Astronomy Picture of the Day

Explanation: Asteroids almost as large as planets are still being discovered in our own Solar System. Recently an asteroid more than half the size of Pluto was found orbiting at a distance only a little further than the Solar System's most distant planet. The large asteroid moves relative to background stars in the discovery images shown above taken by the Oschin Telescope at Palomar, California, USA. Quaoar, the name suggested for the space rock by its discoverers, is one of several large asteroids discovered recently that roam in the distant Kuiper Belt. Quaoar's size was resolved by images from the Hubble Space Telescope. Quaoar is likely a cold world covered in ice from which the Sun appears only as a particularly bright star.