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Does Mars Have Moons?
Answer at a Glance: Mars has two small, misshapen moons that orbit the planet – Deimos and Phobos. They are among the smallest in the solar system. American astronomer Asaph Hall discovered the moons in 1877. Hall named them after the sons of the Greek god of war, Ares, the Greek counterpart to the Roman god Mars. [1]
Dig Deeper
Phobos – Mars Larger Moon
Image Credit: NASA
Phobos, whose name means fear, is the larger of Mars’s two moons, with a mean radius of 7 miles. To put this into perspective, it’s significantly smaller than the Earth’s moon, which has a mean radius of about 1,080 miles. [2] [3]
Orbiting at a height of only 6,000 km above the Martian surface, Phobos is the lowest orbiting moon currently known, making a complete orbit of the planet 3 times per day. [4]
Deimos – Mars Smaller Moon
Image Credit: NASA
Deimos, whose name means flight or “to flee,” is the smaller of Mars’ diminutive moons, with a mean radius of 3.9 miles. However, unlike his brother Phobos, Deimos has a much higher orbit at just over 20,000 km above the planet’s surface and requires about 30 hrs to orbit Mars. [5]
Mars Won’t Always Have Two Moons
Due to Phobos’ unusually low orbit, Mars’ gravitational tidal forces are gradually pulling it closer to Mars at a rate of six feet every hundred years. NASA speculates that in 50 million years or so, these gravitational tidal forces will cause the moon to collide with Mars, shattering it into oblivion. The debris caused by the collision may form a decaying ring around Mars. [6]
Resources
- [1][6] NASA – Solar System Exploration – “Mars Moons.”
- [3] NASA – “Moon Facts.“
- [2][4]NASA – Solar System Exploration – “Phobos – In-Depth.”
- [5] NASA – Solar System Exploration – “Deimos – In-Depth.”
