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The Moon - Introduction

Its hard to imagine the history of Earth without our Moon. For as long as man walked this Earth, the Moon served as "lesser light for the night" and faithful time-piece. The phases of the Moon were used to help guide the Harvest, or help determine the time of the river floods.
How our Moon came to existence is still under speculation. There are several possible scenarios:

Fission Theory - the Earth spinning so fast during early formation that a piece broke off forming the Moon
Capture Theory - the Moon formed elsewhere passed close to Earth and was captured
Co-Creation Theory - the Earth and Moon formed and evolved together
Collisional Ejection Theory - a large piece impacted the Earth and broke off pieces of the …show more content…

The light areas are lunar highlands. The dark features, called maria, are impact basins that were filled with dark lava between 4 and 2.5 billion years ago.
After this time of volcanism, the Moon cooled down, and has since been nearly unchanged, except for a steady rain of "hits" by meteorites and comets. The Moon's surface is charcoal gray and sandy, with much fine soil. This powdery blanket is called the lunar regolith, a term for mechanically produced debris layers on planetary surfaces. The regolith is thin, ranging from about 2 meters on the youngest maria to perhaps 20 meters on the oldest surfaces in the highlands.
Unlike Earth, the Moon does not have moving crustal plates or active volcanoes. However, seismometers planted by the Apollo astronauts in the 1970s have recorded small quakes at depths of several hundred kilometers. The quakes are probably triggered by tides resulting from Earth's gravitational pull. Small eruptions of gas from some craters, such as Aristarchus, have also been reported. Local magnetic areas have been detected around craters, but the Moon does not have a magnetic field resembling Earth's.
A surprising discovery from the tracking of the Lunar Orbiter spacecraft in the 1960s revealed strong areas of high gravitational acceleration located over the circular maria. These mass concentrations (mas-cons) may be caused by layers of denser, basaltic lavas that fill the mare basins.
In 1998, the Lunar

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