What are the ascending and descending nodes of an orbit?
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Welcome, my name is Phil, and in this video, I explain what the ascending and descending nodes of an orbit are.
The ascending and descending nodes are specific points on the orbit of a celestial body (like a planet, moon, or satellite) as it moves around a larger body, typically in an elliptical path. These nodes are particularly important in celestial mechanics and are related to the intersection of two planes: the orbital plane of the body and a reference plane, such as the equatorial plane of the planet around which the satellite orbits or the ecliptic plane in the case of orbits within the solar system.
Ascending Node: This is the point where the orbiting body moves from below the reference plane to above it. In simpler terms, it is where the body "ascends" northward through the plane. For orbits around Earth, this would be the point where the satellite crosses the equator moving from the southern hemisphere to the northern hemisphere. In solar system terms, it’s where a planet or another object crosses from the south to the north of the ecliptic.
Descending Node: This is the point where the orbiting body moves from above the reference plane to below it. This is where the body "descends" southward through the plane. For Earth orbits, this is when the satellite crosses from the northern hemisphere to the southern hemisphere. In the context of the solar system, it is the point where a planet or other object crosses from the north to the south of the ecliptic.