Editing Sun-synchronous orbit (section)

== Applications ==
A Sun-synchronous orbit is useful for [[imaging satellite|imaging]], [[reconnaissance satellite|reconnaissance]], and [[weather satellite]]s,<ref name=":0">{{Cite book |title=Our Changing Planet: The View from Space |url=https://archive.org/details/ourchangingplane00king |url-access=limited |publisher=Cambridge University Press |edition=1st |year=2007 |isbn=978-0521828703 |page=[https://archive.org/details/ourchangingplane00king/page/n356 339]}}</ref> because every time that the satellite is overhead, the surface [[illumination angle]] on the planet underneath it is nearly the same. This consistent lighting is a useful characteristic for [[satellite]]s that image the Earth's surface in visible or [[infrared]] wavelengths, such as weather and spy satellites, and for other remote-sensing satellites, such as those carrying ocean and atmospheric remote-sensing instruments that require sunlight. For example, a satellite in Sun-synchronous orbit might ascend across the equator twelve times a day, each time at approximately 15:00 mean local time.

[[File:Sun-Synchronous Orbit with LST Zones.svg|thumb|upright=1.5|right|Sun-synchronous orbit from a top view of the [[Ecliptic|ecliptic plane]] with [[Solar time|local solar time]] (LST) zones for reference and a [[Orbital node|descending node]] of 10:30. The LST zones show how the local time beneath the satellite varies at different latitudes and different points on its orbit.]]

Special cases of the Sun-synchronous orbit are the '''noon/midnight orbit''', where the local mean solar time of passage for equatorial latitudes is around noon or midnight, and the '''dawn/dusk orbit''', where the local mean solar time of passage for equatorial latitudes is around sunrise or sunset, so that the satellite rides the [[Terminator (solar)|terminator]] between day and night. Riding the terminator is useful for active radar satellites, as the satellites' solar panels can always see the Sun, without being shadowed by the Earth. It is also useful for some satellites with passive instruments that need to limit the Sun's influence on the measurements, as it is possible to always point the instruments towards the night side of the Earth. The dawn/dusk orbit has been used for solar-observing [[scientific satellites]] such as [[TRACE]], [[Hinode (satellite)|Hinode]] and [[PROBA-2]], affording them a nearly continuous view of the Sun.

<gallery widths="400px">
File:Orbit path - Aqua ascending - day.png|As of 2021 [[Aqua (satellite)|Aqua]]'s ascending orbital path crosses equator at 13:30 local time
File:Orbit path - Aqua descending - night.png|As of 2021 Aqua's descending orbital path crosses equator at 01:30 local time
</gallery>