What is Orbital plane (astronomy)?
[[File:Orbit1.svg|thumb|300px|An orbital plane as viewed relative to a plane of reference]] An '''orbital plane''' is the [[geometric]] plane of an [[orbit]]. It is described by its difference from a ''reference plane''. The reference plane for the [[Solar System]] is usually the [[Earth]]'s orbital plane. This defines the [[ecliptic]], the path on the [[celestial sphere]] that the Sun appears to follow over a year. For example, suppose a [[planet]] is orbiting around a [[star]] in an [[elliptical orbit]]. The area within the path is the 'orbital plane' of that planet. The plane of the Earth's orbit around the Sun is called the [[ecliptic]] plane. Sometimes the [[invariable plane]] is used instead. {{Sci-stub}} [[Category:Orbits]]