The Andromeda galaxy is the galaxy next door, a very faint, fuzzy thing in the night sky, larger than a full moon. Textbooks claim it’s visible to the naked eye. Most of us have never noticed it. Too ...

The irregular galaxy Arp 263 lurks in the background of this image from the NASA/ESA Hubble Space Telescope, but the view is dominated by a stellar photobomber, the bright star BD+17 2217.

When the gravity of a foreground galaxy distorts and magnifies light from a background galaxy, the result is either a single Einstein ring or multiple images of the object.