| [Edit]
The ecliptic coordinate system is a celestial coordinate system that uses the ecliptic for its fundamental plane. The ecliptic is the path that the sun appears to follow across the sky over the course of a year. It is also the projection of the Earth's orbital plane onto the celestial sphere. The latitudinal angle is called the ecliptic latitude (denoted β), measured positive towards the north. The longitudinal angle is called the ecliptic longitude (denoted λ), measured eastwards from 0° to 360°. Like right ascension in the equatorial coordinate system, the origin for ecliptic longitude is the vernal equinox. This choice makes the coordinates of the fixed stars subject to shifts due to the precession, so that always a reference epoch should be specified. Usually epoch 2000 is taken, but the instantaneous equinox of the day is possible too.
This coordinate system can be particularly useful for charting solar system objects. Most planets (except Mercury), dwarf planets, and many small solar system bodies have orbits with small inclinations to the ecliptic plane, and therefore their ecliptic latitude β is always small.
|
|
