UGC 2885, which is about 230 million light-years away, is the largest spiral galaxy yet seen in our region of the universe. It's 10 times as massive as our home galaxy, the Milky Way, and spans roughly 260,000 light-years. Much of its great mass consists of dark matter, which emits no detectable energy but reveals its presence through its gravitational pull on the visible matter around it. Astronomer Vera Rubin studied the galaxy in detail decades ago, confirming its dark matter, so today it's also known as Rubin's Galaxy in her honor. The bright star to the left of the galaxy's center is a foreground object and not part of UGC 2885. [NASA/ESA/Benne Holwerda (Univ. Louisville)]
Find out more in our radio program entitled Rubin’s Galaxy.