In astronomy, lunar orbit refers just to the orbit of the Moon around the Earth. Radio telescopes are among many different tools used by astronomers Astronomy (Greek: αστρονομία = άστρον + νόμος, astronomia = astron + nomos, literally, law of the stars) is the science of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earths atmosphere (such as auroras and cosmic background radiation). ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... Earth (often referred to as the Earth, or the earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ...

As used in the space program, this refers not to the orbit of Earth's Moon, but to orbits around that Moon by various manned or unmanned spacecraft. The first spacecraft to reach lunar orbit was the Soviet unmanned vehicle Lunik 1 in 1959. The vehicle flew once around the Moon, returning low quality photographs. Human spaceflight is space exploration with a human crew, and possibly passengers (in contrast to unmanned space missions, which are remotely-controlled or robotic space probes). ... Lunik is a band from Switzerland. ...

The first spacecraft the enter a true lunar orbit, in the sense that it was a satellite continuously going around the Moon, was the USA's Lunar Orbiter 1 in 1965. This was the first of five similar spacecraft launched over a period of thirteen months, all of which successfully mapped the Moon. This was in preparation for the Apollo Project, searching for a suitable landing site. Lunar orbiter spacecraft (NASA) The Lunar Orbiter program was a series of five unmanned Lunar orbiter missions launched by the United States in 1966 through 1967 with the purpose of mapping the lunar surface before the Apollo landings. ... Description Role: Earth and Lunar Orbit Crew: 3; CDR, CM pilot, LM pilot Dimensions Height: 36. ...

The Apollo Project's Command and Service Module remained in lunar orbit while the Lunar Module landed. Selection of an orbit was constrained on the low side by lunar mountains reaching heights of 20,000 feet (nearly seven kilometers), and on the high side by the need to obtain suitable imagery. Lunar Orbiters were mostly around 200 miles altitude while the Apollo Project used roughly 65 miles. Orbital periods were roughly two hours. Description Role: Earth and Lunar Orbit Crew: 3; CDR, CM pilot, LM pilot Dimensions Height: 36. ... Description Role: Lunar landing Crew: 2; CDR, LM pilot Dimensions Height: 20. ...

Gravitational anomalies slightly distorting the orbits of the Lunar Orbiters led to the discovery of mascons, concentrations of mass beneath the lunar surface caused by large impacting bodies at some remote time in the past. These anomalies were too small to be of significance for the short time the Apollo Project's spacecraft were in lunar orbit.