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The Moon

The Moon

The Moon is the only natural satellite of the Earth, and the fifth largest satellite in the Solar System. It is the largest natural satellite of a planet in the Solar System relative to the size of its primary, having a quarter the diameter of Earth.


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The soil of the Moon, called lunar regolith by scientists and Moondust by others, is a rich source of metals and oxygen that can easily be strip mined.  Oxygen can be used for rocket propellant and breathing, silicon for solar panels, iron for construction, calcium for cement, aluminum and magnesium for vehicles, titanium can replace steel, chromium and manganese for alloys, sodium for caustic, potassium and nitrogen for agriculture, sulfur for acid and farming, carbon and hydrogen for water and chemicals, and helium 3 for fusion energy.

Article: Lunar regolith
Source: Lunar regolith

The surface of the moon is scarred with millions of impact craters. There is no atmosphere on the moon to help protect it from bombardment from potential impactors (most objects from space burn up in the Earth's atmosphere). Also, there is no erosion (wind or water) and little geologic activity to wear away these craters, so they remain unchanged until another new impact changes it.

Article: Craters- The Moon
Source: Craters- The Moon

Galileo was the first to recognize the great number of craters which exist on certain parts of the moon's surface. He compared the craters in the south-western quadrant of the moon to the 'eyes' in a peacock's tail. Galileo's chart of the moon, though creditable to him considering his imperfect telescopic means, has very little value except as a curiosity.

Article:   The moon: her motions, as…
Source:  Offline Book/Journal

The moon's mass is approximately 7.35e22 kg with a density about 3/5 that of Earth. It's gravitational pull is about 1/6 of Earth's.

Article: What Is The Moon's Mass?
Source: What Is The Moon's Mass

The moon orbits the earth, and completes one rotation after 27 and a third days. The distance between the Earth and the Moon is 384,385 km. In comparison to the Earth however, the moon's weight and diameter are much smaller. The weight of the moon is 1/81 that of the Earth, and its diameter is ¼ of the Earth's. According to the data, the diameter of the moon is relatively centered, at about 3,479 km.

Article: Diameter of the Moon
Source: Diameter of the Moon

The Moon's orbit, unlike the Earth's, is not firmly fixed in space and its apparent path across the sky is therefore seen to be more tortuous than that of the Sun. But the plane of the Moon's orbit is always inclined to the eliptic by about 5 º.

Article:   The Moon: Our Sister Plan…
Source:  Offline Book/Journal

Space researchers have used invisible X-rays, reflecting off the surface of the moon, to find out what our nearest solar neighbor is made of and how it was formed.

The research, done at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., found oxygen, magnesium, aluminum and silicon present over a large area of the Moon's surface.

Article: Discovery Channel :: What...
Source: Discovery

The earliest recorded opinion as to the moon's condition is the theory of Thales (B.C. 640), that a portion of the moon's lustre is inherent. He recognized the faint light from the illuminated part of the moon's globe at the time of new moon, or rather at the time before and after new moon, when the illuminated portion forms a narrow crescent; and it was also known to him that the moon does not disappear wholly when totally eclipsed. He therefore inferred that she shines in part by native light.

Article:   The moon: her motions, as…
Source:  Offline Book/Journal

There is actually no strict definition of what a moon is, but there are some commonalities between those objects considered moons, also called satellites. They all are:

Distinct, whole objects

Solid objects

In orbit around a more massive body (that presumably orbits a star)

Article: What is a Moon?
Source: What is a Moon?

Although one hemisphere of the Moon is always turned towards the Earth (because of the synchronisation of the Moon's axial rotation with its orbital period), at one time or another it is possible to see slightly more than half of the Moon's surface. Only 41% of the Moon, in fact, is permanently invisible from Earth. Most of the occasional 9% is made visible by what are known as the Moon's optical liberations.

Article:   The Moon: Our Sister Plan…
Source:  Offline Book/Journal