Astronomy Picture of the Day

Explanation: Are these two galaxies really attracted to each other? Yes, gravitationally, and the result appears as an enormous iconic heart -- at least for now. Pictured is the pair of galaxies catalogued as NGC 4038 and NGC 4039,known as the Antennae Galaxies. Because they are only 60 million light years away, close by intergalactic standards, the pair is one of the best studied interacting galaxies on the night sky. Their strong attraction began about a billion years ago when they passed unusually close to each other. As the two galaxies interact, their stars rarely collide, but new stars are formed when their interstellar gases crash together. Some new stars have already formed, for example, in the long antennae seen extending out from the sides of the dancing duo. By the time the galaxy merger is complete, likely over a billion years from now, billions of new stars may have formed.