SSS 2009-01-05

（单词翻译）

This is Scientific American's 60-Second Science. I'm Steve Mirsky . Got a minute ?

We residents of the Milky¹ Way should have a little extra skip in our step today. Turns out our home galaxy² is much bigger and moving a lot faster than we previously³ thought. That’s what researchers from the Harvard–Smithsonian Center for Astrophysics reported January 5th at the meeting of the American Astronomical⁴ Society.

Older studies of our galaxy’s structure and motion used indirect measurements. But we can now use radio telescopes to directly observe certain features of the galaxy when we’re in very different places in our orbit around the sun. And using traditional surveying methods, such as triangulation, researchers came up with the new figures.

First, we’re moving about 600,000 miles per hour in our galactic orbit, a lot zippier than the old estimate of 500,000. And the Milky Way’s total mass is about half again as much as we used to think. Which means we’re about as massive as the nearby Andromeda Galaxy. The Milky Way’s bigger mass does mean a greater chance of a gravity-driven collision with Andromeda. But if that clash occurs, at least now we’re in the same weight-class.

Thanks for the minute for Scientific American's 60-Second Science. I'm Steve Mirsky .