Molniya orbit
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English
[edit]Etymology
[edit]From Russian мо́лния (mólnija, “lightning”) + orbit. The Russian word was used as the name for a series of Soviet/Russian communications satellites, and the orbits which they were placed in.
Noun
[edit]Molniya orbit (plural Molniya orbits)
- A highly elliptical orbit with an eccentricity of 0.74, inclination of 63.4 degrees, an argument of perigee of −90 degrees, and an orbital period of half a sidereal day, around the Earth.
- By analogy, the equivalent orbit for the southern hemisphere, with the argument of perigee changed to +90 degrees.
- (by extension) Both the northern and southern hemisphere orbits for the Earth.
- By analogy, equivalent orbits for other bodies, which provide low apparent motion across the dome of the sky at apoapsis, allowing long duration communications/observation with low tracking rates at polar latitudes.
- (by extension) The orbits around Earth and other bodies with these qualities.
Coordinate terms
[edit]- tundra orbit: a similar orbit with the orbital period extended to one day (a type of geosynchronous orbit)
References
[edit]Molniya orbit on Wikipedia.Wikipedia