Molniya orbits

Noun

Molniya orbit (plural Molniya orbits)

1. 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.
2. By analogy, the equivalent orbit for the southern hemisphere, with the argument of perigee changed to +90 degrees.
3. (broadly) Both the northern and southern hemisphere orbits for the Earth.
4. 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.
5. (broadly) The orbits around Earth and other bodies with these qualities.