"The surface of the Earth is the shore of the cosmic ocean... Recently, we've managed to wade a little way out, and the water seems inviting." - Carl Sagan
Explosion on the Moon!
Pock-marked with craters and splotched with long-cold beds of dark lava, our moon holds thousands of footprints from its violent past. But we don’t really think of it having a violent present.
Well, it still gets its fair share of action. On March 17, 2013, NASA astronomers captured video of a meteorite striking the moon. It made an explosion bright enough to be seen with the naked eye, like a temporary star drawn on the lunar surface. It turns out that these collisions are not that rare.
Most of the moon’s many meteor marks date from a period known as the Late Heavy Bombardment. That, combined with a magma-riffic adolescence gave the moon the special look we know today. Of course, none of that is as violent as the moon’s birth.
Anyway, make sure to watch that video above and see the meteor strike live. You’ll never look at the moon the same way again.
Weather on the outer planets only goes so deep
What is the long-range weather forecast for the giant planets Uranus and Neptune? These planets are home to extreme winds blowing at speeds of over 1000 km/hour, hurricane-like storms as large around as Earth, immense weather systems that last for years and fast-flowing jet streams.
Both planets feature similar climates, despite the fact that Uranus is tipped on its side with the pole facing the sun during winter. The winds on these planets have been observed on their outer surfaces; but to get a grasp of their weather systems, we need to have an idea of what is going on underneath. For instance, do the atmospheric patterns arise from deep down in the planet, or are they confined to shallower processes nearer the surface? New research at the Weizmann Institute of Science, the University of Arizona and Tel Aviv University, which was published online today in Nature, shows that the wind patterns seen on the surface can extend only so far down on these two worlds.
Understanding the atmospheric circulation is not simple for a planet without a solid surface, where Earth-style boundaries between solid, liquid and gas layers do not exist. Since the discovery of these strong atmospheric winds in the 1980s by the Voyager II spacecraft, the vertical extent of these winds has been a major puzzle - one that influences our understanding of the physics governing the atmospheric dynamics and internal structure of these planets. But a team led by Dr. Yohai Kaspi of the Weizmann Institute’s Environmental Sciences and Energy Research Department realized they had a way, based on a novel method for analyzing the gravitational field of the planets, to determine an upper limit for the thickness of the atmospheric layer.
Deviations in the distribution of mass in planets cause measurable fluctuations in the gravitational field. On Earth, for example, an airplane flying near a large mountain feels the slight extra gravitational pull of that mountain. Like Earth, the giant planets of the solar system are rapidly rotating bodies. In fact all of them rotate faster than Earth; the rotation periods of Uranus and Neptune are about 17 and 16 hours, respectively. Because of this rapid rotation, the winds swirl around regions of high and low pressure. (In a non-rotating body, flow would be from high to low pressure.) This enables researchers to deduce the relations between the distribution of pressure and density, and the planets’ wind field. These physical principles enabled Kaspi and his co-authors to calculate, for the first time, the gravity signature of the wind patterns and thus create a wind-induced gravity map of these planets.
By computing the gravitational fields of a large range of ideal planet models - ones with no wind, a task conducted by team member Dr. Ravit Helled of Tel Aviv University - and comparing them with the observed gravitational fields, upper limits to the meteorological contribution to the gravitational fields were obtained. This enabled Kaspi’s team, which included Profs. Adam Showman and Bill Hubbard of the University of Arizona, and Prof. Oded Aharonson of the Weizmann Institute, to show that the streams of gas observed in the atmosphere are limited to a “weather-layer” of no more than about 1000 km in depth, which makes up only a fraction of a percent of the mass of these planets.
Image credit: NASA
Earth from space: Clearwater
This Landsat image from 9 September 2010 features the Clearwater Lakes in Canada’s Quebec province.
Located to the east of the Hudson Bay, what appears to be two separate lakes is actually a single body of water that fills two depressions. The depressions were created by two meteorite impacts, believed to have hit Earth simultaneously up to 290 million years ago.
