How Many Moons Does Mars Have?
Mars is one of the four terrestrial planets in our solar system. Mercury, Venus, and Earth are the other three. It is the fourth planet from the sun and has a diameter of 4220 miles. It is a cold planet, reaching -207 degrees F. and rarely getting above freezing (32 degrees F.).
The Romans named Mars after their god of war but its nickname is the "Red Planet," named because of its reddish color.
Mars has two moons. The two small moons orbiting Mars were discovered in 1877, by Asaph Hall, at the U.S. Naval Observatory.
The names of the two moons, Deimos and Phobos, come from Greek mythology. Deimos and Phobos were the sons of the god of war, Ares. Deimos means “flight” and Phobos means “fear or panic” like “phobia”.
The moons’ orbits are very different. Phobos travels from west to east and makes an orbit in only eleven hours. Deimos travels east to west but takes almost 2.7 days to set and 2.7 days to reappear in the east. Since they are tidally locked, both moons always show the same side of themselves to Mars.
Because Phobos has such a fast orbit, even faster than Mars rotates, it is constantly being drawn closer to the planet. When it gets close enough, it will break apart. This distance is called the "Roche Limit." Any satellite inside this limit will be broken apart by tidal forces.
The two moons of Mars are not spherical. They are most likely asteroids. They could have been formed from a collision of two objects in orbit, or they could have been grabbed by the planet’s gravity.
Life on Mars
At one time, there may have been life on Mars. In 1996, scientists examined a meteorite that came from Mars and found microscopic life on it. The essential elements that form the basis of life were there:
- Carbon
- Oxygen
- Hydrogen
- Water
- An energy source
There is physical evidence of water and an energy source could come from either the sun or geothermal heat.
Water cannot remain on the surface of Mars very long. The temperature is too cold and the thin atmosphere would not allow it. There is, however, frozen water in the polar ice caps and it is believed that water is underneath the surface.
In addition, billions of years ago, Mars experienced great floods. The water probably formed lakes and oceans. It is not known how this happened or how long it lasted but, despite the mystery, it is important to learn about Mars' history to help discover how all the planets evolved. If humans ever travel to Mars, we need to learn as much as possible about it.
Earth and Mars
A day on Mars is also a little longer than on Earth, at approximately 24 hours and 39 ½ minutes. This is very close to Earth’s, but a year (orbit around the sun) is 687 days.
Earth tectonics also differ from that of mars. Earth’s plates slide toward each other or pull apart; Mars’s plates are vertical, with magma pushing up to the surface. So our planetary neighbor is similar to us in some ways but not in all. Many believe that Mars used to be very much like Earth.