Astronomy Picture of the Day

Explanation: The weathered and layered face of Mount Mercou looms in the foreground of this mosaic from the Curiosity Mars rover's Mast Camera. Made up of 21 individual images the scene was recorded just after sunset on March 19, the 3,063rd martian day of Curiosity's on going exploration of the Red Planet. In the martian twilight high altitude clouds still shine above, reflecting the light from the Sun below the local horizon like the noctilucent clouds of planet Earth. Though water ice clouds drift through the thin martian atmosphere, these wispy clouds are also at extreme altitudes and could be composed of frozen carbon dioxide, crystals of dry ice. Curiosity's Mast Cam has also imaged iridescent or mother of pearl clouds adding subtle colours to the martian sky.