe. And so I think we can roll the video that we have.
The flat horizon that we've evolved with has been a metaphor for the infinite: unbounded resources and unlimited capacity for disposal of waste. It wasn't until we really left Earth, got above the atmosphere and had seen the horizon bend back on itself, that we could understand our planet as a limited condition. The Digital Universe Atlas has been built at the American Museum of Natural History over the past 12 years. We maintain that, put that together as a project to really chart the universe across all scales. What we see here are satellites around the Earth and the Earth in proper registration against the universe, as we see. NASA supported this work 12 years ago as part of the rebuilding of the Hayden Planetarium so that we would share this with the world.
The Digital Universe is the basis of our space show productions that we do — our main space shows in the dome. But what you see here is the result of, actually, internships that we hosted with Linkoping University in Sweden. I've had 12 students work on this for their graduate work, and the result has been this software called Uniview and a company called SCISS in Sweden. This software allows interactive use, so this actual flight path and movie that we see here was actually flown live. I captured this live from my laptop in a cafe called Earth Matters on the Lower East Side of Manhattan, where I live, and it was done as a collaborative project with the Rubin Museum of Himalayan Art for an exhibit on comparative cosmology.
And so as we move out, we see continuously from our planet all the way out into the realm of galaxies, as we see here, light-travel time, giving you a sense of how far away we are. As we move out, the light from these distant galaxies have taken so long, we're essentially backing up into the past. We back so far up we're finally seeing a containment around us — the afterglow of the Big Bang. This is the WMAP microwave background that we see. We'll fly outside it here, just to see this sort of containment. If we were outside this, it would almost be meaningless, in the sense as before time. But this our containment of the visible universe. We know the universe is bigger than that which we can see.
Coming back quickly, we see here the radio sphere that we jumped out of in the beginning, but these are positions, the latest positions of exoplanets that we've mapped, and our sun here, obviously, with our own solar system. What you're going to see — we're going to have to jump in here pretty quickly between several orders of magnitude to get down to where we see the solar system — these are the paths of Voyager 1, Voyager 2, Pioneer 11 and Pioneer 10, the first four spacecraft to have left the solar system. Coming in closer, picking up Earth, orbit of the Moon, and we see the Earth. This map can be updated, and we can add in new data.
I know Dr. Carolyn Porco is the camera P.I. for the Cassini mission. But here we see the complex trajectory of the Cassini mission color coded for different mission phases, ingeniously developed so that 45 encounters with the largest moon, Titan, which is larger that the planet Mercury, diverts the orbit into different parts of mission phase.
This software allows us to come close and look at parts of this. This software can also be networked between domes. We have a growing user base of this, and we network domes. And we can network between domes and classrooms. We're actually sharing tours of the universe with the first sub-Saharan planetarium in Ghana as well as new libraries that have been built in the ghettos in Columbia and a high school in Cambodia. And the Cambodians have actually controlled the Hayden Planetarium from their high school.
This is an image from Saturday, photographed by the Aqua satellite, but through the Uniview software. So you're seeing the edge of the Earth. This is Nepal. This is, in fact, right here is the valley of Lhasa, right here in Tibet. But we can see the haze from fires and so forth in the Ganges valley down below in India. This is Nepal and Tibet.
And just in closing, I'd just like to say this beautiful world that we live on — here we see a bit of the snow that some of you may have had to brave in coming out — so I'd like to just say that what the world needs now is a sense of being able to look at ourselves in this much larger condition now and a much larger sense of what home is. Because our home is the universe, and we are the universe, essentially. We carry that in us. And to be able to see our context in this larger sense at all scales helps us all, I think, in understanding where we are and who we are in the universe. | 0.816607 | 3.02234 |
Astronomers from Keio University, Japan, have observed what looks like the largest intermediate-mass black hole within the Milky Way. The object is estimated to weigh 100,000 times the mass of the Sun and is located near the center of the galaxy.
The study, published in Nature Astronomy, focused on a large molecular gas cloud almost 200 light-years from the center of the Milky Way. The team was able to study how the gas is moving, which is consistent with having a massive compact object at its center, which they named CO–0.40–0.22*.
The researchers also noticed how the emissions from the gas cloud resemble the core of the Milky Way, where the supermassive black hole of our galaxy is located, although 500 times less luminous. There’s also quite a difference in size as the Milky Way's supermassive black hole, called Sagittarius A*, is over 4 million times the mass of the Sun.
"This is the first detection of an intermediate-mass black hole (IMBH) candidate in our Milky Way Galaxy," lead author Dr Tomoharu Oka told IFLScience. "This supports the merging scenario of the formation/evolution of supermassive black holes in galactic centers."
The team already suspected the cloud hosted an IMBH, but this is the first detection of a point-like radio source. The new observations were possible thanks to Atacama Large Millimeter/Submillimeter Array whose sensitive antennas were ideal to pick up the extremely cold emissions of interstellar carbon monoxide clouds. The team compared the observations to numerical simulations of the gas cloud and they agreed with the idea of an intermediate-mass black hole hiding within. The team believes CO–0.40–0.22* to be one of the most promising candidates for an intermediate-mass black hole yet.
The discovery of potential new black hole is always an exciting affair but this is particularly important because it provides us with important clues to how supermassive black holes formed. Black holes form in supernova explosions but their size is very much related to their stellar progenitors. So how can black holes exist that are millions, if not billions, of times the mass of our Sun?
One main theory suggests that in the early universe black holes formed a lot more often because the stars were a lot bigger and burned through their fuel more quickly. These black holes would merge, eventually reaching hundreds of solar masses in size. At that point, they would merge with other similar sized black holes and become supermassive black holes.
The team is continuing observations of the source, and they hope that within just a decade of observations they'll be able to describe how it's moving across the galaxy and if it's going to merge with Sagittarius A*. | 0.865552 | 3.989124 |
It's official: There's water ice on the moon, and lots of it. When melted, the water could potentially be used to drink or to extract hydrogen for rocket fuel.
NASA's LCROSS probe discovered beds of water ice at the lunar south pole when it impacted the moon last month, mission scientists announced today. The findings confirm suspicions announced previously, and in a big way.
"Indeed, yes, we found water. And we didn't find just a little bit, we found a significant amount," Anthony Colaprete, LCROSS project scientist and principal investigator from NASA's Ames Research Center at Moffett Field, Calif.
The LCROSS probe impacted the lunar south pole at a crater called Cabeus on Oct. 9. The $79 million spacecraft, preceded by its Centaur rocket stage, hit the lunar surface in an effort to create a debris plume that could be analyzed by scientists for signs of water ice.
Those signs were visible in the data from spectrographic measurements (which measure light absorbed at different wavelengths, revealing different compounds) of the Centaur stage crater and the two-part debris plume the impact created. The signature of water was seen in both infrared and ultraviolet spectroscopic measurements.
"We see evidence for the water in two instruments," Colaprete said. "And that's what makes us really confident in our findings right now."
Based on the measurements, the team estimated about 100 kilograms of water in the view of their instruments — the equivalent of about a dozen 2-gallon buckets — in the area of the impact crater (about 80 feet, or 20 meters across) and the ejecta blanket (about 60 to 80 meters across), Colaprete said.
"I'm pretty impressed by the amount of water we saw in our little 20-meter crater," Colaprete said.
"What's really exciting is we've only hit one spot. It's kind of like when you're drilling for oil. Once you find it one place, there's a greater chance you'll find more nearby," said Peter Schultz, professor of geological sciences at Brown University and a co-investigator on the LCROSS mission.
This water finding doesn't mean that the moon is wet by Earth's standards, but is likely wetter than some of the driest deserts on Earth, Colaprete said. And even this small amount is valuable to possible future missions, said Michael Wargo, chief lunar scientist for Exploration Systems at NASA Headquarters.
Scientists have suspected that permanently shadowed craters at the south pole of the moon could be cold enough to keep water frozen at the surface based on detections of hydrogen by previous moon missions. Water has already been detected on the moon by a NASA-built instrument on board India's now defunct Chandrayaan-1 probe and other spacecraft, though it was in very small amounts and bound to the dirt and dust of the lunar surface.
Water wasn't the only compound seen in the debris plumes of the LCROSS impact.
"There's a lot of stuff in there," Colaprete said. What exactly those other compounds are hasn't yet been determined, but could include organic materials that would hint at comet impacts in the past.
The findings show that "the lunar poles are sort of record keepers" of lunar history and solar system history because these permanently-shadowed regions are very cold "and that means that they tend to trap and keep things that encounter them," said Greg Delory, a senior fellow at the Space Sciences Laboratory and Center for Integrative Planetary Sciences at the University of California, Berkeley. "So they have a story to tell about the history of the moon and the solar system climate."
"This is ice that's potentially been there for billions of years," said Doug Cooke, associate administrator at Exploration Systems Mission Directorate at NASA Headquarters in Washington, D.C.
The confirmation that water exists on the moon isn't the end of the story though. One key question to answer is where the water came from. Several theories have been put forward to explain the origin of the water, including debris from comet impacts, interaction of the lunar surface with the solar wind, and even giant molecular clouds passing through the solar system, Delory said.
Scientists also want to examine the data further to figure out what state the water is in. Colaprete said that based on initial observations, it is likely water ice is interspersed between dirt particles on the lunar surface.
Some other questions scientists want to answer are what kinds of processes move, destroy and create the water on the surface and how long the water has been there, Delory said.
Link to Chandrayaan?
Scientists also are looking to see if there is any link between the water observed by LCROSS and that discovered by Chandrayaan-1.
"Their observation is entirely unique and complementary to what we did," Colaprete said. Scientists still need to work out whether the water observed by Chandrayaan-1 might be slowly migrating to the poles, or if it is unrelated.
Bottom line, the discovery completely changes scientists' view of the moon, Wargo said.
The discovery gives "a much bigger, potentially complicated picture for water on the moon" than what was thought even just a few months ago, he said. "This is not your father's moon; this is not a dead planetary body."
NASA plans to return astronauts to the moon by 2020 for extended missions on the lunar surface. Finding usable amounts of ice on the moon would be a boon for that effort since it could be a vital local resource to support a lunar base.
"Water really is one of the constituents of one of the most powerful rocket fuels, oxygen and hydrogen," Wargo said.
The water LCROSS detected "would be water you could drink, water like any other water," Colaprete said. "If you could clean it, it would be drinkable water."
The impact was observed by LCROSS's sister spacecraft, the Lunar Reconnaissance Orbiter, as well as other space and ground-based telescopes.
The debris plume from the impacts was not seen right away and was only revealed a week after the impact, when mission scientists had had time to comb through the probe's data.
NASA launched LCROSS — short for Lunar Crater Observation and Sensing Satellite — and LRO in June. | 0.811754 | 3.76406 |
The observations confirm that the supermassive object really is a black hole
As far as close shaves with a black hole go, it doesn’t get much closer than this.
Scientists have spotted clouds of gas hurtling around the monster black hole at the center of the Milky Way, not far from the behemoth’s edge. Observed on three separate occasions, the gas clouds careened along at unimaginably fast speeds — 30 percent of the speed of light, researchers report October 31 in Astronomy & Astrophysics.
The gas seemed to be near a boundary known as the innermost stable circular orbit — the closest matter can circle the black hole without falling in. The clumps, which researchers observed when the gas caused flares of infrared light, orbited at a distance just a few times the radius of the black hole’s event horizon, the boundary from beyond which nothing, not even light, can return. That’s equivalent to about a quarter of the distance from Earth to the sun.
Previously, scientists had tracked the motion of a star orbiting close to the black hole. But that star was hundreds of times farther away than the gas.
“What’s exciting now is that we can get closer to the black hole,” says study coauthor Jason Dexter, an astrophysicist at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. The researchers observed the clouds using the Very Large Telescope array in the Atacama Desert of Chile.
These up-close encounters strengthen scientists’ belief that the Milky Way has a bona fide black hole lurking at its center. Harvard University astrophysicist Avi Loeb helped predict the existence of such flares 13 years ago, and the results match expectations. Such measurements could also help physicists test Einstein’s theory of gravity, general relativity, Loeb says.
Source: Science News | 0.845257 | 3.461993 |
Could a collision between 2 asteroids millions of miles away cause an ice age on Earth, some 460 million years ago? A new study of earthly rocks and sediments – plus micrometeorites that fell in Antarctica – suggest it’s possible.
Artist’s concept of the collision between 2 asteroids – some 460 million years ago – that created enough dust to cause an ice age on Earth. Image via Don Davis/Southwest Research Institute/EurekAlert.
Some 460 million years ago, Earth was a frozen world, caught in the grip of a global ice age. For a long time, scientists have been trying to figure what caused this ice age, which occurred in what they call the Ordovician period, and which coincided with a major mass extinction of nearly 61% of marine life. Now they think they may finally know. A new study – announced on September 18, 2019, by the Field Museum in Chicago – suggests the ice age resulted from a collision between two asteroids, not onto Earth, but with each other, in outer space. The collision may have caused much more dust than usual to enter Earth’s atmosphere. The influx of dust may have caused a global cooling that turned Earth into a colder, icier world.
Philipp Heck is one of the paper’s authors and a curator at the Field Museum. He explained in a statement:
Normally, Earth gains about 40,000 tons of extraterrestrial material every year. Imagine multiplying that by a factor of a thousand or ten thousand. Our hypothesis is that the large amounts of extraterrestrial dust over a timeframe of at least two million years played an important role in changing the climate on Earth, contributing to cooling.
Lead author of the research, Birger Schmitz, also at the Field Museum, added:
Our results show for the first time that such dust, at times, has cooled Earth dramatically. Our studies can give a more detailed, empirical-based understanding of how this works, and this in turn can be used to evaluate if model simulations are realistic.
The mid-Ordovician Hällekis section in sedimentary rock in southern Sweden, where the dust samples were found. The time of the asteroid collision/dust impact is represented by the red line. Image via Birger Schmitz/Lund University/ScienceAdvances.
According to these scientists, the greatly increased amount of dust entering Earth’s atmosphere upset the climate balance enough to cause a new ice age, even if it took a couple million years to do it. In the collision, the study concludes, a 93-mile-wide (150-km-wide) asteroid broke apart somewhere between Mars and Jupiter. That was still close enough for much more dust then normal to enter Earth’s atmosphere.
It’s a fascinating hypothesis, but how did the scientists reach this conclusion?
They looked at samples from a place on Earth that is still pretty much frozen year-round: Antarctica. Micrometeorites from Antarctica, which are common, were compared to other 466-million-year-old rocks from sedimentary layers – the mid-Ordovician Hällekis section – in southern Sweden. According to Heck:
We studied extraterrestrial matter, meteorites and micrometeorites, in the sedimentary record of Earth, meaning rocks that were once sea floor. And then we extracted the extraterrestrial matter to discover what it was and where it came from.
A 466-million-year-old fossil meteorite, thought to have been created in the same asteroid collision that caused enough dust to create an ice age. The fossil of a squid-like creature called a nautiloid can also be seen along the top. Image via Field Museum/John Weinstein/EurekAlert.
In order to retrieve the space dust from the rocks, the research team used powerful acid to erode the rock and leave behind the dust particles, which were then analyzed. Then, rock samples from the ancient sea floor were also examined; the scientists wanted to find elements and isotopes that they could identify as having originated from space. As an example, helium atoms on Earth have two protons, two neutrons and two electrons. But, helium atoms that come from the sun are missing one neutron. Since that kind of helium atom, as well as traces of rare metals found in asteroids, were found in the 466-million-year-old rocks, that showed that the dust came from space.
It was already known that there was an ice age at this time, and the new study shows that the timing of it coincided with the extra dust in the atmosphere. As Schmitz said:
The timing appears to be perfect.
The researchers also found other evidence that some of Earth’s water at the time was trapped in glaciers and sea ice, since the analysis of the rocks indicated that the oceans were shallower at this time. All of this together is evidence that the increased dust in the atmosphere created a global cooling and ultimately an ice age.
A chromite grain (light gray) from a micrometeorite in Antarctica. The grain was not included in the present study but is used here to illustrate the distribution of such relict grains in micrometeorites. Image via ScienceAdvances.
It’s a good thing that the cooling process was gradual, as that allowed much of earthly life to adapt to the changing conditions. According to Heck:
In the global cooling we studied, we’re talking about timescales of millions of years. It’s very different from the climate change caused by the meteorite 65 million years ago that killed the dinosaurs, and it’s different from the global warming today – this global cooling was a gentle nudge. There was less stress.
The researchers also noted that it might be tempting to think that dust like this might be a good way to combat climate change. But Heck urges caution even though it’s an idea worth studying:
Geoengineering proposals should be evaluated very critically and very carefully, because if something goes wrong, things could become worse than before. We’re experiencing global warming, it’s undeniable. And we need to think about how we can prevent catastrophic consequences, or minimize them. Any idea that’s reasonable should be explored.
The results of this study provide valuable insight into how a global ice age started millions of years ago – from an asteroid collision in deep space – and may even assist scientists in determining ways to mitigate current climate change.
Some 460 million years ago, Earth was in the grip of a global ice age like the one in this artist’s concept. The new study suggests it was caused by dust from a collision between 2 asteroids. Image via NASA/Gizmodo.
Bottom line: A global ice age 466 million years ago was caused by dust from a collision between two asteroids, a new study suggests.
Paul Scott Anderson has had a passion for space exploration that began when he was a child when he watched Carl Sagan’s Cosmos. While in school he was known for his passion for space exploration and astronomy. He started his blog The Meridiani Journal in 2005, which was a chronicle of planetary exploration. In 2015, the blog was renamed as Planetaria. While interested in all aspects of space exploration, his primary passion is planetary science. In 2011, he started writing about space on a freelance basis, and now currently writes for AmericaSpace and Futurism (part of Vocal). He has also written for Universe Today and SpaceFlight Insider, and has also been published in The Mars Quarterly and has done supplementary writing for the well-known iOS app Exoplanet for iPhone and iPad. | 0.853989 | 3.73104 |
Exoplanets come in various shapes and sizes, from small rocky worlds smaller than Mercury to massive gas giants that would even eclipse Jupiter. Exoplanet hunters have developed complex arrays of telescopes and various methods to identify these distant worlds, but now we are on the verge of finding new exoplanets of various shapes. More details about exoplanets can be found in our article.
Exoplanets revolve around a multitude of stars, but the most interesting targets are the red dwarfs that are most common in our galaxy.
In the era of hunting for inhabited exoplanets (that is, worlds that revolve around their stars in a habitable area at a distance that is not too hot, but not too cold), astronomers discovered that red dwarfs have great potential. Since they are colder and smaller than our Sun, the habitable zones of red dwarfs are more compact. It also means that any inhabited worlds that orbit around a red dwarf make it faster. This orbital feature provides an additional opportunity for telescopes, since such an exoplanet, passing in front of the parent star, will block some sunlight.
The hypothetical exoplanet through the eyes of the artist
Due to its small mass, red dwarfs are also very ancient stars. They are so old that there is a high probability of the birth of stable planetary systems, which for a long period of time would remain livable. The longer the period of existence, the more hypothetical life forms could develop.
Of course, red dwarfs can deliver a lot of problems for hypothetical residential worlds. Red dwarfs, as is known, are quite stormy young stars, having powerful stellar flares. In addition, their habitable zones are so compact that any of the worlds inside this orbit will be gravitationally blocked with a star.
Such a synchronous rotation means that one side of the exoplanet, be it a small rocky world or a gas giant, will be directed towards the star all the time by one side. This cruel tidal environment can have a rather unusual effect on the shape of an exoplanet.
In a new study published in the Royal Astronomical Society's Monthly Notices magazine, researchers from George Mason University, Virginia, focused their attention to detect traces of significant tidal deformation, both in giant gas worlds and in small habitable planets. Understanding the shape of an exoplanet rotating close to its star is a practical goal. Tidal deformation of exoplanets can lead to an underestimation of the radius of the planet, which in turn will lead to overestimated estimates of its density. When studying exoplanets located at a distance of several tens to hundreds of light years, these measurement uncertainties can seriously affect our understanding of the characteristics of exoplanets.
“Imagine if we take a planet like Earth and Mars and place it next to a cool red star and stretch it,” said Prabhal Saxene, a lead researcher at this study. "Analysis of the new form can say a lot, otherwise it will be impossible to see the internal structure of the planet and how it changes over time."
By modeling several exoplanetary configurations around red dwarfs, the Prabala team received an elongated shape of exoplanets when they were tidal blocked with their star. As the researchers noted, the detection of such tidal deformation will be possible when the next generation of observatories is built, such as the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT). | 0.850659 | 3.968822 |
Using the Atacama Large Millimeter/submillimeter Array, or ALMA, astronomers found an unexpected spiral structure surrounding the red giant star R Sculptoris shown here in this visualization. Credit: ALMA (ESO/NAOJ/NRAO)
Sometimes what we can’t see is just as surprising as what lies directly in front of us. This especially holds true in a new finding from the astronomers using the Atacama Large Millimeter/sumbillimeter Array, or ALMA, in Chile. A surprising and strange spiral structure surrounding the old star R Sculptoris is likely being created by an unseen companion, say astronomers.
The team using ALMA, the most powerful millimeter/submillimeter telescope in the world, mapped the spiral structure in three-dimensions. The astronomers say this is the first time a spiral of material, with a surrounding shell, has been observed. They report their findings in the journal Nature this week.
“We’ve seen shells around this kind of star before,” says lead author Matthias Maercker of the European Southern Observatory and Argelander Institute for Astronomy, University of Bonn, Germany in a press release. “But this is the first time we’ve ever seen a spiral of material coming out from a star, together with a surrounding shell.”
Scientists, using the NASA/ESA Hubble Space Telescope found a similar spiral, but without a surrounding shell, while observing the star LL Pegasi. Unlike the new ALMA observations, however, the astronomers could not create a three-dimensional map of the structure. Hubble observations saw the dust while ALMA detected the molecular emission.
ALMA detects the warm glow of carbon monoxide molecules in the far infrared through the multimeter wavelengths allowing astronomers to map the gas emissions surrounding the star in high-resolution. The team believes the strangely shaped bubble of material was probably created by an invisible companion star orbiting the red giant.
As stars like our Sun reach the ends of their lives, they become red giants. Swollen and cool, the stars begin a short-lived helium burning phase. During this time, the stars slough off large amounts of their mass in a dense stellar wind forming an expanding glowing shell around the stellar core. The pulses occur about every 10,000 to 50,000 years and last just a few hundred years. New observations of R Sculptoris show a pulse event rocked the star about 1,800 years ago and lasted for about 200 years. Computer simulations following the evolution of a binary system fit the new ALMA observations, according to the astronomers.
“It’s a real challenge to describe theoretically all the observed details coming from ALMA,” says co-author Shazrene Mohamed, of Argelander Institute for Astronomy in Bonn, Germany and South African Astronomical Observatory. “But our computer models show that we really are on the right track. ALMA is giving us new insight into what’s happening in these stars and what might happen to the Sun in a few billion years from now.”
A wide field view of the red giant variable star R Sculptoris. Credit: ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin
R Sculptoris is considered by astronomers to be an asymptotic giant branch, or AGB, star. With masses between 0.8 and 8 solar masses, they are cool red giants with a tiny central core of carbon and oxygen surrounded by a burning shell of helium and hydrogen burning. Eventually, our Sun will evolve into an AGB star. The glowing shell is made up of gas and dust, material that will be used for making future stars with their retinue of planets and moons and even the building blocks of life.
“In the near future, observations of stars like R Sculptoris with ALMA will help us to understand how the elements we are made up of reached places like the Earth. They also give us a hint of what our own star’s far future might be like,” says Maercker.
This new video shows a series of slices through the data, each taken at a slightly different frequency. These reveal the shell around the star, appearing as a circular ring, that seems to gets bigger and then smaller, as well as a clear spiral structure in the inner material that it best seen about half-way through the video sequence.
Source: European Southern Observatory
Small image caption: What appears to be a thin spiral pattern winding away from a star is shown in this remarkable picture from the Advanced Camera for Surveys on the NASA/ESA Hubble Space Telescope shows one of the most perfect geometrical forms created in space. It captures the formation of an unusual pre-planetary nebula, known as IRAS 23166+1655, around the star LL Pegasi (also known as AFGL 3068) in the constellation of Pegasus (the Winged Horse). Credit: NASA/ESA Hubble | 0.870551 | 3.980101 |
The Pluto-shaped void in our hearts has yet to be filled by Planet 9, copious amounts of Ben & Jerry’s, or anything. Ever since the summer of 2015, when NASA’s New Horizons performed a six-month-long reconnaissance flyby study of Pluto and its moons, fans of the dwarf planet have wondered if or when we’d ever go back. According to New Horizons principal investigator Alan Stern, he and some other planetary scientists are already drawing up the blueprint for a return trip—and this time, it’d be much more than just a flyby.
“The news is not that we have a specific mission design,” Stern told Gizmodo. “The news is that the community is forming around the concept of going back to Pluto with an orbiter mission that would stay and study the planet for years, and do it in ways that we could not have in a simple flyby like New Horizons. It would have much more advanced instrumentation and the ability to map every square inch of the planet, and unravel all the complexity that we found.”
New Horizons, which left Earth on January 19th, 2006, was able to provide us with an unprecedented look at some of the mysterious worlds of the Kuiper Belt, including Pluto, its large moon Charon, and four baby moons—Nix, Hydra, Styx and Kerberos—which are very appropriately named for the Greek underworld gods. We discovered that Pluto is an astonishingly dynamic place, with mountains, chasms, a billowy atmosphere, and maybe even a massive subsurface ocean. Best of all, we learned that the icy world has a soft side, with some unforgettable New Horizons images of the dwarf planet’s heart.
Still, many lingering mysteries remain. Pluto might have wind-blown dunes on it, features thought to be impossible before the flyby. Its mountains, which are made of frozen water, could reveal many secrets about geologic activity on the dwarf planet today. With so much left to learn, the only way to get answers is to go back. And unlike the New Horizons flyby, which didn’t spend enough time loitering to even map both of Pluto’s hemispheres at high resolution, much less monitor changes on the surface, an orbiter that remains in the Pluto system for several years would be able to do both.
“Going back to Pluto is becoming, in the scientific community, a real growing concern instead of just scattered conversation,” Stern said. And so, a few days ago, he and 34 scientists gathered in Houston, Texas to start mapping out what an orbiter mission would look like. Some of this new team is comprised of New Horizons members and seasoned pros in the field, in addition to scientists at the start of their careers.
“You won’t see it presented in the next few months, but I’m sure that by next year you’ll see it in many places,” Stern said. He added that this October, he and his team plan to have a workshop on their new mission concept at the49th meeting of the Division of Planetary Sciences.
“We were so surprised by the level of complexity that we found,” Stern said. “If you would have asked me before we got there if I thought there was ever any real chance of going back, I would have said ‘not really.’ And yet, here we are two years later and thinking about all the mysteries we can’t solve except by going back.”
While the plans are still in their infancy, Stern and his team are hopeful that they can get their concept together in time for the next Planetary Science Decadal Survey, a massive report prepared for NASA and Congress by the planetary science community, which helps to set the space agency’s priorities for solar system exploration. The next Decadal Survey will start being compiled around 2020, Stern said.
Gathering enough support within the scientific community is critical to convince the space agency such a trip would be worth it. The good news for Stern and his team is that the public already has their back. As soon as hetweeted the news about the potential orbiter, Stern’s mentions erupted with well-wishers.
“Hundreds of people were getting involved and cheering it on,” he said. “It’s like the slightest hope of going back to Pluto…the public interest is amazing.” | 0.829887 | 3.512534 |
A long time ago in a galaxy far, far away… a blazar once shone with the brightness of a trillion suns.
That galaxy is OJ 287, and it is located 3.5 billion light-years away in the constellation of Cancer. In other words, we are witnessing the ancient past. We are seeing the galaxy as it was 3.5 billion years ago. The source of the blazar (extremely high-energy quasar) is the interaction of two supermassive black holes that reside in its center. The larger of the two is a staggering 18.35 billion solar masses. The smaller companion, itself having the mass of 150 million Suns, orbits the larger companion every 11-12 years. As its orbit is inclined to the ecliptic, however, it crosses the larger companion’s accretion disk twice during each orbit. Relativistic jets of superheated ionized gases are produced when material from the disk falls into the spinning black hole at close to the speed of light. The black hole’s intense gravity distorts space-time near the poles such that its magnetic field is twisted outward, like the barrel of a gun. That barrel happens to coincide with our line of sight, resulting in a magnificent blazar.
But then again, everything is super-sized with these black holes. In addition to its mind-boggling mass, the event horizon (spherical boundary where light cannot escape) for the larger black hole is approximately 108 billion kilometers (9 times the size of Pluto’s orbit). Its accretion disk stretches further trillions of kilometers. The smaller companion’s event horizon is about 900 million kilometers (about the size of the asteroid belt). The orbits of Mercury, Venus, Earth, and Mars would fit comfortably inside.
Describing black holes in terms of their event horizons helps us visualize their apparent sizes, but it doesn’t represent reality. In reality, black holes only have three externally observable parameters – mass, electric charge, and angular momentum. That is because all the matter in a black hole is compressed into a single point, a singularity. In other words, black holes have zero volume, and thus are infinitely dense.
As amazing as this blazar is, it will not last forever. In about 10,000 years, the smaller black hole’s orbit will decay (orbital energy lost via gravitational radiation) to the point where it will eventually merge with its larger companion. We think of this event as a future event since we have not seen it yet, but in actuality, this merger has already happened ~ 3.49999 billion years ago.
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Closing out a year-and-a-half of exploration, surveys and sampling operations at asteroid Ryugu, Japan’s Hayabusa 2 spacecraft fired thrusters in a departure maneuver Wednesday and headed for Earth with specimens snatched from the asteroid’s dark and rocky surface.
The robotic spacecraft pulsed its control rockets Wednesday to begin moving away from asteroid Ryugu at approximately 0.2 mph (9.2 centimeters) per second, beginning a slow departure that will culminate in the activation of the probe’s ion thrusters to reshape its trajectory and target arrival at Earth in late 2020.
Ground teams at the Japan Aerospace Exploration Agency’s control center in Sagamihara, Japan, confirmed the departure maneuver at 10:24 a.m. Japan Standard Time (0124 GMT Wednesday; 8:24 p.m. EST Tuesday).
Hayabusa 2’s thrusters propelled the spacecraft away from a position roughly 12 miles (20 kilometers) from Ryugu. The spacecraft is programmed to collect a series of farewell images of the half-mile-wide (900-meter) asteroid through Nov. 18, when Hayabusa 2 will be more than 31 miles (50 kilometers) from Ryugu.
According to JAXA, the spacecraft will change its orientation beginning Nov. 18 to prepare for testing of the probe’s ion engines two days later.
Hayabusa 2 carries four ion thrusters, powered by electricity and fueled by xenon gas, to adjust the craft’s course through the solar system. The plasma engines produce low thrust, but can run for months at a time, making for a fuel-efficient propulsion system on deep space missions.
After verifying the performance of the ion engines, Hayabusa 2’s ground team will uplink commands to begin the mission’s return cruise phase after Dec. 3, commencing a year-long transit back to Earth.
Up to three ion engines will fire at one time during Hayabusa’s return cruise.
The departure maneuver Wednesday marked the end of Hayabusa 2’s stay at Ryugu. During its time at the asteroid, the Hayabusa 2 spacecraft performed two touch-and-go landings to collect samples for return to Earth, and delivered a series of mobile robots to scout the asteroid’s surface.
Scientists are eager to analyze the specimens, which they expect may contain organic molecules. Researchers believe asteroids like Ryugu, or a larger body like the one from which Ryugu split off, could have seeded Earth with materials necessary for life.
JAXA unveiled an updated logo for the Hayabusa 2 mission after Wednesday’s departure from Ryugu. The logo is green, symbolizing plant life on Earth.
“If the sample returned from Ryugu contains organics, we may understand how Earth gathered the raw materials for life,” JAXA said in a tweet. “This logo reflects that expectation!”
As of Wednesday, asteroid Ryugu was located around 156 million miles (252 million kilometers) from Earth.
Named for a dragon’s palace in a famous Japanese fairy tale, Ryugu completes one circuit of the sun every 1.3 years. Its path briefly brings it inside Earth’s orbit, making Ryugu a potential impact risk with Earth in the distant future.
The asteroid samples gathered by Hayabusa 2 are stored inside a return capsule, which will separate from the Hayabusa 2 mothership before plunging into Earth’s atmosphere, aiming for a parachute-assisted landing in the Australian Outback at the end of 2020.
