According to NASA, the Curiosity rover, which landed on Mars on August 6, 2012, “brought along eclipse glasses”. The solar filters on its Mast Camera (Mastcam) allow it to stare directly at the Sun. Over the past few weeks, Curiosity has been putting them to good use by sending back some spectacular imagery of solar eclipses caused by Phobos and Deimos, Mars’ two moons.
In fact, since Deimos is so small compared to the disk of the Sun, scientists would say it’s transiting the Sun – the event cannot be considered as a solar eclipse.
Phobos, which is as wide as 16 miles (26 kilometers) across, was imaged on March 26, 2019 (the 2,359th sol, or Martian day, of Curiosity’s mission); Deimos, which is as wide as 10 miles (16 kilometers) across, was photographed on March 17, 2019 (Sol 2350).
Phobos, too, doesn’t completely cover the Sun, so it would be considered an annular eclipse.
Naturally, solar eclipses on Mars are not as spectacular as the solar eclipses here on Earth. Because the Sun and moon appear the same size in Earth’s sky: the Sun’s diameter is about 400 times greater – but the Sun is also about 400 times farther away. That’s how total solar eclipses occur when the Moon passes between the Sun and Earth.
There’s still a margin of uncertainty in the orbits of both Martian moons, but that shrinks with every eclipse that’s viewed from the Red Planet’s surface.
Both moons of Mars were discovered in 1877 by the American astronomer Asaph Hall (October 15, 1829 – November 22, 1907). Phobos is the innermost and larger of the two natural satellites of Mars.
Phobos (Mars I) is a small, irregularly shaped object with a mean radius of 11 km (7 mi) and is seven times as massive as the outer moon, Deimos. The moon is named after the Greek god Phobos, a son of Ares (Mars) and Aphrodite (Venus) and the personification of fear (cf. phobia).
Deimos (Mars II) is the smaller and outermost of the two natural satellites of Mars. has a mean radius of 6.2 km (3.9 mi) and takes 30.3 hours to orbit Mars.
Deimos is 23,460 km (14,580 mi) from Mars, much further than Phobos, which orbits about 6,000 km (3,700 mi) from the Martian surface.
- Curiosity Rover on Wikipedia
- Curiosity Rover mission page on NASA website
- “Curiosity Captured Two Solar Eclipses on Mars” on NASA.gov
- “Curiosity rover captured 2 solar eclipses on Mars” on EarthSky.org
- “NASA’s Curiosity Rover Just Saw 2 Eclipses on Mars! Now You Can, Too” on Space.com
- Phobos on Wikipedia
- Deimos on Wikipedia