Tycho crater on the Moon.
A ray crater is a relatively young impact crater from which radiate streaks of material thrown out during the collision that created the crater. Bright ray craters are found on various bodies in the Solar System including the Moon, Mercury, Ganymede, Callisto, and Oberon. The lunar craters Tycho (shown in the accompanying photo) and Copernicus are particularly conspicuous examples, with bright rays extending for hundreds of kilometers.
Dark ray craters are rare and have been seen mostly on Jupiter's largest moon Ganymede, e.g. the 30-kilometer-wide Kittu.