NASA's Dawn Mission has found permanently shadowed craters on Ceres.
These craters are at the dwarf planet's poles, where they receive no sunlight.
Ceres has just enough gravity to retain water molecules.
If a shadowed crater remains below about -240 degrees Fahrenheit
it is a cold trap.
Shadowed craters on Ceres are cold enough to have been collecting ice over billions of years.
Scientists will investigate further as Dawn continues to explore Ceres.