Mars

Mars is the fourth planet from the Sun in our solar system. It is named after Mars, the god of war in Roman mythology (the counterpart to Ares in Greek mythology), because of its red color as viewed in the night sky. This feature also earned it the name "The Red Planet." Mars has two moons (Phobos and Deimos) which are both small and oddly-shaped, possibly being captured asteroids. The prefix areo- refers to Mars in the same way geo- refers to Earth—e.g. areology versus geology.

Mars' moons

Both Phobos and Deimos are tidally locked with Mars, always pointing the same face towards it. Since Phobos orbits around Mars faster than the planet itself rotates, tidal forces are slowly but steadily decreasing its orbital radius. At some point in the future Phobos will be broken up by gravitational forces (see Roche limit). Deimos, on the other hand, is far enough away that its orbit is being slowly boosted instead.

Related Topics:
Phobos - Deimos - Tidally locked - Roche limit

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Both satellites were discovered in 1877 by Asaph Hall, and are named after the characters Phobos (panic/fear) and Deimos (terror/dread) who, in Greek mythology, accompanied their father the Greek god Ares into battle. Ares was known to the Romans as Mars, the god of war.

Related Topics:
1877 - Asaph Hall - Phobos - Deimos - Greek mythology - Greek - Ares - Romans

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As seen from Mars, Phobos has an angular diameter of between 8' (rising) and 12' (overhead), while Deimos has an angular diameter of about 2'. The Sun's angular diameter, by contrast, is about 21'.

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