THE MOON
The Moon has fascinated mankind throughout the ages. By simply viewing with the
naked eye, one can discern two major types of terrain: relatively bright highlands
and darker plains. It is the second brightest object in the sky after the Sun.
It was first visited by the Soviet spacecraft Luna 2 in 1959. It is the only
extraterrestrial body to have been visited by humans. The first landing was on July
20, 1969; Neil Armstrong became the first man to step onto the surface of the
Moon.
The Moon hasn’t to atmosphere. Radio communications were used because sound waves can only be heard by travelling through the medium of air. The lunar sky is always black because diffraction of light requires an atmosphere. The gravity, to the equal one, is 16 times greater than the one of the Earth.
The gravity
The gravitational forces between the Earth and the Moon cause some interesting effects. The tides. The Moon's 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 line toward the Moon. And because the Earth rotates 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.
The Earth's rotation carries the Earth's bulges slightly ahead of the point directly beneath the Moon. This means that the force between the Earth and the Moon is not exactly along the line between their centres producing a torque on the Earth and an accelerating force on the Moon. This causes a net transfer of rotational energy from the Earth to the Moon, slowing down the Earth's rotation by about 1.5 milliseconds century and raising the Moon into a higher orbit by about 3.8 centimetres per year.
Both the rotation of the Moon and its revolution around Earth takes 27 days, 7 hours, and 43 minutes. This synchronous rotation is caused by an unsymmetrical distribution of mass in the Moon, which has allowed Earth's gravity to keep one lunar hemisphere permanently turned toward Earth.. The same thing has happened to most of the other satellites in the solar system.
The Lunar Interior
Four nuclear powered seismic stations were installed during the Apollo project to collect seismic data about the interior of the Moon. The results have shown:
This picture shows the 3 major divisions of the Lunar interior, the crust, mantle, and core. The lunar crust thickness varies from tens of kilometers in depth (under mare basins) to more than 100 kilometers in some highland regions, with an average thickness of about 70 kilometers. The core radius is between 300 and 425 kilometers.
There is water in the moon?
From Clementine suggested that there may be water ice in some deep craters near the Moon's South Pole which are permanently shaded. This has now been confirmed by Lunar Prospector. There is apparently ice at the North Pole as well.
the surface soil composition
This false-colour photograph of the Moon was taken by the Galileo spacecraft on December 8, 1992. The false-colour processing used to create this lunar image is helpful for interpreting the surface soil composition. Areas appearing red generally correspond to the lunar highlands; while blue to orange shades indicate the ancient volcanic lava flow of a mare, or lunar sea. Bluer mare areas contain more titanium than do the orange regions.
Io/ Moon Relationship
This image shows the relative scale of Io a l Moon . Io is at the left and Luna is at the right. The scale is approximately 7.3 kilometres per pixel.
