NASA's Mars Rover Curiosity Captures Phobos Passing Directly in Front of the Sun

NASA's Mars rover Curiosity captured  Phobos, the larger of Mar's two moons, passing directly in front of the sun on August 17.

The set of three images was taken three seconds apart as Phobos passed in front of the sun.  These are the first full resolution frames that were sent to Earth.  Seen from the surface of the Mars, Phobos does not fully cover the sun, so this solar eclipse is called a ring or annular type.

During the mission's 369^th Martian day, Curiosity with the help of the telephoto-lens camera of the rover's Mast Camera pair, photographed the annular eclipse of the sun by Phobos. These images produced by Curiosity are the sharpest images of a solar eclipse ever captured on Mars.

"This event occurred near noon at Curiosity's location, which put Phobos at its closest point to the rover, appearing larger against the sun than it would at other times of day," Mark Lemmon of Texas A&M University, College Station, a co-investigator for use of Curiosity's Mastcam said in a news release. "This is the closest to a total eclipse of the sun that you can have from Mars." 

The position of Phobos on August 17 as it crossed the sun was just two-three kilometers closer to the center of the sun's position than what the researchers had expected.

The observation made by rover  and the current active Mars Rover Opportunity on the two Martian moon's Phobos and Deimos will help researchers measure the moon's orbit even more accurately.

 Lemmon concluded saying, "This one is by far the most detailed image of any Martian lunar transit ever taken, and it is especially useful because it is annular. It was even closer to the sun's center than predicted, so we learned something."