The exact date of the sample return capsule’s landing has not been confirmed by JAXA. The schedule will depend on the exact date of the start of Hayabusa 2’s return cruise, and is subject to final negotiations between JAXA and the Australian government, according to Yuichi Tsuda, Hayabusa 2’s project manager at JAXA.
Hayabusa 2 carries samples collected from two locations on Ryugu.
The spacecraft performed two precisely-guided touch-and-go landings on the asteroid in February and July. The sample collection in July was targeted to acquire material excavated from beneath Ryugu’s surface by a high-speed impactor deployed by Hayabusa 2 earlier this year.
Scientists will retrieve the asteroid specimens for detailed analysis.
“If we have 0.1 grams (of material), we can do all the sample analysis, but we hope we will have much more,” said Makoto Yoshikawa, Hayabusa 2’s mission manager at JAXA, in September.
“We want to study the organic matter on Ryugu because we want to know the origin of life on the Earth, and we think Ryugu has original matter that became life,” Yoshikawa said. “So our main purpose is analysis of the organic matter on the surface of Ryugu.”
Hayabusa 2 arrived in the vicinity of Ryugu in June 2018 after a three-and-a-half-year journey from Earth. The spacecraft launched Dec. 3, 2014, aboard an H-2A rocket from the Tanegashima Space Center in southern Japan.
During its time at Ryugu, Hayabusa 2 released three mobile landers to hop around the asteroid. Two MINERVA-II landers, developed in Japan, and a larger robot named MASCOT managed by the German and French space agencies beamed back images and scientific data from Ryugu’s surface last year.
Hayabusa 2 deployed a final MINERVA-II lander last month, but the robot suffered a computer fault and did not return any scientific data, JAXA officials said.
Hayabusa 2 is Japan’s second robotic asteroid sample return mission.
The mission’s predecessor, Hayabusa, returned to Earth in June 2010 with microscopic specimens gathered from the surface of asteroid Itokawa, despite multiple technical failures with its propulsion and sample collection systems.
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Follow Stephen Clark on Twitter: @StephenClark1. | 0.800719 | 3.123756 |
The acceleration of particles in astrophysical environments is a major question at the forefront of high energy astrophysics. The most famous cosmic particle accelerators are objects in quite extreme conditions such as supernova remnants or relativistic jets in extragalactic objects. These particle accelerators are responsible for the production of cosmic-rays (high energy charged particles such as electrons, protons, helium ions, heavier ions...). It is usual to distinguih cosmic rays of Galactic origin (below the knee in the spectrum shown below) or extragalactic origin (beyond the knee), even though this separation is still a matter of debate.
Cosmic ray spectrum.
Even though the intrinsic efficiency of pre-supernova massive stars is not expected to be as high as that of supernova remnants (SNRs), for instance, their contribution to the production of low energy (below GeVs) Galactic cosmic-rays may not be negligible. A first interesting class of objects is that of particle-accelerating colliding-wind binaries (PACWBs). These systems are mainly identified as particle accelerators on the basis of the detection of synchrotron radio emission (requiring a population of relativistic electrons). In these systems, the particle acceleration process is believed to be Diffusive Shock Acceleration (DSA) in the region where the stellar winds of the two massive stars collide. The physical conditions ruling the acceleration process are thus dictated by the stellar wind properties, and are expected to vary as a function of the orbital phase if the orbit is eccentric. A second interesting class is that of the so-called Bow Shock Runaways (BSRs). Massive runaway stars (ejected from their formation site) are likely to cross various interstellar regions. Along their way across interstellar clouds, their strong stellar winds will interact with the surrounding interstellar material and produce shocks. In the presence of these hydrodynamic shocks, the DSA mechanism can operate and accelerate particles.
Schematic view of the DSA mechanism.
An important feature that deserves to be emphasized is that these sources are non-thermal emitters. Relativistic electrons can produce synchrotron radiation in the radio domain (and in some extreme cases up to X-ray) and non-thermal X-rays through inverse Compton scattering (and potentially relativistic bremsstrahlung). Relativistic protons can interact with thermal material and produce neutral pions that decay to produce gamma-rays. These particle accelerators can thus be probed through non-thermal radiation produced across the electromagnetic spectrum. Such multiwavelength studies are at the centre of the activities of this group.
A related topic is the study of the influence of cosmic rays generated by massive stars on the energetic processing of molecules of astrochemical interest. This is especially relevant in dark cloud where photochemical processing is not active. All galactic particle accelerators (SNRs, PACWBs, BSRs...) are likely to contribute to the overall population of cosmic-rays that play a decisive role in the origin of the astrochemical diversity in molecular clouds.
Schematic view of a molecular cloud, in the presence of sources of cosmic-rays such as a BSR, a PACWB and a SNR. Figure taken from De Becker 2015, Bull. Soc. Roy. Sci. Liège, 84, 15. | 0.88008 | 4.232937 |
We’ve learned a lot about Mars in recent years. Multiple orbiters and hugely-successful rover missions have delivered a cascade of discoveries about our neighbouring planet. But to take the next step in unlocking Mars’ secrets, we need to get Martian samples back to Earth.
Both the ESA and NASA plan to get samples from Mars back to laboratories here on Earth, where they can be subjected to the type of detailed analysis that’s simply not possible with rovers on the surface of Mars. That effort is called the Mars Sample Return Campaign. Perhaps surprisingly, the hardest part might not be getting the samples back to Earth, but deciding on the order of scientific investigations into those samples.
The samples will be highly-coveted by scientists around the world. They have the potential to unlock secrets and answer pivotal questions in our quest to understand Mars.
“Mars Sample Return would be a huge advancement for Mars science and the exploration of the Solar System”, concludes Sanjay Vijendran, ESA’s Mars Sample Return Campaign Coordinator. “The samples will fundamentally advance our understanding of Mars, the history of our Solar System, and will help us plan for future exploration missions.”
For these samples to live up to their potential, they need to be handled carefully. But it all starts with getting the samples back to Earth.
The ESA and NASA are working together to get these samples to Earth. NASA’s 2020 Mars rover will prepare samples and leave them in vessels on the surface. Then the Sample Return Lander will land a platform near the Mars 2020 Rover landing site. An ESA rover, called the Sample Fetch Rover (SFR), will depart from that platform and gather the samples.
The SFR will deliver them to the platform where they’ll be placed in a canister on the Mars Ascent Vehicle (MAV). The MAV will be the first vehicle to lift off from the Martian surface and will deliver the samples into Mars orbit.
Next is the ESA’s Earth Return Orbiter (ERT), where the samples will be put into a sealed bio-containment system, then delivered to Earth orbit. From there, the samples will be sent to the surface, with the aid of parachutes, to be retrieved. Then the analysis begins.
NASA and ESA are both thinking ahead to how to handle these samples, including rocks, gas, and dust, for maximum science benefit.
The first consideration is controlling contamination. Any exposure to Earth’s atmosphere will change the samples. Just like samples from the Moon, the Martian samples will go into quarantine for protection.
There are guidelines in place to not only protect samples from Earth’s environment, but also to protect Earth from the samples, just in case. In 1959, at the dawn of the space age, the international community created COSPAR, the Committee on Space Research. COSPAR developed many of the guidelines that sought to protect other worlds from Earthly contamination, and vice versa.
Right now, COSPAR is updating its guidelines to prepare for the Mars samples.
It all starts with a Sample Receiving Facility (SRF) where the samples will be quarantined. Even before the sample containers are opened, scientific investigation can begin. These Martian samples will be extremely valuable, so even any Martian dust that has settled on the surface of the sample containers will be studied, before the containers are even opened. The samples can also be studied with non-invasive x-rays before being opened.
Before any samples are opened, the order of investigation and study will be predetermined.
“The sample tubes will contain martian rocks, dust and atmosphere,” says Elliot Sefton-Nash, the MSR Study Scientist from ESA’s Science Support Office, “Even though the plan is to open the tubes in a contained and inert environment, for a few measurements the clock will be ticking: for example, trapped gases in the sample material might start to mix with their surroundings, which could modify the martian chemical signatures that we want to measure.”
There are a multitude of measurements that scientists want to take. The trick is to find the best way to proceed, since some of those measurements are time-sensitive, and others will alter the samples. Also, the samples, according to planetary protection protocols, will eventually have to be sterilized, in case any Martian hitchhikers rode them to Earth.
But the sterilization of the samples is problematic. They have to be sterilized using radiation, chemical processes, or heat, and all those methods can alter the samples. So any scientific investigations that are sensitive to those methods have to be prioritized.
The body that decides how the samples should be handled is called the Mars Sample Return Science Planning Group. The good news is that that group says that roughly 3/4 of the scientific investigations can be done after sterilization.
But there’s still a lot of decisions to puzzle through.
The order in which investigations are done after sterilization is still important, because some measurements will influence the results of others. For example, some measurements will destroy samples in order to get results, and not all measurements can be done on all samples. According to the ESA, the nature of the laboratory doing the work can be a decisive factor.
Precision measurements of carbon in the samples dictates strict control of carbon in the laboratory. It may be that an all-metal laboratory is needed to guarantee valid results. But an all-metal laboratory could contaminate samples for other measurements. Finding the right balance is a big puzzle.
Once the ESA’s Space19+ Council meets and finalizes their involvement with the Mars Sample Return Mission, planning for handling the samples can begin in earnest. It’ll be up to the ESA, NASA, and the scientific community to come up with a plan that delivers the most science from the samples. | 0.865593 | 3.602662 |
In addition to being the only solvent that is capable of supporting life, water is essential to life as we know it here on Earth. Because of this, finding deposits of water – whether in liquid form or as ice – on other planets is always exciting. Even where is not seen as a potential indication of life, the presence of water offers opportunities for exploration, scientific study, and even the creation of human outposts.
This has certainly been the case as far as the Moon and Mercury are concerned, where water ice was discovered in the permanently-shadowed cratered regions around the poles. But according to a new analysis of the data from the Lunar Reconnaissance Orbiter and the MESSENGER spacecraft, the Moon and Mercury may have significantly more water ice than previously thought.
The study that describes the new findings recently appeared in the journal Nature Geoscience. The team was led by Lior Rubanenko and David A. Paige – a graduate student and professor of planetary science from the Department of Earth, Planetary and Space Sciences at the University of California, Los Angeles (UCLA) – with assistance provided by Jaahnavee Venkatrama, a Statistician and UCLA graduate.
When it comes right down to it, Mercury and the Moon have a lot in common. Both are terrestrial (aka. rocky) in nature, composed of silicate minerals and metals that are differentiated between a metallic core and silicate mantle and crust. In addition, they are both oriented in such a way that the Sun never rises high above the horizon, leaving them permanently-shaded.
As a result, these regions are some of the coldest in the Solar System, and topographic depressions (like impact craters) receive no sunlight at all. For decades, scientists have theorized that water ice trapped within them could potentially survive for billions of years. In recent years, this was confirmed by missions like the Lunar Reconnaissance Orbiter (LRO) and the MESSENGER orbiter.
These observations revealed glacier-like ice deposits on Mercury but not the Moon, despite the fact that their polar thermal environments are very similar to each other. However, previous radar and imaging studies showed only patchy, shallow ice deposits in places like the Shakleton crater and other low-lying areas in the South Pole-Aitken Basin.
Nancy Chabot is the instrument scientist for MESSENGER’s Mercury Dual Imaging System from the Johns Hopkins Applied Physics Laboratory (JHUAPL). As she explained:
“We showed Mercury’s polar deposits to be dominantly composed of water ice and extensively distributed in both Mercury’s north and south polar regions. Mercury’s ice deposits appear to be much less patchy than those on the Moon, and relatively fresh, perhaps emplaced or refreshed within the last tens of millions of years.”
This inexplicable difference between Mercury and the Moon is what motivated the UCLA team to conduct a comparative analysis of polar craters on Mercury and the Moon to delve into this difference between the two worlds. By looking over the data again, their analysis raises the possibility that thick ice deposits could also exist in the Moon’s cratered regions.
This conclusion was reached by examining elevation data obtained by MESSENGER and LRO of roughly 15,000 simple craters on Mercury and the Moon that were formed by smaller, less energetic impacts. These craters are between 2.5 km to 15 km (~1.5 mi to 9.3 mi) in diameter, are held together by the strength of the surface dust layer, and tend to be more circular and symmetrical than large craters.
The UCLA scientists used this inherent symmetry to estimate the thickness of ice trapped within them. What they found was that of the craters they examined, a significant number of them were up to 10% shallower when situated near the north pole on Mercury and the south pole of the Moon, but not near the Moon’s north pole.
The team concluded that the most probable explanation for this difference in depth is the accumulation of thick ice deposits on both worlds. This was supported by the fact that the pole-facing slopes of these craters appear to be slightly shallower than their equator-facing slopes and that these differences are more significant in regions where ice stability is promoted by Mercury’s orbit around the Sun.
They also found that these potential subsurface ice deposits coincide with craters that have surface ice. As Rubanenko summarized:
“We found shallow craters tend to be located in areas where surface ice was previously detected near the south pole of the Moon, and inferred this shallowing is most likely due to the presence of buried thick ice deposits.”
And while the ice in Mercury’s cratered northern region has been found to be nearly pure, the deposits detected on the Moon are most likely mixed with the regolith and layered. Lastly, while this trend was observed for smaller simple craters, it does not preclude the possibility that ice could be widespread in larger craters too.
This research may not only help resolve the question regarding the apparent low-abundance of lunar ice (relative to Mercury), it could also have practical applications. Said Noah Petro, the LRO
With multiple plans in place to build research outposts in the Moon’s South Pole-Aitken Basin, the possible presence of even more water ice is very good news. If confirmed, these abundant caches of water ice could facilitate more in the way of outposts, fuel manufacturing operations, the creation of refueling depots, and maybe even a permanent lunar settlement. | 0.837851 | 3.84763 |
Our story begins back in 2004 when the discovery of a 4th planet around the star called 55 Cancri, 55 Cnc e (McArthur et al. 2004, see also Fischer et al. 2008). This planet was reported to have a period of 2.8 days with a minimum mass of 14 Earth masses, but as we’ll see later, this wasn’t to be the final word on 55 Cnc e. The authors used the radial velocity method to find this planet and the four others in the system, a technique that relies on detecting the motion of the star induced by orbiting planets. Both the planets and the star orbit a common point somewhere in between them called the center of mass, and it’s the star’s motion towards and away from us (it’s radial velocity) that we can detect. The star moves very little (velocities are usually measured in meters per second!), but we can still detect this stellar “wobble” for many exoplanet systems.
Often, a periodogram is used to understand the radial velocity measurements; this type of plot depicts the frequencies present in a data set. For example, if there is a planet on a 2.8 day orbit, you would expect to see a peak corresponding to this period. In the periodogram of 55 Cnc below, it is quite obvious that there is a peak there.
But does that mean we have really found a planet with this period?
Dawson & Fabrycky (2010) argue not necessarily. The problem is that there are lots of frequencies other than the star’s gravitational interactions with its planets superimposed on the data. This produces false signals masquerading as planets, called aliases. If we could observe continuously, this wouldn’t be a problem, but we can’t. For example, a daily alias results from only being able to observe at night, while the fact that a single telescope can only observe the star for part of the year gives rise to yearly aliases. Because aliases appear at frequencies related to the true frequency, it is difficult to disentangle the false and true signals. Dawson & Fabrycky demonstrate that the highest peak in the periodogram is not necessarily the true signal and present a method by which to determine which peaks are aliases and which ones aren’t.
Dawson & Fabrycky apply their method of analyzing periodograms to 55 Cnc and discover that the 2.8 day signal is in fact an alias of an even shorter period planet, at a period of 0.7 days. They go on to remodel the 55 Cnc system and demonstrate that their model is a superior fit to the data. If 55 Cnc e does in fact have such a short period, the probability that this planet transits its host star is now 1 in 3. That’s worth following up!
This is where Winn et al., in a paper posted to the arxiv on Thursday, pick up the story. These authors observed 55 Cnc e almost continuously for 14.5 days in February from the Canadian space-based telescope MOST. At nearly the time predicted by Dawson & Fabrycky, a transit is seen, confirming the 0.7 day period. Combining the transit data with two decades worth of high-precision radial velocity measurements, the physical properties of 55 Cnc e are well-determined: it has a mass of 8.6 Earth masses and a radius of 1.6 Earth radii, making its average density a staggering 11 g/cc. With this high density, 55 Cnc e is a rocky-iron planet: similar in composition to our own planet. (It won’t be anything like Earth, however: located as it is so close to a hot star, it is the very definition of inhospitable!) The figures below present 55 Cnc e in the context of theoretical models and other known planets.
One final note: the star 55 Cnc can be seen without the aid of any telescopes. As the authors conclude, “there is some pleasure in being able to point to a naked-eye star and know the mass and radius of one of its planets.” | 0.910447 | 3.998354 |
Title: Exploring cosmic anisotropy with galaxy clusters
Authors: K. Migkas, G. Schellenberger, T. H. Reiprich, F. Pacaud, M. E. Ramos-Ceja and L. Lovisari
First author’s institution: Argelander-Institut für Astronomie, Universität Bonn, Bonn, Germany
Status: Accepted to Astronomy & Astrophysics, open access on arXiv
One of the key properties of our cosmos is that it is isotropic. This means the universe is expected to look the same whichever direction you look, and therefore has no preferred direction or centre. Another property states that the universe is homogeneous – everything looks roughly the same at every point in space. The fulfilment of these two properties over large distances forms the basis of the cosmological principle.
This fundamental pillar of our cosmological model is reinforced by observations of leftover light from the Big Bang, known as the cosmic microwave background. which is impressively uniform. However, measurements of its anisotropy at very small scales have been used to challenge the cosmological principle – see this Astrobite for more.
An important consequence of isotropy is that the expansion of the universe must be the same in every direction. Today’s paper investigates just how constant this expansion is using the largest objects in our cosmos. If the expansion is found to be different depending on where one looks, it could point towards a more anisotropic universe than previously believed, which could have implications for how our universe evolved.
Clusters of galaxies are the biggest gravitationally bound objects in the Universe. These vast, swirling arrangements of red, elliptical galaxies emit brightly in the form of visible starlight. In between these galaxies, a hot energetic gas also radiates in X-rays, which can be observed by space telescopes such as XMM-Newton and Chandra, and used as a detectable signature for a galaxy cluster.
A sky full of clusters
Today’s paper assembles a homogeneously selected sample of 313 galaxy clusters, containing 237 observed by Chandra and 76 observed by XMM, to search for evidence that the universe might not be expanding uniformly in all directions.
The authors use the fact that the temperature of the hot gas in a galaxy cluster has a strong, positive relationship with the X-ray luminosity it radiates. In other words, the hotter the gas, the more luminous the cluster. By fitting a model to the cluster spectrum, it is possible to measure the temperature. Crucially, the temperature of a cluster can be obtained without any assumption about the underlying cosmology. Then, by the relation above, you can predict the luminosity.
The predicted luminosity for a cluster at a given temperature and redshift also depends on a (constant) value A, called the normalisation. We can obtain this value from the luminosity and redshift via the luminosity distance. The resulting value of A is directly related to the expansion of the universe (denoted by H0).
Dividing the sky into slices, the authors study the distribution of temperatures and luminosities, measuring a value for A in each region. In physical terms, a lower/higher value of A means that clusters in some regions are less/more luminous for a fixed temperature. If any significantly different values of A are reported, it could imply that the universe is expanding at a different rate in some parts of the sky than others, and hence showing evidence that our universe might not be isotropic.
Cosmic expansion might be lumpy
After computing the value of A, and hence H0 in each patch of sky, the authors find that one region (shown in purple), displays a significantly different value to the remainder of the sky. The discrepancy in values for the expansion rate is between ~ 66 km/s/Mpc to 75 km/s/Mpc, which is equal to a ~13% difference. This produces a statistically significant tension, meaning there is less than 1% chance that either of these measured values are a fluke.
They go on to repeat this test using an even larger set of galaxy clusters (842) consisting of three independent datasets to see whether the trend persists. They find that it does. Moreover, they find that evidence of a cosmic anisotropy in this particular direction has been discovered previously using other objects such as supernovae, infrared galaxies and quasars.
Not so fast
Today’s paper shows that X-ray observations of galaxy clusters have identified a direction in the sky that might be expanding more slowly relative to others. However, the authors acknowledge the possibility of underestimating cluster luminosities (which result in a lower value for H0), due to various reasons. One reason is differences in the cluster properties. For example, some clusters have low temperatures or high redshifts, both of which affect their luminosity. Another possibility is the interstellar medium of the Milky Way, which consists mostly of hydrogen. Galactic hydrogen absorbs X-ray emission from clusters, making them appear fainter. Finally, gravitational attraction between nearby clusters could dominate over the cosmic expansion at small distances, creating the appearance of local anisotropies. A combination of these effects is not strictly ruled out by the authors’ findings, though each of these effects have been tested individually.
This is the first time the luminosity-temperature relation for galaxy clusters has been used to test the isotropy of the universe (building on an earlier study by the same authors). Future studies will rely on understanding the nature of extragalactic absorption from the gas and dust clouds within and beyond our Milky Way in more detail, in addition to collecting even a larger number of clusters to tell us just how uniform the cosmic expansion actually is. | 0.840333 | 4.102373 |
9 December 2011
The goddess Venus radiates beauty; the planet Venus radiates electromagnetic waves.
These waves were picked up the Venus Express, a European satellite orbiting Earth’s nearby twin, and provide evidence of lightning in its atmosphere.
Here on Earth, lightning creates waves of electromagnetic energy that travel out in arcs aligned with the planet’s magnetic field. The waves contain a symphony of different frequencies, and each component travels at a different speed as it whooshes around the globe – a phenomenon known as dispersion. Scientists call the waves whistlers because they sound like whistling on a radio set.
As far back as the late 1800s, Franco-Prussian war spies heard these whistlers on their ham radios, but had no idea what the signals were. Scientists figured out later that lightning was the cause.
Planetary scientists from the University of California, Los Angeles (UCLA) have now detected whistlers around Venus. Jillian Daniels, a graduate student at UCLA who works with geophysicist Christopher Russell, presented a poster on the work Wednesday morning at the American Geophysical Union’s Fall Meeting.
Unlike Earth, Venus doesn’t have an internally-generated magnetic field. On Earth, water in the planet’s core churns molten iron which produces its field. Venus has no water in its core; instead, the planet’s solar wind induces its magnetic field.
“If you had a ball on a stick with the wind blowing and you put a handkerchief over it, that’s kind of what the field looks like,” Daniels said.
The Venus Express measured electromagnetic bursts from Venus, though only a few had the characteristic “whistling” sounds. It was enough to suggest that lightning does crackle over Venus, probably caused by electric charge differences in the planet’s sulfuric acid clouds, the scientists say. The finding adds more fuel to a longstanding debate over the existence of Venus’ lightning.
Some skeptics point to the fact that the Cassini-Huygens space probe failed to detect lightning while flying past the planet in 1998 and 1999. Daniels doesn’t buy this criticism because the flyby was so brief. “One negative data point is not enough to disprove something,” she said.
Others cite the lack of definitive visual proof: “I’m not convinced the radiofrequency signals from Venus are produced by lightning,” said Hugh Christian, a physicist at the University of Alabama in Huntsville who attended the poster session, adding that he’d want to see more evidence from optical signals.
The whistlers have Daniels convinced, though. “It’s yet another confirmation that what we’re seeing is lightening,” she said.
-Tanya Lewis is a science communication graduate student at UC Santa Cruz. | 0.871376 | 3.624887 |
Light is a major instrument in our interactions with the world around us. Without it, we would be condemned to live in perpetual isolation, and we would have evolved in a dismal darkness that would be as stifling as any self-centered existence. For it is light that weaves the distant corners of the universe into a cosmic wholeness and that informs us of the presence of people and things beyond ourselves. Light reveals shapes and sizes and beauty. It speaks to us of unreachable celestial bodies, of their nature and structure; it tells us if far-flung nebulae are approaching us or receding away. It is thus the source of all knowledge. It guides us and it enlarges our horizons.
But life is not simply knowledge and information. The life experience includes enjoyment, too. Here again light serves us well. There is more to light than brightness. Light is vibration not only of varying intensities, but of varying durations, which causes colors. Color adds splendor to the world. Were it not for colors, the world would be a drab gray of changing shades.
Yet color is not intrinsic to light; it is a result of interactions between vibrations and our optical systems. It is the human brain that transforms undulations into magnificent hues. Our optical system is wondrously complex, and miraculous in what it accomplishes. This arrangement of the retinal screen and nerves turns vibrations into visual reality. All the beauty of forms and splendor of colors, the shimmer and shade and brightness, arise because of whatever the retina and the brain do. The cosmos in all its complexity would be plunged into invisibility if no eye responded to a narrow band in the electromagnetic spectrum. No glorious sunset nor twinkling stars, no glitter or sparkle, if the ethereal vibrations palpitated unnoticed, unrecognized as light and color. How was the universe during those eons before life emerged? It was certainly not resplendent in this grand glory. Even when roses bloomed and leaves changed to their autumnal splendor, it was all bleak and insipid when there were no eyes with rods and cones. Those multicolored creatures in aquariums, the majestic rainbow, the yellow sunflower and the purple violets—all such have been there for eons before the human retina evolved, but never recognized as such. Let us not underestimate our role on this planetary speck in a grand universe. Our eyes add substantially to it all. The human brain shapes an uninteresting and uninspiring surrounding into something spectacular.
There would be no electromagnetic waves without electric charges. There would be no light without the human optical system. Our world of experience is a world of perceived reality indeed.
The properties of light enhance the charms of the world. The changing colors of the diamond beetle, for example, arise not from pigmentation, but from what we call the diffraction of light. The glory of the rainbow and the colors of the icicle result from the simple properties of reflection and refraction. Diamonds would be as inconsequential as a speck of charcoal were it not for light. Rubies, emeralds, and sapphires would be dark as the depths of hell, if there was no light.
Light is also a life-sustaining principle—for it is sunlight that cleverly collaborates with the green of the earth to produce the food that sustains and nourishes life on our planet. If we look for miracles, this is where we find one. Light spans every region of the physical universe, and it has been there since the first big bang of cosmic creation. Nothing we know is as omnipresent or eternal as light.
We are accustomed to associate white with purity, and for generations, it was imagined that white light was the purest of all. But this is not so. White light arises from the mingling of every colored light there is. This surprising root of perceived reality can be discovered with a prism. White light, the most colorless we can imagine, turns out to embody every color from violet to red that spans the rainbow.
How do objects acquire their colors? Why does the leaf appear green and the apple red? This is because the atoms and molecules of most materials absorb some of the visible wavelengths that fall on them. Which particular ones they absorb depends on their structure and constitution. Atoms and molecules have their characteristic tastes for waves, as it were. If a material sucks in every component of white light, it gives us back nothing, and appears dark, as with the charcoal, for example.
Next consider the speed of light: In this age of bullet trains and supersonic jets, speeds of a few hundred miles an hour don’t impress us any more. Yet, we may be shocked to know about speeds in the physical world: The sun and the stars, air molecules and electrons in atoms, move with inconceivably greater speeds, of the order of hundreds of thousands of kilometers an hour. But when we come to the speed of light, it is altogether unimaginable. Light covers 300 million meters a second. We can hardly conceptualize a speed of this magnitude. Yet, this is the most common speed in the universe, for more than anything else, electromagnetic waves pervade every nook and corner of the physical universe.
More impressive is the mind that measures this. By complex and ingenious means, we have come to know quite precisely how fast light travels in empty space and in other media. And this is the fastest speed allowed in the universe. No physical body, massive as stars or minute as electrons, can ever reach a speed equal to that of light. We may, in theory, picture particles zooming with speeds very nearly equal to that of light, but never, never equal to it. Light speed is the ceiling that naught can break through.
There is another aspect of the velocity of light that is even more remarkable. This speed does not depend on the motion of the observer relative to the source of light. Imagine you are riding your bike at 15 km/h toward a car. If the car is approaching you at 60 km/h, it will be appearing to be coming at 75 km/h since every hour this is the amount by which the distance between the car and yourself is diminishing. Likewise, for an observer moving forward in the same direction as the car, the car’s relative speed will be 35 km/h. Only if you are stationary will the car seem to be coming at 60 km/h.
This commonsense calculation won’t work with light! Replace the car with a light wave, and the cyclists with fast moving rockets, and everyone will find light to be traveling with the same speed (relative to oneself). The speed of light is a universal constant, as one says in physics, absolutely independent of the state of motion of the observer.
Strange as it may sound, light itself is invisible: We can never see a ray of light passing somewhere in space. The effulgent beam of light spouting out from a luminous source that a movie company displays as its logo cannot be seen if that light is splashed into empty space, nor the laser beams of science fiction movies. Only when it strikes our retina do we become aware of light. When we stare at the night sky, there is ample sunlight there. But it is only when some of it bounces back from the moon or a planet do we see it, and in the process, become aware of the moon and the planets.
This brings us to another property arising from matter-light interaction. Ever since human beings turned their gaze upward, they have admired the soothing azure tint of the sky. But soon after sunset, all the blueness vanishes. Even when the moon is full and bright, the sky at night is never blue.
Since ancient times, poets and painters have taken note of this, but it is only in the 19th century that we came to understand why it is so. The phenomenon is related to a property of waves called scattering. When light waves fall on a smooth surface, they are reflected back. However, when they encounter small particles, they bounce back every which way: Light is scattered in all directions. Then again, not all wavelengths of light are scattered to the same degree. This depends on the structure and size of the scattering center. When a beam of white light hits a molecule of oxygen or nitrogen, the blue component is scattered away while the red and orange ones go right through. This has a dramatic effect on the perceived world. When sunlight enters the atmosphere, its bluish components are scattered, and when they reach our eyes, the sky looks blue. If our atmosphere were made up of some other (life-supporting) gases that had the property of scattering the green component primarily, we would be enjoying a green sky.
Much of the light that makes normal living possible arises from this property. The light in the room when the windows are open and the light in the shade under a tree is there because light is scattered by the air. Take away the air, and sunbeams will illumine only the patch on which they fall.
So now we come to this realization: Objects are visible to us not simply because of the light that falls on them, but equally because of the air around! Take away the light, and nothing can be seen. Take away the air, and not everything can be seen. Things will not be as visible in a lunar room even in broad daylight because there is no air there.
We light the candle or the log, we flip the switch in the room or press the button on the flashlight, and light appears. Or else we have the sun which, at every rising, floods our surroundings with light also. But, like the city kid who thought that the source of milk was the carton or the bottle, we would be mistaken to think that the source of light is the candle or the log, the light bulb, or the sun.
Light is created in the physical world by complex processes at the heart of matter. In the core of stars, there is the perennial transformation of matter into energy as per the Einstein equation. There, substantial matter is transformed into insubstantial energy: electromagnetic waves of many different wavelengths. So, like aroma from brewing coffee, light emerges from the depths of stars as nuclear brewing goes on.
But when ordinary matter is rendered hot, processes arise that cause the emission of light. The atoms of substances have several levels of energy. Normally, electrons are circulating at the lowest levels, whirling around in the atom, but if enough energy is imparted to any of them, they jump to a higher level, and promptly fall back to a lower one. In the process, they release the absorbed energy as electromagnetic waves. If the wavelength is appropriate, this is visible light. So we say that light results from electronic transitions within atoms. Whether it be light from an electric lamp, or from a candle, the waves result from electronic jumps, that is all. In the one case, we make the electrons jump to a higher orbit by giving them thermal energy through a match stick; in the other case, electrical forces accomplish this. In other words, light arises from the core of matter from atomic transitions involving dancing electrons galloping from orbit to orbit. If we yearn for wonders, this is something we may reflect upon.
Light from any source, when analyzed through a suitable optical device, gives a pattern of colors, be it of discrete lines or broader bands or continuous patches. This pattern is the source’s spectrum. The spectrum revealed by light from a source is characteristic of its chemical composition. It is a sort of fingerprint of the chemical elements present in the source of light. The spectrum can also tell us about the temperature of the source, and even about its motion or rest relative to us.
These discoveries opened up a whole new world for physicists. All we can get from the sun and the stars is light, and light can tell us about the constitution of matter. Just analyze the light from a distant source, and like a letter from a friend, we can know a good deal about the state and substance of the source.
