Einstein cross gravitational lens. Source
It is common knowledge (to use the term loosely) that spiral galaxies like the one shown here have one nucleus, but this one appears to have four. Astronomers think that this galaxy isn't actually that strange, but that a quasar behind the galaxy is emitting light that is being bent into the cloverleaf pattern shown here by the gravity of the galaxy. This effect is known as gravitational lensing. Einstein thought of it a long time ago, but it just seems to strange to be true. But observations continually prove him right.