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sun-synchronous orbit

sun-synchronous orbit
A sun-synchronous orbit.
Image credit: Galactics

A special case of a near-polar orbit in which a satellite, in going around the Earth, passes over the same points on the Earth's surface at the same local times each day and a different swathe of territory on each orbit. This kind of orbit involves passing close to both poles and crossing the meridians at a carefully-chosen angle. Sun-synchronous orbits are typically low Earth orbits with altitudes of 550 to 850 km.

A dawn-dusk orbit is a special case of a sun-synchronous orbit in which a satellite perpetually trails the shadow of the Earth cast by the Sun. Because the satellite is close to the shadow, the part of the Earth's surface directly below the satellite is always at sunset or sunrise, hence the name of this type of orbit. An advantage of it is that the satellite always has its solar panels bathed in sunlight so that it can produce power by this means continuously.

[Thanks to Doug Adler of the Space Science & Engineering Center, University of Wisconsin-Madison, for a correction to this page]

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