they are types of orbits of the artificial satellites:-
Low earth orbit (LEO): about 160 Km to 640 Km above the earth, so the delay is very small and the losses is small too.
Medium Earth orbit (MEO): 1600 to 4200 km above the earth, and uses for navigation communications like GPS.
Geostationary orbit (GEO): about 36000 Km above the equator, the delay and losses are greater, but the advantages is more coverage (it covers 40% of the earth) and there no nedd to track the satellite, so the earth terminal is cheaper, but the GEO is more expensive than MEO and LEO. GEO uses for Satellite TV Broadcasting.
All closed orbits are elliptical.
LEO: mobile phones, pagers; MEO: GPS systems; GEO: cable and direct television; HEO for military and science
Jo Jo Jo
Heo Gyun was born in 1569.
Heo Jeok was born in 1610.
Heo Jeok died in 1680.
Heo Jun was born in 1546.
Heo Mok died in 1682.
Heo Mok was born in 1595.
Heo Nanseolheon was born in 1563.
Heo Nanseolheon died in 1589.
Heo Gyun died in 1618.