Molniya orbit

Meaning

Noun

• 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.
• 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.
• The orbits around Earth and other bodies with these qualities.

Origin

• From мо́лния + 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.