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
Dark ray craters are rare and have been seen mostly on
Jupiter's largest moon Ganymede, e.g. the 30-km-wide Kittu.
GEOLOGY AND PLANETARY