The larger of the two to the northwest is about 36 km in diameter and has a ring of islands in the centre. The smaller is about 26 km in diameter. A string of islands separate the two water-filled craters.
The name ‘Clearwater Lakes’ comes from the clarity of its water. The surrounding terrain is dotted with smaller lakes and rivers. The topography of this area, known as the Canadian Shield, was shaped by the huge ice sheets and glaciers from the last ice ages covering the area up to 15,000 years ago.
Image credit: USGS/ESA
Mars Rover Opportunity examines clay clues in rock
NASA’s senior Mars rover, Opportunity, is driving to a new study area after a dramatic finish to 20 months on “Cape York” with examination of a rock intensely altered by water.
The fractured rock, called “Esperance,” provides evidence about a wet ancient environment possibly favorable for life. The mission’s principal investigator, Steve Squyres of Cornell University, Ithaca, N.Y., said, “Esperance was so important, we committed several weeks to getting this one measurement of it, even though we knew the clock was ticking.”
“What’s so special about Esperance is that there was enough water not only for reactions that produced clay minerals, but also enough to flush out ions set loose by those reactions, so that Opportunity can clearly see the alteration,” said Scott McLennan of the State University of New York, Stony Brook, a long-term planner for Opportunity’s science team.
This rock’s composition is unlike any other Opportunity has investigated during nine years on Mars — higher in aluminum and silica, lower in calcium and iron.
The next destination, Solander Point, and the area Opportunity is leaving, Cape York, both are segments of the rim of Endeavour Crater, which spans 14 miles (22 kilometers) across. The planned driving route to Solander Point is about 1.4 miles (2.2 kilometers). Cape York has been Opportunity’s home since the rover arrived at the western edge of Endeavour in mid-2011 after a two-year trek from a smaller crater.
The team identified Esperance while exploring a portion of Cape York where the Compact Reconnaissance Spectrometer for Mars (CRISM) on NASA’s Mars Reconnaissance Orbiter had detected a clay mineral. Clays typically form in wet environments that are not harshly acidic. For years, Opportunity had been finding evidence for ancient wet environments that were very acidic. The CRISM findings prompted the rover team to investigate the area where clay had been detected from orbit. There, they found an outcrop called “Whitewater Lake,” containing a small amount of clay from alteration by exposure to water.
Image credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.
During the day, some of us are lucky enough to be able to look up and see a clear blue beautiful sky and ‘our’ radiant Sun. During the night, most of us can gaze into the night sky and see lots of little bright points, stars. When we look up and see what we call ‘our Sun’, it can be hard to imagine that what we see also looks like this:
Most of you may look at this and instantly know that it’s a Star. However, there are a fair amount of people who don’t realize that our night sky is full of millions of Stars like this, smaller, bigger and some the same size. Some people don’t know that the Sun is actually a star. I’ve got to admit that the image above looks nothing like what I see with the naked eye when looking up into the Sky:
You’ve probably been told that staring directly at the Sun is bad for your eyes. However, we don’t have to have uncomfortable staring contests with the Stars to try and get them to give up their secrets! After years and years of research, scientists have managed to find out quite a bit about the oh-so-secretive Stars without losing a staring contest.
Firstly, stars go through the same process that we do in the sense that they are born, live and then die. The difference is that they do it far more dramatically and take a much longer time doing it. Depending on the mass of the Star, the lifetime can range from a few million years to trillions of years!
Naturally, this is where the comparisons between humans and Stars have to stop. The birth place of a Star is a huge, cold cloud of gas and dust, nebulae/nebulas.
These clouds begin to shrink, a result of their own gravity. As a cloud begins to shrink it gets smaller and the cloud breaks up into clumps. Eventually, these clumps reach high enough temperatures and get so dense that nuclear reactions begin. When the temperature reaches about 10 million degrees Celsius, the clump becomes a new star, a protostar. A protostar is not very stable. In order to live on, the protostar will need to achieve and maintain equilibrium, a balance between gravity pulling atoms towards the center of the protostar and gas pressure pushing heat and light away from the center. When a star can no longer maintain this balance, it dies.