In 1868, Janssen was in India to observe a total solar eclipse. He studied the solar prominences that are particularly visible during eclipses. Here he was puzzled by a strange line in its spectrum. This was like finding the fingerprint of an individual that is not in the police records. He sent this to Joseph Lockyer, an expert on solar spectra. After careful study of the line, Lockyer concluded that this must be a hitherto unknown element. He called it helium in honor of the sun. If detective stories are fascinating, this one can beat any. Consider the tortuous route: A lens-grinder recognizes the spectra of elements in the 1820s, an astronomer discovers a new element in the sun in the 1860s. Light unraveled the existence of an element that is out there, 93 million years away.
So we see how physicists have a way of finding out what the sun is made up of, and Polaris and Betelgeuse. It gradually became clear that stars and planets, high and mighty as they seem, are made up of the same sort of stuff as makes up this our modest planet. Aristotle wasn’t quite right when he preached that celestial bodies consisted of incorruptible matter while earthly ones degenerate and decay. No, all bodies are created equal, though not all posses equal amounts of every kind of matter. Analysis and reductionism can give lots and lots of interesting information about perceived reality.
Whether we like it or not, our eyes are sensitive to—that is to say, we can see—only a narrow band of the electromagnetic spectrum. But this is not to say that other regions of the spectrum are insignificant or that we cannot know about them. One of the goals of science is to unravel every aspect of physical reality that can be perceived, whether directly or indirectly.
Beyond red light, there are electromagnetic waves of longer wavelengths: the so-called infrared (IR) or heat radiations. Beyond this are the microwaves.
In 1932, while he was trying to eliminate the hissing noise associated with radio reception, Karl Jansky discovered that the Earth is being showered from outer space by electromagnetic waves of wavelengths longer than the infrared. Let us reflect on this for a moment. When we look at the sky and see the sun or the stars, clearly light reaches us from the heavens. But who would have thought that we are also being inundated constantly with imperceptible microwaves? And if light can tell us so much about the sun and the stars, could microwaves also tell us other things? Thus began radio astronomy: the exploration of the universe, not with the aid of visible light, but with the microwaves that are continuously pouring into our terrestrial world from many niches in the universe. In mindless physical reality, waves are mere carriers of energy. In the world of perceived reality, they carry information, too.
Radio telescopes have expanded our vision of the universe. They have put into evidence a great many sources of microwaves: those arising from supernova eruptions, others originating from electrons going amuck in interstellar magnetic fields, and yet others coming from transitions in the atoms of hydrogen spread all over space. Radio astronomers have detected carbon-containing molecules like cyanogens and formaldehyde, suggesting possibilities of organic structures elsewhere in the universe. They have discovered that elliptical galaxies emit considerably more radio waves than do most others. Thanks to microwaves, we have come to know of thousands of incredibly powerful extra-galactic radio sources that are among the most fantastic objects in the outskirts of our universe— mammoth star-like agglomerations spewing out incredible amounts of energy as they rush away at delirious speeds: respectable fractions of the speed of light. These have been named quasi-stellar objects or quasars. Radio astronomy is another window into the universe through which we recognize more wonders of perceived reality.
Many astronomers are convinced that somewhere out there among the countless billions there must be more mind-endowed entities, perhaps not our replicas, but maybe life forms more evolved than ourselves, thinking and feeling, probing and inventing. If they are intelligent beings, they must have their radio astronomers, too—sending “knock-knock” signals and expecting “who’s there?” responses. So we are on the lookout for communications from extra-solar intelligence, not in hard-copy postage, but in cryptic coding of microwaves. Eager cosmic eavesdroppers from among us have been spending countless hours and tidy sums to see if one of their recordings is a patterned signal of sorts. Whether we succeed in this quest for a cosmic connection is not as important as the fact that human ingenuity has come up with tangible ways of confirming whether or not there is interstellar intelligence. Like prayer, irrespective of whether it reaches a target, the effort itself enhances the human spirit.
In the 1940s, microwaves were used to determine the location and motion of distant objects. The invention that accomplished this is the radar. Like all inventions, it has evolved to considerable complexity, used not only to take planes through thick and opaque clouds, but also to help controllers spot and guide them. Microwaves are the principal carriers of television signals and they also serve in long-distance telephony. They penetrate right through the reflecting layers of the upper atmosphere and are thus useful in communicating with astronauts in space. They have come to serve computers and medicine, and yes, they also help us heat foods quickly. Science is no longer natural philosophy: love of knowledge of nature. Rather, it has become a tool for application and power, an instrument to exploit and control nature. This ceaseless obsession to make life more comfortable, enjoyable, and materially fulfilling often loses sight of the grander goal of science, which is to probe into and interpret the wonders of the world, to uncover the subtle cogs and wheels of atoms and laws that make the world tick, and to marvel at the roots of perceived reality.
According to an ancient Chinese legend, a supreme architect called P’an Ku was born of the Cosmic Egg. Working hard for 18,000 years, he built this grand universe of ours. The ripples of this momentous event have not quite died out: P’an Ku’s breath and sighs are still present as winds and rising clouds, the roaring majesty of his voice still resounds in thunder, his flesh congealed into our earth, where his lush hair has become green grass and tall trees. Subterranean metals and minerals are vestiges of his bones, while the abundant sweat of his lasting labors still drip down as rain. Yes, he also had lots of lice infecting his body, and they may still be seen as swarms of humans populating the earth.
This picturesque tale underscores the idea that what we perceive today are consequences of a distant event, a majestic primordial event of immense complexity that ultimately grew into the forms and patterns of today.
But wonder of wonders, an echo of the big bang can be perceived by Homo sapiens these long eons after it occurred. For in 1966, radio astronomers reported the discovery of a microwave radiation that is all pervasive and isotropic. It is interpreted as a remnant of the world-generating big bang. In other words, the enterprise of radio astronomy has put into evidence what may well be described as the first shriek of Baby Cosmos.
At the lower end of invisible electromagnetic waves, we have the X-rays of radiography, and gamma rays whose wavelengths are so short that atomic dimensions are large compared with them. Their frequencies are mind-boggling: of the order of 1022 Hz. Even as visible light emerges from electronic jumps in atoms, gamma rays arise when nuclei shiver, as it were—an electromagnetic outpouring of nuclear agitation. Gamma rays are like super-penetrating bullets. When they encounter a living cell, they simply shatter it.
Gamma rays from unknown sources were detected in space in the 1970s. The Compton Gamma Ray Observatory was launched as a satellite to study them. Now we know that they are produced in abundance in distant galaxies.
Ordinarily, light consists of many waves that move along different directions, their phases not quite in step, somewhat like crowds walking out of the sports stadium. This is only to be expected if we recall that light emerges every time an electron jumps to a higher orbit and promptly falls back to a lower one. Since atoms are distributed at random and the lifting-up energy reaches them in a random manner also, the ensuing waves arise independently without any coherence. But it is possible to create perfectly coherent light—i.e., light made up of identical waves in perfect step. Since this is the result of light amplification by simulated emission of radiation, it has received the acronym of laser. In our crowd analogy, a laser is like the same crowd walking out in perfectly synchronized step along a single path.
The contrivance to produce a narrow pencil of bright red light moving along a straight line like an arrow started out as a toy. One could use it in a lecture to point to a diagram on a screen. But very soon, the invention found the most unexpected applications. Today, lasers are used in compact discs and in check-out counters. They are used to clean up paintings, to treat detached retinas, in communication systems, and in detecting continental drifts. They are integral to our computers and serve in precise measurements. Thanks to lasers, we have come to know the distance of the moon with an error of just one foot. It is remarkable that human ingenuity has created a kind of light that, as far as we are aware, never existed before. Human beings are knowers and doers also.
Thus far, I have reflected on light as a wave that wings its way from point to point as electromagnetic vibrations. But light also behaves as if it is a volley of infinitesimally small specks of pure vibrations, carrying tiny bits of energy, while spinning furiously on an axis. Light (any electromagnetic wave, for that matter) behaves as if it is made up of innumerable little bundles of energy zooming with the same speed of 300 million meters per second in empty space.
The particle aspect of electromagnetic waves is called the quantum or the photon. The energy carried by a photon depends on the frequency of the associated wave; the higher the frequency, the more the energy borne by the photon. But then, particle and energy are fundamentally different: One is localized, and the other diffused. How can the same thing be both? But it is, or so it seems from all experiments. It is this sort of thing that made Niels Bohr say that if you are not jolted by it, you haven’t understood quantum theory.
But then, one may wonder, how can a logical and calculating physicist burst into tears when faced with a tragedy? Yes, she can, because that is part of being fully human.
Similarly, light behaves as particle or wave depending on the circumstance. Is not a coin both head and tail? Throw it, and only one side will show up when it falls on the floor. It is like that with light also: It is both wave and particle; do an experiment, and only one aspect will become apparent.
These are among the fascinating features of light, both visible and invisible. In the spiritual poetic vision, it was there when God asked it to be. | 0.872353 | 3.110531 |
Reprinted from the Island Free Press
NASA recently announced the discovery of seven Earth-size exoplanets orbiting TRAPPIST-1, which is a star and planetary system initially discovered using the TRAnsiting Planets and PlanetesImals Small Telescope.
Scientists think all seven are rocky planets, based upon their measured densities. Scientists believe it is possible that all of them could have liquid water, but three are in the habitable “Goldilocks Zone.” That means the orbits are in a range that’s not too hot and not too cold for liquid water. Liquid water is considered essential for the development of life as we know it.
TRAPPIST-1 is about 40 light-years from Earth. That means a spacecraft traveling at 52,000 mph would take more than 500,000 years to reach the exoplanet orbiting it.
I recently had a neat experience. At about 9:15, I stepped out of the observatory for a minute. As I opened the door, I saw the shooting star of a lifetime – a fireball that streaked down toward the western horizon burning out after two or three seconds. The fireball itself was brighter than Venus.
I reported the occurrence to the American Meteor Society and found out I wasn’t the only person who saw it.
February also offered some very good opportunities to observe distant galaxies. My favorite image is this one of Messier 63, the Sunflower Galaxy.
The Sunflower Galaxy is 37 million light-years away. It’s a member of the M51 Group and has a visual magnitude of +9.3.
What to Look for in March
The sun set at 5:57 p.m. on March 1, with the moon, Mars, Venus and Uranus all just above the western horizon at sunset. With a magnitude of -4.6, Venus is very easy to spot. The moon is the only other object in the night sky that is brighter and it will be about 8 degrees above Venus. Mars and Uranus will appear very close to the moon. Mars is the red object you can see with the unaided eye and Uranus is the blue object you can’t see unless you’ve got a good pair of binoculars or a telescope.
Mars and Uranus will stay close to the western horizon throughout the month. Mars will seem to appear in the same area of the evening sky each night. Uranus will get closer and closer to the horizon with each passing day. By the end of the month, you will probably not be able to see Uranus, because the brightness of the setting sun will obscure the planet.
Venus will appear closer to the evening horizon with each passing day. Then, starting on March 20, you will be able to see Venus in both the evening and morning. Venus will set at 7:56 p.m.; the sun sets at 7:13 p.m. and rises at 6:45 a.m., just before sunrise at 7:03. This dual role as evening and morning star will be short-lived. Don’t expect to see Venus in the evening skies after March 24.
Mercury will start to be visible in the western skies starting around the middle of the month. It will appear higher above the western horizon each evening until early April. This makes the end of March an excellent opportunity to observe this small planet.
Jupiter rose in the east at 9:04 p.m. on March 1. Spica rises right after it, slightly to the south. The pair will continue to appear together throughout the month.
Saturn began the month rising at 2:14 a.m. By the end of the month, it will rise at 1:21 a.m.
If the skies are very clear and very calm, you might be able to see Canopus, the second-brightest star in the night sky, during the first part of the month. It will appear near the southern horizon almost directly beneath Sirius, the brightest star in the sky. If you have never heard of Canopus, try reading “Dune” by Frank Herbert. Arrakis, also known as “Dune,” is the third planet orbiting Canopus. If you don’t have time to read the book, you might like the movie. I have not found any evidence of any exoplanets orbiting this star.
- First Quarter: March 5
- Full moon: March 12
- Last Quarter: March 20
- New moon: March 27
This story is provided courtesy of the Island Free Press, a digital newspaper covering Hatteras and Ocracoke islands. Coastal Review Online is partnering with the Free Press to provide readers with more environmental and lifestyle stories of interest along our coast. You can read other stories about Hatteras and Ocracoke here.
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It costs about $500 to produce this and all other stories on CRO. You can help pay some of the cost by sponsoring a day on CRO for as little as $100 or by donating any amount you're comfortable with. All sponsorships and donations are tax-deductible. | 0.919023 | 3.307795 |
From: Ames Research Center
Posted: Friday, August 10, 2007
Dr. Scott Sandford presented a Director's Colloquium about samples returned to Earth from a comet named Wild 2 by the Stardust spacecraft.
The informative presentation was especially unique because the audience got the chance to wear 3D glasses and view the comet in 3D. At one time, probably in 1974, this comet had a close encounter with Jupiter, whose gravity altered the comet's orbit so that it now comes closer to the Earth. Wild 2 is different because of this and has a far more prestine outer layer than other comets. There are three podcasts from Sandford available online (podcast 1, podcast 2, podcast 3).
The Stardust capsule launched on Feb. 7, 1999 and traveled a total distance of 2.88 billion miles on its seven-year journey. It came back with the first solid sample return from outside the Earth-moon system in history. Aerogel, the world's lowest density solid, was used to collect the samples. The Stardust spacecraft encountered the Wild 2 comet on Jan. 2, 2004, collected samples from its coma (the cloud of gas and dust that surrounds the central nucleus), and then stored the samples inside a capsule. After collecting the samples, the capsule experienced the fastest reentry into the Earth's atmosphere ever attempted.
On Jan. 15, 2006 the capsule parachuted into the Utah Test and Training Range in Utah where it bounced four times on landing but did not damage any of the samples inside. In the Dec. 15, 2006 issue of Science contained a series of articles about what we learned from the Stardust mission. We learned that when the solar system formed. There was a lot of "mixing" going on. We know this because the specimens are so varied. For example, the samples contain both high temperature and low temperature components. Also, comets, or at least Comet Wild 2, really are repositories of relatively unprocessed early solar system composition. Stardust samples are a legacy that will be used by scientists for generations to come.
// end // | 0.854995 | 3.148794 |
When the Juno mission reached Jupiter on July 5th, 2016, it became the second mission in history to establish orbit around the Solar System’s largest planet. And in the course of it conducting its many orbits, it has revealed some interesting things about Jupiter. This has included information about its atmosphere, meteorological phenomena, gravity, and its powerful magnetic fields.
And just yesterday – on Monday, July 10th at 7:06 p.m. PDT (11:06 p.m. EDT) – just days after the probe celebrated its first year of orbiting the planet, the Juno mission passed directly over Jupiter’s most famous feature – the Great Red Spot. This massive anticyclonic storm has been a focal point for centuries, and Juno’s scheduled flyby was the closest any mission has ever come to it.
Jupiter’s Great Red Spot was first observed during the late 17th century, either by Robert Hooke or Giovanni Cassini. By 1830, astronomers began monitoring this anticyclonic storm, and have noted periodic expansions and regressions in its size ever since. Today, it is 16,000 kilometers (10,000 miles) in diameter and reaches wind speeds of 120 meters per second (432 km/h; 286 mph) at the edges.
As part of its sixth orbit of Jupiter’s turbulent cloud tops, Juno passed close to Jupiter’s center (aka. perijove), which took place at 6:55 p.m. PDT (9:55 p.m. EDT). Eleven minutes later – at 7:06 p.m. PDT (10:06 p.m. EDT) – the probe flew over the Great Red Spot. In the process, Juno was at a distance of just 9,000 km (5,600 miles) from the anticyclonic storm, which is the closest any spacecraft has ever flown to it.
During the flyby, Juno had all eight of its scientific instruments (as well its imager, the JunoCam) trained directly on the storm. With such an array aimed at this feature, NASA expects to learn more about what has been powering this storm for at least the past three and a half centuries. As Scott Bolton, the principal investigator of Juno at the Southwest Research Institute (SwRI), said prior to the event in a NASA press release:
“Jupiter’s mysterious Great Red Spot is probably the best-known feature of Jupiter. This monumental storm has raged on the Solar System’s biggest planet for centuries. Now, Juno and her cloud-penetrating science instruments will dive in to see how deep the roots of this storm go, and help us understand how this giant storm works and what makes it so special.”
This perijove and flyby of the Giant Red Spot also comes just days after Juno celebrated its first anniversary around Jupiter. This took place on July 4th at 7:30 p.m. PDT (10:30 p.m. EDT), at which point, Juno had been in orbit around the Jovian planet for exactly one year. By this time, the spacecraft had covered a distance of 114.5 million km (71 million mi) while orbiting around the planet.
The information that Juno has collected in that time with its advanced suite of instruments has already provided fresh insights into Jupiter’s interior and the history of its formation. And this information, it is hoped, will help astronomers to learn more about the Solar System’s own history of formation. And in the course of making its orbits, the probe has been put through its paces, absorbing radiation from Jupiter’s powerful magnetic field.
As Rick Nybakken, the project manager for Juno at NASA’s Jet Propulsion Laboratory, put it:
“The success of science collection at Jupiter is a testament to the dedication, creativity and technical abilities of the NASA-Juno team. Each new orbit brings us closer to the heart of Jupiter’s radiation belt, but so far the spacecraft has weathered the storm of electrons surrounding Jupiter better than we could have ever imagined.”
The Juno mission is set to conclude this coming February, after completing 6 more orbits of Jupiter. At this point, and barring any mission extensions, the probe will be de-orbited to burn up in Jupiter’s outer atmosphere. As with the Galileo spacecraft, this is meant to avoid any possibility of impact and biological contamination with one of Jupiter’s moons.
Further Reading: NASA | 0.851287 | 3.631814 |
Dark matter sleuths to design world's largest WIMP catcher
A team of researchers led by a Case Western Reserve University physicist is planning the world's largest, most sensitive experiment to catch the stuff of dark matter, stuff that's proved way beyond invisible.
The researchers are seeking WIMPs, short for weakly interacting massive particles, which aren't and don't act like atoms that comprise regular matter.
Scientists believe that WIMPs could have been born of the Big Bang, stream through us by the billion every second and provide the mass needed to keep galaxies, including our Milky Way, from flying apart.
"We know there's dark matter, we just don't know what it is," said Tom Shutt, who holds the Agnar Pytte Chair of Physics at Case Western Reserve and is the principal investigator for the project.
Shutt's group, which merged with the group led by Physics Department Chairman Dan Akerib, has received a three-year, $3.2 million National Science Foundation grant to design a 20-ton liquid xenon WIMP detector, called LZD.
The group has proposed LZD as a major experiment for the Deep Underground Science and Engineering Laboratory, a national lab planned for the abandoned Homestake Gold Mine, nearly a mile beneath Lead, S.D.
The WIMP detector would be 2,000 times larger than the XENON 10 detector, a 10-kilogram prototype experiment in Gran Sasso, Italy, and 70 times larger than the 300 kilogram Large Underground Experiment, or LUX. The LUX project, led by Shutt and Brown University physicist Rick Gaitskell, will begin operating next year in South Dakota's Sanford Underground Science and Engineering Laboratory, also in the former Homestake mine.
Why build bigger?
"It's like using a larger light collector in a telescope," Akerib said. "It increases your chances of seeing what you want to see."
The 20-ton experiment would increase the chance of seeing a WIMP by more than 30,000 times over XENON 10, and more than 150 times over LUX because of increased size and sensitivity and longevity, Shutt explained.
WIMPs are hard to detect because they don't give off radiation. They don't interact with regular matter through electromagnetic forces, but pass through regular matter unimpeded, researchers believe.
That theory was bolstered by NASA's observations of two distant galaxies colliding in 2006. While a cloud of galactic gas dragged out from the friction of striking other regular matter, changes in gravity showed that dark matter had already passed through.
Shutt and Akerib say liquid xenon is the right stuff to catch a WIMP. The element is nearly completely inert, unpolarized and hard to polarize. Only dark matter particles can permeate into the inner region of the xenon liquid without being detected elsewhere, Shutt said.
What each experiment looks for is a chance strike: a WIMP knocking into a Xenon atom, something on the scale of a neutron colliding with the atom. The collision would produce a minute flash of light that supersensitive detectors would locate, amplify and analyze. In tests, LUX has detected the collision of single neutrons with liquid xenon atoms. LZD would be even more sensitive, by three orders of magnitude, giving the experiment an acuity akin to seeing an ant in the span of the Milky Way, Akerib said.
When LUX is lowered underground in 2010, the researchers will seek WIMPs. They will also field test their equipment and the underground lab and master the technology they expect to use in the 20-ton model.
Before attempting to build LZD, however, the research group wants an interim step. They are seeking funding for a 1.5 ton detector, called LZS.
The experiments are buried deep in the Earth for the same reason the Hubble Space Telescope was launched into orbit: to avoid interference. In orbit, Hubble is freed of Earth's obscuring atmosphere. Underground, WIMP experiments are shielded from hundreds of billions of charged particles that strike the surface of the earth annually, leaving the detector with a clear view should a WIMP strike.
What do we get out of this?
Detecting a WIMP would go a long way toward understanding how the universe works and confirm the dark matter theory that unseen matter must exist or galaxies would lack the mass to form, cluster and rotate as they do, Shutt said.
But the work goes beyond that.
"This is very much connected to big philosophical questions: What are we made of? What did we come from?" Akerib said.
Scientists expect the new technology could lead to another class of super-sensitive detectors for medicine and global security, including particle detectors that can tell what's happening in a distant nuclear facility and whether a country has or is building nuclear weapons.
The LUX and LZ projects compete with technologies that use germanium crystals frozen to nearly absolute zero or liquid argon detectors, in the race to find WIMPs. The groups will compete for funding to build their largest and best experiments.
Masahiro Morii, a physics professor at Harvard who helped build electronics for LUX, is among a growing number of researchers joining the xenon group. "Liquid xenon has a distinct advantage: it's straight forward to scale up," Morii said. And, "It's ahead of the other technologies by 3 to 5 years." | 0.882219 | 3.285811 |
Once again, nuclear physicists believe that they have found evidence of the elusive sterile neutrino. First posited some time ago, the theories behind this fourth neutrino have been hazy, and somewhat unverifiable. However now, after a long dormant period, the idea has gained traction again, thanks to some recent developments. But don’t start rewriting the physics textbooks just yet. While we would all dearly love to believe that we’re on the verge of a major breakthrough, unfortunately, there may be a far simpler explanation and one that will disappoint those looking to believe in a resurrection.
Sterile Neutrino: the Missing Link
As everyone knows, neutrinos are nearly massless particles that interact through a very, very weak nuclear force. As a result, they barely interact with any of the other matter around them. Three varieties are accepted in general physics: mu, theta and electron neutrinos. The different states are, to a degree, interchangeable: scientists have found that neutrinos are able to morph between different states by reaching a certain level of oscillation. But for a few decades, there has been speculation that the fourth kind of neutrino could possibly exist: the sterile neutrino. This article, so scientists believed, would be incapable of interacting with matter in any way. It could only be formed by one of the other neutrinos oscillating into it. Similarly, it would end if the sterile neutrino oscillated into another form. The idea was first put forward in the Nineties, at the Liquid Scintillator Neutrino Detector in Los Alamos. They detected a number of electron neutrinos that didn’t match the expected amount, and theorised that it was possible they were the result of a number of mu neutrinos oscillating into sterile neutrinos, and then into electron neutrinos.
Does New Evidence Shed New Light?
The latest developments in this area have come from the scientists working on the Mini Booster Neutrino Experiment in Batavia, Illinois. They believe that they have found even more convincing evidence of the theoretical oscillations required to create sterile neutrinos. Following a less successful test in 2013, they now believe that their latest findings are enough to correlate with the initial theories regarding the concept. However, while this is good news for believers in the concept, the reality is that a number of flaws still exist in their methodology. This was succinctly pointed out by scientists at China’s Daya Bay Reactor Neutrino Experiment. The sterile neutrino theory has been relying on using the presence of antineutrinos as evidence of the changing states, and therefore evidence of the sterile neutrino. They pointed out that the entire theory could easily be completely unprovable if it turned out that the researchers had made an error in their estimations on the number of antineutrinos produced by uranium-235. Similarly, the ESA’s Planck spacecraft recently made an unprecedentedly exact measurement of cosmic microwave background left by the Big Bang. Their results showed only the standardly accepted three types of neutrinos.
Is this whole sterile neutrino business simply a lot of fuss about nothing? It’s too early to tell. The original theory was put forward some time ago, and there’s still plenty of time for further evidence to be collected. Watch this space. | 0.868163 | 3.987663 |
Feast your eyes, my friends, on this — by far the most detailed image ever of a young star and its protoplanetary disk. Here you can see the young star HL Tau, which is only about one million years old, as dust and gas swirl around it, gradually forming into planets and asteroids. Believe it or not, a few billion years ago, this is what our very own Solar System would’ve looked like.
This photo was captured by ALMA, the Atacama Large Millimeter/submillimeter Array — a giant telescope consisting of 66 individual antennas, located high up in the Atacama desert in northern Chile. According to the European Southern Observatory (ESO) which operates ALMA, this image comes from some of the telescopes first observations in its “new and most powerful mode” (ALMA has been under construction for years, but only recently have they installed enough antennas and moved them into the right position for high-res deep-space imaging).
In the middle of the image is HL Tau, a young star about 450 light years distant in the constellation Taurus. Previous observations had told us that there was a dust cloud around HL Tau, but it wasn’t until ALMA gazed upon the star that the nature of the dust cloud became apparent. Seeing a protoplanetary disk in such detail is groundbreaking — and seeing such a disk around a star that’s just one million years old is astounding. We had previously thought that it took a lot longer for a star’s cloud of dust and gas to accrete, through gravity, into planets and asteroids.
The gaps between the rings of the disk, incidentally, are the telltale sign that planets and asteroids are currently being assembled. As gravity causes larger and larger accretions of rock and gas, they sweep up more dust and gas — effectively snowballing and carving out gaps in the disk as they continue to orbit the star. This is the same process by which the rings of Saturn were formed.
Back here on Earth, this high-resolution observation of HL Tau’s protoplanetary disk will hopefully tell us a lot about how our own Solar System formed, some four billion years ago. Previously, we could only make educated guess and simulate the formation of planets and stars — but now, thanks to ALMA, we can actually watch it happen in the real world, in almost real time. Science is pretty awesome. | 0.873338 | 3.733194 |
NOEL KING, HOST:
Tonight, a European space probe will fly past the Earth on its way to Mercury, the planet closest to the sun. That mission will ping around the inner solar system before getting to its destination. Here's NPR's Joe Palca.
JOE PALCA, BYLINE: Normally, when a mission milestone like a fly-by occurs, scientists gather at Mission Control to monitor the spacecraft's progress - not this time.
JORN HELBERT: We will all be at home. We all do this from our living rooms, kitchens - wherever we are.
PALCA: Jorn Helbert with the Institute of Planetary Science in Berlin is one of the scientists on the BepiColombo mission. The probe launched in 2018. Its goal is to find out what Mercury is made of, which will help scientists revise their ideas of how the solar system formed. When it flies by, Earth's gravity will slow the probe down so it can head inward toward Mercury. But Helbert says Earth's gravity alone won't do the trick.
HELBERT: So in October, we do a fly-by of Venus that, again, will slow us down a bit.
PALCA: And that's just the start.
HELBERT: Then there will be another fly-by of Venus in April of the following year. And then we have six fly-bys of Mercury, every time slowing down a little bit. But in the end, we are basically at the orbital speed of Mercury and then can go into orbit around Mercury.
PALCA: That's in 2025. In addition to the data it records at Mercury, BepiColombo will take some measurements during each fly-by. As it approaches Earth, for example, BepiColombo will measure the thermal infrared radiation from the moon, something mission scientists say has never been done before from space. Helbert says it will be the first time one of the mission's scientific instruments has been put to use making scientific measurements.
HELBERT: Hopefully, by even early afternoon on Friday, we have a first idea on how the data looks like.
PALCA: Like a lot of us, Helbert and his colleagues have found the stay-at-home orders to prevent the spread of COVID-19 a bit, well, tedious.
HELBERT: We are also all very happy to have a positive distraction.
PALCA: Something everybody could use about now.
Joe Palca, NPR News.
(SOUNDBITE OF DIAMANS' "MIRAGE") Transcript provided by NPR, Copyright NPR. | 0.873496 | 3.006355 |
On February 15, 2020, a team of astrophysicists uncovered a small, fast-moving object on the detector of the 1.5m telescope at the summit of Mount Lemmon, Arizona. The telescope is part of a group of three telescopes that image the sky for the Catalina Sky Survey, a NASA mission to study asteroids and comets passing close to Earth.
Following the discovery of the object, now named 2020 CD3, it was shown to be gravitationally bound to the Earth. 2020 CD3 is thus a tiny moon, with a size between 1 and 6 metres. Its orbital characteristics indicate that it belongs to the Arjuna family of asteroids, a class of near-Earth asteroids with an orbit very similar to that of the Earth’s orbit around the Sun.
This is not the first time Earth has captured an asteroid and turned it into a moon for a short time. 1991 VG and 2006 RH120 are two asteroids that were briefly turned into Earth moons in 1991 and 2006, respectively.
2020 CD3 was captured by Earth between 2012 and 2018. It left Earth’s orbit between March 6 and 7, 2020. It is therefore a fairly long capture. Since the tiny moon was discovered by chance almost as it was leaving its orbit around the Earth, it is very likely that several other tiny moons were never discovered or were overlooked because their trajectories in an image were too similar to those of an artificial satellite.
For more information | 0.841037 | 3.229582 |
New Tool for Astronomers – Second Planck Catalogue of Compact Sources Released
9 July 2015ESA's Planck mission is the source for a new catalogue, eagerly awaited by the scientific community, and available online from today. The Second Planck Catalogue of Compact Sources uses data from the entire mission to identify tens of thousands of compact sources, as well as providing polarisation data for several hundred of them. The new catalogue surpasses its predecessors not only in the quantity of sources but also in the quality of data. It will be an asset to astronomers working in a wide range of fields.
ESA's Planck telescope set out to measure tiny fluctuations in the Cosmic Microwave Background (CMB) – the thermal footprint left by the Big Bang. To achieve this, it continuously scanned the sky between 2009 and 2013, detecting the CMB as well as the foreground emissions arising from cosmic structures lying between the CMB and ourselves. The study of these foreground structures, which had to be carefully mapped and characterised in order to be separated from the CMB, has resulted in a valuable by-product: an extensive catalogue of tens of thousands of individual compact sources, released today. These sources appear to Planck as bright point-like spots superposed on wide expanses of more diffuse emission and consist mainly of galaxies located at great distances from the Milky Way, though compact objects within our Galaxy also appear in the catalogue.
|Map of selection of compact sources from the Second Planck Catalogue of Compact Sources. Credit: ESA and the Planck Collaboration|
ESA has released compact source catalogues from Planck in the past but in this instance the diverse and extensive catalogue includes data from the full Planck mission. The mission involved surveying the entire sky in nine different wavelengths spanning the far-infrared to radio, covering the spectral range 30 GHz to 857 GHz. The result is a catalogue with datasets from five surveys using the telescope's High Frequency Instrument (HFI) channels and a remarkable eight surveys using the Low Frequency Instrument (LFI) channels. This is a significant leap forward from the one and a half surveys used for the Early Release Compact Source Catalogue, released in 2011, and the 2.5 used in the 2013 catalogue that followed.
"There are a number of ways in which the data in this catalogue surpass those of its predecessors in more than just quantity," explains Marcos López-Caniego from ESA, responsible for the LFI portion of the survey. "For example, for the LFI channels, which cover the frequency range 30 to 70 GHz, averaging data over eight surveys has dramatically increased the sensitivity."
"Another major advance is in the better understanding of the contents of the catalogue," adds Diana Harrison from the Institute of Astronomy, University of Cambridge, UK, who was responsible for the HFI section of the catalogue. "One of the major complications at the wavelengths that Planck observes is to distinguish truly compact individual sources from variations in the diffuse emission which arises from gas and dust in our own Galaxy. In this catalogue there has been a totally new treatment of the reliability of the sources, especially in the HFI channels, which has resulted in much higher confidence in its contents."
The improvements to the reliability and sensitivity of the data are just part of the reason that this extensive database differs from those that came before. Planck has polarisation sensitive instruments in seven of the nine frequencies it observes in and this catalogue, unlike its predecessors, offers polarisation data for several hundred compact sources.
