longitude of the ascending node

astronomy

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June 30, 2026

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In astronomy, the longitude of the ascending node is a crucial element used to describe an object's orbit. It defines the orientation of the orbit's plane in space.1

Specifically, the ascending node is the point where a celestial body, like a planet or comet, crosses from below to above the ecliptic plane (the apparent path of the Sun). The longitude of the ascending node measures the angular distance eastward along the ecliptic from the vernal equinox to this ascending node. This measurement, along with the inclination of the orbit, helps to fix the orientation of the orbital plane.231

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celestial mechanics
Perturbations of elliptical motion
…angle Ω is called the longitude of the ascending node. Angle ω (called the argument of perihelion) is the angular distance from the ascending node to the perihelion measured in the orbit plane.
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…angle Ω is called the longitude of the ascending node. Angle ω (called the argument of perihelion) is the angular distance from the ascending node to the perihelion measured in the orbit plane.
Read More