6The Moon Above
Ever since the beginning of time, creatures have looked up and seen a great white orb floating in the sky above them. The Romans named it Luna, the Greek Selene and Artemis, and numerous other cultures designated their own names and deities to this heavenly sphere.
But what is the Moon, really? It is almost as bright as the Sun, our own personal star. People have landed on it, walked on it, something that has not yet been achieved on any other planet. What is there to know about the Moon, though?
Depending on what day of the month you look up at the night sky, the Moon may not be a whole circle. It could appear smaller-the Moon is not shrinking, this is just an effect of the “revolution” of the Moon around the Sun. The angle of the Sun to Moon to Earth slowly changes as each day goes by, thus the Moon “shrinks”. Each of these revolutions take about 29 days.
Ten years before the first landing, the “Luna 9” landed on the Moon’s surface. In 1969, the landing took place on July 20th. Apart from being the only extraterrestrial body that we humans have landed on, it is the only one from which we have samples that are studied by scientists. During the “Apollo” and “Luna” programs, 382 kg of these samples have been taken from the Moon. They continue to be extensively studied by the scientists so that even more knowledge can be gained. One way the scientists examine these rocks is by dating them. Some of the specimens have been dated to 4.6 and 3 billion years old. This is significant because some of the rocks found on Earth date back to barely 3 billion years old. Through these rock samples studies have been made to learn more things about the early beginnings of our solar system that we could not find on Earth.
Scientists also study two maps of the Moon made by the shuttle “Clementine” and “Lunar Prospector”.
But the Moon is responsible for more than you may think. Due to the gravitational pull between the Earth and the Moon, the tides change. The tide tends to be higher on the side where the Moon is closer to the Earth, and lower on the side it is not. This is possible because-obviously- the oceans are not stiff, they stretch outwards slightly towards the Moon. The tides change twice everyday, because the Earth rotates faster than the Moon does. This gravity effect does not change the land plates, because they are much more rigid than the ocean plates. This complicated effect produces a “torque” on the Earth and an accelerated force on the Moon. Due to this, the one side of the Moon is constantly facing the Earth.
We call the side that we don’t normally see the “Dark side of the Moon”, because it was thought to be unknown. However, today, that meaning can no longer be considered truthful. The Moon’s orbit is not entirely-circular, so for a few days during the month, a couple degrees of the “dark side” can be seen. And, we also have maps of the “dark side”, so the Moon’s “dark side” is, in reality, not so dark at all!
Unlike the Earth and Sun, the Moon has no atmosphere. However, from data gained by the “Lunar Prospector” it is suspected that deep within the Moon’s core, there may be frozen ice, including some at the Moon’s North Pole. In 2008, another shuttle the “Reconnaissance Orbiter” is planned to go on a voyage to the Moon to collect more information.
Though the Moon has no atmosphere, it does have layers. The crust averages to be about 68 km thick. It’s thinnest point is basically “0” underneath Mare Crisium and 107 km in an area north of the crater Korolev.
The Moon’s inside, however, has become inactive. The center of its mass is offset from where it should be due to the many gravitational anomalies between the Earth and Moon. It is about 2 km in the direction of Earth, and its crust is thinner on the side that faces Earth.
On the Earth’s crust, its terrain varies into two main categories. The heavily cratered old highlands, and the new, smoother, younger, maria. 16% of the Moon’s surface are covered by the maria, which are crater impacts that became flooded with molten lava. For a reason not yet understood, these maria are on the side closer to the Earth. These craters are giving names of famous figures in the history of science .They include Tycho, Copernicus, and Ptolemaeus. The far side have been given names such as Apollo, Gagarin, and Korolev-there is a Russian bias due to the fact that the “Lunar 9”, the ship that obtained the images of the far side, was a Russian vessel. Two especially huge craters are the South Pole-Aitken, which is the largest impact basin in the solar system; and the Orientale, which is an excellent model for what scientists call a “multi-ring” crater.
The “Apollo” program I mentioned earlier was also important for another reason: it helped shed light on the subject of the forming of the Moon. There were three original theories: that the Earth and Moon were formed at the same time from a “Solar Nebula”; that the Moon split off of the Earth; and finally, that the Moon was formed elsewhere and was trapped in Earth’s gravitational pull. These theories all have their own problems to them. The newer and more agreed upon theory is that the Earth collided with a Mars-sized object, and the ejected material then eventually formed the Moon. As with all scientific theories, there are “bugs” in this idea as well. But, scientists are working tirelessly to work them out.
Today, there is no global magnetic field around the Moon. However, some of those ever-important show that perhaps, early in the beginnings of the Moon’s creation, there may have been one. As it also has no atmosphere, it is constantly exposed to a “solar wind”, which carries ions that embeds themselves into the Moon. The tireless efforts of the scientists are being made to study these samples to learn more about the solar winds.
Whether it’s capturing the romantic imagination of young lovers, or perplexing scientists, the Moon is certainly a topic worth spending a minute thinking about.
http://www.seds.org/nineplanets/nineplanets/luna.html
Subject: The Moon Above 