"For those sources that have been significantly detected in polarisation maps we have used the latest calibration of Planck data, and improved pipelines, to measure the polarised flux densities of the sources," explains Marcos. "In other words, we have measured and included the amount of polarised light we have collected radiating from these sources, which means that they can be studied in both total intensity and polarised light."
|Data from the Second Planck Catalogue of Compact Sources are used to map polarised compact sources across the sky, in this example from the 30 GHz channel. Credit: ESA and the Planck Collaboration|
Catalogue use and applications
The catalogue can be accessed from the ESA Planck Legacy Archive hosted at ESA's European Space Astronomy Centre (ESAC) and is available to all researchers. Data are provided in standard fits format tables that can be used with a variety of astronomical tools. A search tool allows users to search by coordinate or common name.
"The catalogue is built with flexibility in mind due to the wide variety of astronomical objects that are contained within it," explains Jan Tauber, Planck Project Scientist at ESA. "The menagerie of sources in the catalogue includes radio galaxies, blazars, infrared-luminous galaxies, galaxy clusters, supernova remnants, cold molecular cloud cores, stars with dust shells, as well as many other unidentified objects, and the list of fields within astronomy which could benefit from the catalogue is just as long!"
The availability of a much larger catalogue of compact sources than has previously been available is of great value to researchers working on other CMB experiments. These sources sorely contaminate CMB data and with the aid of the new catalogue they can now be quickly identified, and removed from, observation data.
As well as the use in CMB research the catalogue will be of use to radio astronomers as it extends the range of frequencies currently available from ground-based telescopes, widening the scope of their research and potentially allowing them to study the emission from their chosen galaxy at nine frequencies with polarisation data in seven channels.
|Detailed view of Centaurus A as seen by Planck. Credit: ESA and the Planck Collaboration|
Researchers from across astronomy – including optical, infrared, radio, X-ray and gamma ray astronomers – will benefit from the catalogue, which can be used to build spectral energy distribution plots of individual objects or whole classes of objects. In other words, plotting the brightness of objects, over a range of frequencies, giving valuable clues to their properties. For others, a key benefit of the catalogue will be the ability to combine its full mission maps and single survey maps with the new tools in the Planck Legacy Archive to produce maps from specific periods of time. This will allow for long-term and short-term studies of how the objects vary over time.
Astronomers looking at far-infrared wavelengths will find the catalogue of particular use, on account of Planck having two channels in common with ESA's Herschel telescope, which provides maps of many of these sources with much higher resolution.
In order to serve the needs of this hugely varied community of users the catalogue includes four different measures of the amount of polarised light, and total intensity, for each source – each measure determined using a different photometry method – so that the user can choose the one most suitable for their needs.
A hint at the potential of the catalogue is evidenced by some results that have already emerged from earlier targeted searches for specific compact sources. Researchers using the 2013 catalogue found in the Planck maps the location of potential precursors of the vast galaxy clusters that we see in our local Universe, and used Herschel to map those sources in detail, confirming a subset of them.
These are just some of the applications that the new catalogue might have and even more are expected to emerge.
"What we are releasing here is an important product of the Planck mission," Tauber comments. "This suite of compact sources represents a lasting legacy that we are confident will produce new and exciting findings across the breadth of astronomy research."
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 three frequency bands in the range 30–70 GHz, and the High Frequency Instrument, which includes six frequency bands in the range 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 2013.
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, 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.
Institute of Astronomy, University of Cambridge, UK
Tel: +44 1223 766 660
ESA European Space Astronomy Centre (ESAC), Madrid, Spain
Tel: +34 91 813 1481
ESA Planck Project Scientist
Scientific Support Office
Directorate of Science and Robotic Exploration
ESA, The Netherlands
Tel: +31 71 565 5342 | 0.867039 | 3.880831 |
NASA's Genesis sample capsule not only stirred up dust and dirt when it crash landed in Utah last week, but also debate concerning the return to Earth of future extraterrestrial samples - specifically from Mars.
While the high-speed impact of the return canister was not planned, the capsule's design did permit the survival of some samples. However, due to a breach of the science canister caused by the crash, the space specimens were contaminated once exposed to Earth's atmosphere.
The Genesis probe, along with the homeward bound Stardust spacecraft carrying bits of a comet and interstellar particles, serve as precursor missions to snag, bag, and lug back to Earth select pieces of Martian real estate.
NASA engineers and scientists have been grappling for decades with methods, procedures, and the price tag for robotically returning Mars samples.
One concern is that Martian samples could contain microbial life. Whether that's the case or not, great care in handling specimens of Mars is a high priority -- not only to protect our planet from virulent biology, albeit a low probability, but also guarding the samples from Earth contamination.
The desert dust kicked up by the Genesis is settled as scientists work to retrieve some of its precious cargo. But talk about how best to orchestrate a future Mars sample mission is far from coming to rest.
Trashed and twisted hardware
The Genesis sample canister augured into the Utah Test and Training Range (UTTR) at a speed of nearly 200 miles per hour (322 kilometers per hour). Onboard was a treasured stash of solar wind samples, embedded in breakable collector arrays.
With the capsule successfully rocketing through Earth's atmosphere, the plan then called for a mid-air helicopter recovery of the sample return capsule underneath an unfurled parafoil - a wing-like parachute.
But the parachute system failed to deploy. The return sample canister was banged up and severely damaged by the high-speed impact, leaving scientists to pluck through trashed and twisted hardware in the hopes of salvaging science data.
"We'll have to wait and see what the results and lessons learned from the Genesis mishap reviews are to see how they will affect Mars Sample Return designs," said Mark Adler, Mars Exploration Rover Mission Manager and an engineer at the Jet Propulsion Laboratory (JPL) in Pasadena, California.
As currently envisioned, the Mars Sample Return mission uses a completely passive entry vehicle -- that is, hardware holding the specimen canister would be aerodynamically stable through landing on Earth. The MSR entry craft would not use or require a parachute, Adler explained.
"The samples of Martian rock and soil would be in a container designed to withstand the impact and maintain its integrity as well as the integrity of the samples," Adler said.
This design has been the lead candidate for about seven years, and a full-scale model was drop-tested at UTTR in 2000, he said.
A Mars Sample Return (MSR) mission is at least nine years away, so statements about the MSR final design should be taken "with the appropriate-sized grain of salt," he noted.
Photo Gallery of Genesis Mission
Complete Genesis Coverage
"Furthermore, public review and input on the environmental impact of MSR would be required before a final decision could be made to proceed with the mission," Adler told SPACE.com.
"It is clear, though, that the Genesis experience bolsters the previous conclusion that an MSR entry vehicle must be designed to maintain containment of the samples in the event that a parachute or any other entry, descent, and landing deployment or actuation fails," Adler said.
Seeing that the Genesis sample canister was breached and its contents exposed to Earth's biosphere, "the Mars Sample Return mission needs to be rethought entirely," said Barry DiGregorio, a research associate with the Cardiff Center for Astrobiology in the United Kingdom.
DiGregorio is also director for the International Committee Against Mars Sample Return (ICAMSR), an activist group established to increase public awareness regarding Mars-to-Earth transit of samples, along with any possible negative consequences that could occur due to an MSR canister either becoming opened unintentionally on impact, or lost during entry into the Earth's atmosphere.
In 2000, DiGregorio said, NASA was moving forward with its "faster, better cheaper" plan to return Martian soil samples as soon as 2003 and 2005 in a capsule design not unlike Genesis, with the exception that the MSR capsule would not use a parafoil or drogue chute. Instead it would use atmospheric friction to slow its descent and then directly impact the same general area in the Utah desert that Genesis did, he said.
Given the Genesis experience, DiGregorio argues that NASA's new Moon, Mars and beyond quest should include the establishment of a human-tended planetary sample
quarantine facility on the Moon as a part of any scientific outpost there.
"Examining Martian soil and rock samples on the Moon offers a 100 percent guarantee that Earth's biosphere would not become back-contaminated with any possible Martian microorganisms," DiGregorio said.
John Rummel, Planetary Protection Officer at NASA Headquarters in Washington, D.C., advised that there will likely always be a desire to bring back materials from elsewhere, and study that material in the most capable laboratories that are available, which are on Earth.
Genesis involved an in-air snatch, the softest way to land, due to the fragile nature of its collection devices and the requirement for molecular-level purity for its sub-microscopic samples of the solar wind, Rummel said.
NASA's Stardust mission will bring comet samples back to Earth in January 2006. The collection material, aerogel, is also fairly fragile, although the particles are bigger, Rummel said. Therefore, Stardust will land by parachute in Utah, sans the mid-air helicopter catch.
Rummel said designs being studied for the most recent analyses of a Mars sample return mission are anticipating a much more robust sample collection canister, and a strict containment requirement. Although a non-parachute landing would be hard, the sample canister will be cushioned inside the Earth Entry Vehicle, to minimize effects on both the sample and the container.
"Genesis did not have a planetary protection requirement for containment. There were no concerns about that mission from an exobiology perspective," Rummel said. "It is unfortunate that the parachute on Genesis failed to open, but sample return missions requiring strict containment will likely plan to do without one. The Genesis failure
makes that case pretty well...while emphasizing the importance of good navigation for safe sample return missions."
Martian somethings: how real?
"Everyone agrees that we must be as careful as possible with the Mars sample," said Wendell Mendell, Manager of the Office for Human Exploration Science at NASA's Johnson Space Center (JSC) in Houston, Texas.
The sample curation group at JSC believes they have the expertise and have access to other expertise sufficient to reduce any risk to an infinitesimal level, he said.
"The question is whether we want to spend billions or tens of billions of dollars to make the risk even more infinitesimal," Mendell said, noting that his views are his own and not official NASA positions.
Mendell said he is open to being persuaded that there is a real danger to bringing back a "Martian something" that could disrupt the Earth. "But I have never heard any argument based on logic and/or science that caused me to increase my personal concern. There is every reason to believe that 'Martian somethings' have landed on Earth with regularity."
Making a choice
As for DeGregorio's idea of a sample handling facility on the Moon, Mendell brought out a nagging question: What to do with the human crew that will eventually interact with the sample?
"If we keep the samples on the Moon for study, do we sacrifice everyone who studies them to minimize the risk even further? Where do we draw the line? Some people would like to draw the line at staying on Earth and keep away from space," Mendell explained.
A capsule can be built to withstand the impact speed experienced by the Genesis same return container, Mendell said. He added that scientists who want to study the sample do not want a hard impact on return and would insist on a mission design to minimize that possibility.
"A few years ago, we at JSC argued for a shuttle capture in order to safe the sample under human supervision before returning it to Earth," Mendell said. "Now, of course, everyone knows the shuttle can break up on return. Besides, the shuttle will not exist in 2013 when the sample is returned."
It is his personal view, Mendell said, that all of this boils down to making a choice: "One, forget about it, or two, do the best you can to minimize the risk and still make the event affordable to the space program."
- Genesis Mission: Crash Video and Complete Coverage | 0.909847 | 3.183045 |
Mars moon got its grooves from rolling stones, study suggests
Credit: NASA/JPL-Caltech/University of Arizona
PROVIDENCE, R.I. [Brown University] — A new study bolsters the idea that strange grooves crisscrossing the surface of the Martian moon Phobos were made by rolling boulders blasted free from an ancient asteroid impact.
The research, published in Planetary and Space Science, uses computer models to simulate the movement of debris from Stickney crater, a huge gash on one end of Phobos’ oblong body. The models show that boulders rolling across the surface in the aftermath of the Stickney impact could have created the puzzling patterns of grooves seen on Phobos today.
“These grooves are a distinctive feature of Phobos, and how they formed has been debated by planetary scientists for 40 years,” said Ken Ramsley, a planetary science researcher at Brown University who led the work. “We think this study is another step toward zeroing in on an explanation.”
Phobos’ grooves, which are visible across most of the moon’s surface, were first glimpsed in the 1970s by NASA’s Mariner and Viking missions. Over the years, there has been no shortage of explanations put forward for how they formed. Some scientists have posited that large impacts on Mars have showered the nearby moon with groove-carving debris. Others think that Mars’ gravity is slowly tearing Phobos apart, and the grooves are signs of structural failure.
Still other researchers have made the case that there’s a connection between the grooves and the Stickney impact. In the late 1970s, planetary scientists Lionel Wilson and Jim Head proposed the idea that ejecta — bouncing, sliding and rolling boulders — from Stickney may have carved the grooves. Head, a professor in Brown’s department of Earth, Environmental and Planetary Sciences, was also a coauthor of this new paper.
For a moon the size of the diminutive Phobos (27 kilometers across at its widest point), Stickney is a huge crater at 9 kilometers across. The impact that formed it would have blown free tons of giant rocks, making the rolling boulder idea entirely plausible, Ramsley says. But there are also some problems with the idea.
For example, not all of the grooves are aligned radially from Stickney as one might intuitively expect if Stickney ejecta did the carving. And some grooves are superposed on top of each other, which suggests some must have already been there when superposed ones were created. How could there be grooves created at two different times from one single event? What’s more, a few grooves run through Stickney itself, suggesting that the crater must already have been there when the grooves formed. There’s also a conspicuous dead spot on Phobos where there are no grooves at all. Why would all those rolling boulders just skip one particular area?
To explore those questions, Ramsley designed computer models to see if there was any chance that the “rolling boulder model” could recreate these confounding patterns. The models simulate the paths of the boulders ejected from Stickney, taking into account Phobos’ shape and topography, as well as its gravitational environment, rotation and orbit around Mars.
Ramsley said he had no expectations for what the models might show. He wound up being surprised at how well the model recreated the groove patterns seen on Phobos.
“The model is really just an experiment we run on a laptop,” Ramsley said. “We put all the basic ingredients in, then we press the button and we see what happens.”
The models showed that the boulders tended to align themselves in sets of parallel paths, which jibes with the sets of parallel grooves seen on Phobos. The models also provide a potential explanation for some of the other more puzzling groove patterns.
The simulations show that because of Phobos’ small size and relatively weak gravity, Stickney stones just keep on rolling, rather than stopping after a kilometer or so like they might on a larger body. In fact, some boulders would have rolled and bounded their way all the way around the tiny moon. That circumnavigation could explain why some grooves aren’t radially aligned to the crater. Boulders that start out rolling across the eastern hemisphere of Phobos produce grooves that appear to be misaligned from the crater when they reach the western hemisphere.
That round-the-globe rolling also explains how some grooves are superposed on top of others. The models show that grooves laid down right after the impact were crossed minutes to hours later by boulders completing their global journeys. In some cases, those globetrotting boulders rolled all the back to where they started — Stickney crater. That explains why Stickney itself has grooves.
Then there’s the dead spot where there are no grooves at all. That area turns out to be a fairly low-elevation area on Phobos surrounded by a higher-elevation lip, Ramsley says. The simulations showed that boulders hit that lip and take a flying leap over the dead spot, before coming down again on the other side.
“It’s like a ski jump,” Ramsley said. “The boulders keep going but suddenly there’s no ground under them. They end up doing this suborbital flight over this zone.”
All told, Ramsley says, the models answer some key questions about how ejecta from Stickney could have been responsible for Phobos’ complicated groove patterns.
“We think this makes a pretty strong case that it was this rolling boulder model accounts for most if not all the grooves on Phobos,” Ramsley said.
Related Journal Article | 0.881047 | 3.752564 |
Have you ever looked up at a night sky full of stars? It’s probably not easy to see because of the bright city lights. However, if you do, you will see many celestials such as comets, moons and stars shining bright. The majority of people can't figure out what kinds of stars they are seeing. Even if you don't know much about the universe, you’d better to look at the sky carefully in May because a comet will be approaching Earth and this is a rare opportunity for you to see one. A comet is a small celestial body belonging to the solar system that orbits the sun or planets in a circular motion. It has a specific cycle, due to its fixed orbit. However, the cycle length varies widely from a few years to hundreds of thousands of years. Comets are mainly produced from the Kuiper belt or Ort cloud and gravitate towards the solar system.
Comets are largely divided into three parts: the nucleus, coma and tail. The nucleus is the center of the comet, consisting of rock, iced water vapor, iced methane and iced ammonia. Usually, the diameter of a comet's core is several kilometers long. There is also active evaporation taking place on the surface of nucleus. During this process, gases and dust are released. This atmosphere of the comet is called a coma. A coma looks clearer as it gets closer to the sun. Also, the comet's tail is divided into two parts, the Dust-tail and Ion-tail, depending on its composition. The tail forms on the opposite side of the direction of the comet's progress, and become longer as it nears the sun. However, comets are so small that we don't have many opportunities to observe them with our bare eyes, but there have been exceptions. When they occur, the comets involved are referred to as 'the great comets'. For instance, the IKEYA-SEKI comet was discovered in 1965 and is a representative of the great comets. When the comet approached Earth, its apparent magnitude was -7 and appeared as bright as crescent moon. The comet inspired the animation movie 'Your Name' released in Japan.
Another great comet is expected to emerge in the 21st century. Its full name name is Asteroid Terrestrial-impact Last Alert System (ATLAS) comet (C1219 Y4) and was first observed in December, 2019. The comet's orbital cycle is about 6,000 years and it is now passing between Earth and Mars. It can be seen near the Camelopardus with high-performance telescopes. It is estimated that the ATLAS Comet will be closest to Earth at about 0.78AU on May 23rd, 2020 and is expected to be closest to the sun around May 31st, 2020.
When it was first discovered, it was expected to have an apprent brightness of -6.7, so we should be have been able to see it with our naked eyes when it comes closest to the earth. However, according to recent observations reported, ATLAS won’t be as bright as expected. On April 6th, 2020, Quanzhi Ye (University of Maryland) and Qicheng Zhang(Caltech) reported the possibility of the comet ATLAS’s fragmentation.
Based on the images of the comet from April 2nd to 5th, they said its form changed from starlike and compact to elongated and fuzzy. This change often means that the comet is heading for fragmentation. Because of its change in form, on April 19th, the apparent brightness of ATLAS was downgraded to -4.95 when it will be closest to earth. This means that its brightness will have decreased by about five times. However, on April 29, Korea Astronomy & Space Science Institue reported that ATLAS’s flagmentation has been confrimed. Using Optical Wide-field patroL Network, which is an astronomical observation facility, they observed the ATLAS’s nucleus splited into several pices and some of them fall off. They also said, the more they approach to the sun, the more its collapse gets worse.
At first, experts didn’t expect that the ATLAS comet would get further split after it had progressed to some fragment. Unfortunately, however, the ATALAS comet is collapsing even at this moment. If you can’t be seen this comet, you probably won't be able to see the Great Comet in our lifetime. Therefore, this makes us feel sorry not only for astronomers but also for us.
|▲ The comet has fragmented into more than a dozen pieces. (Photo from NASA)|
Apparent magnitude (brightness): Rating of the brightness of the celestial body measured on Earth. The smaller number, the brighter it is. A difference of 1.0 in magnitude corresponds to a brightness ratio of , or about 2.512.
Camelopardus: The constellation of Giraffe.
1AU (Astronomical Unit) : One of the units that measures distance in astronomy, which is about 149.6 million kilometers between Earth and the sun.
박근후, 임재도 [email protected] | 0.833204 | 3.787432 |
Last night when we went out to photograph Jupiter and Venus, Melissa and I also took a photo of the Southern Cross. We noticed a small cluster of stars just off to the left and slightly below Beta Crucis. Not being that familiar with the night sky, we looked into it and it turns out to be the star cluster known as the Jewel Box Cluster (NGC 4755). It was discovered by Nicolas Louis de Lacaille in 1751–1752 and later named the Jewel Box by Sir John Herschel who described it as looking like “a casket of variously coloured precious stones.” It is located 6,440 light years from Earth, and contains around 100 stars.
According to the One-Minute Astronomer, since early European navigators had no telescopes to resolve it, they classified the Jewel Box as the star kappa Crucis.
It is an open cluster, a group of up to a few thousand stars that were formed from the same giant molecular cloud and having approximately the same age. By the standards of star longevity, open clusters are ephemeral, generally surviving for only a few hundred million years. The Jewel Box is one of the youngest open clusters known, and is estimated to be 14 million years of age, a real astronomical baby. Since it is so young, most of its members are still blue-white main sequence stars. Main sequence stars fuse hydrogen atoms to form helium atoms in their cores, and this applies to around 90 percent of the stars in the universe, including the sun. Despite most stars being blue-white, the brightest stars in the Jewel Box cluster are supergiants, and include some of the brightest stars in the Milky Way galaxy, which is why it stands out adjacent to the Southern Cross.
So we set off again this evening to try and get a better view of it. It is impressive when viewed with binoculars or the camera’s lens. The three brightest members of the cluster are arranged in a straight line, which astronomers call the ‘traffic lights’ due to their varying colours.
Here is a video of the hubble zooming into the Jewell Box cluster, which is pretty cool. | 0.802112 | 3.460511 |
The eta Aquariids (ETA) are active between April 17 and May 24. The strongest activity is usually seen near May 7, when rates can reach 25-30 meteors per hour as seen from the tropical areas of the Earth. Unlike most major annual meteor showers, there is no sharp peak for this shower, but rather a plateau of good rates that last approximately one week centered on May 7. The eta Aquariids are particles from Halley’s Comet, which last passed through the inner solar system in 1986. The meteors we currently see as members of the eta Aquariid shower separated from Halley’s Comet hundreds of years ago. The current orbit of Halley’s Comet does not pass close enough to the Earth to be a source of meteoric activity.
The eta Aquariids are only visible during the last couple of hours before the start of morning twilight. The reason for this is that the radiant (the area of the sky where these meteors appear to shoot from) is situated approximately 60 degrees west of the sun. Therefore it rises before the sun in the morning hours. The time of radiant rise is between 2:00 and 3:00 local summer time (LST), depending on your longitude. The real key is the latitude. There is an observing window for this shower between the time the radiant rises and the beginning of morning nautical twilight. This window ranges from zero at 60 degrees north latitude to all night in Antarctica. Unfortunately in Antarctica, the radiant never rises very high in the sky and most of the activity is not visible from there. The best combination of a large observing window and a decent radiant altitude occurs between the equator and 30 degrees south latitude. From this area the radiant reaches a maximum altitude of 50 degrees at nautical twilight. The observing window ranges from 3.5 hours at the equator to slightly over 4.0 hours at 30 degrees south latitude. Going further south will increase your observing window but the maximum altitude will begin to fall closer to the horizon.
Since most meteor observers live in the northern hemisphere, here are the conditions at several different latitudes: the observing window for 50N is 1.5 hours with a radiant altitude of 15 degrees. The observing window for 40N is 2.25 hours with a radiant altitude of 25 degrees. The observing window for 30N is 2.75 hours with a radiant altitude of 35 degrees.
Near maximum, the radiant may be easily spotted as it lies near the “water jar” in Aquarius. This “Y” shaped pattern of stars is also known as the “peace sign” to some observers. It should be noted that very few meteors are actually seen at the radiant. This position just happens to be the apparent source of the activity. More activity is seen further up in the sky where longer shower members can be seen. That is why it is advised to look half-way up in the sky. Do not look straight up as this is the direction of least meteoric activity. By looking at the zenith you are looking though the thinnest slice of atmosphere possible. This is great for lunar and planetary viewing but not for meteor observing. Have the horizon be at the bottom of your field of view and your center will lie near the optimal forty-five degree altitude zone.
The conditions for viewing the eta Aquariids in 2019 are close to perfect. A new moon will occur on May 4, only a few days before maximum activity. The moon will not start to interfere with viewing these meteors until May 13, when it sets shortly after the radiant rises in the opposite side of the sky.
To best see these meteors you should start viewing near the time the radiant rises. This is between 2:00 and 3:00am for most observers situated at mid-northern latitudes. It would be best to view toward the eastern half of the sky with the radiant in the lower portion of your field of view. This way you can see these meteors shooting in all directions out of the radiant, even downwards. This suggestion is good for all observers no matter your location. These meteors will shoot in all directions, especially low in the northeast and southeastern sky. The best ones will shoot straight upwards through the center of your field of view. The eta Aquariids are swift meteors leaving a high percentage of persistent trains. Unlike the Geminids and Perseids, fireballs from this source are rare.
The graphs below show eta Aquariid and sporadic activity from 2007-2017. Each dot represents a single hourly rate reported by a single observer, corrected for effective time, obstructions, sky conditions, and zenith angle. Reported sporadic rates are also plotted for reference (also corrected for effective time, obstructions, and sky conditions). Each plot is in terms of Solar Longitude, not date, allowing direct comparison between years. The expected maximum for the eta Aquariids each year lies at solar longitude 46.2 Due to the usually low zenith angle of this shower, there is a large amount of data scatter and a broad, ill-defined peak even in a good year without lunar interference.
The graphs are courtesy of James Richardson using data from the International Meteor Organization (IMO). It should be noted that the corrected rate values do not represent rates that anyone will actually see, but are simply a way of combining raw meteor hourly rates from multiple observers in various locations and observing under disparate conditions. The corrected raw data does a good job of showing the ramp up and ramp down of each shower as they occur/occurred, where the actual ZHR will be roughly in the *middle* of the plotted numbers (that is, don’t follow the top of the plot, watch the middle of the plot). Also note that the vertical scale is logarithmic, such that a typical shower will generally ramp up and down in ‘saw tooth’ fashion, forming a triangular peak (sometimes with asymmetrical sides).
Meteor shower rates, as seen by an individual observer, are quite random (following a Poisson distribution), more random than most people intuitively expect, such that wide variations from one hour to the next can occur, or wide variations between two observers at two different locations in the same hour. The plots also point to the importance of observer accuracy in reporting their observations: times, counts, limiting magnitude, sky obscuration, shower member identification. I think it is elucidating for observers to see their raw and minimally corrected (normalized) rates directly, rather than as a averaged, single value with error bars. | 0.865435 | 3.846649 |
In order to understand how the system works, it is important to become familiar with the fundamental concept that forms the foundation of this system.
A fundamental aspect of Human Design is based on what is scientifically known as the Neutrino.
Neutrinos are unusual particles that carry an infinitesimal amount of mass. About 3 trillion neutrinos, and the material information they carry, pass through every square inch of the planet per second. Our Sun produces about 70 percent of all neutrinos that travel through our solar system, with the remaining 30 percent emitted by other stars in our Galaxy, and a small amount from the planet Jupiter.
In 2015, the scientists Takaaki Kajita (Super-Kamiokande Collaboration) and Arthur B. McDonald (Sudbury Neutrino Observatory Collaboration) were awarded a Nobel Prize for the discovery of neutrino oscillations, which shows that neutrinos have mass. Ra Uru Hu published this as the science behind the Human Design System as early as 1991.
Since Neutrinos have an infinitesimally small amount of mass, as the stream passes through us it leaves information. It is a stream of information, and within each of us exist particles that connect us to the stream. At the moment of birth, we are imprinted by the information carried by the neutrino stream via the planets. This imprint is reflected within your Human Design Chart, and determines your particular Design. This information provides us with the knowledge to understand our nature, potential, and forms of interaction.Next > Ra Uru Hu & The History of the Human Design System | 0.822011 | 3.151353 |
Planet Hunters Introduction
Hi, I’m Meg Schwamb a postdoctoral fellow at Yale University and member of the Planet Hunters Team. Welcome to Planet Hunters! We’ve been working hard, and we are excited to finally show you the finished product!
In the last decade, we have seen an explosion in the number of known planets orbiting stars beyond our own solar system. With ground based transit searches, stellar radial-velocity observations, and microlensing detections, over 500 extrasolar planets (exoplanets) have been discovered to date. Studying the physical and dynamical properties of each of these new worlds has revolutionized our understanding of planetary formation and the evolution of planetary systems. But we have just barely scratched the surface in understanding the diversity of planetary systems and planet formation pathways.The current inventory of known exoplanets has been limited to mostly Jupiter-sized or larger gas-rich planets, most orbiting extremely close to their parent stars. The current inventory of known exoplanets has been limited to mostly Jupiter-sized or larger gas-rich planets, most orbiting extremely close to their parent stars. While these planets have provided great insight into the formation of giant planets, beyond Mercury, Venus, Earth, and Mars, in our own solar system, little is known about the formation and prevalence of rocky terrestrial planets in the universe.
Finding Earth-size planets is a difficult task because the transit-signals, the dimming of the star’s light caused be a planet moving in front of the star, are so shallow. For a Jupiter-size planet, the transit depth is ~1% of the star’s brightness. For an Earth-size planet transiting a Sun-like star the decrease in brightness is less than .001%. Ground-based surveys have not reached the sensitivity to detect such planets around stars similar to our Sun, but with NASA’s space-based Kepler mission, launched in March 2009, astronomers are primed to start a new era in the study of exoplanets. Even with the exceptional data from the Kepler telescope, finding these Earth-sized planets will be extremely difficult, but in the age of Kepler, the first rocky planets will likely be detected including the potential to find Earth-like planets residing in the habitable zone, warm enough to harbor liquid water and potentially life on their surfaces.
NASA’s Kepler spacecraft is one of the most powerful tools in the hunt for extrasolar planets. The Kepler data set is unprecedented, both in observing cadence and in the photometric precision. Before Kepler, the only star monitored this precisely was our own Sun. The lightcurves reveal subtle variability that has never before been documented. The Kepler data set is a unique reservoir waiting to be tapped. Kepler lightcurves are now publicly available with the first data release this past June and the next release scheduled for February 2011.
The Kepler Team computers are sifting through the data, but we at Planet Hunters are betting that there will be transit signals which can only be found via the remarkable human ability for pattern recognition. Computers are only good at finding what they’ve been taught to look for. Whereas the human brain has the uncanny ability to recognize patterns and immediately pick out what is strange or unique, far beyond what we can teach machines to do. With Planet Hunters we are looking for the needle in the haystack, and ask you to help us search for planets.
This is a gamble, a bet, if you will, on the ability of humans to beat machines just occasionally. It may be that no new planets are found or that computers have the job down to a fine art. That’s ok. For science to progress sometimes we have to do experiments, and although it may not seem like it at the time negative results are as valuable as positive ones. Most of the lightcurves will be flat devoid of transit signals but yet, it’s just possible that you might be the first to know that a star somewhere out there in the Milky Way has a companion, just as our Sun does.
Fancy giving it a try? | 0.848518 | 3.879975 |
Astronomers have warned of the sun entering a "catastrophic hibernation" period, which leads to its blocking and entering the lower stage of solar energy, which may cause freezing weather and earthquakes.
Experts believe that we are on the verge of entering the deepest period of "recorded" sunlight ever recorded, with the sunspot virtually gone, according to the British newspaper "The Sun".
"The minimum amount of solar energy actually happened, which is deep. The sun's magnetic field has become weak, allowing additional cosmic rays in the solar system," said astronomer Tony Phillips.
"Excess cosmic rays pose a threat to the health of astronauts and travelers in the polar air, and affect electrochemistry in the upper atmosphere of the Earth, and may help cause lightning."
NASA scientists fear it will be a recurrence of the "Delton Minimum" phenomenon, which occurred between 1790 and 1830, which led to periods of severe cold, loss of crops and famine, and powerful volcanic eruptions.
Temperatures decreased by up to 2 ° C over 20 years, which destroyed the world's food production.
On April 10, 1815, the second largest volcanic eruption occurred in 2000 years on Mount Tambora, Indonesia, killing at least 71,000 people, and also leading to what is called a year without summer in 1816, when snow fell in July.
So far this year, the sun has been "empty" with no sunspot 76 percent of the time, a rate that was only exceeded once in the space age last year, when it was 77 percent blank.
A previous study revealed that the sun, although it is the most important source of energy for life on Earth, is "slightly sleepy" compared to other stars in the universe.
Astronomers from the Max Planck Institute in Germany compared the sun to hundreds of similar stars, using data from NASA's Kepler Space Telescope, and researchers chose stars with a similar surface temperature, age and spin to the Sun in the Milky Way.
The results showed that the sun is very weak compared to most other stars about 5 times.
"We were very surprised that most sunlike stars are much more active than the sun," said Alexander Shapiro of the Max Planck Institute.
The researchers say it is not clear whether the sun has been "going through a quiet period" for 9,000 years or is it less bright than other similar stars.
Real Madrid midfielder Toni Kroos has revealed his desire to complete his contract with his Spanish club before deciding on his retirement.
German midfielder Toni Kroos has expressed his desire to complete his contract with his current club Real Madrid, which runs until 2023, before he thinks to end his career and professional career.
"My goal is to continue playing for Real Madrid in the next three seasons," Crose said, who moved from Bayern Munich to Real Madrid in 2014, during an interview with "Eurospor" in Germany.
The player who won the 2014 World Cup title with the German national team continued that in the year 2023 "I will be thirty-three years old, and it will be a good time to ask the question: How do I feel on the physical level, are I still motivated, do I have a desire to continue? Then we will see what happens ".
