Two sides of the Moon: The Moon is in synchronous rotation, meaning that it keeps nearly the same face turned away from Earth at all times. Early in the Moon's history, its rotation slowed and became locked in this configuration as a result of frictional effects associated with tidal deformations caused by the Earth..
Nevertheless, small variations resulting from the eccentricity of the lunar orbit, termed librations, allow a total of about 59 per cent of the lunar surface to be visible from Earth at one time or another.The side of the Moon that faces Earth is called the near side, and the opposite side the far side. The far side should not be confused with the dark side, which is the hemisphere that is not being illuminated by the Sun at a given moment. The far side of the Moon was first photographed by the Soviet probe Luna 3 in 1959. One distinguishing feature of the far side is its almost complete lack of maria. Near side of the moonFar side of the moonNote: All friend requests will of course be accepted.
Impact craters Lunar crater Daedalus on the Moon's far side.The Moon's surface everywhere shows evidence of having been affected by impact cratering. Impact craters form when asteroids and comets collide with the lunar surface, and globally about half a million craters with diameters greater than 1 km can be found.
Since impact craters accumulate at a nearly constant rate, the number of craters per unit area superposed on a geologic unit can be used to estimate the age of the surface (see crater counting). The lack of an atmosphere, weather and recent geological processes ensures that many of these craters have remained relatively well preserved in comparison to those found on Earth.The largest crater on the Moon, which also has the distinction of being the largest known crater in the Solar System, is the South Pole-Aitken basin. This impact basin is located on the far side, between the South Pole and equator, and is some 2,240 kilometres in diameter and 13 kilometres in depth. Prominent impact basins on the near side include Imbrium, Serenitatis, Crisium, and Nectaris.Seasons: Summer Winter
Eclipses The 1999 solar eclipse.Eclipses can occur only when the Sun, Earth, and Moon are all in a straight line. Solar eclipses can occur near a new moon, when the Moon is between the Sun and Earth. In contrast, lunar eclipses can occur near a full moon, when the Earth is between the Sun and Moon.
Because the Moon's orbit around the Earth is inclined by about 5° with respect to the orbit of the Earth around the Sun, eclipses do not occur at every full and new moon. For an eclipse to occur, the Moon must be near the intersection of the two orbital planes.The periodicity and recurrence of eclipses of the Sun by the Moon, and of the Moon by the Earth is described by the saros cycle, which has a period of approximately 6,585.3 days (18 years 11 days 8 hours).The March 2007 lunar eclipse.The angular diameters of the Moon and the Sun as seen from Earth overlap in their variation, so that both total and annular solar eclipses are possible. In a total eclipse, the Moon completely covers the disc of the Sun and the solar corona becomes visible to the naked eye. Since the distance between the Moon and the Earth is very slightly increasing over time, the angular diameter of the Moon is decreasing. This means that hundreds of millions of years ago the Moon could always completely cover the Sun on solar eclipses so that no annular eclipses were possible.Likewise, about 600 million years from now (assuming that the angular diameter of the Sun will not change), the Moon will no longer cover the Sun completely and only annular eclipses will occur.A phenomenon related to eclipse is occultation. The Moon is continuously blocking our view of the sky by a 1/2 degree-wide circular area. When a bright star or planet passes behind the Moon it is occulted or hidden from view. A solar eclipse is an occultation of the Sun. Because the Moon is close to Earth, occultations of individual stars are not visible everywhere, nor at the same time. Because of the precession of the lunar orbit, each year different stars are occulted.The next total lunar eclipse will take place on August 28, 2007. It will be visible from the Americas, the Pacific Ocean, eastern Asia and Oceania. The next solar eclipse takes place on September 11, 2007, visible from southern South America and parts of Antarctica. The next total solar eclipse, on August 1, 2008, will have a path of totality beginning in northern Canada and passing through Russia and China.