Highly elliptical orbit Highly elliptical orbit A highly elliptical orbit (HEO) is an elliptic orbit with high eccentricity, usually referring to one around Earth. Examples of inclined HEO orbits include Molniya orbits, named after the Molniya Soviet communication satellites which used them, and tundra orbits. Such extremely elongated orbits have the advantage of long dwell times at a point in the sky during the approach to, and descent from, apogee. Bodies moving through the long apogee dwell appear to move slowly, and remain at high altitude over high-latitude ground sites for long periods of time. This makes these elliptical orbits useful for communications
Orbit of the Moon and nights of about 15 Earth days, the sun will be "up" for 173 days as it will be "down"; polar sunrise and sunset takes 18 days each year. "Up" here means that the centre of the sun is above the horizon. Lunar polar sunrises and sunsets occur around the time of eclipses (solar or lunar). For example, at the Solar eclipse of March 9, 2016, the moon was near its descending node, and the sun was near the point in the sky where the equator of the moon crosses the ecliptic. When the sun reaches that point, the centre