How do we “know” any of this?
Infrared observatories such as ESA’s Herschel space observatory (launched in May 2009) are able to detect the heat that comes from such stars that we are not able to see, and therefore give us the information we need to research further.
If the critical temperature in the core of a protostar is never reached, it ends up as a brown dwarf, never achieving “star status”. However, if the critical temperature in the core of a protostar is reached then nuclear fusion begins. It is no longer classified as a protostar. It’s defined as a Star in the moment that it begins fusing the hydrogen in the core into helium. Simply put, nuclear fusion is a nuclear reaction where two or more atomic nuclei collide at high speeds and form a new type of atomic nucleus, in this case hydrogen forms helium.
“When a star can no longer maintain this balance, it dies.”
At “Star Status”, Stars spend the majority of their lives fusing hydrogen. So what happens when the hydrogen fuel is gone? Well, the Stars fuse helium into carbon and after a while, into even heavier elements. Maintaining the balance between gravity and gas pressure becomes very hard. The Stars eventually start to collapse on themselves. Before the Star’s inevitable collapse, nuclear reactions outside of the core cause the dying Star to expand outwards and this is what we call the “Red Giant” phase. It really is as dramatic as it sounds.
How dramatic the death is, depends on the mass of the Star. Our Sun is expected to turn into a white dwarf Star. If a Star has a slightly larger mass than our Sun, it may undergo a supernova explosion and leave behind a neutron Star. If even larger, at least three times the mass of the Sun, the Star could even implode to form an infinite gravitational warp in space, a black hole!
Some stars are only just beginning to form, others are in the Main Sequence and some have begun to die. Luckily for us, there is an amazing diagram, The Hertzsprung – Russell diagram that shows the relationships and differences between Stars:
The diagram shows the temperature of the Stars and the Star’s luminosity. The vertical axis represents the Stars luminosity. Luminosity is the amount of energy a Star radiates in one second, where every Star is compared to each other based upon our Sun. Our sun is in the yellow part of the main sequence, and therefore has luminosity 1, all other Stars are compared to ours in this sense.
The horizontal axis represents the Star’s surface temperature, in Kelvin. Here we have higher temperatures on the left and lower temperatures on the right. Usually we go from lower to higher; however, it’s more adequate to see that a star in the upper left corner of the diagram is both hot and bright. A star in the upper right corner of the diagram is both cold and bright, what kind of star would this be? Take a look at the diagram. Happy Star hunting!
Preaching to Infinity has a Facebook page!
All the good stuff from here goes there and back again through a top secret wormhole built under a mountain in Colorado Springs.
Check it out at facebook.com/preachingtoinfinity/ and hit the like button. There will be some exclusive stuff for Tumblr and Facebook so it is wise to follow both.
Happy cosmic wanderings!
Next destination: space
ESA astronaut Luca Parmitano left for Baikonur, Kazakhstan today, his last stop before heading to the International Space Station on 28 May.
His launch on a Soyuz rocket will be the culmination of more than two years of preparation that has seen Luca training in Russia, Canada, Japan, Europe and the US at facilities of the Station partners.
Luca and his crewmates, cosmonaut commander Fyodor Yurchikhin and NASA astronaut Karen Nyberg, spent the last few weeks in Moscow, Russia passing their final exams for flying the Soyuz spacecraft. They received their official tickets to the Space Station on 10 May when the Soyuz examination board declared them qualified to fly.
The crew will stay at the traditional Cosmonaut Hotel for the last days before launch. Luca, Fyodor and Karen will be quarantined to make sure they do not take any unwanted bacteria or viruses to the Space Station. Family and support personnel such as flight surgeons will be the only people allowed to stay with them.
