The Moon

The Moon is an average of 238,855 miles (384,400 kilometers) away.

The Moon likely formed after a Mars-sized body collided with Earth several billion years ago.

The Moon is rotating at the same rate that it revolves around Earth (called synchronous rotation), so the same hemisphere faces Earth all the time.

With a radius of about 1,080 miles (1,740 kilometers), the Moon is less than a third of the width of Earth.

The Moon makes a complete orbit around Earth in 27 Earth days and rotates or spins at that same rate, or in that same amount of time.

The Moon has a very thin and weak atmosphere.

While you were there, you'd notice that the gravity on the surface of the Moon is one-sixth of Earth's, which is why in footage of moonwalks, astronauts appear to almost bounce across the surface.

Earth's only natural satellite and the fifth largest moon in the solar system.

Earth is the only planet in our solar system with only one moon.

Pluto is about two-thirds the diameter of Earth's Moon

Europa is about the size of Earth's moon, with a diameter of 3,130 kilometers (1.945 miles).

The Moon is the brightest celestial object in Earth's night sky

Humans first arrived in orbit with Apollo 8 (sent by the United States) on December 24, 1968, and then on the surface with Apollo 11 on July 20, 1969, making the Moon the only celestial body beyond Earth that humans have visited.

The first spaceflights to an extraterrestrial body were to the Moon, starting in 1959 with the flyby of Luna 1 (sent by the Soviet Union), and the intentional impact of Luna 2, followed in 1966 by the first soft landing (by Luna 9) and orbital insertion (by Luna 10).

Kennedy's 1961 commitment to a crewed Moon landing before the end of the decade, the United States, under NASA leadership, launched a series of uncrewed probes to develop an understanding of the lunar surface in preparation for human missions: the Jet Propulsion Laboratory's Ranger program, the Lunar Orbiter program and the Surveyor program.

Kennedy's 1961 commitment to a crewed Moon landing before the end of the decade, the United States, under NASA leadership, launched a series of uncrewed probes to develop an understanding of the lunar surface in preparation for human missions: the Jet Propulsion Laboratory's Ranger program, the Lunar Orbiter program and the Surveyor program.

Kennedy's 1961 commitment to a crewed Moon landing before the end of the decade, the United States, under NASA leadership, launched a series of uncrewed probes to develop an understanding of the lunar surface in preparation for human missions: the Jet Propulsion Laboratory's Ranger program, the Lunar Orbiter program and the Surveyor program.

Water vapor has been detected by Chandrayaan-1 and found to vary with latitude, with a maximum at ~60-70 degrees; it is possibly generated from the sublimation of water ice in the regolith.

Between 2004 and 2006 the first spacecraft by the European Space Agency (ESA) (SMART-1) orbited the Moon, recording the first detailed survey of chemical elements on the lunar surface.

In 1994, the bistatic radar experiment located on the Clementine spacecraft, indicated the existence of small, frozen pockets of water close to the surface.

Dust counts made by LADEE's Lunar Dust EXperiment (LDEX) found particle counts peaked during the Geminid, Quadrantid, Northern Taurid, and Omicron Centaurid meteor showers, when the Earth, and Moon pass through comet debris.

In 2009, LCROSS sent a 2,300 kg (5,100 lb) impactor into a permanently shadowed polar crater, and detected at least 100 kg (220 lb) of water in a plume of ejected material.

The Chinese Lunar Exploration Program reached the Moon for the first time with the orbiter Chang'e 1 (2007-2009), obtaining a full image map of the Moon.