Hubble finds Andromeda's star formation slowing over 500 million years
NASA's Hubble Space Telescope just found that the Andromeda galaxy has been slowing down its star-making for about 500 million years, with an even steeper drop in the last 40 million.
By mapping two-thirds of Andromeda's disk and studying 200 million stars, scientists pieced together this cosmic slowdown.
Hubble study links starburst to merger
Turns out, Andromeda had a big burst of star formation about two billion years ago, probably after merging with another galaxy.
Since then, things have quieted down, especially in a ring 32,000 light-years from its center.
Lead author Tobin Wainer of the University of Washington says it's not because the galaxy ran out of material; he calls it more like a breather after all that action.
Hubble's deep dive helps us understand how galaxies like ours change over time.