It was Sol 713, or the 713th day since the touchdown of NASA’s Curiosity rover on Mars. According to earthly calendars, it was August 8, 2014. The martian early morning sun was only 17.75 degrees above the eastern horizon, when, from the floor of the Gale Crater, the rover’s 100mm MastCam camera caught Mars’ larger moon Phobos passing in front of the sun.
The sun as viewed from Mars at the time was in front of the constellation of Taurus the Bull.
Mars was some 221.55 million kilometers / 137.58 million miles from the sun at the time. Phobos was only 7,849 kilometers / 4,874 miles from Mars. Yet Phobos is so small it still did not cover the sun completely.
The large Stickney Crater on Phobos is seen in profile against the sun as the ‘flat’ bit, facing downwards, with Hall Crater on the right hand side of the lumpy, asteroidal moon.
Andrew R. Brown, an avid follower of the space program, writes frequently about space topics for EarthSky. Over several years, he has also suggested observations that were carried out by imaging teams of some space missions. He has lives in Ashford, Kent, United Kingdom and works for local government, Kent County Council.