Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

October 19, 1998 Olympus Mons from Orbit Credit: Mars Global Surveyor Project, MSSS, JPL, NASA

Explanation: Olympus Mons on Mars is the largest volcano in the Solar System. Although three times higher than Earth's Mount Everest, Olympus Mons would not be difficult to climb because of the volcano's great breadth. Covering an area greater than the entire Hawaiian volcano chain, the slopes of Olympus Mons typically rise only a few degrees at a time. The low gravity of Mars combined with a relatively static surface crust allow volcanoes this large to build up over time. This representative-color image was taken last April by the Mars Global Surveyor spacecraft currently orbiting Mars.