Black Hole Threatens to Consume Gas Nebula

A simulation of how the gas cloud may break apart as it approaches the black hole.

Credit: ESO/MPE/MARC SCHARTMANN

There is nothing stirs the imagination more than the awesome power of cosmic black holes.

Star-size black holes are powerful enough, but the super-massive black holes that lurk at the centers of most galaxies are millions of times more powerful.

When they swallow a star or a giant gas cloud, we call the resulting flare of energy a quasar, which can be visible halfway across the universe.

Now it’s about to happen right in our back yard. Back in 2011, astronomers spotted an interstellar gas cloud traveling towards the Milky Way’s own super-massive black hole, which is about the mass of four million Suns.

By the scientists’ calculations, the cloud will meet its doom in September or October 2013. “The impact will be deeper and more exciting than we thought,” says Stefan Gillessen, of the Max Planck Institute for Extraterrestrial Physics, in Garching, Germany, and the lead author of the Nature report that first announced the cloud’s existence.

Ordinarily, astronomers would expect an interstellar cloud like this (as well as any stars in the vicinity) to be orbiting the central black hole at an angle, spiraling in only gradually.

Not this one, though. “It’s remarkable how directly it’s moving toward the black hole,” says Reinhard Genzel, of the University of California, Berkeley, one of Gillessen’s co-authors. “Someone really aimed it very well.”

Astronomers have already seen changes in the cloud’s structure since it was first discovered. “There are clear signs that it’s being stretched,” says Gillesen.

That’s a result of tidal forces: the cloud’s leading edge feels the black hole’s gravity much more strongly than the trailing edge.

The difference in speed between front and rear is about 360 miles per second, and by April, says Gillesen, “we’re pretty sure the cloud should be starting to shred apart.” It is reminiscent, albeit on a much larger scale, of the fragmentation of Comet Shoemaker-Levy 9, which was tidally broken apart by Jupiter’s gravity before plunging to its death in July 1994.

Earth's Gravitational Pull Threatens Near-Earth Asteroids

Asteroids, such as Itokawa, pictured here, are thought to be more like piles of rubble loosely clung together, than solid chunks of rock. Credit: ISAS/JAXA

steroids may want to think twice before they swing too close to Earth. A new study has found that our planet's gravity can cause seismic tremors, or asteroid-quakes, if the space rocks stray too close.

This process could explain why many space rocks orbiting nearby appear pristine, as if they were covered in a new and clean surface, researchers said.

Normally, asteroids are weather-beaten, their top coats of rock made dirty and reddened by the onslaught of charged particles streaming off the sun during up to 4 billion years or more of wandering the solar system.

"Any part of the surface that's facing into the sun is hit by the solar wind, which damages the mineral grains and turns them red," said the study's lead researcher Richard Binzel of MIT. "An analogy is a sunburn."

Like a sunburn on your skin, the reddening of an asteroid is only skin deep, with fresher material lurking just beneath the sun-drenched surface of the space rock, he added.

But when asteroids approach the Earth, our planet's gravity may induce small quakes that shake up the space rocks, causing the weathered pebbles on their surface to turn over, revealing their cleaner undersides. Asteroids are thought to be more like piles of rubble loosely clung together, than solid chunks of rock, which means even a small tremble could displace surface material.

"All of the particles that got reddened are going to flip over and you're going to have new material that's fresh now out facing the sun," Binzel told SPACE.com. "So it's going to change the color of the asteroid from red to a brighter gray."

The idea has been suggested before, but now Binzel and his colleagues have finally found observational evidence that it's happening.

Barbeque Mentality Threatens Rare Mountain Gorillas

The habitat of rare mountain gorillas in the Democratic Republic of Congo is being threatened by charcoal production, officials said.

Thousands of kilns mounded from dirt within the 3,000-square-mile Virunga National Park produce charcoal for rebel forces. The park is home to about 200 endangered mountain gorillas.

The rebels fund their fighting by selling the charcoal to refugees who fled the violence of the region and now live near the city of Goma, park ranger Jean Bosco Bichamakara told The Times of London in a story reported Saturday.

To break the reliance on charcoal, villagers and refugees are being urged to use presses, paid for by the Rwandan wildlife service, that turn briquettes leaf mulch, rice husks and other organic waste into fuel briquettes, Bichamakara said. The rangers buy the villagers' surplus briquettes and sell them in Goma for a third the price of charcoal.

"There are 550 presses being used now," Bichamakara said. "Our objective is to have 1,000 by the end of the year and 6,000 by the end of 2011, all to diminish the threat to our environment."

NASA; Debris from Ariane rocket threatens ISS Spacestation

Space Shuttle Discovery astronauts Danny Olivas and Nicole Stott exit the International Space Station's Qwest airlock at the beginning of their spacewalk in this image from NASA TV.

The U.S. space agency is tracking debris from a portion of a European Artiane 5 rocket, that was launched more than three years ago.


The debris could pass close enough to require astronauts to fire thrusters to move the station and shuttle Discovery that is docked there out of the way, NASA officials said at a briefing.

The debris posed no immediate danger to the station or the shuttle, the agency said.

The debris, which is in an oval-shaped orbit that makes it difficult to track, will make its closest approach to the station at 11:06 a.m. EDT (3:06 p.m. GMT) on Friday, NASA said.

The debris will not force NASA to delay the second of three spacewalks planned outside the station on Thursday. NASA might decide to take no action, or could "reboost" the station from its current orbit 220 miles above the Earth after astronauts complete their second space walk, it said