Astronomy Picture of the Day

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

January 21, 1996

Mercury's Faults
Credit: NASA, JPL, Mariner 10, Copyright Calvin J. Hamilton (LANL)

Explanation: The surface of the planet Mercury is not without fault. In this case, however, "fault" refers to unusual surface features that are the topic of much speculation. The above fault line is called Santa Maria Rupes, and runs through many prominent craters. The meandering feature is thought to be the result of huge forces of compression on Mercury's surface. Such rupes probably originate from large impacts and a general shrinking of Mercury's crust, which in turn causes parts of the crust to push above other parts.

Tomorrow's picture: Betelgeuse, Betelgeuse, Betelgeuse

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