Earth's+moon+(shefali)

There are two types of lunar periods:

 * =====Synodic: the movement of the moon around the Earth relative to the sun, or we can say the movement of the moon around the Earth by an observer (standing on Earth) relative to the sun. =====
 * =====Sidereal: measuring the movement of the moon around the Earth relative to the stars (fixed stars). In simple words, the stars tell us how the moon is moving around the earth. =====

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The moon revolves around the earth at an average distance of 384,403 at an average speed of 3,700 km/h. the time that the moon takes for one revolution in an elliptical orbit around the earth is 27 days 7 hours and 43 minutes. One lunar month is 29days 12 hours and 44 minute (earth’s time) =====

Different theories are considered such as:

 * =====When a planet-like object or asteroid as much as the size of Mars, the energy that took place was 100 times larger than that required wiping out the dinosaurs. This collision threw large amounts of rocks, parts of the young planet earth, which included a large rock, our moon today. =====
 * =====Moon was a part of earth that separated from earth due to its rapid spinning =====
 * =====Earth and moon formed at the same period of time. =====
 * =====It was formed separately from Earth and as a terrestrial planet, but was involved as a moon due to greater gravitational force of the Earth =====

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The second and third theory mentioned above states that the moon doesn’t have an iron core which most terrestrial planets do; therefore these theories seem more just than the other theories. =====

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The core of the moon mostly contains iron but contains sulphur and other elements too. The crust of the moon is 42 miles deep. The lunar surface is mostly 43% oxygen, 20% silicon, 19% magnesium, 10% iron, 3% calcium and small amounts of manganese, chromium and titanium. =====

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The moon only has a tiny atmosphere, which comes from outgassing (process of release of gases from process of the planet itself such as evaporation, sublimation, phase conversion, etc.). a lot of the atmosphere on the moon is created by the internal process of changing of mantle of moon into gases, which creates gas and a layer or atmosphere. There are gases present in the atmosphere of the moon such as methane, nitrogen, carbon dioxide and monoxide, helium, oxygen, argon, etc. but really only in trace amounts. =====

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The moon and Earth has similar volcanic activity going on such as the inner core melts and the mantle keeps on forming but as the moon is much smaller and doesn’t clearly have a core, the process of forming new mantle has finished 2 billion years ago. =====

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There have been more than 100 elements found on the moon but the main ones are: Silicon, iron, aluminium, calcium, magnesium, titanium, apatite and oxygen. =====