Space Exploration Stack Exchange is a question and answer site for spacecraft operators, scientists, engineers, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
...or, "What is the inclination of a satellite that travels over Earth's equator?"
Considering Earth's axial tilt is 23.4°, it's a significant difference - is the inclination calculated relative to the plane of ecliptic, or relative to Earth's global coordinates?
Considering the sun-synchronous satellites travel at inclination of 98 degrees I'm inclined (pun unintended) to believe it's the former but I prefer to ask in case I'm guessing wrong.
This is another one of those data that you'd normally expect to be accompanied by with respect to what (plane of reference) metadata and explaining what they're quoted for. In Earth orbit, if this "w.r.t." isn't given, it's safe to assume that the reference zero angle is the equatorial plane in the direction of Earth's rotation on its axis (e.g. TLE, Two-Line Element sets also give values with the plane of reference being the equatorial plane and prograde as 0 angle of the primary body, i.e. ascending node), but you'd often also find sources quoting values relative to something else, say the Laplace's invariable plane, ecliptic, or alike. Sadly, this crucial metadata is often also missing and you're then required to find more reliable quotes somewhere else or dig for metadata to properly interpret quoted values, since they can be ambiguous and a subject to misinterpretation without it.
