Saturday, March 20 2004 @ 02:12 AM CST
Contributed by: dgrosvold
Astronomers have finally confirmed something they had long suspected: there is
a super-massive black hole in the center of our Milky Way galaxy. The evidence? A star near the galactic center orbits something unseen at a top speed of 5000 km/s. Only a black hole 2 million times more massive than our Sun could cause the star to move so fast. (See the Oct. 17, 2002, issue of Nature
for more information.)
Still, a key mystery remains. Where did the black hole come from? For that matter, where do any
super-massive black holes come from? There is mounting evidence that such "monsters" lurk in the middles of most galaxies, yet their origin is unknown. Do they start out as tiny black holes that grow slowly, attracting material piecemeal from passing stars and clouds? Or are they born big, their mass increasing in large gulps when their host galaxy collides with another galaxy?
A new space telescope called LISA (short for "Laser Interferometer Space Antenna") aims to find out. Designed by scientists at NASA and the European Space Agency, LISA doesn't detect ordinary forms of electromagnetic radiation such as light or radio waves. It senses ripples in the fabric of space-time itself--gravitational waves.