Tuesday, January 06, 2009
a bigger & faster galaxy - and it's ours.
from sky & telescope:
The team finds that the galaxy's rotation rate is 270 kilometers per second (600,000 miles per hour). This is 15 percent faster than previously thought. And that in turn means the Milky Way is more massive than previously believed. In fact, it puts our galaxy on equal footing with our nearest large neighbor, the Andromeda Galaxy (M31).
Because Andromeda has more stars than the Milky Way, astronomers have generally assumed that it was about 50 percent more massive. But this new result agrees with a study published two years ago by Mark Wilkinson (Cambridge University, England) and his colleagues. By studying the motions of satellite dwarf galaxies and globular clusters, they found that the Milky Way is at least as massive, and maybe more so, than Andromeda.
“We should no longer think of the Milky Way as the little sister of the Local Group of galaxies,” says Reid. “The two galaxies are basically fraternal twins — equal in mass.”
and we are all moving at 600,000 miles per hour...