The Sciences

The Tiniest Galaxy in the Universe

Meet Segue 2, the galaxy that is millions of times smaller than the Milky Way.

By Liz KruesiJan 28, 2014 8:05 PM
Segue 2, the smallest known galaxy, is just one of many similar diminutive galaxies astronomers expect to find around the Milky Way, as shown in this colorful simulation. | Garrison-Kimmel, Bullock/University of California, Irvine.


Sign up for our email newsletter for the latest science news

Astronomers can measure a galaxy’s mass by how stars move within it: The faster they move, the more massive it is. 

With this knowledge, a University of California, Irvine, team found that Segue 2, discovered in 2009, weighs at most 150,000 times more than our sun — the puniest galaxy known. (Our normal-size Milky Way is 10 million times more massive.) 

Segue 2 is probably just one of many such astronomical miniatures orbiting the Milky Way, says UCI astronomer Evan Kirby: “Simulations predict that there should be tens of thousands of these things.”

[This article originally appeared in print as "The Tiniest Galaxy in the Universe."]

1 free article left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

1 free articleSubscribe
Discover Magazine Logo
Want more?

Keep reading for as low as $1.99!


Already a subscriber?

Register or Log In

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Our List

Sign up for our weekly science updates.

To The Magazine

Save up to 40% off the cover price when you subscribe to Discover magazine.

Copyright © 2023 Kalmbach Media Co.