While what exactly goes on within the event horizon of a black hole is still well within the realm of theoretical physics (and it’s said that at the very heart of a black hole physics as we know it gets a serious kick in the pants) researchers are learning more and more about what happens in the immediate vicinity around a black hole, within the flattened disk of superheated material falling inexorably in toward the center. Using supercomputers, scientists can model the behavior of black holes’ accretion disks and see how gas behaves as it gets accelerated and drawn inward, heated to millions and even billions of degrees.
Here, an animation shows the activity around an active, non-rotating stellar-mass black hole. Taking 27 days to complete on a supercomputer at UT Austin, it shows “a turbulent froth orbiting the black hole” at relativistic speeds — that is, very close to the speed of light. Using this data, scientists are able to see how a black hole heats gas and emits different kids of x-rays… it’s the next best thing to being there! (Actually, it’s probably a much better thing than being there.)
Ever since high-resolution images of Mars’ surface have become available, scientists have wondered about the cause of long gullies seen running down along the slopes of ridges and crater walls. Here on Earth such features are often created by water flowing downhill, carving channels as it goes — but on Earth similar features usually end in fans of deposited material, while on Mars the channels simply just… stop.
To search for an answer to this mystery, NASA researchers took a field trip to some southwestern sand dunes and saw what happened when they sent various materials sliding down the slopes. As it turns out, dry ice — that is, frozen carbon dioxide, which is plentiful on Mars — does a very nice impression of a sled, picking up considerable momentum on black diamond and bunny slopes alike. The reason? Sublimation creates a pocket of gas that the slab of solid CO2 sits on, cutting down friction and giving it a smooth air-ride downhill.
Scientists working with data from NASA’s Cassini mission have confirmed the presence of a population of complex hydrocarbons in the upper atmosphere of Saturn’s largest moon, Titan, that later evolve into the components that give the moon a distinctive orange-brown haze. The presence of these complex, ringed hydrocarbons, known as polycyclic aromatic hydrocarbons (PAHs), explains the origin of the aerosol particles found in the lowest haze layer that blankets Titan’s surface. Scientists think these PAH compounds aggregate into larger particles as they drift downward.
“With the huge amount of methane in its atmosphere, Titan smog is like L.A. smog on steroids.”
– Scott Edgington, Cassini deputy project scientist
It’s time for Curiosity to get into high gear! NASA’s Mars Science Laboratory mission is approaching its biggest turning point since landing its rover, Curiosity, inside Mars’ Gale Crater last summer.
Curiosity is finishing investigations in an area smaller than a football field where it has been working for six months, and it will soon shift to a distance-driving mode headed for an area about 5 miles (8 kilometers) away, at the base Mount Sharp.
“We’re hitting full stride,” said Mars Science Laboratory Project Manager Jim Erickson of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We needed a more deliberate pace for all the first-time activities by Curiosity since landing, but we won’t have many more of those.”
Earth may display its seas on its surface for all the Universe to see, but further out in the Solar System liquid oceans are kept discreetly under wraps, hidden beneath cratered surfaces of ice and rock. And while Saturn’s moon Enceladus sprays its salty subsurface ocean out into space, other moons are less ostentatious — Europa, Ganymede, Titan… all are thought to have considerable underground oceans of liquid water, based on measurements of their mass, density, and shape.
Now, scientists are suggesting that Saturn’s 700-mile-wide moon Dione may also have a subsurface ocean… and may have even once exhibited icy geysers like its smaller sibling Enceladus.
That’s not a suggestion; it’s an order.
It doesn’t matter if it’s not scientifically accurate, or that asteroid fields don’t really work like that, or that you can’t “swim” through space. None of that matters with something at this level of cool. Enjoy!
Video and music by Professor Soap
On the afternoon of Friday, May 31, 2013, at 4:59 p.m. EDT, the nearly two-mile-wide asteroid 1998 QE2 will pass by our planet at a distance of about 5.86 million km (3.64 million miles)… about 15 times the distance between Earth and the Moon. And although it poses no threat of impacting Earth neither during this pass nor in the foreseeable future, on the eve of its close approach NASA revealed a surprising discovery about this cosmic visitor: it has a little moon of its very own!