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Explanation: Hurtling through space a mere 3,000 miles above the Martian surface, the diminutive moon Phobos (below and left of center) was imaged against the backdrop of a large shield volcano by the Viking 2 Orbiter in 1977. This dramatic picture looks down from the Orbiter's viewpoint about 8,000 miles above the volcano, Ascraeus Mons. Phobos itself is 5,000 miles below the Orbiter. North is toward the top with the Sun illuminating the scene from the South (black dots are reference marks). For scale, Ascraeus Mons is about 200 miles across at its base while asteroid sized Phobos is about 15 miles in diameter. In this spectacular moon-planet image, volcanic calderas (craters) are visible at the summit of Ascraeus Mons -- while impact craters on the sunlit side of Phobos' surface can also be seen!
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Mars - Phobos - Martian moon - Viking project
Publications with words: Mars - Phobos - Martian moon - Viking project
See also:
- Full Moon, Full Mars
- APOD: 2025 January 15 Á Wolf Moon Engulfs Mars
- APOD: 2024 December 3 Á Ice Clouds over a Red Planet
- APOD: 2024 November 10 Á Valles Marineris: The Grand Canyon of Mars
- APOD: 2024 September 9 Á Mars: Moon, Craters, and Volcanos
- APOD: 2024 June 5 Á Shadow of a Martian Robot
- Ares 3 Landing Site: The Martian Revisited