Typically, the Perseverance rover is looking down, scouring the Martian terrain for rocks that may reveal aspects of the planet’s ancient past. But over the last several weeks, the intrepid robot looked up and caught two remarkable views: solar eclipses on the Red Planet, as the moons Phobos and Deimos passed in front of the Sun.
Full solar eclipses don’t happen on Mars. The planet’s moons are too small to fully block out the Sun as they pass in front of it. When they do pass, though, their movements can clue researchers into the moons’ orbits, as well as how the moons’ movements affect the Martian interior.
Perseverance landed on Mars in February 2021; since then, the rover has kept busy imaging the planet’s geology and coring rock samples for their—cross your fingers—eventual return to Earth. Perseverance hit 1,000 sols (that is to say, Martian days) on the planet in December 2023.
The rover spotted the moon Deimos passing in front of the Sun on January 20 corresponding to Sol 1037. Weeks later, corresponding to February 8 on Earth, Perseverance witnessed Phobos making the same crossing.
Phobos (meaning fear) is six times more massive than Deimos (panic); in footage of the two moons eclipsing Mars, their size difference is apparent. Phobos blocks out more of the Sun’s light than Deimos. Deimos is also about 2.5 times farther from Mars than Phobos, making it look like a pebble against the Sun compared to Phobos’ large, potato-shape silhouette.
Fun fact: Phobos is on a collision course with Mars; it will either break up or crash into the planet in tens of millions of years, according to NASA. Conversely, the tiny Deimos is slowly moving away from Mars.
Thankfully, that gives Perseverance plenty of time to gaze at the Martian moons. That is, when it’s taking a break from its typical, and arguably more crucial, duty: searching for signs of ancient life on Mars.