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article imageMars once had many moons

By Tim Sandle     Jul 11, 2016 in Science
Mars, the red planet that is most like Earth in our solar system, once had several moons. It is thought the satellites now form part of the asteroid belt.
Mars has two moons, which appear rather misshapen compared with other planetary satellites. The moons are named Phobos and Deimos. The two moons are named after the figures Phobos (representing panic or fear) and Deimos (symbolizing terror or dread), from Greek mythology. The two, personified as boys, accompany their father Ares, god of war, into battle. In Roman mythology Ares is known as Mars.
New research suggests that Mars once had a larger family of moons. These moons were probably made of rock from the Martian surface. This probably happened, Science News reports, as the result of a powerful impact several billions of years ago. This discovery has come about through observations and computer modelling,
The origins of Phobos and Deimos themselves remains uncertain. Scientists think they either also arose from the planet itself, as a result of a collision; or they are asteroids that became captured by the planet’s gravitational pull. While the captured asteroids theory remains the most probable explanation, the orbits of the two moons don't match this point of origin. Discover Magazine (@DiscoverMag) called this, via Twitter, (pun intended) a "smashing discovery." Not to be outdone, Gizmodo (@Gizmodo) refers to the news as a "badass new theory on the origin of Mars' moons."
The new research suggests that Mars ‘reclaimed' the group of many moons, and that these small satellites eventually impacted the Martian surface. This same effect could one day occur with the current two moons. While Deimos is in a stable orbit, Phobos is developing stress fractures due to the pull from Mars.
There is also evidence that Phobos is edging closer to the Martian surface, although a future impact would take a billion years to occur. This was reported to the 47th meeting of the American Astronomical Society’s Division for Planetary Science last year. Phobos orbits closer to Mars, with its closest point at 9,377 kilometres (5,827 miles); while Deimos orbits Mars at a distance of 23,460 kilometers (14,580 miles).
There is also a possibility that some of these smaller moons helped to form Phobos and Deimos. On this basis, there is, according to the lead researcher, Pascal Rosenblatt (from the Royal Observatory of Belgium in Brussels), much more to learn.
The research is published in the journal Nature Geoscience. The research paper is headed “Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons.”
More about Mars, moons, Solar system, Phobos, Deimos
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