The Moon is Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

's only known natural satellite
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....

,There are a number of near-Earth asteroids including 3753 Cruithne
3753 Cruithne
3753 Cruithne is an asteroid in orbit around the Sun in approximate 1:1 orbital resonance with the Earth. It is a periodic inclusion planetoid orbiting the Sun in an apparent horseshoe orbit. It has been incorrectly called "Earth's second moon", but it is only a quasi-satellite. Cruithne never...

 that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term (Morais et al, 2002). These are quasi-satellite
A quasi-satellite is an object in a 1:1 orbital resonance with its planet that stays close to the planet over many orbital periods.A quasi-satellite's orbit around the Sun takes exactly the same time as the planet's, but has a different eccentricity , as shown in the diagram on the right...

s and not true moons. For more information, see Other moons of Earth.
and the fifth largest satellite in the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...


1178    Five Canterbury monks see what is possibly the Giordano Bruno crater being formed. It is believed that the current oscillations of the Moon's distance from the Earth (on the order of metres) are a result of this collision.

1959    Luna 1 becomes the first spacecraft to reach the vicinity of the Moon.

1959    The Soviet probe ''Luna 2'' crashes onto the Moon, becoming the first man-made object to reach it.

1959    The world sees the far side of the Moon for the first time.

1961    Apollo program: U.S. President John F. Kennedy announces before a special joint session of the Congress his goal to initiate a project to put a "man on the Moon" before the end of the decade.

1962    Apollo Project: NASA announces plans to build the C-5 rocket booster. It became better known as the Saturn V moon rocket, which launched every Apollo moon mission.

1962    Ranger program: Ranger 3 is launched to study the moon. The space probe later misses the moon by 22,000 miles (35,400 km).

1962    NASA's Ranger 4 spacecraft crashes into the Moon.

1964    Ranger program: Ranger 7 sends back the first close-up photographs of the moon, with images 1,000 times clearer than anything ever seen from earth-bound telescopes.

1965    Project Ranger: The Ranger 8 probe launches on its mission to photograph the ''Mare Tranquillitatis'' region of the Moon in preparation for the manned Apollo missions. ''Mare Tranquillitatis'' or the "Sea of Tranquility" would become the site chosen for the Apollo 11 lunar landing.