The Moon is the only natural satellite of the Earth. The moon has the radius of 1,738 km. This radius is approximately one-quarter of the size of the Earth. It moves around the Earth in an elliptical orbit of small eccentricity.
The distance of the moon from the Earth varies between 356,000 kilometers to 407,000 kilometers.
The moon completes to orbit the Earth and returns to the same position in the sky within 27 days, 7 hours, 43 minutes and 11 seconds. This is called as the sidereal month.
As the Earth moves in its orbit around the sun with the same direction of the moon, the moon needed to return to the same phase – 29 days, 12 hours, 4 minutes and 28 seconds, tend to be longer. This is called as the synodic month.
The average velocity of the moon is about 1023 kilometers per second and corresponds to a mean angular velocity in the sky of about 33 minutes of arc per hour, a little greater to the moon’s diameter.
Oxygen is the most abundant element found on the moon. Oxygen composes at least 60% of the moons crust, by weights.
The second element which found to be abundant is the silicon which composes 16 – 17 %.
The third element is the aluminum composes 6 -10 %, followed by calcium with 6 % magnesium with 2 – 5 % and titanium with 1 – 2 %. (contacts america review)
The moons lunar surface has two different types of terrain. The first surface is rough, it is relatively bright and replate with mountains. It occupies more than two and nine-tenths of its far side.
The second surface in the moon is much darker and smoother compared to the first surface.
The faces of the moon depend upon what fraction of its sunlit hemisphere can be seen from the Earth. In orbiting the Earth, its phases changes from, the new moon, going to the crescent, going to the gibbons and lastly to the full moon.
After the full moon, it then decreases to the reverse order, to gibbons, to the third quarter, to the crescent and lastly back to the new moon.
Because the moon rotates on its own axis in the same period that it revolves around the Earth, the same side of the moon always faces the Earth.
With respects to the stars, the moon takes about 27.3 days to complete one revolution around the Earth, but it takes about 29.5 days with respect to the sun because of the Earth’s simultaneous motion as it travels around the sun.