Weird Science
Newcastle Herald
Tuesday January 17, 2006
GALAXIES, astronomers tell us, are big.
Really big. Like so big that even if you could travel at the speed of light (about 300,000 kilometres per second) it would still take you about 100,000 years to get from one side of our galaxy to the other. And that's provided you didn't hit any of the 200-odd billion stars and other bits of cosmic debris that make up our Milky Way.Really, really big.Which is why it came as a bit of a shock last week when astronomers announced they'd found a new galaxy right in our backyard.At a meeting of the American Astronomical Society astronomer Robert H Lupton of Princeton university reported that it appeared another galaxy was colliding with our own a mere 30,000 light years from us near the constellation of Virgo.It appeared the foreign galaxy was much smaller, with only a few hundred thousand stars. Lupton said some of the stars in this invader had been observed for centuries, but nobody noticed because they were so closely interwoven with our own.It wasn't until the Sloan Digital Sky Mapping Survey, which has spent the past five years measuring the distances to nearly 50 million stars to create a three dimensional map of our galaxy, that astronomers noticed something interesting.It appeared there was a large arrangement of stars almost at right angles to the Milky Way's main disc. "It's like looking at the Milky Way with a pair of 3D glasses," said Lupton. "This structure that used to be lost in the background suddenly snapped into view." "We believe it is almost certainly a dwarf galaxy merging with the Milky Way. It is almost certainly a galaxy being ripped up, eaten, and otherwise digested by our galaxy. "So the Milky Way is still growing. It's not a static system. It's growing by cannibalising smaller neighbors."Lupton said it would take about another billion years for the Milky Way to finish eating its unfortunate neighbour.
© 2006 Newcastle Herald
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