Through the ages, the Moon, our closest celestial body has aroused curiosity in our mind much more than any other objects in the sky.
With the history of the early solar system etched on it beckons mankind from time immemorial to admire its marvels and discover its secrets. Understanding the moon provides a pathway to unravel the early evolution of the solar system and that of the planet earth.
The average distance from the Earth to the Moon is 384,399 kilometres (238,854 miles), which is about 30 times the diameter of the Earth. The Moon is about one-third the size of the Earth and has a diameter of 3,474 kilometres (2,159 miles). It is the fifth largest moon in the Solar System behind Ganymede, Titan, Callisto, and Io. The Moon makes one complete orbit about the Earth every 27.3 days, and the periodic variations in the geometry of the Earth-Moon-Sun system are responsible for the lunar phases that repeat every 29.5 days. The gravitational attraction of the Moon is responsible for the tides on Earth.
The Moon is the only celestial body on which human beings have orbited and landed. The first man-made object to escape Earth's gravity and pass near the Moon was the Soviet Union's Luna 1, the first man-made object to impact the lunar surface was Luna 2, and the first photographs of the normally occluded far side of the Moon were made by Luna 3, all in 1959. The first spacecraft to perform a successful lunar soft landing was Luna 9 and the first unmanned vehicle to orbit the Moon was Luna 10, both in 1966. The United States' Apollo program achieved the first (and only) manned missions to the Moon, culminating in 6 landings between 1969 and 1972.
Indian Space Research Organization (ISRO) has launched unmanned lunar mission, Chandrayaan-1, on October 22, 2009