Croes believes that "3 years in football is a long time. 3 years in Real Madrid is even longer," referring to the level required to play for the club, which has been crowned 13 times in the Champions League throughout its history.
In his speech, Kroos mentioned his departure from German club Bayern Munich 6 years ago, after disputes with some of the club's officials, who crowned a champion of the Bundesliga in the last seven seasons.
"Some people in Bayern may have regretted letting me go, but this regret does not apply to me at all, I had my convictions, and Bayern had its convictions, and there was no other way but separation," Cross said.
Searches are continuing for a vaccine or antiretroviral treatment for the new Coronavirus, which has killed hundreds of thousands of people and infected more than 4.6 million people worldwide.
As the search for a vaccine for the virus that adversely affected global economies continues, other research continues to find a way to disrupt or combat it, outside the human body, so that it joins efforts to stop the Covid-19 epidemic.
And recently, a preliminary study reached a substance that can protect surfaces from the new Corona virus and germs, for a period of up to 90 days, by spraying them on surfaces, such as trains and buses, and forming an anti-virus layer.
According to the study, prepared by researchers at the University of Arizona and not yet reviewed by other scientists, the amount of viruses present on the surfaces, which were sprayed with this antibacterial, decreased by 90 percent in 10 minutes and by up to 99.9 percent after two hours.
This technology "is the next big development in containing the epidemic ... I think it is especially important for heavily used surfaces like subway trains and buses that are regularly sanitized but people who successively re-pollute it," said Charles Gerba, the university's microbiologist and lead author, told AFP. ".
Gerba added that "this technology does not replace ordinary cleaning and sterilization, but rather protects the stages between regular cleaning and sterilization."
The university team tested the material specifically designed for anti-virus by Allied Bioscience, which also funded the study.
According to France Press, the researchers conducted their experiment on the Human Coronavirus, "229E", which is similar in composition and genetic characteristics to Coronavirus, but it has slight flu symptoms.
And spray the innovative material, which causes a change in the proteins of the virus and attacks the layer that protects it, so that it covers the various surfaces provided that the process is repeated every 3 to 4 months.
, Dr. Abeer Almadawy
declared owner and president of the Castle Journal
About the new official name
Which departs from Egypt and the Netherlands
And the global media
In which you will start dealing with companies and other organizations around the world officially in accordance with international law for investment and business
Castle Journal is a British company licensed number 10675 since 2015 and has many offices located around the world
Our offices in Egypt and the Netherlands are defined in the CJG consolidated press
International standardized through its own newspapers and magazines
This electronic journal depends on the new technology that will be provided by 5G methods, all of which are integrated in the global unified media
And the new media, adding that the Earth is now just a small city
Where the world itself will share news, information and technology
But CJG respects the World Health Organization and the right to think before you follow it
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The new global unified media is to control the creation of a unified world based on a full understanding of peace, tolerance and respect
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A prominent scientist at the World Health Organization has warned that the world may need a period of time between 4 and 5 years in order to control the Corona epidemic.
The leading Indian scientist with the organization Sumaya Swaminathan said that the decisive factors for the long-term defeat of "Covid 19" include the evolution of the virus and preventive measures, and most importantly the development of a vaccine.
And Swaminathan, a pediatrician, considered that "the vaccine now seems the best way" to get out of the crisis, but pointed to the existence of obstacles related to its effectiveness and safety, in her comments to the British newspaper "Financial Times".
And I continued, "I say that within 4 or 5 years we can control this epidemic."
Another WHO official said earlier that the virus could become endemic, such as the HIV virus that causes AIDS, doubting any attempt to predict when it will continue to spread.
Mike Ryan, Executive Director of the WHO Emergency Program, said in an online press briefing: "It is important to put forward these words: This virus may just become another virus that is endemic in our societies. This virus may never disappear."
He added: "I think it is necessary to be realistic, and I do not imagine that anyone can predict when this disease will disappear. I see that there are no promises in this regard and there are no dates. This disease may settle to become a long-term problem, and it may not be so."
However, Ryan said the world had achieved some control over how it dealt with the disease, but it would take "tremendous efforts" even if a vaccine was reached, which he described as "a major achievement."
More than 100 possible vaccines are being developed, many of them in clinical trials, but experts have confirmed the difficulty of finding effective vaccines against the emerging corona virus.
Ryan noted that there are vaccines for other diseases, such as measles, and yet they have not been completely eradicated
Governments around the world are fighting over how to reopen their economies while continuing to contain the virus, which has infected nearly 4.3 million people, according to Reuters statistics, and has killed nearly 300,000.
Doctors in Italy have spoken of the first clear evidence linking Covid 19 disease caused by the emerging coronavirus, and a rare and serious disorder that affects autoimmune.
An autoimmune disorder is a disorder that affects the immune system while fighting what are believed to be foreign substances, causing it to mistakenly attack the body's own tissues.
According to the British newspaper "The Guardian", this sometimes requires that some children undergo life-saving treatment in the intensive care units, when they have corona.
This appears to be the latest find about the Corona virus, which scientists say they do not know much about, especially after it was found that it has many symptoms that go beyond the respiratory system, and its effects affect parts other than the lungs, as is well known.
And mysterious cases of the new exhibitor appeared last month, when health officials in Britain issued a warning to doctors, as a number of children were hospitalized with symptoms of strange nature.
These symptoms were a mixture of "toxic shock" and other symptoms that usually appear as a result of a defective immune system, known as "Kawasaki".
On Tuesday, a hospital in London announced the death of a 14-year-old, the first known death among children in Britain. Between 75 and 100 children are being treated for the Corona virus.
Symptoms of a new infection that affects children due to an immune system disorder include: fever, rash, red eyes, chapped lips, and abdominal pain.
Doctors suspected that corona plays a role in the disorder that affects children, which provokes an excessive immune response to them.
However, this suspicion was confirmed in Italy, specifically in Bergamo, in the north of the country, the city most affected by Corona, as records there showed that the children's cases of "Kawasaki" had risen to 10 after the epidemic arrived, compared to three before it.
Of the 10 children treated for this disorder between mid-February and mid-April, 8 were found to be infected with the emerging coronavirus.
And even the other two cases, the doctors said that their negative diagnosis was wrong.
Officials at the Elysee Palace said Thursday that officials from the French company "Sanofi" for the pharmaceutical industry will attend a high-level meeting in the presidential palace next week.
The company had stated that the vaccines it manufactures in the United States may go to American patients first have aroused President Emmanuel Macron's anger.
The official said, "These statements have offended all concerned, starting with the president."
He added that he has no knowledge of any direct contact by telephone with Paul Hudson, Chief Executive Officer "Sanofi".
He continued, saying: "Next week, a meeting will be held in the Elysee to try to overcome this and work together." It is not yet clear who will attend the meeting.
In the context of the same, Chief Executive Officer of "Sanofi" Paul Hodson said, today, it is necessary to reach any vaccine for the virus Corona to all regions, hours after the government warned the French giant pharmaceutical to suggest that some countries will receive the priority of the arrival of the vaccine.
Hudson said he regretted his remarks on Wednesday that any vaccine developed by Sanofi in the United States could go to American patients, pointing to the need for a real debate in Europe about how the bloc countries move collectively and faster in the search for a new vaccine and that "Sanofi" were paid The block for months to do so. | 0.879791 | 3.263657 |
Scientists celebrated another success with Japan’s Hayabusa 2 spacecraft late Wednesday (U.S. time), when the robot explorer accomplished a second pinpoint touch-and-go landing on asteroid Ryugu, this time to collect a sample of pristine dust and rock excavated by an explosive impactor earlier this year.
Using rocket thrusters to control its descent, and guided by a laser range finder, Hayabusa 2 glacially approached Ryugu on autopilot Wednesday, slowing to a relative speed of about 4 inches per second (10 centimeters) per second in the final phase of the landing.
Hayabusa 2 maneuvered over a bright navigation aid released on the asteroid’s surface earlier this year to mark the landing site, then went in for the final descent, with the probe’s sampling horn extending from the front of the spacecraft.
Telemetry data and imagery downlinked from Hayabusa 2 show the spacecraft briefly touched down on the asteroid at 9:06 p.m. EDT Wednesday (0106 GMT; 10:06 a.m. Japan Standard Time Thursday), and began climbing away from Ryugu seconds later, pulsing its thrusters to counteract the half-mile-wide (900-meter-wide) asteroid’s feeble gravity.
In a press conference around four hours later, officials hailed the brief landing as a perfect success, following the mission’s first touch-and-go landing on Ryugu in February.
“Hayabusa 2 today executed a second touchdown, and we were able to obtain (information about) the history of the solar system,” said Yuichi Tsuda, Hayabusa 2’s project manager at the Japan Aerospace Exploration Agency.
Ground teams cheered when data streaming back from the spacecraft, currently orbiting the sun in lock-step with Ryugu more than 151 million miles (244 million kilometers) from Earth.
Launched in December 2014, Hayabusa 2 is Japan’s mission to travel to an asteroid and collect samples for return to Earth. Scientists are eager to analyze specimens from Ryugu, a dark asteroid rich in carbon, a critical building block of life.
Researchers will study the samples for clues about the formation of the solar system 4.6 billion years ago, and perhaps the origin of water and life on Earth.
Mission managers last month decided to send Hayabusa 2 on a second sampling run to gather bits of rock and dust from a second location on Ryugu, providing scientists with more varied materials to examine when the mission returns to Earth late next year.
Hayabusa 2’s sampling mechanism works by firing a metal bullet into the asteroid once the probe’s sampler horn contacts the surface. The projectile is designed to force bits of rock and dust through the sampler horn into a collection chamber inside spacecraft.
Takanao Saiki, Hayabusa 2’s project engineer and flight director at JAXA, told reporters in a press briefing Thursday that data downlinked by the spacecraft showed the temperature rose in the projectile’s firing mechanism, suggesting the system functioned as intended during the touch-and-go landing.
Three images taken by a camera on-board Hayabusa 2 showed the sampling horn contacting the asteroid, then violently blasting away debris from the surface. Countless tiny asteroid fragments were visible around the spacecraft in the final snapshot in the three-image sequence released by JAXA.
“The third picture is really amazing,” said Makoto Yoshikawa, Hayabusa 2’s mission manager “It’s really awesome, a large amount of chips of rocks are flying off.”
“This is a wonderful picture, I think,” Tsuda said. “Hayabusa 2 touched the surface of Ryugu, so this is evidence.”
A different view of the landing site taken by Hayabusa 2’s navigation camera shows a cloud of debris left behind moments after the spacecraft took off from the asteroid.
With its second and final sample collection complete, Hayabusa 2 started to climb back to a “home position” roughly 12 miles (20 kilometers) from the asteroid. The spacecraft closed the lid to the sample catcher device containing the asteroid pay dirt, and ground teams will later send commands to seal it inside the re-entry canister that will carry the material through Earth’s atmosphere at the end of the mission.
“There’s nothing I need to complain about, everything moved perfectly,” Tsuda said through a translator. “It was a perfect operation, so … it’s a 1,000 score out of a 100.”
Not only did the specimens gathered Wednesday come from a different location on Ryugu than the first sampling run, scientists say the materials originated from underneath the asteroid’s surface, where they may have escaped radiation and other space weathering effects for billions of years.
The pristine samples were exposed during a daring, unprecedented bombing run by the Hayabusa 2 spacecraft in April. The probe deployed an explosive charge to fire into the asteroid at high speed, carving a fresh crater and ejecting buried materials around the impact site, ripe for retrieval by Hayabusa 2.
“We decided to obtain the samples in this particular area so that we would be able to sample the subsurface materials … and because our operation was perfectly conducted, therefore, we can observe that we obtained some subsurface samples,” said Seiichiro Watanabe, Hayabusa 2’s project scientist from Nagoya University.
“Bringing the subsurface materials (back to Earth) will be something no other country can do in the coming 20 years or so,” Watanabe said.
Hayabusa 2’s sampler carrier has three chambers to separate materials gathered from each landing. Officials decided to press ahead with the second sampling run after assessing the scientific benefits and engineering risks of the maneuver, but with two samples now on-board the spacecraft, mission managers do not plan to attempt a third sampling run.
While Hayabusa 2 explores Ryugu, NASA’s OSIRIS-REx mission is surveying asteroid Bennu before moving in to collect a sample there in 2020 for return to scientists on Earth in 2023.
OSIRIS-REx is designed to bring home at least 60 grams, or 2.1 ounces of samples from Bennu, significantly more than Hayabusa 2. But OSIRIS-REx is only expected to collect a single sample from one location on Bennu’s surface.
NASA and JAXA agreed in 2014 to share their asteroid samples.
Named for a dragon’s palace in a famous Japanese fairy tale, asteroid Ryugu completes one circuit of the sun every 1.3 years. Its path briefly brings it inside Earth’s orbit, making Ryugu a potentially hazardous asteroid.
The orbit made Ryugu an attractive candidate for a sample return mission.
The Hayabusa 2 spacecraft arrived at Ryugu in June 2018, and deployed three mobile scouts to hop around the asteroid’s surface last September and October, achieving another first in space exploration.
Hayabusa 2 will depart Ryugu in November or December, and fire its ion engines to head for Earth, where it will release a re-entry capsule protected by a heat shield to land in Australia in December 2020.
Email the author.
Follow Stephen Clark on Twitter: @StephenClark1. | 0.813566 | 3.188323 |
transmitted a dedicated radio message to the stars at 5pm on 16th
November 1974 from a radio telescope situated in Arecibo in Puerto Rico (left),
although other radio and television transmissions had been drifting into space
for decades; the inadvertent result of normal terrestrial broadcasting. The
message sent was a three-minute signal targeted towards a group of stars 24,000
light years away and was primarily intended to be a demonstration that
terrestrial radio astronomy had reached a level that would allow interstellar
radio communication over vast distances.
The event was also significant, for by sending such a message,
the scientists involved were also signalling that they believed there was (or
is) some intelligent life ‘out there’ to receive and respond to their call. So, what is the possibility of life out there trying to make
contact with a race on this planet (I say race, as it cannot be assumed that it
is humanity that any ‘aliens’ may be wishing to contact.) Frank Drake produced a formula in 1961 that could be used to
calculate an answer:
N = R x Fp x Ne x F1 x Fi x Fc x
Actually, the formula doesn’t give an answer as such, for any
number generated can only be based on the numbers attributed to each part of the
formula. That said, essentially it works like this:
determined that N signifies the number of civilisations in our galaxy
attempting to make contact.
R stands for the average rate of star
formulation and based on observations from the Hubble telescope this is
generally accepted to be around ten stars each year. Fp is the fraction of stars
that could contain planetary systems and whilst this is much debate about this,
a figure of one in ten is not unreasonable. Next Ne signifies the number
of these planets that are Earth-like. Based on our own solar system, this could
be determined as 1.
F1 stands for the fraction of
these Earth-like planets on which life could develop. This is fairly
straightforward, either life develops or it doesn’t therefore F1 is
either 1 or 0. If 0, then the overall formula will always generate a figure of
zero as well. We will accept the view expressed by Professor Jesco Puttkamer,
former Senior Staff Scientist of Advanced Programmes of Space Flight, NASA, who,
when asked "Could you give me a clear mathematical probability of the existence
of life in outer space?" replied "One … one is certainty." (1) We also now not
only believe their might have been life on Mars, but the moons of Jupiter are
also being suggested as probable homes for possible micro-organisms) so F1 will be 1.
Fi is the fraction of these
planets where life has become intelligent. On Earth there are a number of
intelligent species, so applying this to Drake’s formula, a number between 1 and
4 could be used. Conservatively, this will be determined as 1 (representing
humanity on Earth.)
Fc refers to the number of these
species that actually want to communicate with us. We are now purely in the
realms of speculation, but for arguments sake, it will be assumed perhaps 1 in
10 of these species would want to talk generating a figure of 0.1 for Fc.
Finally L represents the
lifetime of a civilisation (in years). The first part of this book demonstrated
how civilisations can rise and fall, but we will use a figure of 5000 years –
from the founding of Egypt to the present day when we are able to transmit
signals to the stars (although hopefully mankind will survive somewhat
Using these figures,
the formula calculates that N, (the number of
advanced civilisations wanting to make contact) is 10 x 0.1 x 1 x 1 x 0.1 x
5000. This suggests that there are 500 civilisations in this galaxy alone (one
galaxy in a universe of 100 billion) who may be trying to contact us.
Having calculated the number of races that might be trying to
contact us, the next question is, how could they space travel to reach us? Albert Einstein
advises us that nothing can travel faster than the speed of light (E=MC2) and
late twentieth century space missions to the nine known planets of the Solar
System have revealed no signs of intelligent life there. Therefore, any one
visiting us must be travelling from outside the Solar System, yet the distances
involved suggest that such travel is not achievable.
Space is so infinite that it is measured in ‘light years’;
that is, the time it would take light to travel any given distance. | 0.909899 | 3.373106 |
August 6, 2013 report
New evidence that cosmic impact caused Younger Dryas extinctions
(Phys.org) —A period of rapid, intense cooling, known as the Younger Dryas, took place about 13,000 years ago. Scientists think this sudden change in climate caused the extinction of many large mammals, such as the mammoth, and was the reason for the disappearance of North America's Clovis people. According to one hypothesis, a cosmic impact caused the climate to cool. Using data from the Greenland ice core, Michail Petaev and his colleagues at Harvard University have found what appears to be evidence of this impact. Their research appears in the Proceedings of the National Academy of Sciences.
Measurements of oxygen isotopes in the Greenland ice core show that around 13,000 years ago an episode of rapid cooling, which lasted only about 1,000 years, occurred. During this time, many megafauna became extinct and evidence of the Clovis people, one of the earliest human societies to inhabit the Americas, disappeared from the archeological record.
According to one hypothesis, a cometary airburst triggered massive wildfires, which caused the climate to cool. Many scientists have rejected this hypothesis, citing lack of sufficient evidence, in favor of others. The most widely accepted one says that during the deglaciation process, fresh water from the proglacial lake Agassiz discharged into the Arctic Ocean, altering ocean currents.
However, Petaev's team says that geomorphological and chronological data do not support this. They claim that evidence for another hypothesis, that the eruption of the Laacher See volcano caused a volcanic winter in the northern hemisphere, is also lacking.
Now, the researchers claim to have uncovered evidence of a cosmic impact at the Younger Dryas boundary. When examining samples from Greenland Ice Sheet Project 2 (GISP2), they found that platinum concentration increased by about 100 times approximately 12,900 years ago.
Platinum/iridium and platinum/aluminum ratios were very high, indicating that the platinum probably did not have a terrestrial source. While most volcanic rocks have high Pt/Ir ratios, their Pt/Al ratios are low. Mantle rocks have low levels of aluminum, but their Pt/Ir ratios are much lower than that measured in the ice core.
On the other hand, Pt/Ir and Pt/Al ratios in magmatic iron meteorites are very high, suggesting that the platinum found in the ice core came from a meteor.
Debris from a cosmic impact would have caused the climate to cool so quickly that species would have been unable to adapt, leading to their extinction. The Clovis people would not have been able to cope with the catastrophic changes to their environment.
The research lends support to recent claims that a sedimentary layer containing iridium grains and glass-like carbon with nanodiamonds, found at many northern hemisphere sites around the Younger Dryas boundary, is evidence of a meteor impact.
Petaev and his colleagues caution that future researchers must locate an impact site in order to confirm this hypothesis.
One explanation of the abrupt cooling episode known as the Younger Dryas (YD) is a cosmic impact or airburst at the YD boundary (YDB) that triggered cooling and resulted in other calamities, including the disappearance of the Clovis culture and the extinction of many large mammal species. We tested the YDB impact hypothesis by analyzing ice samples from the Greenland Ice Sheet Project 2 (GISP2) ice core across the Bølling-Allerød/YD boundary for major and trace elements. We found a large Pt anomaly at the YDB, not accompanied by a prominent Ir anomaly, with the Pt/Ir ratios at the Pt peak exceeding those in known terrestrial and extraterrestrial materials. Whereas the highly fractionated Pt/Ir ratio rules out mantle or chondritic sources of the Pt anomaly, it does not allow positive identification of the source. Circumstantial evidence such as very high, superchondritic Pt/Al ratios associated with the Pt anomaly and its timing, different from other major events recorded on the GISP2 ice core such as well-understood sulfate spikes caused by volcanic activity and the ammonium and nitrate spike due to the biomass destruction, hints for an extraterrestrial source of Pt. Such a source could have been a highly differentiated object like an Ir-poor iron meteorite that is unlikely to result in an airburst or trigger wide wildfires proposed by the YDB impact hypothesis.
© 2013 Phys.org | 0.801334 | 3.652637 |
Newborn stars in the Milky Way
Brazilian researchers have identified two star clusters in a molecular cloud located in remote regions of our galaxy, a distance well beyond the typical one in which stars form. The results of this study, published in Monthly Notices of the Royal Astronomical Society, shed light on some models of star formation and show how the space around the galaxy is much less empty than you might imagine.
Credit: Camargo et al. 2015
Brazilians astronomers have made a remarkable discovery: they have identified two star clusters in the peripheral regions of the Milky Way. The results of this study, published in Monthly Notices of the Royal Astronomical Society, shed light on some models of star formation and show how the space around the galaxy is much less empty than you might imagine.
We know that the Milky Way has a bar structure and its branch spiral arms consist of stars, gas and dust. If it was cut view, it would appear relatively flat and you would see most of the material is distributed in the disk and in the central regions. Stars form in dense agglomerations of gas, in so-called giant molecular clouds (Giant Molecular Clouds, GMC), which are mainly located in the inner regions of the galactic disk. If there are many compressions in a single GMC, then you can have favorable conditions to generate almost all the stars, a process that ultimately leads to the formation of a star cluster.
Credit: D. Camargo/NASA/WISE
Analyzing the data space observatory WISE (Wide-Field Infrared Survey Explorer), the researchers, led by Denilso Camargo, Federal University of Rio Grande do Sul in Porto Alegre, Brazil, and author of the study, not only found GMC distributed thousands of light years above and below the galactic plane, but they have identified one that surprisingly contains two star clusters. It is the first time that astronomers found that there are “newborn” stars in these peripheral regions of the galaxy. Named with the name of the principal author, Camargo and Camargo 438 439, the clusters are in the giant molecular cloud HRK 81.4-77.8. It is believed that this cloud formed 2 million years ago and it extends for about 16,000 light years below the galactic disk, a distance beyond the typical one in which stars form.
Credit: D. Camargo/NASA/WISE
To explain the formation of these two clusters, Denilso proposed two hypotheses. In the first, based on the so-called “chimney model”, violent events of high energy, such as supernova explosions, expel gas and dust out of the galactic disk. The material then falls into a fusion process which ultimately causes the formation of a GMC. The “fireplace model”, however, requires the explosion of hundreds of massive stars, of different generations, so that it creates a “super wind” that pushes the cloud HRK 81.4-77.8 in the position where it is now. In addition, over millions of years, the “bubble” created by the stellar explosions may have further compressed the material forming more stars and thus feeding the expulsion of other material, creating a kind of “galactic fountain” where the gas and dust fall again in the galactic disk. The other idea, however, is based on the fact that the interaction between the Milky Way and satellite galaxies, that of the Magellanic Clouds, may disrupt the gas that falls into the galaxy leading to the formation of a new GMC and then the birth of new stars. | 0.823989 | 3.910638 |
For the first time in human history, scientists have detected gravitational waves from the tremendous collision between two neutron stars. Previous observations of gravitational waves had shown evidence of mergers between black holes — mysterious, unfathomably deep pits of empty space-time millions of light years away.
This time, scientists from the European Southern Observatory explained at a conference on Monday, the gravitational waves had emanated from something huge and concrete that scientists could observe with a telescope.
Speaking at the conference, Radboud University astrophysicist Samaya Nissanke, Ph.D., emphasized the immensity of the bodies involved in the crash. The colliding neutron stars, about 130 million light years away, are about as big as the sun but have a density so high we can barely begin to imagine it.
The density of those stars is “so high that basically you can cram the entirety of humanity into a sugar cube,” she said.
A neutron star is the collapsed core of a high-mass star after it erupts into a supernova. When two objects that colossal slam into each other in an event known as a kilonova, they erupt into a fireball so massive that it shoots out bursts of gamma rays and sends ripples through space time — which are what we now know as gravitational waves, she explained.
These waves, first proposed by Albert Einstein when he published his general theory of relativity, are what the world’s interferometers picked up in mid-August.
First, the United States National Science Foundation’s Laser Interferometer Gravitational-Wave Observatory (LIGO), in collaboration with the Virgo Interferometer in Pisa, Italy, picked up the waves on August 17; then, ten seconds later, NASA’s Fermi Gamma-ray Space Telescope and the European Space Agency’s INTErnational Gamma Ray Astrophysics Laboratory (INTEGRAL), picked up a short gamma-ray burst from the same area of the sky.
Working together, these observatories determined that the signal was coming from a patch of sky over Chile, and telescopes across the globe rapidly swiveled toward it to capture the event. What scientists at Chile’s Paranal Observatory in Chile showed was an extremely bright spot in a galaxy known as NGC 4993. In the weeks following the event, telescopes captured its brilliance slightly fading and becoming slightly redder.
In the conference, Nissanke explained that the signal from the neutron star collision (assigned the code GW170817,) was much stronger and lasted much longer than the gravitational waves created by the merging of black holes. Previous signals lasted only a few seconds, whereas this one lasted 100 seconds — the longest one ever observed.
Not much is known about about kilonovas, but scientists have theorized that heavy elements like gold and platinum are forged in the fires of those crashes. These elements, together with other radioactive waste, are thought to make up the cloud of debris surrounding the kilonova, which mushroomed out of the collision with such speed and force that it grew from the size of a small city to the size of the solar system in a single day, said Daniel Kasen, a theoretical astrophysicist at the University of California, Berkeley, in an interview with NPR. It’s estimated that the collision released 10 times the Earth’s mass in pure gold.
In a series of papers on the monumental discovery that will be published in journals such as Astrophysical Journal Letters, Nature, and Science, the 70 research groups (comprising over 3,000 scientists) involved with the discovery will outline the international efforts to determine that all of the detections were coming from that single monumental collision, radiating 100 million times more energy than the sun.
This story is developing. | 0.858092 | 3.990625 |
Crescent ♉ Taurus
Moon phase on 21 July 2060 Wednesday is Waning Crescent, 23 days old Moon is in Taurus.Share this page: twitter facebook linkedin
Previous main lunar phase is the Last Quarter before 1 day on 20 July 2060 at 13:24.
Moon rises after midnight to early morning and sets in the afternoon. It is visible in the early morning low to the east.
Moon is passing about ∠12° of ♉ Taurus tropical zodiac sector.
Lunar disc appears visually 4.2% wider than solar disc. Moon and Sun apparent angular diameters are ∠1970" and ∠1889".
Next Full Moon is the Sturgeon Moon of August 2060 after 21 days on 12 August 2060 at 00:51.
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 23 days old. Earth's natural satellite is moving from the second to the final part of current synodic month. This is lunation 748 of Meeus index or 1701 from Brown series.
Length of current 748 lunation is 29 days, 9 hours and 52 minutes. It is 2 hours and 15 minutes shorter than next lunation 749 length.
Length of current synodic month is 2 hours and 52 minutes shorter than the mean length of synodic month, but it is still 3 hours and 17 minutes longer, compared to 21st century shortest.
This New Moon true anomaly is ∠54.1°. At beginning of next synodic month true anomaly will be ∠84.5°. 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°).
1 day after point of perigee on 20 July 2060 at 04:58 in ♈ Aries. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 12 days, until it get to the point of next apogee on 3 August 2060 at 08:10 in ♎ Libra.
Moon is 363 927 km (226 134 mi) away from Earth on this date. Moon moves farther next 12 days until apogee, when Earth-Moon distance will reach 404 228 km (251 176 mi).
1 day after its ascending node on 20 July 2060 at 22:57 in ♈ Aries, the Moon is following the northern part of its orbit for the next 13 days, until it will cross the ecliptic from North to South in descending node on 3 August 2060 at 14:41 in ♎ Libra.
1 day after beginning of current draconic month in ♈ Aries, the Moon is moving from the beginning to the first part of it.
9 days after previous South standstill on 12 July 2060 at 09:29 in ♑ Capricorn, when Moon has reached southern declination of ∠-27.639°. Next 3 days the lunar orbit moves northward to face North declination of ∠27.680° in the next northern standstill on 25 July 2060 at 08:10 in ♋ Cancer.
After 6 days on 27 July 2060 at 12:49 in ♌ Leo, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.848363 | 3.113517 |
31 relations: Annie Jump Cannon, Antonia Maury, Apparent magnitude, Arequipa, Astronomical catalog, Astronomy, Carbon star, CD-ROM, Centre de données astronomiques de Strasbourg, Durchmusterung, Edward Charles Pickering, Epoch (astronomy), EZ Canis Majoris, Harvard College Observatory, Henry Draper, NASA, Peru, Photographic magnitude, Right ascension, Slitless spectroscopy, Southern Hemisphere, Spectral line, Spectroscopy, Spectrum, Star catalogue, Stellar classification, Strasbourg, Vega, VizieR, Williamina Fleming, Wolf–Rayet star.
Annie Jump Cannon (December 11, 1863 – April 13, 1941) was an American astronomer whose cataloging work was instrumental in the development of contemporary stellar classification.
Antonia Maury (March 21, 1866 – January 8, 1952) was an American astronomer who published an important early catalog of stellar spectra.
The apparent magnitude of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth.
Arequipa is the capital and largest city of the Arequipa Region and the seat of the Constitutional Court of Peru.
An astronomical catalog or catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery.
Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.
A carbon star is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen; the two elements combine in the upper layers of the star, forming carbon monoxide, which consumes all the oxygen in the atmosphere, leaving carbon atoms free to form other carbon compounds, giving the star a "sooty" atmosphere and a strikingly ruby red appearance.
A CD-ROM is a pre-pressed optical compact disc which contains data.
The Centre de Données astronomiques de Strasbourg (CDS; English translation: Strasbourg Astronomical Data Center) is a data hub which collects and distributes astronomical information.
In astronomy, Durchmusterung or Bonner Durchmusterung (BD), is the comprehensive astrometric star catalogue of the whole sky, compiled by the Bonn Observatory (Germany) from 1859 to 1903.
Prof Edward Charles Pickering FRS(For) HFRSE (July 19, 1846 – February 3, 1919) was an American astronomer and physicist and the older brother to William Henry Pickering.
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.
EZ Canis Majoris (also designated as EZ CMa or WR 6) is a Wolf-Rayet star in the constellation of Canis Major.
The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy.
Henry Draper (March 7, 1837 – November 20, 1882) was an American doctor and amateur astronomer.
The National Aeronautics and Space Administration (NASA) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program, as well as aeronautics and aerospace research.
Peru (Perú; Piruw Republika; Piruw Suyu), officially the Republic of Peru, is a country in western South America.
Before the advent of photometers which accurately measure the brightness of astronomical objects, the apparent magnitude of an object was obtained by taking a picture of it with a camera.
Right ascension (abbreviated RA; symbol) is the angular distance measured only eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point above the earth in question.
Slitless spectroscopy is astronomical spectroscopy done without a small slit to allow only light from a small region to be diffracted.
The Southern Hemisphere is the half of Earth that is south of the Equator.
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies.
Spectroscopy is the study of the interaction between matter and electromagnetic radiation.
A spectrum (plural spectra or spectrums) is a condition that is not limited to a specific set of values but can vary, without steps, across a continuum.
A star catalogue (Commonwealth English) or star catalog (American English), is an astronomical catalogue that lists stars.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.
Strasbourg (Alsatian: Strossburi; Straßburg) is the capital and largest city of the Grand Est region of France and is the official seat of the European Parliament.
Vega, also designated Alpha Lyrae (α Lyrae, abbreviated Alpha Lyr or α Lyr), is the brightest star in the constellation of Lyra, the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus.
The VizieR Catalogue Service is an astronomical catalog service provided by Centre de données astronomiques de Strasbourg.
Williamina Paton Stevens Fleming (May 15, 1857 – May 21, 1911) was a Scottish-American astronomer.
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of highly ionised helium and nitrogen or carbon. | 0.848688 | 3.693885 |
Unlike most of the planets, which follow almost exactly circular orbits around the Sun only varying in their distance from the Sun by a few percent, Mercury has a significantly elliptical orbit.
