The Moon :: Essays Papers

The MoonThe Moon is the only natural satellite of Earth orbit 384,400 km from Earth diameter 3476 km mass 7.35e22 kg Called Luna by the Romans, Selene and Artemis by the Greeks, and many other names in other mythologies. The Moon, of course, has been known since prehistoric periods. It is the second brightest object in the sky after the Sun. As the Moon orbits most the Earth once per month, the angle between the Earth, the Moon and the Sun changes we see this as the cycle of the Moons phases. The time between successive new moons is 29.5 days (709 hours), slightly different from the Moons orbital period (measured against the stars) since the Earth moves a significant distance in its orbit slightly the Sun in that time. Due to its size and composition, the Moon is sometimes classified as a terrestrial planet along with Mercury, Venus, Earth and Mars. The Moon was first visited by the Soviet space vehicle Luna 2 in 1959. It is the only extra terrestrial body to have been visited by humans. The first landing was on July 20, 1969 (do you remember where you were?) the function was in December 1972. The Moon is also the only body from which samples have been returned to Earth. In the summer of 1994, the Moon was very extensively mapped by the little spacecraft Clementine and again in 1999 by Lunar Prospector. The gravitative forces between the Earth and the Moon cause some interesting effects. The most obvious is the tides. The Moons gravitational attraction is stronger on the side of the Earth nearest to the Moon and weaker on the opposite side. Since the Earth, and particularly the oceans, is not perfectly rigid it is stretched out along the byplay toward the Moon. From our perspective on the Earths surface we see two small bulges, one in the direction of the Moon and one directly opposite. The effect is much stronger in the ocean water than in the solid crust so the water bulges are higher. And because the Earth ro tates much faster than the Moon moves in its orbit, the bulges move around the Earth about once a day giving two high tides per day.