On September 30, NASA’s Perseverance Rover captured a unique sight as it looked up at the Sun from the Martian surface, appearing to spot a “googly eye” in the sky.

What the rover actually witnessed was an eclipse caused by Mars’ moon Phobos passing in front of the Sun.

Phobos, the larger of Mars’ two moons, provided the rover with this celestial display on its 1,285th Martian day of exploration. Due to Phobos’ small size, it doesn’t completely block the Sun; instead, it creates a dark silhouette as it crosses the solar disk.

NASA released a video of the event on October 30, showing Phobos—a moon about 17 miles wide and shaped like a potato—transiting across the Sun. For a brief moment, the shadow of Phobos resembled a pupil with the Sun as the iris.

Though impressive to us on Earth, solar eclipses occur much more frequently on Mars since Phobos orbits the planet every 7.6 hours, unlike Earth’s moon, which takes 27.3 days. Perseverance actually captured a similar eclipse earlier this year.

“Because Phobos’ orbit is nearly aligned with Mars’ equator and close to its surface, moon transits occur on most days of the Martian year,” NASA noted in a post with the video.

As Phobos appeared as a fast-moving dark disc across the Sun, its shadow, or antumbra, simultaneously traveled across Mars’ surface.

The footage, taken by Perseverance’s powerful Mastcam-Z camera system, not only fascinates eclipse enthusiasts but also helps scientists study Phobos and track changes in its orbit. According to Space, Phobos is gradually drawing closer to Mars, moving approximately six feet nearer every 100 years. In about 40 million years, it’s expected that Phobos will ultimately crash into the Red Planet.