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In contrast, the Lunar distance (LD or ), or Earth–Moon characteristic distance, is a unit of measure in astronomy. More technically, it is the semi-major axis of the geocentric lunar orbit . The lunar distance is on average approximately 385,000 km (239,000 mi), or 1.28 light-seconds ; this is roughly 30 times Earth's diameter or 9.5 times ...
Considering the Earth–Moon system as a binary planet, its centre of gravity is within Earth, about 4,671 km (2,902 miles) [24] or 73.3% of the Earth's radius from the centre of the Earth. This centre of gravity remains on the line between the centres of the Earth and Moon as the Earth completes its diurnal rotation.
where F g is the gravitational force acting between two objects, M E is the mass of the Earth, 5.9736 × 10 24 kg, m s is the mass of the satellite, r is the distance between the centers of their masses, and G is the gravitational constant, (6.674 28 ± 0.000 67) × 10 −11 m 3 kg −1 s −2.
Although the Moon's Hill sphere extends to a radius of 60,000 km (37,000 mi), [6] the gravity of Earth intervenes enough to make lunar orbits unstable at a distance of 690 km (430 mi). [ 7 ] The Lagrange points of the Earth-Moon system can provide stable orbits in the lunar vicinity, such as halo orbits and distant retrograde orbits .
Clickable image, highlighting medium altitude orbits around Earth, [a] from Low Earth to the lowest High Earth orbit (geostationary orbit and its graveyard orbit, at one ninth of the Moon's orbital distance), [b] with the Van Allen radiation belts and the Earth to scale To-scale diagram of low, medium, and high Earth orbits Space of Medium Earth orbits (MEO) as pink area, with Earth and the ...
Thus, a geostationary orbit is defined as a geosynchronous orbit at zero inclination. Geosynchronous (and geostationary) orbits have a semi-major axis of 42,164 km (26,199 mi). [10] This works out to an altitude of 35,786 km (22,236 mi). Both complete one full orbit of Earth per sidereal day (relative to the stars, not the Sun).
Space of high Earth orbits (HEO), between medium Earth orbits (MEO) and the orbit of the Moon. A high Earth orbit is a geocentric orbit with an apogee farther than that of the geosynchronous orbit, which is 35,786 km (22,236 mi) away from Earth. [1] In this article, the non-standard abbreviation of HEO is used for high Earth orbit. [2]
GTO is a highly elliptical Earth orbit with an apogee (the point in the orbit of the moon or a satellite at which it is furthest from the earth) of 42,164 km (26,199 mi), [3] or a height of 35,786 km (22,236 mi) above sea level, which corresponds to the geostationary altitude.