... Steep Cliffs on Mars . ... Also visible in the above image of the Martian North Polar Cap are red areas of rock and sand, white areas of ice, and dark areas of unknown composition but hypothesized to be volcanic ash. ... A Message From Earth . ... NGC 1499: California Nebula . ... Our own Sun also lies within the Milky Way's Orion Arm, only about 1,500 light-years from the California Nebula. ... Because Mercury orbits so close to the Sun, it never wanders far from the Sun in Earth's sky. ...