Cosmonauts Pavel Vinogradov, Alexander Misurkin and NASA astronaut Chris Cassidy are already on the Station and will welcome the new Expedition when the Soyuz docks on 29 May.
Image credit: NASA
Astronaut Chris Cassidy
Expedition 35 Flight Engineer Chris Cassidy, who currently is living and working aboard the International Space Station, is captured in a close-up image in the Quest Airlock prior to a spacewalk.
Image credit: NASA
“First Evidence for Extraterrestrial Sources of High-Energy Neutrinos” —Reports Antarctica Observatory
Although cosmic rays were discovered 100 years ago, their origin remains one of the most enduring mysteries in physics. Until now. A massive telescope at the IceCube Neutrino Observatory in the Antarctic ice reports the detection of 28 extremely high-energy neutrinos that might have their origin in cosmic sources. Two of these reached energies greater than 1 petaelectronvolt (PeV), an energy level thousands of times higher than the highest energy neutrino yet produced in a manmade accelerator.
“We’re looking for the first time at high energy neutrinos that are not coming from the atmosphere,” says Francis Halzen, principal investigator of IceCube and the Hilldale and Gregory Breit Distinguished Professor of Physics at University of Wisconsin–Madison. “This is what we were looking for,” he adds.
Because they rarely interact with matter and are unimpeded by gravity, neutrinos can carry information about the workings of the highest-energy and most distant phenomena in the universe. Though billions of neutrinos pass through the Earth every second, the vast majority originate either in the sun or in the Earth’s atmosphere. Far rarer are high-energy neutrinos that may hail from the most powerful cosmic events — such as gamma ray bursts, black holes, or star formation — where they would be created in association with high-energy cosmic rays that can reach energies up to thousands of PeVs.
Postdoctoral fellow Nathan Whitehorn described 28 high-energy neutrino events captured by the detector between May 2010 and May 2012. These events, including two that exceeded the unprecedented energy level of 1 PeV, were one of the main goals for building a detector such as IceCube.
“Their properties are strongly inconsistent with what you would expect of atmospheric sources and are almost exactly what you would expect from an astrophysical source,” Whitehorn says. It is premature to speculate where these neutrinos originated, he adds, but the IceCube collaboration is continuing to refine and expand the analysis.
IceCube is comprised of more than 5,000 digital optical modules suspended in a cubic kilometer of ice at the South Pole. The National Science Foundation-supported observatory detects neutrinos through the tiny flashes of blue light produced when a neutrino interacts with a water molecule in the ice.
The first hints of high-energy neutrinos came with the unexpected discovery in April 2012 of two detector events above 1 PeV. An analysis of those events was reported last month in a paper submitted to the journal Physical Review Letters. An intensified search, led by Whitehorn and fellow WIPAC scientists Claudio Kopper and Naoko Kurahashi Neilson, turned up 26 additional events exceeding 30 teraelectronvolts (TeV; one-thousandth of a PeV), which will be described in a forthcoming publication.
The Daily Galaxy via http://www.news.wisc.edu/21790
Question: If 2 black holes get near each other, can they then gravitationally pull matter out of the other black hole & back into “normal” space?
The short answer is no.
A black hole (in the traditional sense) is defined as an object that has collapsed so that its radius is equal to, or less than, the Schwarzschild of the object.
What does this mean?
Every object has a Schwarzschild radius; this is the point at which an object’s mass is so compressed that the gravitational influence overpowers the other forces of nature and it collapses to a singularity.
Of course, not every object is massive enough to collapse to its Schwarzschild radius. The Earth’s Schwarzschild radius, for example, is about the diameter of a small marble. If you were to apply enough energy to the Earth and compress its mass to that size, it would collapse to form a black hole. The same is true for humans, except I’d need to compress you to a point some 10-million times smaller than a marble in order to turn you into a black hole.
So, what is special about the Schwarzschild radius? This is the point at which the escape velocity for the object is equal to the speed of light. Obviously, since you can’t travel ,or faster than, the speed of light you can’t get out of a black hole neither can another black hole pull you out.
