September 5, 1877: Opposition and Exciting Discoveries The Martian moons, Phobos (left) and Deimos (right), photographed by the Viking orbiters. Deimos’s smooth surface is contrasted with the grooved, pitted, and cratered surface of Phobos. The prominent cavity on the end of Phobos is the crater Stickney. The images are not to scale; Phobos is about 75 percent larger than its companion.
Stickney Crater Image Credit: HiRISE, MRO, LPL (U. Arizona), NASA Stickney Crater, the largest crater on the martian moon Phobos, is named for Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the Red Planet's moons in 1877. Over 9 kilometers across, Stickney is nearly half the diameter of Phobos itself, so large that the impact that blasted out the crater likely came close to shattering the tiny moon.
#Astronomy: #Deimos: The Smaller Martian Moon - #Mars is the only terrestrial planet to host multiple moons. The smaller of the 2, the lumpy moon Deimos, bears more resemblance to an asteroid than to most moons in the solar system, a similarity that raises questions about its formation. On August 12, 1877, the focused search for Martian moons by American astronomer Asaph Hall resulted in the discovery of Deimos. Six days later, he identified the second Martian moon, Phobos.
Mars Moon Phobos Likely Forged by Catastrophic BlastCredit: ESA/DLR/FU Berlin (G. Neukum)The ESA spacecraft Mars Express took this image of Phobos on March 7, 2010. This image has been enhanced for seeing features in the less-illuminated part of the moon.