Scholastic News
News
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
 • 
Mars
Space
Activities
Teachers

See All Special Reports
Collision Course
By Ezra Billinkoff

A composite X-ray(blue) image of the galaxy cluster Abell 400 shows radio (pink) jets in a vast cloud of multimillion degree X-ray.
A composite X-ray(blue) image of the galaxy cluster Abell 400 shows radio (pink) jets in a vast cloud of multimillion degree X-ray.
(Photo: X-ray: NASA/CXC/AIfA/D.Hudson & T.Reiprich et al.; Radio: NRAO/VLA/NRL)
April 10, 2006—What looks like a black hole, behaves like a black hole, but is bigger than a black hole? Two black holes! Astronomers last week discovered a pair of enormous black holes far out in the galaxy that appear to be dancing toward a collision.

Scientists who are studying this phenomenon say that although the black holes do seem to be moving toward each other, this is no ordinary courtship. It seems "more like the mating of black widow spiders," says Craig Sarazin, of the University of Virginia. "One of the black holes . . . will eat the other."

Black holes are objects in outer space that are so dense that nothing can escape their gravity. They often sit in the center of a galaxy—like the Milky Way—and suck up everything near them. The gravitational pull of a black hole is so intense that not even light (which travels faster than anything else in space) can make it past without being swallowed.

Black holes, like the one at the center of the Milky Way, are enormous. Scientists call some of them "supermassive," because they can be a few million times the size of most stars. Their size, their mass, and their inescapable gravity make black holes an immense force of nature in outer space.

Because there is no light near black holes, astronomers cannot actually see them; they are completely invisible to us on Earth. Scientists manage to detect the existence of a black hole by watching what happens to other objects, or matter, floating in space.

So how did scientists manage to get a good look at a region so far away? The team used an orbiting NASA observatory known as Chandra. This special observatory uses X-rays rather than light to peer far out into space. Right before a star gets sucked into a black hole, it produces a large number of X-rays.

"We want to look at the universe in X-rays because the most violent, explosive objects in the universe make X-rays, not visible light," says Sarazin of the decision to use Chandra.

Unanswered Questions

Scientists believe black holes are some of the oldest objects in space. Many astronomers follow the black holes because there may be clues about the beginning of the universe hidden within them. However, as Sarazin and his team explain, there are still many unanswered questions.

"There is no way to determine how a black hole was created, or what kinds of things it has swallowed, by just looking at the resulting black hole," Sarazin said. "You have to catch it when it is sitting down to dinner or still eating [other objects in space]."

Scientists believe that the discovery of two merging black holes will help explain how black holes come into existence, and how they get larger. They also know that the resulting, single black hole will be able to swallow up billions of stars' worth of mass.

While the two black holes appear to be advancing toward each other, a collision won't be happening anytime soon. Astronomers say this is not likely to occur for several million years. In the meantime, they keep their eyes on the sky, looking for the next exciting space discovery.