Who discovered the moons of Mars and when?
American astronomer Asaph Hall discovered both moons at the US Naval Observatory in Washington, D.C. He found Deimos on the 12th of August 1877 and Phobos on the 18th of August 1877.
Questions about Moons of Mars
Short answers, pulled from the story.
What are the names of the two moons of Mars and what do they mean?
The two moons are Phobos and Deimos. Phobos means fear and panic, and Deimos means terror and dread. Both names come from Greek mythology; Phobos and Deimos were twin sons of Ares who accompanied him into battle.
How big are Phobos and Deimos compared to Earth's Moon?
Phobos and Deimos are very small compared to Earth's Moon. Phobos has a diameter of 22.2 km and Deimos measures 12.6 km across. Seen from Mars's equator, a full Phobos appears about one-third the size of a full Moon as seen from Earth.
What will happen to Phobos in the future?
Phobos is gradually spiraling inward because tidal forces are reducing its orbital radius. When it crosses the Roche limit, it will be torn apart by those tidal forces and either crash into Mars or form a ring around the planet.
Where did the moons of Mars come from?
The origin of the Martian moons remains scientifically contested. Leading hypotheses include capture of carbonaceous asteroids and formation from debris ejected by a giant impact on Mars that reaccreted in orbit. Researchers from ETH Zurich and the US Naval Observatory proposed the moons are fragments of a common parent body disrupted 1 to 2.7 billion years ago.
What missions have explored the moons of Mars?
Two Soviet probes launched in 1988 under the Phobos program both failed before completing intended landings, though Phobos 2 did photograph Phobos. The Russian Fobos-Grunt probe failed at launch in 2011 and re-entered Earth's atmosphere on the 15th of January 2012. JAXA plans to launch the Martian Moons eXploration mission in 2026, targeting a return of at least 10 grams of Phobos regolith to Earth in July 2029.