Its distance from the Sun varies between 0.307 AU at perihelion (closest approach to the Sun), and 0.467 AU at aphelion (furthest recess from the Sun). This variation, of over 50%, means that its surface receives over twice as much energy from the Sun at perihelion as compared to aphelion.
However, this makes little difference to Mercury's telescopic appearance, since little if any detail on its surface can be resolved by ground-based telescopes. Although its changing seasons have an incredible effect upon its surface temperatures, there is little change that is visible to amateur observers.
The exact position of Mercury at the moment it passes aphelion will be:
|Object||Right Ascension||Declination||Constellation||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 02 August 2017|
10 days 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.
|02 Aug 2017||– Mercury at aphelion|
|26 Aug 2017||– Mercury at inferior solar conjunction|
|12 Sep 2017||– Mercury at greatest elongation west|
|12 Sep 2017||– Mercury at dichotomy| | 0.899488 | 3.661302 |
How hard would it be for humans to colonize an exoplanet with a size
significantly different than that of earth (but otherwise suitable for
Let's deal with low-gravity exoplanets first:
Much of the data has been obtained by experiments on people in micro-gravity and zero gravity - so much has to be extrapolated from these data sets.
Short Term Issues:
"...crew members face an increased risk of developing kidney stones, due to
decreased urine output, urine acidity, and increased calcium excretion
of bone loss).
Results from this investigation suggest that supplementation with
citrate may decrease the risk of renal stone formation..."
So that's perhaps simple to resolve.
Long Term Issues:
Disuse Osteoporosis and Muscle Mass Decrease.
This has been well documented in zero and microgravity studies
Obvious things like Nervous system protection by the skull and spine would make it necessary to maintain a certain degree of bone density.
Whilst Muscle mass and bone density decrease after extended periods in low-gravity could be considered an adaptive function - and may only become an issue if people are going to move between different gravity environments - there are other associated considerations.
Essential Nutrient depletion.
"Between meals, the body maintains a constant concentration of calcium
by absorbing it from bone and releasing it into the bloodstream. This
constant calcium level in the bloodstream allows proper neural,
muscular, and endocrine (hormone) functioning, as well as other
cellular activities (e.g., blood clotting).
Bone is also a good source of phosphate, hydrogen, potassium, and
magnesium. Like calcium, these minerals are used by many systems of
the body for a wide range of purposes.
Less buffer is available during the day if less mineral is present in
total, probably making mineral supplements essential.Researchers are
currently pursuing multiple lines of research, including hormone
level, diet, and exercise."
"For example, nine of the 27 astronauts (33 percent) exhibited
expansion of the cerebrospinal fluid space surrounding the optic
nerve, and six (22 percent) showed flattening of the back of the
eyeball, researchers said.
Micro-gravity-induced intracranial hypertension represents a
hypothetical risk factor and a potential limitation to long-duration
A series of experiments at NASA is designed to test this:
" It is hypothesized that the head-ward fluid shift that occurs ...
leads to increased pressure in the brain, which may push on the back
of the eye, causing it to change shape.
10.22.18 Results of experiments: Science Results for Everyone Information Pending"
Stiff Arteries, Hypertension, Cardiovascular Disease:
"As humans get older on Earth, arteries stiffen and this causes an
increase in blood pressure (hypertension) and elevates the risk for
cardiovascular disease. Recently, it has been observed that some crew
members returning from the International Space Station (ISS) have much
stiffer arteries than when they went into space. The results could
provide insight into potential countermeasures to help maintain crew
member health, and quality of life for everyone.
10.25.18 Science Results for Everyone Information Pending "
Inflammatory and Oxidative stress.
"The objective of Defining the Relationship Between Biomarkers of
Oxidative and Inflammatory Stress and the Risk for Atherosclerosis in
Astronauts During and After Long-duration Spaceflight (Cardio Ox) is
to determine whether biological markers of oxidative and inflammatory
stress are elevated during and after space flight and whether this
results in an increased, Ultrasound scans of the carotid and brachial
arteries will be obtained at the same time points, as well as through
5 years after landing, as an indicator of cardiovascular health.
10.04.18 Science Results for Everyone Information Pending "
Treatments for many of the above which fall within current medical science's capability.:
Malcolm Cohen, chief of the Human Information Processing Research Branch at NASA Ames:
Cohen has been spinning research subjects in something far more impressive than a carnival ride. He's been studying engineers, mountain climbers, teachers and other paid volunteers as they live for up to 22 hours in a giant, 58-foot diameter centrifuge.
"...hypergravity could be used to train athletes, providing an
environment in which exercises could be conducted with more benefit in
shorter time. People who suffer from muscle atrophy might be exposed
to it, to stress their muscles more effectively."
"...cardiovascular deconditioning, loss of muscle mass, loss of bone
density, and a host of other problems. Artificial gravity could
prevent all that -- and centrifuges are one plausible way to generate
"There are so many options for how best to implement hypergravity most
effectively," says Cohen. "Low intensity for long durations, high
intensity for short durations, short radius centrifuges ... We know a
lot, he says, but there's much more to learn."
Mineral supliments, and vitamin D.
"...some meta-analyses have found a benefit of vitamin D supplements
combined with calcium ..."
"Bisphosphonates are useful in decreasing the risk of future fractures
in those who have already sustained a fracture due to osteoporosis.
Risedronate, Etidronate, Alendronate. Teriparatide (a recombinant
parathyroid hormone) has been shown to be effective..."
There are Unknown Unknowns, that we will no doubt have to come to terms with in due time.
It is as yet unclear how effective each treatment would prove and presumably the daily regimen would depend on the specific planetary conditions and would need to be adapted for each individual person's unique physiology.
Any adaptations that the geneticists decided on could be applied on an ongoing basis, with medical science keeping up with any shortfalls.
High Gravity Exoplanets.
The Effect of increasing G:
A hard slap on the face may impose hundreds of g-s locally but may
not produce any obvious damage; a constant 15 g-s for a minute .. may
They're exposed to hypergravity, too: up to 3.2-g at launch Cohen
points out, "fluid weighs more." The heart has to change the way it
operates, pumping faster, and working harder to push the blood all the
way to the brain. This could cause (..people..) to become dizzy or
even, in extreme cases, to pass out.
The relative effect of increased gravity when standing is to increase the blood pressure in the feet and decrease it in the head.
Then when you bend over lowering the position of your head relative to the heart, the blood pressure in your head will shoot up.
Humans can cope with such changes at Earth Gravity, but as Gravity increases, the magnitude of the pressure change also increases.
We might need to make some changes to our Cardio-Vascular system, but how can we decide what?
Think of Giraffes:
Special support structures in the arteries withstand 300/180
millimeters of mercury, preventing them from bursting.As it drops its
head down to drink, specialized valves in the neck counter the
potentially explosive effects of gravity, blocking blood flowing back
into the skull. Meanwhile, a built-in pressure suit in its
extraordinarily long legs prevents fluid and blood from pooling in its
Understanding of these remarkable features is still relatively
limited. But the giraffe's physiology is a growing area of research
for evolutionary biologists and comparative physiologists looking to
understand its unique characteristics and apply that knowledge to
solving issues in human health.
What about their blood vessels:
Interestingly, the "unnaturally" high blood pressure in giraffes does
not culminate in severe vascular lesions, nor does it lead to heart
and kidney failure, whereas in humans, the same blood pressure is
exceedingly dangerous and will cause severe vascular damage.
The 2 feet long heart weighs around 12 kg and is incredibly powerful
to pump the blood all the way up its long neck and legs. Moreover,
the heart has evolved to have a small radius and thick muscle walls,
giving it high power. Also, a series of valves located in the blood
vessels that lead up the neck prevent the blood from flowing back to
the heart in between beats. The walls of the vessels also thicken
as the neck grows longer with age, to avoid rupturing under
But their legs:
The muscle and skin around the legs fit tightly, increasing the
pressure of the blood in the lower body, stopping it draining down.
The layer of tight skin on its legs not only maintains pressure but
also prevents the vessels from bursting. Furthermore, if the giraffe
were to get cuts, this thick skin and inner fascia would prevent
blood pooling and excessive bleeding.
What stops them having a Brain Haemorage when they bend down to drink:
Luckily for the giraffe, nature has provided them with a complex
pressure-regulation system that controls blood flow. In their brain,
there are blood vessels that connect to the convoluted valves or blood
sponge in the large neck veins. They are meant specifically to reduce
the blood pressure before it enters the brain. Their function is to
stop the blood from flowing backward when it dips its head. It is
called the Rete mirabile. This amazing organ collects the blood at
the skull base and regulates the blood quantity released into the
brain. It prevents the head from swelling when it bends over. And it
works in reverse as well. When the giraffe quickly lifts its head, the
organ stops blood from draining out the brain quickly, saving the
animal from fainting.
So, if we adjust our vascular systems to more closely match that of a Giraffe, we could ease our way.
As many will have heard from the news, these can help build muscle or bone marrow capacity, or of course building bone density, there are many side effects to be very wary of: infertility, hypogonadism, erectile dysfunction, amenorrhea, rhabdomyolysis - and too many others to list both physical and psychological. Possibly best used sparingly with the best medical evidence in mind only.
Some Usefull Tech:
These could help decrease wear and tear on joints and help support the intra- vertebral disks, stop colonists shrinking and ageing before their time.
"Powered exoskeleton (also known as power armor, powered armor,
powered suit, exoframe, hardsuit or exosuit) is a wearable mobile
machine that is powered by a system of electric motors, pneumatics,
levers, hydraulics, or a combination of technologies that allow for
limb movement with increased strength and endurance..."
High g is not comfortable, even with a g-suit.
In older fighter aircraft, 6 g was considered a high level, but with
modern fighters 9 g or more can be sustained structurally.
Pilots in Red Bull Air Race World Championship have worn a g-suit
called g-Race Suit since the 2009 season. The g-race suit is a liquid
(water) filled, autonomous and aircraft independent working full-body
g-protection system. It is tailor-made for each pilot and can be fine
adjusted via lacings.
The g-race suit contains four so-called "fluid muscles" which are
sealed, liquid-filled tubes. Each fluid muscle extends from the
shoulder to the ankle. Two fluid muscles – each filled with
approximately 1 litre of fluid for a total of around 4 litres (1.1 US
gal) per g-race suit – are routed vertically on the front side of the
g-race suit and two are routed vertically on the rear side of the
g-race suit. The suit weighs on average 6.5 kilograms (14 lb) in
total, and its fabric is made out of a special mix of Twaron and
Nomex. The counter pressure effect occurs instantaneously without any
time delay versus an up to two second delay before reaching full
system protection in standard pneumatic, inflatable g-suits. The race
pilot utilizes the g-race suit interactively by muscle straining and
breathing techniques to achieve an improved cardiac output and thus
(SE Ref above)
The story of John Paul Stappe who in a fluid bath survived a 46.2 g acceleration.
Though there is little experimental data except: he broke several bones in the process and it was for just a short period. It may provide comfort and relief in a moderate to high g environment.
Telepresence or Remote Handling:
The Apparatus for Remote Control of Humanoid Robots (ARCHR) is an
intuitive teleoperation system for high degree of freedom robots with
Think The big yellow thing Sigourney Weaver drove in Aliens, but remote controlled from the comfort of your warm salt-water bath.
There are things we can do to adapt ourselves which are within our capacity now, but insufficient experimental evidence is yet available to be precise about what would be needed under what circumstances - it'd perhaps be wise to park in orbit with the colonists in hypersleep and have a scientific and technical team gather more data, whilst slowly deciding what adaptations to make. | 0.858763 | 3.325193 |
Someone recently sent me a link to a really terrific crank. This guy really takes the cake. Seriously, no joke, this guy is the most grandiose crank that I’ve ever seen, and I doubt that it’s possible to top him. He claims, among other things, to have:
- Demonstrated that every mathematician since (and including) Euclid was wrong;
- Corrected the problems with relativity;
- Turned relativity into a unification theory by proving that magnetism is part of the relativistic gravitational field;
- Shown that all of gravitational/orbital dynamics is completely, utterly wrong; and, last but not least:
- proved that the one true correct value of is exactly 4.
I’m going to focus on the last one – because it’s the simplest illustration of both his own comical insanity, of of the fundamental error underlying all of his rubbish.
Let’s start at the beginning, with his introduction:
Historically, pi is the numerical relationship between the diameter and circumference of a circle. It is a geometric constant. What do we mean by geometric? Operationally, geometry is the study of drawn figures. The ancients actually drew their figures on paper (and some of us still do). All the concepts of geometry applied to these figures. A line was a drawn line. A circle was a drawn circle. Of course geometry soon invented some other postulates to help with the mathematics. A point was defined as having no extension, a line was defined as having no width, and so on. But the equations were still understood to apply to the figures. Geometry was always only partially abstract.
In this context, pi was assumed to be a dimensionless constant. It transformed one length to another. This is clear from the basic equation: .
You can see that pi takes us from one length to another and therefore we must assume it is dimensionless.
What I will show in this paper is that this assumption is false. I will show that pi is not dimensionless. It is not dimensionless for the basic reason that the circumference is not a length. Nor is it a distance.
Quite a lot of crankery, right there. Some of it actually makes a bit more sense that it appears at first glance. I’m not saying that it actually make sense, but that given his rather peculiar definitions (which he discusses elsewhere), it’s not quite a bogglingly nonsensical as it appears.
One of his fundamental ideas is that Euclid got the concept of a point wrong. According to Mathis, there are two kinds of points: drawn points, and mathematical points. And you can only meaningfully apply numbers to drawn points; any attempt to assign a number to a mathematical point is completely erroneous. As an implication of this, all numbers must, inevitably, have units. There is, in Mathis’s world, no such thing as a dimensionless number: a dimensionless number is an abstract point, which can’t have a number assigned to it.
Back to his words, as he tries to explain some of this in the context of geometry:
Geometry dismisses time as a consideration. Geometry is understood to be taking place at a sort of imaginary instant. For instance, when we are given or shown a radius, we do not consider that it took some time to draw that radius. We do not ask if the radius was drawn at a constant velocity or if the pencil was accelerating when it was drawn. We don’t ask because we really don’t care. It doesn’t seem pertinent. It seems quite intuitive to just postulate a radius, draw it, and then begin asking questions after that.
It turns out that this nonchalance is a mistake. It is a mistake because by ignoring time we have ignored many important subtleties of the problem of circular motion and of circle geometry.
It’s hard to overstate just how completely and utterly wrong this is.
The fundamental goal of mathematics is abstraction: that is, it’s about taking something that you want to study, and focusing narrowly on that, discarding anything that isn’t essential to understand it. Euclidean geometry is concerned with shapes; it doesn’t matter how they were drawn, or whether they were drawn at all.
But Mathis is absolutely obsessed with idea that drawing something is absolutely critically important. A drawn point is meaningful; an abstract mathematical point is not. A drawn line is different from an abstract mathematical line. And, obviously, a drawn circle is fundamentally different from an abstract circle. Per his reasoning, an abstract circle isn’t particularly meaningful. You can’t (according to him) do something like compute the ratio of the circumference to the diameter in an abstract circle – because that would be applying numbers to something formed of abstract points.
Let’s see a bit more of where he goes with this:
As a simple example of this, when we draw a circle on a Cartesian graph, e make an entirely different set of assumptions than the ones above, although few have seemed to notice this. You would think you could draw a Cartesian graph anywhere you wanted and it wouldn’t make any theoretical difference to the geometry. You could draw a graph on the wall, on the floor, on any flat surface. You would think all you are doing is making things a bit easier on yourself as an artist and a geometer. Just as the old artists would square off their paper in order to make drawing a head easier, a geometer squares off a section of the world in order to create a tidy little sub-world where things can be put in order.
But all this is completely false. Drawing the graph changes everything. If you draw a circle without a graph, then you can say to yourself that the line (that is now the circumference of the circle) is a length. As a length, it can have only one dimension. A length is a one-dimensional variable, right? Perhaps you can see where I am going with this, and you say, “Wait, a circle curves, so we must have two dimensions, at least. We must have an x and a y dimension.” Yes, at the least we must have that. You saw this because you began to think in terms of the Cartesian graph and you could see in your head that the curve implied both x and y dimensions. Very good. But you are not halfway there yet. Take the circle and actually put it into a Cartesian graph. What you find is that the curve is now an acceleration. In fact, any curve is an acceleration in a two-dimensional graph. We all learned this in high school, although I don’t think it sunk far in for most of us.
That line that represents a circumference is taking on dimensions very fast now. At first we thought it was just a length. Then we saw that it required two dimensions. Now we can see that it is an acceleration. What next?
We’ve gotten to the depths of his kookiness here. In his world, a curve drawn on a graph isn’t something that can represent an acceleration: a curve is an acceleration. In his reasoning (in so far as I can follow it), this is because a drawn curve must have units (it’s drawn, so it’s real and has units!); and since the units that he chooses to apply to it look like an acceleration, then the curve is an acceleration. Alternatively, if you’re drawing a curve, in order for the drawn curve to be a curve and not a line, your hand must be accelerated. The curve is that acceleration.
Once again, it’s pretty hard to know just where to begin with how wrong this is. A curve can be a representation of a physical phenomena; it can describe a value with units. But a curve, in math, is not the physical phemonenon that it could represent. The process of drawing and the thing drawn are, to Mathis, the same thing. In Mathis’s world, a circle drawn with a compass, and a circle drawn by tracing another circle are fundamentally different, regardless of the fact that they’re indistinguishable.
This pretty much defeats the entire purpose of mathematics. One more quote of his, just because it’s so perfect:
Now let us return to the geometric circle. All the equations of geometry are created by assuming that time is not a factor. You can’t really just ignore time, so what the geometry does is assume that all underlying time intervals are equal. What does that mean, specifically? Well, it must mean that all the lines are understood to have been drawn with the same velocity. We can ignore the velocity since we define it as equivalent. What does that mean?
It means that the radius is a velocity itself.
Mathis is remarkably long-winded; the stuff I’ve shown you so far gives you the gist. He just keeps on with the same basic nonsense, building it up more and more. The circumference of a circle, according to Mathis, isn’t a distance. Because, you see, a distance is one-dimensional – but the circumference of a circle curves, so that it’s two-dimensional (Note that that’s his wording, not mine; in another typical example of his confusion, he doesn’t distinguish between the edge of the circle, and the circumference. To him, the curve, the distance, and the process of drawing it are all the same thing.)
All of his stuff really, ultimately, comes down to one basic problem: he is absolutely unable to distinguish between the act of drawing something, and the nature of the thing that he drew.
So, for example, he goes on at great length about how calculus is all wrong. The reasoning comes down to the fact that he doesn’t believe in mathematical points, because you can’t draw them. But calculus is based ultimately, on the concept of infinitely small points. You the derivative of a curve by finding the slope of that curve at a point. But if you draw a point, it’s not infinitely small. It’s got a finite size; to be able to draw it, it’s got to have a finite size. Therefore, there’s no such thing as a point, and if there are no points, there’s no calculus. (He does go on about reformulating calculus so that it doesn’t require points.)
So where does the stuff come from?
You need to go through a whole lot of craziness to actually get to it, but it’s more of the same. The root concept is that there is no distinction between a circle, and the process of drawing a circle. The radius of a circle isn’t a length, it’s a velocity. (Or
a distance. Sometimes it’s one, sometimes the other. But we won’t worry about that; consistently is the hobgoblin of a small mind!)
So what’s ?
Well… that’s a bit tricky, because he redefines terms like bloody crazy.
But, basically… is a velocity. By which he means an acceleration. Sort-of. Kind of. Maybe. Ish.
He’s rewritten the equations of orbital dynamics as . That makes no real sense, but it doesn’t matter. Just take it as given for the moment.
Now… you can rewrite that equation as . And the circumference of a circle is . So, obviously, , and is an acceleration. Or.. a velocity. Or… something.
See, it can’t be a straightforward acceleration… because, in his universe, an acceleration is a force with a direction. That’s fine. But… there’s no such thing as a point. And in an orbit, because it’s going in a circle, the direction of the centripetal force changes from instant to instant. But there’s no such thing as an instant, because an instant is a point in time. So there’s no such thing as an orbital acceleration, because the acceleration changes from instant to instant. So, therefore, it’s not an acceleration, but rather a velocity. (No, it doesn’t make sense. Don’t worry.)
But… By his reasoning above, we’ve shown that the circumference of a circle is measured in units of velocity squared. So you can’t talk about as the unitless ratio of the circumference to the diameter – because the circumference is measured in units like , and is measured in.. well, I’m not really sure, because he’s so inconsistent about whether it’s a velocity, or an acceleration, or something else…
But if you continue with his reasoning… Well, let’s not really continue with his reasoning – he takes his time, and frankly, this is giving me a headache. The gist of it is: is an acceleration. And if you think of an object going clockwise around a circle: at the top of the circle, it’s got velocity going towards the right. 90 degrees later, it’s got velocity 0 to the right, but down. And 90 degrees after that, it’s got velocity v to the left, but 0 down. and so on. So, around the circle, it’s been accelerated 8 times the initial . And since , that means that , so .
I’ll close with his summary of what he’s “discovered” in this mess.
We have discovered several important things.
- Pi is a centripetal acceleration and has the dimensions of acceleration.
- The circumference of any circle has the dimensions , if written out in full.
- If the radius is treated as a distance, then the circumference has the dimensions .
- Pi is not applicable to orbits or most other physical circles, since the tangential velocity is not equal to the radial velocity. There is no pi in the sky.
- In orbits and all other circular motion . Something may equal , but it isn’t a velocity.
- There is no such thing as orbital velocity. There is only tangential velocity. The curve described by an orbit is not a distance, nor is it a velocity. It has the dimensions , just like the circumference.
Insanity. Sheer, utter, insanity. This is the kind of rubbish that makes me want to poke my own eyes out, just so I don’t need to look at any more of it. | 0.841767 | 3.22459 |
eso1335 — Photo Release
The Odd Couple
Two very different gas clouds in the galaxy next door
7 August 2013
ESO’s Very Large Telescope has captured an intriguing star-forming region in the Large Magellanic Cloud — one of the Milky Way’s satellite galaxies. This sharp image reveals two distinctive glowing clouds of gas: red-hued NGC 2014, and its blue neighbour NGC 2020. While they are very different, they were both sculpted by powerful stellar winds from extremely hot newborn stars that also radiate into the gas, causing it to glow brightly.
This image was taken by the Very Large Telescope (VLT) at ESO's Paranal Observatory in Chile — the best place in the southern hemisphere for astronomical observing. But even without the help of telescopes like the VLT, a glance towards the southern constellation of Dorado (The Swordfish or Dolphinfish ) on a clear, dark night reveals a blurry patch which, at first sight, appears to be just like a cloud in the Earth's atmosphere.
At least, this may have been explorer Ferdinand Magellan's first impression during his famous voyage to the southern hemisphere in 1519. Although Magellan himself was killed in the Philippines before his return, his surviving crew announced the presence of this cloud and its smaller sibling when they returned to Europe, and these two small galaxies were later named in Magellan's honour. However, they were undoubtedly seen by both earlier European explorers and observers in the southern hemisphere, although they were never reported.
The Large Magellanic Cloud (LMC) is actively producing new stars. Some of its star-forming regions can even be seen with the naked eye, for example, the famous Tarantula Nebula. However, there are other smaller — but no less intriguing — regions that telescopes can reveal in intricate detail. This new VLT image explores an oddly mismatched pair: NGC 2014 and NGC 2020.
The pink-tinged cloud on the right, NGC 2014, is a glowing cloud of mostly hydrogen gas. It contains a cluster of hot young stars. The energetic radiation from these new stars strips electrons from the atoms within the surrounding hydrogen gas, ionising it and producing a characteristic red glow.
In addition to this strong radiation, massive young stars also produce powerful stellar winds that eventually cause the gas around them to disperse and stream away. To the left of the main cluster, a single brilliant and very hot star seems to have started this process, creating a cavity that appears encircled by a bubble-like structure called NGC 2020. The distinctive blueish colour of this rather mysterious object is again created by radiation from the hot star — this time by ionising oxygen instead of hydrogen.
The strikingly different colours of NGC 2014 and NGC 2020 are the result of both the different chemical makeup of the surrounding gas and the temperatures of the stars that are causing the clouds to glow. The distances between the stars and the respective gas clouds also play a role.
The LMC is only about 163 000 light-years from our galaxy, the Milky Way, and so is very close on a cosmic scale. This proximity makes it a very important target for astronomers, as it can be studied in far more detail than more distant systems. It was one of the motivations for building telescopes in the southern hemisphere, which led to the establishment of ESO over 50 years ago. Although enormous on a human scale, the LMC contains less than one tenth of the mass of the Milky Way, and spans just 14 000 light-years — by contrast, the Milky Way covers some 100 000 light-years. Astronomers refer to the LMC as an irregular dwarf galaxy; its irregularity, combined with its prominent central bar of stars, suggests that interactions with the Milky Way and another nearby galaxy, the Small Magellanic Cloud, could have caused its chaotic shape.
This image was acquired using the visual and near-ultraviolet FOcal Reducer and low dispersion Spectrograph (FORS2) instrument attached to ESO's VLT, as part of the ESO Cosmic Gems programme .
Although this constellation is often identified with the swordfish there are reasons to think that the less commonly known dolphinfish may be a better match. More details are given here.
This star is an example of a rare class called Wolf-Rayet stars. These short-lived objects are very hot — their surfaces can be more than ten times as hot as the surface of the Sun — and very bright and dominate the regions around them.
This picture comes from the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.
ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.
ESO, Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591 | 0.898014 | 3.80334 |
Welcome back to Constellation Friday! Today, in honor of the late and great Tammy Plotner, we will be dealing with the “keel of the ship”, the Carina constellation!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.
One of these constellations, known as Argo Navis, would eventually be divided into three asterism – one of which became the southern constellations of Carina. Bordered by the Vela, Puppis, Pictor, Volans, Chamaeleon, Musca and Centaurus constellations, Carina is one of 88 modern constellations that are currently recognized by the IAU.
Name and Meaning:
The stellar southern constellation Carina is part of the ancient constellation known as Argo Navis. It is now abbreviated and represents the “Keel”. While Carina has no real mythological connection, since its stars weren’t visible to the ancient Greeks and Romans, it does have a fascinating history. Argo Navis (or simply Argo) was a large southern constellation representing the Argo, the ship used by Jason and the Argonauts in Greek mythology.
The Argo was built by the shipwright Argus, and its crew were specially protected by the goddess Hera. The best source for the myth is the Argonautica by Apollonius Rhodius. According to a variety of sources of the legend, the Argo was said to have been planned or constructed with the help of Athena.
According to other legends it contained in its prow a magical piece of timber from the sacred forest of Dodona, which could speak and render prophecies. After the successful journey, the Argo was consecrated to Poseidon in the Isthmus of Corinth. It was then translated into the sky and turned into the constellation of Argo Navis. The abbreviation for it was “Arg”, and the genitive was “Argus Navis”.
History of Observation:
Carina is the only one of Ptolemy’s list of 48 constellations that is no longer officially recognized as a constellation. In 1752, French astronomer Nicolas Louis de Lacaille subdivided Argo Navis into Carina (the keel of the ship), Puppis (the Poop deck), and Vela (the sails). Were this still considered to be a single constellation, it would be the largest of all, being larger than Hydra.
When Argo Navis was split, its Bayer designations were also split. Whereas Carina got the Alpha, Beta and Epsilon stars, Vela got Gamma and Delta, Puppis got Zeta, and so on. The constellation Pyxis occupies an area which in antiquity was considered part of Argo’s mast. However, Pyxis is not typically considered part of Argo Navis, and in particular its Bayer designations are separate from those of Carina, Puppis and Vela.
The Carina constellation consists of 9 primary stars and has 52 Bayer/Flamsteed designated stars. It’s alpha star, Canopus, is not only he brightest star in the constellation, but the second brightest in the night sky (behind Sirius). This F-type giant is 13,600 times brighter than our Sun, with an apparent visual magnitude of -0.72 and an absolute magnitude of -5.53.
The name is the Latinized version of the Greek name Kanobos, presumably derived from the pilot of the shop that took Menelaus of Sparta to Troy to retrieve Helen in The Iliad. It is also known by its Arabic name, Suhail, which is derived from the Arabic name for several bright stars.
Before the launching of the Hipparcos satellite telescope, distance estimates for the star varied widely, from 96 light years to 1200 light years. Had the latter distance been correct, Canopus would have been one of the most powerful stars in our galaxy. Hipparcos established Canopus as lying 310 light years (96 parsecs) from our solar system; this is based on a parallax measurement of 10.43 ± 0.53 mas.
The difficulty in measuring Canopus’ distance stemmed from its unusual nature. Canopus is too far away for Earth-based parallax observations to be made, so the star’s distance was not known with certainty until the early 1990s. Canopus is 15,000 times more luminous than the Sun and the most intrinsically bright star within approximately 700 light years.
For most stars in the local stellar neighborhood, Canopus would appear to be one of the brightest stars in the sky. Canopus is outshone by Sirius in our sky only because Sirius is far closer to the Earth (8 light years). Its surface temperature has been estimated at 7350 ± 30 K and its stellar diameter has been measured at 0.6 astronomical units 65 times that of the sun.
If it were placed at the centre of the solar system, it would extend three-quarters of the way to Mercury. An Earth-like planet would have to lie three times the distance of Pluto! Canopus is part of the Scorpius-Centaurus Association, a group of stars which share similar origins.
Next up is Miaplacidus (beta Carinae), an A-type subgiant located approximately 111 light years from Earth. It is the second brightest star in the constellation and the 29th brightest star in the sky. The star’s name means “placid waters”, which is derived from the combination of the Arabic word for waters (miyah) and the Latin word for placid (placidus).
Then there’s Eta Carinae, a luminous blue variable (LBV) binary star that is between 7,500 and 8,000 light years distant from Earth. The combined luminosity of this system is four million times that of our Sun, and the most massive star in the system has between 120 and 250 Solar Masses. It is sometimes known by its traditional names, Tseen She (“heaven’s altar” in Chinese) and Foramen.
Also, it is believed that Eta Carinae will explode in the not-too-distant future, and it will be the most spectacular supernovae humans have ever seen. This supernova (or hypernova) might even affect Earth, since the star is only 7,500 light years away, causing disruption to the upper layers of the atmosphere, the ozone layer, satellites, and spacecraft could be damaged and any astronauts who happen to be in space could be injured.
Avior (epsilon Carinae) is another double star system, consisting of a K0 III class orange giant and a hot hydrogen-fusing B2 V blue dwarf. With an apparent magnitude of 1.86 and is 630 light years distant, it is the 84th brightest star in the sky. The name Avior was assigned in the late 1930s by Her Majesty’s Nautical Almanac Office as a navigational aid, at the request of the Royal Air Force.
Aspidiske (aka. Iota Carinae) is a rare spectral type A8 Ib white supergiant located 690 light years from Earth. With a luminosity of 4,900 Suns (and seven Solar Masses), it is the 68th brightest star in the sky and is estimated to be around 40 million years old. It is known by the names Aspidiske, Turais and Scutulum, all diminutives of the word “shield,” (in Greek, Arabic and Latin, respectively).
Since the Milky Way runs through Carina, there are a large number of Deep Sky Objects associated with it. For instance, there’s the Carina Nebula (aka. the Eta Carinae Nebula, NGC 3372), a large nebula surrounding the massive stars Eta Carinae and HD 93129A. In addition to being four time as bright as the Orion Nebula (Messier 42), it is one of the largest diffuse nebulae known.
The nebula is between 6,500 and 10,000 light years from Earth, and has an apparent visual magnitude of 1.0. It contains several O-type stars (extremely luminous hot, bluish stars, which are very rare). The first recorded observation of this nebula was made by the French astronomer Nicolas Louis de Lacaille in 1751-52, who observed it from the Cape of Good Hope.
The Carina Nebula contains two smaller nebulae – the Homunculus Nebula and the Keyhole Nebula. The Keyhole Nebula – a small, dark cloud of dust and with bright filaments of fluorescent gas, was named by John Herschel in the 19th century. It is about seven light years in diameter, and appears contrasted against the bright nebula in the background.
The Homunculus Nebula (Latin for “Little Man”) is an emission nebula embedded within the Eta Carinae Nebula, immediately surrounding the star Eta Carinae. The nebula is believed to have formed after an enormous outburst from the star, which coincided with Eta Carinae becoming the second brightest star in the night sky. The light of this outburst was visible from Earth by 1841.
There’s also the Theta Carinae Cluster (aka. the Southern Pleiades, because of its resemblance to the Pleiades cluster. This open cluster was discovered by Lacaille in 1751, is located approximately 479 light years from Earth and is visible to the naked eye. The brightest star in the cluster, as the name indicates, is Theta Carinae, a blue-white dwarf.
