The origins of the Moon are not yet known, and are still open to debate. Among the many theories scientists suggest the following: that it was split from the Earth; that it was a separate body captured by the Earth’s gravity; that it formed in orbit around Earth; or that it was formed from debris thrown off when another body the size of Mars struck Earth.
The Moon’s composition is rocky with a surface heavily scarred by meteorite impacts that have formed craters up to 240 km (150 mi) across. Seismic observations indicate that the Moon’s surface extends downwards for tens of kilometres; below this crust is a solid mantle about 1,100 km thick, and below that a silicate core, part of which may be molten. Rocks brought back by astronauts show the Moon is 4.6 billion years old and about the same age as Earth. It is made up of the same chemical elements as the Earth, but in different proportions, and differs from Earth in
that most of its surface features were formed when hit repeatedly by meteorites within the first billion years of its history. The youngest craters on the moon are surrounded by ejected rock, while the largest scars have been filled by dark lava to produce the lowland plains called seas. It is these dark patches that form the so-called “man-in-the-Moon” patterns.
The moon is the Earth’s only natural satellite and is about a quarter of its size. It takes the moon about 27.3 days to revolve around Earth, during which it travels an average distance of 384,000 km.
There are approximately 13
Full Moons in a calendar year, which on average rise about 51 minutes later each proceeding day. As a general guide to when the moon rises an old traditional saying states: “The New Moon rises at sunrise, the first quarter at noon, the Full Moon rises at sunset and the last quarter at midnight”.
Because of a loss of orbital energy due to gravity from the Earth, the Moon is gradually moving away from the Earth. In the early history of the Earth, the Moon would have looked about 3 times larger in the sky because it was closer to the Earth.
The Moon has almost no atmosphere and because of its weak gravity, all types of gases escape from its surface. Without atmosphere there is no wind or water erosion, which makes the moons surface about the same now as it was 3 billion years ago. In July 1969 when Neil Armstrong and Edwin (Buzz) Aldrin the first astronauts to walked on the moon left their footprints, little would they have realised that their footprints would remain unchanged on its surface for the next 10 million years.
The surface temperature of the moon fluctuates from roughly +300° F during it’s 2-week daytime periods, to -270 F during it’s 2-week night time periods. This is because there is not enough atmosphere to keep the moon warm at night, or to protect it from the Suns rays in the daytime.
The moon causes many of the tides in the Earth’s oceans. This is because of the gravitational force between the Earth and Moon. At Full Moon and New Moon, the Sun, Earth and Moon are lined up, which produces higher than normal tides (called spring tides or high tides). When the Moon is at its first or last quarter, smaller neap tides form (a tide that shows the least range between high and low tides).
Though several flags of the
United States have been symbolically planted on the moon, the U.S. government makes no claim to any part of the Moon’s surface. The U.S. is party to the “Outer Space Treaty”, a universal agreement that places the Moon under the same jurisdiction as International Waters. This treaty also restricts the use of the Moon to peaceful purposes, and specifically bans weapons of mass destruction (including nuclear weapons) as well as military installations. A second treaty called the “Moon Treaty” also proposed to restrict the exploitation of the Moon’s resources by any single nation, but so far this has not been signed by any of the major nations involved with space exploration.
Books in PDF format to read:
Edna Kenton - The Book Of Earths
Aristotle - On Dreams
Austin Osman Spare - A Book Of Satyrs
