All About Moons I Oxford Open Learning


    All About Moons

    There’s so much for us to learn and for budding astronomers to discover about the marvellous moons of our solar system. Here are some interesting facts about the moons in our solar system.

    What Are Moons?

    Known as natural satellites, moons come in many types, shapes and sizes. Structurally, they are generally solid bodies, and few have atmospheres. Most moons were likely formed by discs of gas and dust circulating around planets in the early years of our solar system. Our Moon has a core, mantle and crust. The inner core is solid, iron-rich and 149 miles in radius. The crust of the moon is a bedrock covered by a loose layer of dust, broken rocks, and other related materials.

    How Many Moons Are There In The Solar System?

    There are hundreds of moons in our solar system. The number of planetary moons as they are known traditionally is currently stated by NASA as being 289. This number has changed a number of times. 12 of Jupiter’s moons were only discovered early this year, whilst Saturn has had 62 added only this month. What constitutes a traditional, planetary moon is something that is also often a matter for debate, and if designations are changed, then the number of moons can change at the same time!

    Different Planets, Different Orbits

    The Earth’s Moon’s phases repeat every 29.5 days, but its orbit around the Earth only takes 27. This is due to the fact that as the Moon moves around Earth, the Earth also moves around the Sun. The Moon must travel a little more to make up for the added distance and complete its phase cycle.

    Mars has two moons; Phobos and Deimos. Phobos is believed to be getting closer to Mars at a rate of 1.8 meters every hundred years. This means that it could eventually either crash into Mars in 50 million years or break up into a ring.

    Many of Jupiter’s outer moons (there are believed to be between 80 and 95 in total) have highly elliptical orbits and orbit backwards (opposite to the spin of the planet). Their orbit times vary dramatically; Adtrastea has just a 7 hour orbit, whilst the modestly named S/2033 J 2 has a 980 day orbit. Elsewhere, Saturn’s largest Moon, Titan, orbits every 15 days and 22 hours, whilst Uranus’s largest Moon, Titania, takes 209 hours. Neptune’s largest Moon, Triton, takes 141 hours.

    Are There Different Types Of Moons?

    Yes, they are classified in two different types according to their orbits. There are regular moons, which have prograde orbits (meaning they orbit in the direction of their planets’ rotation) and lie close to the plane of their equators. Then there are irregular moons, whose orbits can be pro (direct motion) or retrograde (against the direction of their planets).

    Is Pluto Actually A Moon?

    Pluto was considered to be a Moon before the discovery of Charon, also known as Pluto I, and the largest of Pluto’s natural satellites. It was popular to assume that Pluto was a former moon of Neptune that had somehow escaped its orbit, and it is now known as a dwarf planet. Despite its small size, it has five moons. It was named by an 11-year-old girl, Ventia Burbey, in 1930.

    Which Moons Could Be Colonisable?

    The strongest candidates are currently icy satellites, such as those of Jupiter and Saturn—Europa and Enceladus respectively, in which subsurface liquid water is believed to exist.

    Which Moons Have The Most Interesting Features?

    Many of the Moons in our solar system have interesting features. Saturn’s largest Moon, Titan, experiences dust storms and monsoonal rains. Neptune’s largest Moon, Tritan, is the only large moon in our solar system that orbits in the opposite direction of its planet’s rotation.

    So there you have it, all manner of facts to add to your lunar armoury. But if you want to find out more from NASA, you can visit their site here.

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