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Mars Exploration Program

Mercury Passes in Front of the Sun, as Seen From Mars


Mercury Transit of the Sun, Seen From Mars
Mercury Transit of the Sun, Seen From Mars
This animated blink comparison shows five versions of observations that NASA's Curiosity rover made about one hour apart while Mercury was passing in front of the sun on June 3, 2014. Two sunspots, each about the diameter of Earth, also appear, moving much less than Mercury during the hour.

This is the first transit of the sun by a planet observed from any planet other than Earth, and also the first imaging of Mercury from Mars. Mercury fills only about one-sixth of one pixel as seen from such great distance, so the darkening does not have a distinct shape, but its position follows Mercury's expected path based on orbital calculations.

The observation by the telephoto camera of Curiosity's two-eyed Mast Camera instrument is available online at:

"This is a nod to the relevance of planetary transits to the history of astronomy on Earth," said Mark Lemmon of Texas A&M University, College Station, a member of the Mastcan science team. "Observations of Venus transits were used to measure the size of the solar system, and Mercury transits were used to measure the size of the sun."

The observations were made on June 3, 2014, from Curiosity's position inside Gale Crater on Mars. In addition to showing the Mercury transit, the same Mastcam frames show two sunspots approximately the size of Earth. The sunspots move only at the pace of the sun's rotation, much slower than the movement of Mercury.




Credit: NASA/JPL-Caltech

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