60-Second Science

Milky Way Now in Larger Size!

A study presented at the meeting of the American Astronomical Society finds that we're moving 100,000 miles per hour faster in our galactic orbit than we thought, and that the Milky Way Galaxy is half again as massive as previously believed. Steve Mirsky reports

[The following is an exact transcript of this podcast.]

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

—Steve Mirsky 

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