Then there’s the Wishing Well Cluster (aka. NGC 3532), an open cluster in Carina. Approximately 1,321 light years distant, the cluster is composed of about 150 stars that appear through a telescope like silver coins twinkling at the bottom of a wishing well. The cluster lies between the constellation Crux (the Southern Cross) and the False Cross asterism in Carina and Vela, and was first object observed by the Hubble Space Telescope in May 1990.
Carina is the 34th largest constellation in the sky, occupying an area of 494 square degrees. It lies in the second quadrant of the southern hemisphere (SQ2) and is visible at latitudes between +20° and -90° and is best seen during the month of March. Before you even begin with a telescope or binoculars, be sure to stop and just take a good look at Alpha Carinae – Canopus.
Canopus is essentially white when seen with the naked eye (though F-type stars are sometimes listed as “yellowish-white”). The spectral classification for Canopus is F0 Ia (Ia meaning “bright supergiant”), and such stars are rare and poorly understood; they are stars that can be either in the process of evolving to or away from red giant status. This in turn made it difficult to know how intrinsically bright Canopus is, and therefore how far away it might be.
Since the Milky Way runs through Carina, there are a large number of open clusters in the constellation, making it a binocular observing paradise. NGC 2516 is a magnitude 3.1 open cluster originally discovered by Abbe Lacaille in 1751 with a 1/2″ spyglass. This gorgeous 30 arc minute spread of stars is also known as Caldwell 96 and graces many observing lists, including the Astronomical League Open Cluster, Deep Sky and Southern Observing Clubs.
It is commonly known as the “Southern Beehive Cluster” (for it does resemble northern Messier 44) and it contains about 100 stars the brightest of which is an fifth magnitude red giant that lies near the center. As far as stellar age goes, this star cluster is very young – only about 140 million years old!
Now hop to IC 2602, popularly known as the “Southern Pleiades” for is resemblance to northern Messier 45. This galactic cluster contains more than 50 stars and is approximately 500 light years away from Earth. At its heart is blue-white star Theta Carinae, and it can be found by forming a triangle in the sky with Beta and Iota Carinae. With a stellar magnitude of 2.0, this object is easily seen as a nebulous patch to the unaided eye!
Another nebula that can been seen unaided but is better in binoculars is the Homunculus, an emission nebula surrounding the massive star Eta Carinae. The nebula is embedded within a much larger H II region, the Eta Carinae Nebula. Even though Eta Carinae is about 7,500 light-years away, structures only 10 billion miles across (about the diameter of our solar system) can be distinguished.
Dust lanes, tiny condensations, and strange radial streaks all appear with unprecedented clarity. Excess violet light escapes along the equatorial plane between the bipolar lobes. While there is relatively little dusty debris between the lobes down by the star; most of the blue light is able to escape. The lobes, on the other hand, contain large amounts of dust which absorb blue light, causing the lobes to appear reddish.
The Eta Carinae Nebula, or NGC 3372 itself is fascinating. It is a hypergiant luminous blue variable star in the Carina constellation, one of the most massive stars yet discovered. Because of its mass and the stage of life, it is expected to explode in a supernova in the “near” future. Stars in the stellar mass class of Eta Carinae, with more than 100 times the mass of the Sun, produce more than a million times as much light as the Sun.
They are quite rare — only a few dozen in a galaxy as big as the Milky Way. They are assumed to approach (or potentially exceed) the Eddington limit, i.e., the outward pressure of their radiation is almost strong enough to counteract gravity. Stars that are more than 120 solar masses exceed the theoretical Eddington limit, and their gravity is barely strong enough to hold in their radiation and gas.
Now hop just three degrees away to NGC 3532 – known as the “Wishing Well Cluster”. This open star cluster is one of the jewels of the southern sky and is also referred to as Caldwell 91 and is on many observing lists. Want another? Try globular cluster NGC 2808, also known as Bennett 41. Beautiful NGC 2808 is a fine example of a symmetrical and strongly compressed globular cluster.
Viewable in binoculars and totally resolvable in a 6″ telescope, this is another of Dreyer’s remarkable objects described as very large extremely rich, and gradually reaching an extremely condensed status in the middle. NGC 2808 contains thousands of magnitude 13-15 stars!
For double star fans, take on Epsilon Carinae, also known by the name Avior. Epsilon Carinae is a binary star located 630 light years away from our solar system. The primary component is a dying orange giant of spectral class K0 III, and the secondary is a hot hydrogen-fusing blue dwarf of class B2 V. The stars regularly eclipse each other, leading to brightness fluctuations on the order of 0.1 magnitudes.
Now try Upsilon Carinae – part of the Diamond Cross asterism in southern Carina. It’s name is Vathorz Prior, a name of Old Norse-Latin origin meaning “Preceding One of the Waterline”. Located approximately 1623 light years from Earth, the star system is made of two components. Upsilon Carinae A, is a white A-type supergiant with an apparent magnitude of +3.01 while its companion, Upsilon Carinae B, is a blue-white B-type giant 5 arc seconds away.
But no constellation would be complete without a true telescope challenge. Planetary nebula NGC 3211 (RA 10h 17m 50.4s Dec -62° 40´ 12″) heralds in at about 12th magnitude. For even more fun, try NGC 2867 (R.A. 09h 21m 25.3s Dec. -58° 18′ 40.7″). You’ll find it about a degree north/northeast of Iota. Iota Carinae. NGC 2867 may be no more than 2,750 years old.
Strangely, it is one of only a few dozen objects known to have a Wolf-Rayet star (type WC6) as its central star. NGC 2867 was discovered by John Herschel from Felhausen observatory at the Cape of Good Hope on April’s Fools Day, 1834 – appropriate since Herschel was almost fooled into thinking it was a new planet. Its size and appearance were certainly planet-like and it was only after careful checking that Herschel was convinced it was a nebula.
Now try NGC 3247 (RA 10 : 25.9 Dec -57 : 56 ). This is a very cool, very small galactic cluster with associated nebulosity. At around magnitude 8, you won’t find the rich little cluster much of a problem, but use minimal magnifcation to appreciate the true field!
While at the telescope, also look up NGC 3059 (9 : 50.2 Dec -73 : 55). Now, we’ve got a spiral galaxy cutting its way through the dust of the Milky Way! With an apparent magnitude of 12, and a 3.2 arc minute diameter, this barred spiral galaxy is going to present a nice, unique challenge to southern hemisphere observers.
There are myriad other things to look at in Carina as well, so don’t see this lovely constellation short! There is also a meteor shower associated with the constellation of Carina, too. The Eta Carinids are a lesser known meteor shower lasting from January 14 to 27 each year. The activity peaks on or about January 21. It was first discovered in 1961 in Australia. Roughly two to three meteors occur per hour at its maximum. It gets its name from the radiant which is close to the nebulous star Eta Carinae.
Like finding buried treasure, this new image of the Carina Nebula has uncovered details not seen before. This vibrant image, from ESO’s Very Large Telescope shows not just the brilliant massive stars, but uncovers hundreds of thousands of much fainter stars that were previously hidden from view. Hundreds of individual images have been combined to create this picture, which is the most detailed infrared mosaic of the nebula ever taken and one of the most dramatic images ever created by the VLT.
Although this nebula is spectacular when seen through telescopes, or in normal visible-light pictures, many of its secrets are hidden behind thick clouds of dust. Using HAWK-I infrared camera along with the VLT, many previously hidden features have emerged from the murk. One of the main goals of the astronomers, led by Thomas Preibisch from the University Observatory, Munich, Germany, was to search for stars in this region that were much fainter and less massive than the Sun. The image is also deep enough to allow the detection of young brown dwarfs.
The dazzling but unstable star Eta Carinae appears at the lower left of the new picture. This star is likely to explode as a supernova in the near future, by astronomical standards. It is surrounded by clouds of gas that are glowing under the onslaught of fierce ultraviolet radiation. Across the image there are also many compact blobs of dark material that remain opaque even in the infrared. These are the dusty cocoons in which new stars are forming.
The Carina Nebula lies about 7,500 light-years from Earth in the constellation of Carina.
This video zooms in on the new infrared view of the Carina Nebula:
It’s beautiful…. But it’s cold. By utilizing the submillimetre-wavelength of light, the 12 meter APEX telescope has imaged the frigid, dusty clouds of star formation in the Carina Nebula. Here, some 7500 light-years away, unrestrained stellar creation produces some of the most massive stars known to our galaxy… a picturesque petri dish in which we can monitor the interaction between the neophyte suns and their spawning molecular clouds.
By examining the region in submillimetre light through the eyes of the LABOCA camera on the Atacama Pathfinder Experiment (APEX) telescope on the plateau of Chajnantor in the Chilean Andes, a team of astronomers led by Thomas Preibisch (Universitäts–Sternwarte München, Ludwig-Maximilians-Universität, Germany), in close cooperation with Karl Menten and Frederic Schuller (Max-Planck-Institut für Radioastronomie, Bonn, Germany), have been able to pick apart the faint heat signature of cosmic dust grains. These tiny particles are cold – about minus 250 degrees C – and can only be detected at these extreme, long wavelengths. The APEX LABOCA observations are shown here in orange tones, combined with a visible light image from the Curtis Schmidt telescope at the Cerro Tololo Interamerican Observatory.
This amalgamate image reveals the Carina nebula in all its glory. Here we see stars with mass exceeding 25,000 sun-like stars embedded in dust clouds with six times more mass. The yellow star in the upper left of the image – Eta Carinae – is 100 times the mass of the Sun and the most luminous star known. It is estimated that within the next million years or so, it will go supernova, taking its neighbors with it. But for all the tension in this region, only a small part of the gas in the Carina Nebula is dense enough to trigger more star formation. What’s the cause? The reason may be the massive stars themselves…
With an average life expectancy of just a few million years, high-mass stars have a huge impact on their environment. While initially forming, their intense stellar winds and radiation sculpt the gaseous regions surrounding them and may sufficiently compress the gas enough to trigger star birth. As their time closes, they become unstable – shedding off material until the time of supernova. When this intense release of energy impacts the molecular gas clouds, it will tear them apart at short range, but may trigger star-formation at the periphery – where the shock wave has a lesser impact. The supernovae could also spawn short-lived radioactive atoms which could become incorporated into the collapsing clouds that could eventually produce a planet-forming solar nebula.
What can we say? Another Hubble stunner, and just wait until you see flythough video below. This is an absolutely gorgeous look inside the Carina Nebula. The radiation from massive stars inside the nebula eats away at cold molecular clouds, creating bizarre, fantasy-like structures. These are one-light-year-tall pillars of cold hydrogen and dust, imaged by the Hubble Space Telescope’s Advanced Camera for Surveys, in a composite image from observations taken in 2005 in hydrogen light (light emitted by hydrogen atoms) along with observations taken in oxygen light (light emitted by oxygen atoms) in 2010. What Hubble can see from about 7,500 light-years away is nothing short of breathtaking.
Here’s the regular video – in which there are 3-D-type flythough effects:
Massive stars live fast and die young. But they are also beautiful. This amazingly spectacular new image from ESO shows the brilliant and unusual star Wolf-Rayet 22 nestled within billowing, colorful folds of the Carina Nebula. WR 22 is one of many exceptionally hot and brilliant stars contained by the beautiful Carina Nebula (also known as NGC 3372), a huge region of star formation in the southern Milky Way. The image was captured by ESO’s Wide Field Imager at the La Silla Observatory in Chile.
Wolf–Rayet stars are named after the two French astronomers who first identified them in the mid-nineteenth century, and WR 22 is one of the most massive ones we know of. It is a member of a double star system and has been measured to have a mass at least 70 times that of the Sun. Although the star lies over 5000 light-years from the Earth, it is so bright that it can just be faintly seen with the unaided eye under good conditions.
The colorful backdrop of the Carina Nebula is created by the interactions between the intense ultraviolet radiation coming from WR 22 and other hot massive stars within the nebula, and the vast gas clouds, mostly hydrogen, from which they formed. The central part of this enormous complex of gas and dust lies off the left side of this picture as can be seen in image another image on the ESO website. This area includes the famous star Eta Carinae, one of the most massive stars and unstable stars in the universe. | 0.886199 | 3.23573 |
The moon is just a few days past full on the nights of April 21 and 22. Meanwhile, the Lyrid meteor shower is expected to put forth its greatest number of meteors during the predawn hours on April 22 and especially April 23. If you’re a veteran meteor-watcher, you’re already shaking your fist at the moon. Its glare will drown out all but the brightest Lyrids. However, the moon offers its own delights, sweeping past Jupiter – the largest planet in our solar system and second-brightest planet in our skies – on these mornings. Also, you can look for the bright star Vega, which nearly marks the radiant point of the Lyrid meteor shower. Both Jupiter and Vega should have no trouble overcoming the moon-drenched skies. Find them, enjoy them … and maybe you’ll spot a meteor, too!
By the mornings of April 24 and 25, the moon will have passed Jupiter to appear near Saturn.
The greatest number of Lyrid meteors usually falls in the few hours before dawn. That’s when the radiant point – near the star Vega in the constellation Lyra – is highest in the sky. For that reason, that’s when you’re likely to see the most meteors, albeit, this year, in the light of the moon.
Note for Southern Hemisphere observers: Because this shower’s radiant point is so far north on the sky’s dome, you’ll see fewer Lyrid meteors. But you might see some! If you want to watch, try the moonlit skies between midnight and dawn on April 22 and/or 23.
On a dark night, this shower typically offers about 10 to 15 meteors per hour at its peak. Unfortunately, in 2019, the moon is sure to bleach out a good number of Lyrid meteors. That is, the meteors will be flying. If you’re out watching, you might notice a few. Hopefully, a few of the brighter ones will prevail over the moonlight.
2019 is also a good year to see the Lyrid meteor shower’s radiant point, just to the right of beautiful blue-white Vega, the brightest light in the constellation Lyra the Harp. Vega is bright enough to be visible from some light-polluted cities. It’s bright enough to be visible in moonlight. What’s a radiant point? If you trace the paths of these Lyrid meteors backward on the sky’s dome, you’ll find that they appear to originate from near Vega, which is the heavens’ fifth brightest star.
It’s from Vega’s constellation Lyra that the Lyrid meteor shower takes its name.
You don’t need to identify a shower’s radiant point in order to watch a meteor shower. The meteors radiate from this point, but they appear unexpectedly, in any and all parts of the sky.
However, knowing the rising time of a radiant point helps you know when the shower is best in your sky. Assuming you’re in the Northern Hemisphere, Vega rises above your local horizon – in the northeast – around 9 to 10 p.m. local time. It climbs upward through the night.
The higher Vega climbs into the sky, the more meteors you’re likely to see. By midnight, Vega is high enough in the sky that meteors radiating from her direction streak across your sky. Just before dawn, Vega and the radiant point shine up high, and the meteors will be raining down from the top of the sky (assuming you’re in the Northern Hemisphere).
Why do the meteors radiate from a single part of the sky? The radiant point of a meteor shower marks the direction in space – as viewed from Earth – where Earth’s orbit intersects the orbit of a comet. In the case of the Lyrids, the comet is comet Thatcher. This comet is considered the “parent” of the Lyrid meteors. Like all comets, it’s a fragile icy body that litters its orbit with debris. When the bits of debris enter Earth’s atmosphere, they spread out a bit before they grow hot enough (due to friction with the air) to be seen. So meteors in annual showers are typically seen over a wide area centered on the radiant, but not precisely at the radiant.
Only 10 to 15 meteors per hour doesn’t sound like many. But even an hour under a still, dark sky – raining down a dozen or so meteors – is a treat. Plus, the April Lyrids can surprise you. They’re known to have outburts of several times the usual number – perhaps up to 60 an hour or so – on rare occasions. Meteor outbursts aren’t always predictable. So – like a fisherman – you’ll want your lawn chair, a thermos of something to drink, whatever other gear you feel you need – and then you need to wait. Not a bad gig.
Bottom line: That bright moon in the sky before sunup will drown most of the ongoing Lyrid meteor shower from view. But the moon offers its own delights, sweeping past Jupiter in the next few mornings. In 2019, the peak numbers of Lyrid meteors are expected to produce the greatest numbers before dawn April 23, though in moonlit skies.
The EarthSky team has a blast bringing you daily updates on your cosmos and world. We love your photos and welcome your news tips. Earth, Space, Human World, Tonight. | 0.840255 | 3.654128 |
so Far only serve to calculations as evidence of Black holes in the universe. Now, astronomers present the first recording of a previously unseen object, proving Einstein's theory of relativity.
at the same Time as made in six locations around the Globe, astronomers a unique recording of a Black hole. The researchers of the project the Event Horizon Telescope (EHT) for the image of two cosmic objects to the visor.
One of the objects is Sagittarius A*, a supermassive black hole, presumably located in the center of the milky way. It has four million solar masses and is located about 26.000 light years from the earth.
to catch a glimpse of a black hole, and to improve the image quality, researchers have radio telescopes in Hawaii, closed in Arizona, Spain, Mexico, Chile and the South pole to a global network.views to the centre of the milky way
With a conventional telescope can be Sagittarius A* is not spot. The visible light must be achieved by half of the milk road trips, to the earth. On the road it will be attenuated by cosmic dust is so strong that even on the shots of the Hubble space telescope is nothing. Astronomers are looking with radio telescopes to the center of the milky way.
the image quality, the researchers radio telescopes in Hawaii, Arizona, Spain, Mexico, Chile and the South pole to a global network. In the project, the European southern Observatory ESO, which has its headquarters in Garching near Munich is involved.
another object that have examined the astronomers, is located in the center of the giant galaxy M87 - it's supposed to be a black hole that has the 1500-times the mass of Sagittarius A*. It is located about 55 million light-years from earth, its gigantic size makes it a good object of observation. | 0.889444 | 3.282674 |
Twin NASA probes aimed at the Sun are sending home super-sized panoramasof Earth's nearest star as they take up positions to track explosive solarstorms.
Instrumentsand cameras aboard NASA's two SolarTerrestrial Relations Observatory (STEREO) spacecraft have zoomed out for aplanetary orbit-hopping view that stretches from the Sun to Earth's orbit, a distance of93 million miles (150 million kilometers). The panorama [image]serves as shakedown for STEREO's science toolsto take three-dimensional scans of the Sun's coronalmass ejections (CMEs), the first of which are expected in April [newvideo].
"Thispanoramic view is absolutely unique," Russ Howard, principal investigator forthe STEREO instruments that took the new images, told reporters Thursday,adding that the probes have already spotted a CME event. "We're still seeingthe evolution of this material as it goes out into to interplanetary space."
Howardleads STEREO's five-imager Sun-Earth ConnectionCoronal and Heliospheric Investigation (SSECHI) instrumentsuite for NASA at the Naval Research Laboratory in Washington, D.C. [image].
CMEs aremassive eruptions from Sun that spew high-energy particles atprodigious speeds which, if they pass by Earth, can poseradiation hazards for astronauts in space, afflictorbiting satellites and interfere with power and communications systems on Earth.
"They canget their memories reset or power supplies wiped out," mission projectscientist Michael Kaiser, of NASA's Goddard Space Flight Center in Greenbelt,Maryland, said of CME-susceptible spacecraft, during Thursday'spress briefing. "They need to know when [CMEs] are coming so they can be set insafe mode."
STEREO's plannedtwo-year mission is expected to build near real-time 3-D views of thoseeruptions by positioning twin Sun-watching probes at stations leading andtrailing the Earth in its orbit [image].The mission, researchers hope, will yield better forecasts for severe space weather and determine howCMEs speed up and slow down as they flow out from the Sun.
Themission's two spacecraft spotted a CME event between Jan. 24 and Jan. 25, andwatched as the eruptions first sped away from the Sun at more than 750 miles (1,207kilometers) per second only to slow to about 500 miles (804 kilometers) per second.The observations also caught the last vestiges of the tail of CometMcNaught, the brightest comet seen in 30 years, mission scientists said [image].
"This is adiscovery. ... We have never been able to see the progress of the CME from theSun, from its origin, all the way out," Dan Moses, a SSECHI science team memberat the Naval Research Laboratory. "We see that this is different from ourinitial models."
Since theirOctober 2006 launch, STEREO's two probes, dubbed A and B for "Ahead" and"Behind," have not yet traveled far enough apart to begin theirthree-dimensional Sun observations. Once in their final positions in April,STEREO A--ahead of Earth--will make a complete orbit around the Sun in 347 days,while STEREO B-- behind and further out of Earth's orbit--will complete onecircuit in 387 days [image].
Missionmanagers said the STEREO probes are in good health and have enough propellantonboard to last a decade. The Applied Physics Laboratory at Johns Hopkins University in Laurel, Maryland, is overseeing the $550 million mission for NASA's Goddard Space Flight Center.
MadhulikaGuhathakurta, NASA's STEREO program scientist at the agency's Washington, D.C.headquarters, pledged that STEREO's first 3-D Sun images will be released tomuseums nationwide and via the Internet.
"Theseimages are just unbelievable," Guhathakurta said of the new panoramas.
- NEWVIDEO: STEREO's Sun Sights
- VIDEO: The Sun'sStorms
- DoubleVision: STEREO Spacecraft to Scan Sun in 3D
- IMAGES:Sun Storms
- IMAGES:Solar Flares
- LIVE Sun Cam | 0.836512 | 3.01626 |
This image of the brown dwarf, Gliese 229b, was created using the Hubble Space Telescope. Compared to Jupiter, Gliese is about twice as large and 40 times as massive.
Click on image for full size
During the early 1900's, which is not very long ago, astronomers were
unaware that there were other galaxies outside our own Milky Way Galaxy
. When they
saw a small fuzzy patch in the sky through their telescopes, they
called it a nebula
examined closely, some of the nebulae had a spiral shape. So
astronomers at first called these "spiral nebulae". These nebulae
were all believed to be part of our Galaxy, our community of stars.
Edwin Hubble studied the "spiral nebulae" and found that they were
composed of stars. These nebulae were not nebulae at all, but other
communities of billions of stars held together by gravity - galaxies!
Suddenly, our universe was much bigger. We realized that our Galaxy
was just one of many billions of galaxies in the universe.
Hubble studied galaxies for a very long time, and after seeing many,
many galaxies, he realized that he could put them into groups based on
their shape: spirals, ellipticals, or irregulars. His work helped
us to understand that the appearance of galaxies depends on our point
of view, and on what's happening in the galaxies.
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Members of the science community are proclaiming a new era in space research after discovering the first verified source of a super-energetic subatomic particle called a high-energy neutrino.
Researchers from the Pennsylvania State University say that these neutrinos contain energies that are thousands to millions of times greater than those generated by particle colliders/accelerators such as the European Organization for Nuclear Research’s (CERN) Large Hadron Collider, located on the border between France and Switzerland.
Using ground and space-based telescopes, a global team of scientists was able to trace the path of one of these particles to a flaring supermassive black hole in the center of a galaxy some 3.7 billion light-years away in the Orion constellation.
The neutrino itself was detected on September 22, 2017, at the IceCube Neutrino Observatory in Antarctica.
According to the National Science Foundation, a new system that sends alerts to telescopes around the world was activated in less than a minute after the subatomic particle crashed into one of the observatory’s underground detectors buried deep beneath the Antarctic ice.
The alert included the incoming neutrino’s coordinates to help the telescopes zero in on its possible pathway.
The discovery comes after astronomers spent decades trying to detect and find out where and how these ghostly little particles are produced.
The team’s findings were published in two papers in the journal Science. – (Paper 1 – Paper 2)
“Each messenger — from electromagnetic radiation, gravitational waves and now neutrinos — gives us a more complete understanding of the universe, and important new insights into the most powerful objects and events in the sky,” commented France Córdova, Director of the National Science Foundation, in an NSF press release. | 0.86976 | 3.508841 |
One of the world's largest and most sensitive radio telescopes was completed in Westerbork in 2019. The team of Dutch and international researchers using the telescope discovered major variations in the behaviour of Fast Radio Bursts.
Fast Radio Bursts, or FRBs, emit enormous quantities of energy that travel across the universe. However, scientists have yet to identify the source of this bright radio light. As the results from Westerbork show, we are still far from solving this puzzle. The first scientific results from the new high-speed receiver cameras will be published in scientific journal Astronomy & Astrophysics this week.
The discoveries were made by Leon Oostrum, PhD candidate at the Netherlands Institute for Radio Astronomy (ASTRON) and University of Amsterdam 'As these initial results are already showing, FRBs remain a source of many mysteries', Oostrum explains.
In an effort to understand the FRB phenomenon, researchers used the Westerbork telescope to examine the first two discovered radio sources that regularly emit short pulses, known as R1 and R2. R1 was seen to emit a total of 30 pulses, while R2 remained invisible despite 300 hours of observations. Contrary to expectations, R2's behaviour immediately proved entirely different to that of R1. R2 may be invisible because its pulses are too weak, or because it emits radio light in a 'colour' that is undetectable to the Westerbork telescope. In another potential scenario, R2 may have temporarily or permanently stopped emitting pulses. The reason for R2's invisibility is still unknown.
The R1 pulses are the first radio bursts to have been recorded at Westerbork. The telescopes will now start searching for new radio sources. The more bursts the researchers discover, the more they will learn about their origin.
Research leader Joeri van Leeuwen (ASTRON): 'We've reused Westerbork's existing antenna, which means we now have access to an extremely sensitive telescope. We equipped the telescope with a hyper-modern receiver called Apertif and a huge supercomputer, and we can now record the universe at a rate of 20,000 images per second.
Thanks to this full overhaul, the Westerbork radio telescope - owned by ASTRON - has regained its position as one of the world's best radio telescopes. The image is composited from the signals from 12 different antennae, allowing the researchers to create a highly detailed picture of the celestial sky. The new Apertif technology allows them to instantaneously capture detailed images of large expanses of the sky. Whereas other comparable telescopes operate at shutter speeds of 1 second, the Apertif supercomputer can make recordings with multiple images every 1/1000th of a second.
Oostrum: 'That combination doesn't exist anywhere else in the world, and it will be crucial in unravelling the workings of these mysterious fast radio bursts.' | 0.828464 | 3.89325 |
NASA’s Hubble Space Telescope captured an eerie interstellar image earlier this summer. The space agency released the photo to kick off Halloween week. Goddard Space Flight Center also posted a fun, spine-tingling video of the scary discovery on YouTube.
Of course, Hubble’s chilling image is not really an alien monster casting its ominous gaze upon the Earth. However, the spooky space form’s true identity might be even more frightening.
Intergalactic Head-On Collision
The “ghost’s” two “eyes” are the bright cores of a pair of galaxies that met in a violent head-on collision. According to a NASA report, a ring of young blue stars outlines the “face.” Meanwhile, clumps of new stars form the space specter’s “mouth” and “nose.”
Collectively, astronomers catalog the entire system as “Arp-Madore 2026-424 (AM 2026-424).” Galaxy collisions frequently happen. However, head-on impacts like the one that created the Arp-Madore system rarely occur. Researchers suggest that the ring shape produced by the crash is short-lived. As such, this creepy formation might only last about 100 million years.
Ultimately, the vibrant band of stars that make up the ghost’s “nose” and “face” formed after the pair of galaxies collided. Consequently, the impact “stretched the galaxies’ disks of gas, dust, and stars outward” to make this unique structure.
“The galaxies have to collide at just the right orientation to create the ring,” NASA reported in a statement. “The galaxies will merge completely in about 1 to 2 billion years, hiding their messy past.”
Another rare phenomenon caused the ghoulish form’s eyes to look almost the same size. Big, neighboring galaxies typically swallow smaller galaxies. However, these colliding giants appear to be the same size. Thus, the unusual symmetry presents a haunting “face” with deep-set, skull-like eyes.
Overall, the unsettling image seems a little surreal. Instead of existing 704 million light-years from Earth, it seems like the creepy space “face” could leer down in an episode of “Tales From the Crypt.”
More Freaky Finds
The Hubble Space Telescope has ironically made some other eerie discoveries. Last week, NASA posted another image captured by the orbiting system called “Medusa in the Sky.”
The “Medusa merger” photo reflects what happened when an early galaxy “consumed a smaller, gas-rich system.” The streams of dust and stars shooting out of the merged galaxies’ core notably look a lot like the mythological monster’s slithering snakes.
Meanwhile, the Spitzer Space Telescope eyed a massive star that’s about 15 to 20 times heavier than the sun that looks like a giant interstellar pumpkin. Researchers fittingly dubbed the celestial body the “Jack-o’-lantern Nebula.”
Hubble scientists captured the “ghost” face this summer as part of a “snapshot program” that studies unusual characteristics of interacting galaxies.
Overall, NASA plans to use Hubble’s detailed observational data to pick targets for the James Webb Telescope, which is scheduled to launch in 2021. | 0.877171 | 3.264856 |
Welcome to another edition of Constellation Friday! Today, in honor of the late and great Tammy Plotner, we take a look at the “Southern Cross” – the Crux constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.
One of these constellations is known as Crux, a small constellation located in the southern skies. Despite its size, it is one of the most well-known constellations in the southern hemisphere due to its distinctive cross-shape. Today, it has gone on to become one of the 88 modern constellations currently recognized by the International Astronomical Union (IAU).
Name and Meaning:
For the people of the Southern Hemisphere, the Crux constellation has a great deal of cultural significance. The Incas knew the constellation as Chakana (Quechua for “the stair”), and a stone image of the stars was found in Machu Picchu, Peru. To the Maori, the constellation was known as Te Punga, or “the anchor”, due to the important role it played in maritime navigation.
To the Aborigines of Australia, the cross and the Coalsack Nebula together represented the head of the Emu in the Sky. This mythical bird is associated with several Aborigine creation myths and is one of the most important constellations in their astronomical traditions. Because of this significance, the Southern Cross is represented on the flags of Australia, Papua New Guinea, New Zealand Brazil, and Brazil.
The first recorded instance of Crux being named is believed to have occurred in 1455, when Venetian navigator Alvise Cadamosto made note of an asterism in the southern skies that he called carr dell’ostro (“southern chariot”). However, historians generally credit Portugese astronomer Joao Faras with the discovery, which occurred in 1500 when he spotted it from Brazil and named it “Las Guardas” (“the guards”).
By the late 16th century, Crux began to be depicted as a separate constellation on celestial globes and maps. In these and subsequent maps, the name Crux was used (Latin for “Cross”), referring to the constellation’s distinct shape.
History of Observation:
Crux was originally considered to be part of Centaurus, but as the precession of the equinoxes gradually lowered these stars below the European horizon, they were lost sight of, and so was the memory of these stars. At one time, around 1000 BCE, the stars of Crux were visible to the northern hemisphere, but by 400 CE they had slipped below the horizon for most populated areas.
Even though it was originally plotted on Ptolemy’s Almagest, it first appeared as “Crux” on the charts of Petrus Plancius and Jodocus Hondius in 1598 and 1600 – both navigators. It is known that Amerigo Vespucci mapped the stars of Crux on his expedition to South America in 1501, and with good reason!
Two of the stars of Crux (Alpha and Gamma, Acrux and Gacrux respectively) are commonly used to mark due south. Following the line defined by the two stars for approximately 4.5 times the distance between them leads to a point close to the Southern Celestial Pole. A definite point needed for navigation! In 1920, Crux was included among the 88 modern constellations recognized by the IAU.
Of the major stars in Crux, Alpha Crucis (Acrux) is the brightest, and the 12th brightest star in the night sky. It is located approximately 320 light years away and is a multiple star system composed of Alpha-1 Crucis (a B class subgiant) and Alpha-2 Crucis (a B class dwarf). Both stars are very hot and their respective luminosities are 25,000 and 16,000 times that of the Sun.
Beta Crucis (Becrux, or Mimosa) is the second brightest star of the Southern Cross and the 20th brightest star in the night sky. It is approximately 350 light years distant, is classified as a Beta Cephei variable, and is a spectroscopic binary composed of two stars that are about 8 AU apart and orbit each other every five years. The name Mimosa refers to its color (blue-hued).
Gamma Crucis (Gacrux) is a red giant that is approximately 88 light years distant from Earth. It is the third brightest star in the Crux constellation and the 26th brightest star in the sky. Located about 400 light years distant from Earth, this binary star is composed of a M4 red dwarf star and a A3 white dwarf star.
Crux is also associated with several Deep Sky Objects, the most notable of which is the Coalsack Nebula. This object is easily seen as a dark patch in the southern region of the Milky Way (hence the name) and crosses into the neighboring constellations of Centaurus and Musca. It is located about 600 light years from Earth and is between 30 and 35 light years in radius. In Aboriginal astronomy, the nebula represents the head of the Emu.
