One summer night in 1877, American astronomer Asaph Hall was looking through his telescope in Washington, D.C. Mars was at ...

A mysterious moon, a vanished Soviet spacecraft, and monolith-like objects standing alone in the Martian dust—what’s really ...

See stunning photos of Phobos and Deimos, the small moons of Mars, as seen by spacecraft on and orbiting the Red Planet. Phobos is the largest moon of Mars, with Deimos as a smaller satellite.

Phobos is such a close companion of Mars, about 60 times closer than the moon orbiting Earth, that it has crossed with MAVEN’s path multiple times a day during the orbiter’s mission.

An image of Phobos from March 23, 2008, taken by the High Resolution Imaging Science Experiment camera on NASA’s Mars Reconnaissance Orbiter.

The origins of Phobos and Deimos remain uncertain. While their misshapen forms and their cratered surfaces suggested they were asteroids captured by the gravitational pull of Mars, previous ...

In the case of Mars' Phobos, the moon's size and shape ‒ roughly 17 miles long on its longest side ‒ make it impossible for it to completely cover the sun's disk.

Because Phobos is so close to Mars—3,700 miles, compared with the average 237,675 miles between Earth and its moon—there's significant pull between the two bodies, Hurford says.

From Mars' Jezero Crater, the Perseverance rover, which landed on the planet in 2021, captured a series of images on Feb. 8 of the odd-shaped tiny moon Phobos passing in front of the much-larger sun.

Previously unpublished photos of Mars' moon Phobos hint that the mysterious satellite may actually be a trapped comet — or perhaps just a piece of one, along with its twin moon Deimos.

The curios moon Phobos, captured by the Mars Express Orbiter in 2008. ESA/DLR/FU Berlin (G. Neukum), CC BY-SA 3.0 IGO An asteroid sneeze.

Astronomer Asaph Hall discovered Mars’ two moons, Phobos and Deimos, in 1877. He named them for the Greek gods associated with fear and panic.