NASA's Mars rover Curiosity has snapped stunning shots of a brief partial solar eclipse on the Red Planet, capturing images of the tiny Martian moon Phobos crossing the face of the sun.
Curiosity took the photos of Phobos on Thursday (Sept. 13), roughly five weeks after landing inside the Red Planet's huge Gale Crater on Aug. 5.
The images, taken with Curiosity's Mast Camera (Mastcam), look very different than the solar eclipses on Earth that we're used to. That's because our planet's moon is about 2,160 miles across (3,476 kilometers), big enough to block out the solar disk entirely when Earth, moon and sun are perfectly aligned. Even partial eclipses of the sun by our moon are impressive celestial events.
While Phobos orbits much closer to Mars than our moon does to Earth, it's just 14 miles across (22 km) on average. So Phobos takes only a small bite out of the sun during a Martian solar eclipse.
Mars' other moon, Deimos, is even smaller and farther away from the Red Planet's surface than Phobos, so it blots out even less of the sun when crossing — or transiting — the solar disk. Many scientists think both Phobos and Deimos are asteroids that Mars' gravity captured long ago.
The eclipse photos were no lucky occurrence. Curiosity scientists and mission managers had been planning to snap them for a while, and the rover will likely take more such images in the coming days and weeks.