Then there’s the Kappa Crucis Cluster (aka. the “Jewel Box” or “Herschel’s Jewel Box”), an open star cluster that is located approximately 6,440 light years from Earth. It contains roughly 100 stars and is one of the youngest clusters ever discovered (only 14 million years old). To the naked eye, the cluster appears like a star near Beta Crucis.
The constellation itself consists of four bright, main stars and 19 stars which have Bayer/Flamsteed designations. It is bordered by the constellations of Centaurus and Musca. At present, Crux is visible at latitudes between +20° and -90°. While it is fairly circumpolar for the southern hemisphere, it is best seen a culmination during the month of May.
Now, let’s take out binoculars and examine its stars, started with Alpha Crucis, the “a” shape on our map. Its proper name is Acrux and it is the twelfth brightest star in the night sky. If you switch your binoculars out for a telescope, you’ll find that 321 light year distant Acrux is also a binary star, with components separated by about 4 arc seconds and around one half stellar magnitude difference in brightness.
The brighter of the two, A1 is itself a spectroscopic binary star – with a companion that orbits no further away than our own Earth, yet is around 14 times larger than our own Sun! Needless to say, there’s a very good chance this star may one day go supernova. While you’re there, take a look an addition 90 arc seconds away for a third star. While it may just be an optical companion to the Acrux system, it does share the same proper motion!
Back to binoculars an on to Beta Crucis – the “B” shape on the map. Mimosa is located about 353 light years away from our solar system and it is also a spectroscopic binary star. This magnificent blue/white giant star is tied at number 19 as one of the brightest stars in the sky, and if we could put it side by side with our Sun it would be 3000 times brighter. Mimosa is also a multiply-periodic Beta-Cephi type star, too, fluxing by about 1/10 of a magnitude in as little as hours. What’s going on? Inside Beta Crucis the iron content is only about half that of Sol and it’s nearing the end of its hydrogen-fusing stage. When the iron core develops? Watch out! It’s supernova time….
Now hang on to your binoculars and head north for Gamma Crucis, the “Y” shape on the map. Gacrux, is a red giant star approximately 88 light-years away from Earth. Did you notice its optical companion about 2 arc minutes away at an angle of 128 degrees from the main star? While the two look close together in the sky, the secondary star is actually 400 light years away! Gacrux shows its beautiful orange coloring to prove it has evolved off of the main sequence to become a red giant star, and it may even be evolving past the helium-burning stage.
Move on now to Delta Crucis – the figure “8” on our map. Decrux is a red giant star located about 360 light years away from our vantage point. Delta Crucis is also Beta Cephei variable and changes its brightness just a tiny bit over a period of about an hour and 20 minutes. Another cool factoid about Delta Crucis is that it’s a fast rotator – spinning at a speed of at least 194 kilometers per second at the equator and making a full rotation in about 32 hours.
This massive star also produces a massive stellar wind, shooting off 1000 times more material than our own Sun every second of every day! Or try R Crucis… It’s also a Beta-Cephi type variable star, but it changes by nearly a full stellar magnitude in just a little over five days!
Keep your binoculars handy and head back to Beta and sweep south a degree and a half for the Kappa Crucis star cluster. This beautiful galactic cluster of stars commonly known as the Jewel Box (NGC 4755). After you see its glittering collection of multi-colored stars, you’ll understand how it got its name! It is one of the youngest clusters, perhaps only a few million years old.
Kappa Crucis is also right on the edge of a dark void in the sky called the “Coal Sack”. While you’re looking around, you’ll notice that there seem to be very few stars in this area. That’s because they are being blocked by a dark nebula! The Coal Sack is a large, dark dust cloud about 500 light years away and it’s blocking out the light from stars which lie beyond it. The few stars you do see are in front of the cloud and much nearer to the Earth.
Now it’s telescope time. Head to Alpha Crucis and slightly less than 2 degrees east for NGC4609. Also on the edge of the Coalsack, this large, fairly condensed open cluster contains about 40 members and they are well spread across the sky. The pattern somewhat resembles the constellation of Orion (in the imagination, of course!). Mark you observing notes for Caldwell 98. Next stop? Back to Delta and less than 3 degrees south/southwest for NGC4103, another open cluster on the edge of night. With a little bit of imagination, this grouping of stars could appear to look like a celestial water tower!
Be sure to check out The Messier Catalog while you’re at it!
For more information, check out the IAUs list of Constellations, and the Students for the Exploration and Development of Space page on Canes Venatici and Constellation Families. | 0.849258 | 3.558114 |
Well, it’s finally happened. We made it to Pluto.
The most distant of the classical planets, Pluto was demoted to level of ‘dwarf planet’ by the International Astronomical Union back in 2006, but that minor setback did nothing to quell public enthusiasm for the little-planet-that-could. Unfortunately, Pluto’s unusual orbit prevented it from being able to be visited by either of the Voyager probes back in 1989, so while we have been privy to detailed photographs and tantalizing scientific data from every other member of our solar system, from Mercury through Neptune, Pluto has always been for us little more than a dot against a background of stars.
That is, until July, 2015, when the NASA New Horizons probe completed its decade-long journey and finally visited Pluto. Better late than never, right?
New Horizons captured massive amounts of data, and gave scientists and armchair planetologists quite a bit to think about. However, in our excitement to finally put a ‘face’ with Pluto’s name, let’s not forget the probe that made it all possible. The New Horizons probe is an advanced collection of computer circuitry, designed to operate in the dead of interplanetary space without any support other than the signals beamed to it across 4.67 billion miles of empty vacuum. And while the hardware that makes up the probe is impressive, the applications and programs that were used to help get it to the outer fringes of our solar system are no-less amazing. Let’s take a moment and look at several apps that helped us finally catch a glimpse of our most camera-shy solar neighbor.
- SPICE Toolkit
Space is a funny place. For one thing, without a strong gravitational influence (such as we feel pulling us downward when we are standing on the surface of the Earth), it can be really difficult to determine direction, orientation, or even momentum. New Horizons uses a version of a tried-and-true NASA program collection, known as the SPICE Toolkit. These apps make it possible for the probe and its handlers to know where the spacecraft is located in relation to its point of origin and its destination. The SPICE Toolkit also allows scientists to keep track of onboard instrument orientation, and any events onboard the spacecraft that might affect the probe’s ability to do its job.
- Nucleus RTOS (variation)
In order for the probe’s CPU to be able to function in the way it is designed to, the Command and Data Handling system is based upon the widely-used Nucleus Real Time Operating System, which is estimated as being part of approximately 2.11 billion devices worldwide. Nucleus is scaleable, and as such can fulfill a number of functions beyond command and data handling. Everything from defibrillators and other medical equipment, to personal phones, to advanced surveillance systems, all have the potential to be operated using the Nucleus RTOS. That’s right, the same cameras that provide your office with business security, might just share a program or two with the probe that finally snapped a shot of Pluto.
- REX Although the New Horizons probe may be small, it carries with it parts and programs from many different locations. Take REX, for example. REX stands for Radio Science Experiment, and is a device and set of programs developed at Stanford University. REX uses radio transmissions from Earth to help determine Pluto’s atmospheric composition, temperature, and pressure. It does this by measuring the amount of atmospheric interference in the incoming radio waves. REX is used to gather so much data, that it will actually be an entire year before the whole dataset is downloaded.
- Playstation processor This one is actually hardware, not software, but it’s interesting enough that we’re going to mention it anyway. When New Horizons was launched back in 2006, it needed a CPU that could stand the strain of interplanetary travel and solar radiation. So what did they go with? Well, if you read the section heading, you already know. The Playstation video game console, first released in 1994, is now over twenty years old, and was already outdated back when the probe was being designed. However, the probe’s creators weren’t interesting in finding the newest and most powerful CPU available; they wanted something reliable. So, they created a radiation-hardened, specially-designed version of the Playstation CPU, and sent it off on a journey into the unknown. It will continue its journey outward, until many thousands of years from now it eventually encounters other stars, and perhaps even other worlds. By then, humanity itself may be long gone, but the Playstation CPU housed inside our ambassador to the stars will continue on its mission, until time itself ceases to exist.
Hmm. Not a bad destiny for something that was designed to play Tomb Raider and Crash Bandicoot.
Lee Ying has over 10 years experience in the tech and security industry. He currently writes for various websites, if you would like to contact him you can find him on LinkedIn: . Follow me on Twitter @LeeYing101 | 0.873639 | 3.612261 |
Crescent ♎ Libra
Moon phase on 5 December 2042 Friday is Waning Crescent, 23 days old Moon is in Virgo.Share this page: twitter facebook linkedin
Previous main lunar phase is the Last Quarter before 1 day on 4 December 2042 at 09:19.
Moon rises after midnight to early morning and sets in the afternoon. It is visible in the early morning low to the east.
Lunar disc appears visually 8.7% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1785" and ∠1947".
Next Full Moon is the Cold Moon of December 2042 after 21 days on 26 December 2042 at 17:43.
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 23 days old. Earth's natural satellite is moving from the second to the final part of current synodic month. This is lunation 530 of Meeus index or 1483 from Brown series.
Length of current 530 lunation is 29 days, 18 hours and 1 minute. It is 1 hour and 37 minutes longer than next lunation 531 length.
Length of current synodic month is 5 hours and 17 minutes longer than the mean length of synodic month, but it is still 1 hour and 46 minutes shorter, compared to 21st century longest.
This lunation true anomaly is ∠201.7°. At the beginning of next synodic month true anomaly will be ∠232°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
9 days after point of perigee on 25 November 2042 at 22:40 in ♉ Taurus. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 2 days, until it get to the point of next apogee on 8 December 2042 at 00:37 in ♏ Scorpio.
Moon is 401 544 km (249 508 mi) away from Earth on this date. Moon moves farther next 2 days until apogee, when Earth-Moon distance will reach 405 435 km (251 926 mi).
11 days after its ascending node on 24 November 2042 at 01:03 in ♈ Aries, the Moon is following the northern part of its orbit for the next day, until it will cross the ecliptic from North to South in descending node on 7 December 2042 at 05:37 in ♎ Libra.
11 days after beginning of current draconic month in ♈ Aries, the Moon is moving from the beginning to the first part of it.
6 days after previous North standstill on 29 November 2042 at 03:21 in ♋ Cancer, when Moon has reached northern declination of ∠28.344°. Next 8 days the lunar orbit moves southward to face South declination of ∠-28.294° in the next southern standstill on 13 December 2042 at 13:29 in ♐ Sagittarius.
After 7 days on 12 December 2042 at 14:29 in ♐ Sagittarius, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.83659 | 3.252264 |
Astonished astronomers said Wednesday they had found rings around an asteroid, the smallest object known to have this feature and only the fifth after Jupiter, Saturn, Uranus and Neptune.
The twin rings around a rock called Chariklo were spotted in June last year as it passed in front of a star. As expected, the star seemed to vanish for a few seconds as Chariklo blocked its light — a phenomenon known as occultation. But the mini-eclipse turned out to be much more than the astronomers were expecting. Two narrow, dense rings — a feature believed to be limited to the four giant planets of our Solar System were blocking the light of the star. In a new paper in Nature, the team of scientists not only reconstructed the shape and size of Chariklo itself but also the shape, width and orientation of its twin halos.
These were seven and three km (4.3 and 1.8 miles) wide respectively, separated by a nine-km gap. Like Saturn’s rings, Chariklo’s may be composed of water ice.
Chariklo is a lumpy 250-km-wide rock discovered in 1997 and named after a water nymph in Greek mythology. It orbits the Sun between Saturn and Uranus, more than a billion kilometres from Earth. It is a Centaur, a category of celestial bodies that share the characteristics of comets, which are made of ice and dust and form tails when they pass near the Sun, and asteroids which are made of metallic rock, have shorter orbits and tend to cluster in groups. Centaurs have unstable orbits that cross those of the giant planets and live for a few million years.
Origin of Chariklo’s rings
The origin of Chariklo’s rings are a mystery for now, but may be the result of a debris-releasing collision with another body.
A ring system detected around the Centaur (10199) Chariklo Braga-Ribas, F. et al. Nature http://dx.doi.org/10.1038/nature13155 | 0.869757 | 3.702255 |
Astronomers have found the first direct evidence that some star explosions are triggered by compact stars called white dwarfs.
Scientists studying the youngest type of Ia supernova ever found worked backward to pinpoint its explosion time with unparalleled accuracy. In doing so, they confirmed that a white dwarf was the source of the blast, and gleaned insights into the nature of the dwarf's companion star.
The discovery occurred in August, when astronomer Peter Nugent spotted a surprising object while poring over data from the Palomar Transit Survey's robotic telescope at Palomar Observatory in Southern California. The object was quickly confirmed to be a type Ia supernova. High-resolution follow-up observations were made within hours by the Keck telescope in Mauna Kea, Hawaii, identifying the elements that burst from the blast.
The speedy response allowed Nugent and his team to follow the evolution of the supernova, called SN 2011fe. [Amazing Photos of Supernova Explosions]
As the light of the explosion reached the brightness of 2.5 billion suns, then slowly faded, the team worked backward to determine exactly when the supernova occurred. Located only 21 million light-years from Earth in the Pinwheel Galaxy, the supernova is the closest one to our planet in 25 years. (A light-year is the distance light travels in a year, about 6 trillion miles, or 10 trillion kilometers.)
"We were able to pinpoint the explosion time very accurately, to an uncertainty of just twenty minutes," Nugent, of Lawrence Berkeley National Laboratory, told SPACE.com.
Knowing how much energy the supernova put out allowed the researchers to, in effect, rewind the stellar explosion to see how it began. Measurements of elements such as nickel enabled them to put a lower limit on the size of the source.
The astronomers also found large clumps of fast-moving carbon and oxygen that disappeared within hours.
"The early observations helped us to constrain the explosion really accurately," Nugent said.
With their results, the team was able to conclude that the cause of the supernova was an extremely compact star known as a white dwarf.
White dwarfs are small, dense stars whose Earth-like radius encompasses a sun-like mass. The core of a white dwarf is too cool to undergo fusion, so its energy slowly dissipates into space.
Astronomers have long suspected that these remnants of dead stars were the source of type Ia supernovae, but SN 2011fe provides the first direct evidence.
Searching for the second
A firsthand examination of the light from the supernova also revealed information about the celestial body that once orbited the white dwarf.
In a type 1a supernova, material flowing from a second star onto the white dwarf overloads the compact relic and triggers the blast. The companion could be anything from a large red giant star to another white dwarf.
When stars explode, a shockwave rushes outward. Collisions with material around it cause the region to flare brightly. By studying the light from SN 2011fe, Nugent's team was able to rule out specific types of stars as the companion.
The neighbor star could not have been a red giant, Nugent explained, because collisions between the debris and a large, massive star would have been very obvious. The resulting light would have been several magnitudes brighter than what was detected.
Similarly, a white dwarf companion would have been ripped apart, leaving a debris field for the shockwave to collide with, causing an impact that wasn't seen in the data.
"The only thing we were left with was a star not too different from our sun as the companion," Nugent said.
In an accompanying paper, Weidong Li of the University of California at Berkeley also sought information about the companion.
"There were some very deep images from the Hubble Space Telescope prior to the discovery of this supernova," Li told SPACE.com.
Li and his team examined more than a decade's worth of data from NASA's space-based telescope in search of the second star in the pair.
But no star was detected, allowing them to place an upper limit on the size of the companion. A red giant, for instance, would have been visible in the images.
Ultimately, Li and his team concluded that the companion could be a main sequence or subgiant star, or even another white dwarf.
Combined with Nugent's data, this narrows down the identity of the companion star.
"A low mass main sequence star is the object most likely, given the two different ways we went about trying to constrain the progenitor," Nugent said.
Both papers were published in the Dec. 15 issue of the journal Nature. | 0.816871 | 4.061206 |
NASA released a new photo of the space telescope “Hubble”, made by the thirtieth anniversary of operation in space. It shows two nebulae of the large region of star formation in the nearby in our galaxy, the Large Magellanic cloud, reported on the website of the Observatory.
Hubble is the most famous and successful orbital Observatory from working today. He was launched into space on 24 April 1990, and over three decades of work in earth orbit spent 1.4 million of observations. The total volume of accumulated data is tens of terabytes, they used to write more than 17 thousand scientific articles in the field of astrophysics and cosmology. In particular, observations made with the telescope, played a key role in the discovery of the accelerated expansion of the Universe, you can read about it in our article “have Worked for 52”. Yet the scientific program of the telescope, has repeatedly Podlesovskaya, calculated until June 2021. It is expected that in the future his replacement will come a new space Observatory “James Webb”.
To the thirtieth anniversary of its work, the telescope got a new picture, the designation “Outer reef”, which shows two nebula NGC 2014 and NGC 2020, is located in a large region of star formation in the Large Magellanic cloud. This companion galaxy of the milky way located at a distance of about 163 thousand light-years from the Sun.
In the Central part of NGC 2014 there is a group of bright, massive stars that powerful stellar winds have cleared the space around them from gas and dust to form “bubbles”, and gradually destroy the nearby large cloud of gas. Ultraviolet radiation from the stars ionizes the hydrogen in the nebula causing it to glow. Nebula NGC 2020 is developed because of the star wolf-Rayet, which is 15 times more massive than the Sun and about 200 thousand times brighter. The active star loses its substance in the form of powerful stellar winds and a few million years can explode as a supernova.
To look at beautiful pictures of objects from the Messier catalogue, obtained by the space telescope “Hubble”, in our gallery. | 0.908551 | 3.257935 |
Fr.: boucle de Barnard
A very faint nebular shell of huge size enveloping the central portion of Orion.
Fr.: boucle bleue
An evolutionary behavior of certain stars, particularly massive stars, which return to the blue stage after becoming a red supergiant. The phenomenon appears as a blueward loop on the theoretical evolutionary tracks.
Fr.: boucle coronale
An arc-like structure in the Sun's → corona that is found around → sunspots and in → active regions. These structures are associated with the closed magnetic field lines that connect magnetic regions on the solar surface. The loops are sometimes as high as 10,000 km with their two ends situated in photosphere regions of opposite magnetic polarity. This implies that the coronal loops are tubes of magnetic flux filled with hot plasma. They last for days or weeks but most change quite rapidly.
Fr.: boucle du Cygne
A large supernova remnant in the → constellation → Cygnus, some 80 light-years across, lying about 2,500 light-years away. The loop is expanding at over 100 km/s and is thought to be about 30 000 years old.
Fr.: boucle de rétroaction
Fr.: cycle d'hystérésis
A closed curve showing the change in magnetic induction of a ferromagnetic body to which an external field is applied as the intensity of this field is varied from +Hs to -Hs and back again, where Hs is the magnetic field intensity corresponding to saturation.
Anything shaped more or less like a loop, i.e. portion of a cord, ribbon, etc.,
folded or doubled upon itself.
Probably of Celtic origin (cf. Gael. lub "bend," Ir. lubiam), influenced by O.N. hlaup "a leap, run."
Gerdâl, from gerd "round, a circle" (Mid.Pers. girdag "disk, round," from gird/girt "round, all around," Proto-Iranian *gart- "to twist, to wreathe," cf. Skt krt "to twist threads, spin; to wind; to surround;" kata- "a twist of straw," Pali kata- "ring, bracelet," Gk. kartalos "a kind of basket," kyrtos "curved") + → -al.
Fr.: protubérance en boucle
A very bright active prominence in the form of a loop seen in Hα after a rather big flare. Also called "post-flare loops," they connect the feet where the two-ribbon flares were seen. The lifetime of loop prominences is several hours.
Fr.: Boucle du Loup
An large nonthermal radio source in the constellation → Lupus, identified as a very old supernova remnant. It is also an extended source of soft X-rays.
Fr.: Boucle de la Licorne
A faint filamentary loop of nebulosity about 1 kpc distant, the remnant of a supernova that occurred about 300,000 years ago. It contains the Rosette Nebula as well as the Cone Nebula. | 0.808731 | 3.676708 |
Crescent ♌ Leo
Moon phase on 16 July 2015 Thursday is New Moon, less than 1 day young Moon is in Cancer.Share this page: twitter facebook linkedin
Moon rises at sunrise and sets at sunset. It's part facing the Earth is completely in shadow.
Lunar disc is not visible from Earth. Moon and Sun apparent angular diameters are ∠1814" and ∠1888".
Next Full Moon is the Buck Moon of July 2015 after 14 days on 31 July 2015 at 10:43.
There is high New Moon ocean tide on this date. Combined Sun and Moon gravitational tidal force working on Earth is strong, because of the Sun-Moon-Earth syzygy alignment.
At 01:24 on this date the Moon completes the old and enters a new synodic month with lunation 192 of Meeus index or 1145 from Brown series.
29 days, 13 hours and 29 minutes is the length of new lunation 192. It is 2 hours and 19 minutes shorter than next lunation 193 length.
Length of current synodic month is 45 minutes longer than the mean length of synodic month, but it is still 6 hours and 18 minutes shorter, compared to 21st century longest.
This New Moon true anomaly is ∠112.8°. At beginning of next synodic month true anomaly will be ∠144.1°. 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°).
10 days after point of perigee on 5 July 2015 at 18:54 in ♒ Aquarius. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 4 days, until it get to the point of next apogee on 21 July 2015 at 11:02 in ♍ Virgo.
Moon is 395 164 km (245 544 mi) away from Earth on this date. Moon moves farther next 4 days until apogee, when Earth-Moon distance will reach 404 837 km (251 554 mi).
8 days after its descending node on 8 July 2015 at 00:07 in ♈ Aries, the Moon is following the southern part of its orbit for the next 5 days, until it will cross the ecliptic from South to North in ascending node on 21 July 2015 at 19:32 in ♍ Virgo.
21 days after beginning of current draconic month in ♍ Virgo, the Moon is moving from the second to the final part of it.
2 days after previous North standstill on 14 July 2015 at 04:24 in ♊ Gemini, when Moon has reached northern declination of ∠18.417°. Next 12 days the lunar orbit moves southward to face South declination of ∠-18.344° in the next southern standstill on 28 July 2015 at 17:34 in ♐ Sagittarius.
The Moon is in New Moon geocentric conjunction with the Sun on this date and this alignment forms Sun-Moon-Earth syzygy. | 0.823901 | 3.105675 |
When reflecting on the so-called (according to NASA) reflections of light inside the Occator crater on the surface of the dwarf planet Ceres, it’s a good idea not to get too attached to the explanation. Researchers analyzing data not from the Dawn spacecraft but from a planet-hunting telescope say the lights are brightening and dimming at random times throughout the day for no apparent reasons. Is it again time to suspect aliens?
While Dawn sent back stunning photos from its approach to and orbit of Ceres, there are other ways to watch it. Astronomers from the INAF-Trieste Astronomical Observatory in Trieste, Italy, used the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph at the European Southern Observatory (ESO) in Chile to observe Ceres for two nights in July 2015 and August 2015. Specifically, they watch the rotation of Ceres as is spins once every nine hours.
The result was a surprise. We did find the expected changes to the spectrum from the rotation of Ceres, but with considerable other variations from night to night.
Antonino Lanza, co-author of the report in the journal Monthly Notices of the Royal Astronomical Society, says they expected to see the reflections change due to the rotation in Ceres’ position relative to the Sun, but the random changes in brightness may indicate that the material causing the lights is not hydrated magnesium sulfates (Epsom salts) , as NASA said in its latest reports on the Dawn photos, but something volatile that is affected by the heat of the Sun.
The spots were also observed to move faster than predicted based on the velocity of Ceres rotation. Combined with the random changes in brightness, the astronomers speculate that the the lights are caused by reflections off of not solid hydrated magnesium sulfates but plumes of gas released by the evaporation of some frozen material pushed to the surface by activity beneath it. That activity could be volcanoes, geysers, water flow or something yet to be determined.
Meanwhile, Dawn is still in orbit and still sending back pictures, which NASA will now compare to the analysis of the Harp astronomers, says Chris Russell, Dawn’s principal investigator at UCLA.
We are now comparing the spots with the reflective properties of salt, but we are still puzzled by their source. We look forward to new, higher-resolution data from the mission’s next orbital phase.
Controversy and competition on the cause of the curiosities in the crater of Ceres. No aliens but still fun and interesting. | 0.838316 | 3.526392 |
Here, you can find March 2020 astronomy calendar. Astronomy is the foundation upon which astrology can operate. Actually, astrology and astronomy were treated together, under the Latin name of astrologia, being separated only by the Western 17th century philosophy. For sure: a good astrologer needs to study astronomy.
9th March: Full Moon and Supermoon
The full moon is the lunar phase when the Moon appears fully illuminated from Earth’s perspective. This takes place when Earth is located directly between the Sun and the Moon. More exactly, the ecliptic longitudes of the Sun and Moon differ by 180°). This means that the lunar hemisphere facing Earth – the near side –appears as a circular disk (being completely sunlit), while the far side is dark.
This full moon is also the second supermoon of 2020 (the first was on 9th February, the third on 8th April and the fourth and the last on 7th May). The Moon will be at its closest approach to the Earth and may look slightly larger and brighter than usual.
March full moon was known by early Native American tribes as the Full Worm Moon because this was the time of year when the ground would begin to soften and the earthworms would reappear. Other names for this full moon were Wind Moon, Little Grass moon, Sore-Eye Moon, Crow Moon, Sap Moon, Lenten Moon, Chaste Moon, Death Moon and Crust Moon.
20th March: March Equinox
The March equinox or Northward equinox is the equinox on the Earth when the subsolar point (the point at which the sun is perceived to be directly overhead that is, where the sun’s rays strike the planet exactly perpendicular to its surface) appears to leave the Southern Hemisphere and cross the celestial equator, heading northward as seen from Earth.
The March equinox is known as the vernal equinox in the Northern Hemisphere and as the autumnal equinox in the Southern. So, this is the first day of spring (vernal equinox) in the Northern Hemisphere and the first day of fall (autumnal equinox) in the Southern Hemisphere.
The Sun will shine directly on the equator and there will be nearly equal amounts of day and night throughout the world.
24th March: New Moon
The New Moon is when the Sun and Moon are aligned, with the Sun and Earth on opposite sides of the Moon. The new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the unaided eye, except when silhouetted during a solar eclipse. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.
24th March: Mercury at Greatest Western Elongation
In astronomy, a planet’s elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The planet Mercury reaches greatest western elongation of 27.8 degrees from the Sun. March 24th is the best time to view Mercury since it will be at its highest point above the horizon in the morning sky. Look for the planet low in the eastern sky just before sunrise.
24th March: Venus at Greatest Eastern Elongation
In astronomy, a planet’s elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The planet Venus reaches greatest eastern elongation of 46.1 degrees from the Sun. March 24th is the best time to view Venus since it will be at its highest point above the horizon in the evening sky. | 0.829651 | 3.02973 |
NewScientist reports that “NASA’s FERMI satellite has confirmed a previous hint that there is more antimatter than expected coming from space. The bad news is that the result strongly almost certainly rules out Dark Matter as the source.”
In 2008 an excess of antimatter positrons was detected by the Russian-European PAMELA satellite. The new FERMI observations doubled the energy of positrons (up to 200 GigaElectronVolts – GeV) that could be detected. Unfortunately for the Dark Matter conjecture, extra positrons were found at these higher masses/energies.
Big Bang’s “missing mass” needs Dark Matter – which has never been detected – only theorized. To detect Dark Matter (which allegedly doesn’t interact with anything, except that it should invoke gravity to get galaxy rotation working and might have some weak force) anti-matter needs to disappear at a specific energy-mass level to indicate that Dark Matter exists at that energy-mass.
The disappearance of anti-matter at a specific energy-mass would mean that Dark Matter is combining with anti-matter at that energy-mass and both evaporated / were converted to energy.
An Italian experiment called DAMA suggests that Dark Matter particles may exist at 100 GeV. However some researchers believe these newer results eclipse the DAMA results.
While this does not necessarily mean that dark matter does not exist, it does mean anti-matter seen by the PAMELA experiment was not the elusive missing Dark Matter.
Unfortunately for all Dark Matter conjectures, researchers Gallo and Feng showed in 2008 that galaxy rotation curves are just fine; that they are perfectly understandable using Newtonian mechanics without resorting to speculative and exotic Dark Matter ideas.
Measurement of separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope, Fermi LAT Collaboration, 2011 | 0.857873 | 3.570406 |
A strange, metal brew lies buried deep within Jupiter and Saturn, according to a new study by researchers at the University of California, Berkeley, and in London.
The study, published in this week’s online edition of the journal Proceedings of the National Academy of Sciences, demonstrates that metallic helium is less rare than was previously thought and is produced under the kinds of conditions present at the centers of giant, gaseous planets, mixing with metal hydrogen and forming a liquid metal alloy.
“This is a breakthrough in terms of our understanding of materials, and that’s important because in order to understand the long-term evolution of planets, we need to know more about their properties deep down,” said Raymond Jeanloz, professor of astronomy and of earth and planetary science at UC Berkeley and one of the authors of the study. “The finding is also interesting from the point of view of understanding why materials are the way they are, and what determines their stability and their physical and chemical properties.”
Jeanloz studies pressures tens of millions of times greater than Earth’s atmospheric pressure – the kinds of forces felt inside Jupiter and Saturn, so called “gas giants” that lack a solid surface. The core of the Earth, which is small and dense compared to the cores of these gas giants, contains pressures of about 3.5 million times atmospheric pressure. Pressures at Jupiter’s core, for example, reach 70 million times Earth’s atmospheric pressure, the planet’s massive size more than offsetting its low density. The cores of Jupiter and Saturn are a balmy 10,000 to 20,000 degrees Celsius, two to four times hotter than the surface of the sun.
In this study, Jeanloz and Lars Stixrude, earth sciences professor at University College London, took a closer look at what happens to helium under such extreme conditions.
Most studies of materials in gaseous planets have focused on hydrogen, Jeanloz said, because it is the predominant element of both these planets and the universe. But even though hydrogen is the lightest element, its behavior is fairly complicated due to its tendency to form molecules of two bonded hydrogen atoms, Jeanloz said. Jeanloz and Stixrude wanted to study a simpler element, to more easily understand the effects of extreme temperatures and pressure.
So, they picked helium, the second most abundant element, which comprises five to 10 percent of the universe. They used theories based on quantum mechanics to calculate the behavior of helium under different pressures and temperatures. Although these equations are only approximations, Stixrude said, the researchers’ predictions closely matched experimental results for lower pressures.
Under Earthly conditions, helium is a colorless, see-through, electrically insulating gas. But under the kinds of pressure and temperature found at the centers of Jupiter and Saturn, the researchers found that helium turns into a liquid metal, like mercury.
“You can imagine this liquid looking like mercury, only less reflective,” Jeanloz said.
The finding was a surprise, as scientists had assumed that high pressures and high temperatures would make metallization of elements such as helium more difficult, not easier, Jeanloz said. He and his colleagues had previously found that helium starts to have some metal-like qualities in experiments at extremely high pressure, but they have not yet been able to experiment with helium under the conditions found inside giant planets.
A metal’s key characteristic is its ability to conduct electricity, meaning electrons can flow through it like water flowing unimpeded down a riverbed.
“High temperatures make the atoms jiggle around, and so people thought that raising the heat would deflect the electrons, like putting enough rocks in a stream to block the flow of water,” Jeanloz said. “The scattering caused by atoms was thought to make it harder for the electrons to flow down the stream.”
But it turns out that the atoms’ jostling also creates new ways for the electrons to move, almost as if new crevices had opened in the ground for the river’s flow, Jeanloz said.
Scientists recently discovered that hydrogen metalizes under lower temperatures and pressures than was previously appreciated. The dogma in the field was that the characteristics of hydrogen and helium were different enough that the two wouldn’t mix inside giant gaseous planets, Jeanloz said. The researchers’ findings, however, indicate that the two elements probably do mix, forming a metal alloy like brass, but liquid.
This finding also speaks to one of the many mysteries of these large planets, Stixrude said. More energy is emitted from Jupiter and Saturn than they absorb from the sun, and scientists don’t understand where it comes from. One of the prevailing theories is that droplets of helium condense out
of the planets’ outer atmospheres and fall to their centers as “helium
rain,” releasing gravitational energy. But Jeanloz and Stixrude’s findings show that helium and hydrogen are probably a more homogenous mix than was previously suspected, meaning that helium rain is unlikely.
“Now, we have to look elsewhere for this energy source,” Stixrude said. | 0.837914 | 3.905621 |
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