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.

2024 September 9
A panoramic view of the surface of Mars. Several landforms are 
visible including craters and volcanos. A small dark moon is superposed
in front of part of the surface. 
Please see the explanation for more detailed information.

Mars: Moon, Craters, and Volcanos
Image Credit: ESA, DLR, FU Berlin, Mars Express; Processing & CC BY 2.0 License: Andrea Luck; h/t: Phil Plait

Explanation: If you could fly over Mars, what might you see? The featured image shows exactly this in the form of a Mars Express vista captured over a particularly interesting region on Mars in July. The picture's most famous feature is Olympus Mons, the largest volcano in the Solar System, visible on the upper right. Another large Martian volcano is visible on the right horizon: Pavonis Mons. Several circular impact craters can be seen on the surface of the aptly named red planet. Impressively, this image was timed to capture the dark and doomed Martian moon Phobos, visible just left of center. The surface feature on the lower left, known as Orcus Patera, is unusual for its large size and oblong shape, and mysterious because the processes that created it still remain unknown. ESA's robotic Mars Express spacecraft was launched in 2003 and, among many notable science discoveries, bolstered evidence that Mars was once home to large bodies of water.

Tomorrow's picture: golden space horse


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