Phobos circles Mars every 7.6 hours, meaning solar eclipses on Mars are far more common than eclipses on Earth. A transit of Phobos usually lasts only 30 seconds or so due to its quick orbit. "Because Phobos' orbit is almost perfectly in line with the Martian equator and relatively close to the planet's surface, transits of the moon occur on most days of the Martian year," NASA officials said in a statement. "At the same time that Phobos appeared as a large black disc rapidly moving across the face of the Sun, its shadow, or antumbra, moved across the planet's surface."

Measuring only about 17 miles at its widest point, Phobos is roughly 157 times smaller in diameter than Earth's moon. Mars' other moon Deimos is even smaller.

It's not the first time a NASA rover has witnessed Phobos blocking out the Sun. Perseverance has captured several Phobos transits since landing at Mars' Jezero Crater in February 2021. Curiosity captured a video in 2019 and Opportunity captured an image in 2004. "By comparing the various images, scientists can refine their understanding of the moon's orbit to learn how it's changing," NASA officials said. "Phobos is getting closer to Mars and is predicted to collide with it in about 50 million years."