It’s important to realize that, outside of the Schwarzschild radius (also known as the event horizon), spacetime is normal. You can interact with a black hole in the same ways you interact with any other object of mass.
Image credit: NASA/CXC/A.Hobart
Have you ever noticed that almost every barn you have ever seen is red? There’s a reason for that, and it has to do with the chemistry of dying stars. Seriously.
Yonatan Zunger is a Google employee who decided to explain this phenomenon on Google+ recently. The simple answer to why barns are painted red is because red paint is cheap. The cheapest paint there is, in fact. But the reason it’s so cheap? Well, that’s the interesting part.
Red ochre—Fe2O3—is a simple compound of iron and oxygen that absorbs yellow, green and blue light and appears red. It’s what makes red paint red. It’s really cheap because it’s really plentiful. And it’s really plentiful because of nuclear fusion in dying stars. Zunger explains:
The only thing holding the star up was the energy of the fusion reactions, so as power levels go down, the star starts to shrink. And as it shrinks, the pressure goes up, and the temperature goes up, until suddenly it hits a temperature where a new reaction can get started. These new reactions give it a big burst of energy, but start to form heavier elements still, and so the cycle gradually repeats, with the star reacting further and further up the periodic table, producing more and more heavy elements as it goes. Until it hits 56. At that point, the reactions simply stop producing energy at all; the star shuts down and collapses without stopping.
As soon as the star hits the 56 nucleon (total number of protons and neutrons in the nucleus) cutoff, it falls apart. It doesn’t make anything heavier than 56. What does this have to do with red paint? Because the star stops at 56, it winds up making a ton of things with 56 neucleons. It makes more 56 nucleon containing things than anything else (aside from the super light stuff in the star that is too light to fuse).
The element that has 56 protons and neutrons in its nucleus in its stable state? Iron. The stuff that makes red paint.
And that, Zunger explains, is how the death of a star determines what color barns are painted.
i love this
Black hole-powered jets plow into galaxy
This composite image of a galaxy illustrates how the intense gravity of a supermassive black hole can be tapped to generate immense power. This multi-wavelength view shows 4C+29.30, a galaxy located some 850 million light years from Earth.
The radio emission (pink) comes from two jets of particles that are speeding at millions of miles per hour away from a supermassive black hole at the center of the galaxy. The estimated mass of the black hole is about 100 million times the mass of our Sun. The ends of the jets show larger areas of radio emission located outside the galaxy.
The X-ray data (blue) show a different aspect of this galaxy, tracing the location of hot gas. The bright X-rays in the center of the image mark a pool of million-degree gas around the black hole. Some of this material may eventually be consumed by the black hole, and the magnetized, whirlpool of gas near the black hole could in turn, trigger more output to the radio jet.
Most of the low-energy X-rays from the vicinity of the black hole are absorbed by dust and gas, probably in the shape of a giant doughnut around the black hole. This doughnut, or torus blocks all the optical light produced near the black hole, so astronomers refer to this type of source as a hidden or buried black hole. The optical light (gold) seen in the image is from the stars in the galaxy.
Image credit: NASA
The Milky Way near the Northern Cross
This beautiful image of the sky near the bright star Deneb (just above center) reveals the stars, nebulae, and dark clouds along the plane of our Milky Way Galaxy as seen from the northern hemisphere (near Columbia Missouri, USA). Just below Deneb lies the suggestively shaped North America emission nebula. Deneb is the brightest star in the constellation Cygnus, located in the tail of this celestial swan. Cygnus contains the asterism known as the Northern Cross and marks one side of the “Great Rift” in the Milky Way, a series of dark obscuring dust clouds which stretches on through the constellation Sagittarius. Deneb defines the top of the Northern Cross while the body of the cross extends past the upper right corner of the picture. Cygnus also harbors the most famous candidate for a black hole in our galaxy, Cygnus X-1.
Image credit: Andy Steere