eccentric anomaly
Quick Summary
In astronomy, an eccentric anomaly is one of three ways to describe a planet's, satellite's, or star's position within its orbit around a central mass. It is an angle measured from the center of an elliptical orbit to a point determined by drawing a perpendicular line from the planet's actual position to a circle that circumscribes the ellipse.1
This concept is part of celestial mechanics, which uses orbital parameters like semi-major axis and eccentricity to describe elliptical motion. The eccentric anomaly, along with true anomaly and mean anomaly, helps specify a celestial body's position relative to its perihelion (closest point to the Sun).12
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anomalyThe eccentric anomaly is the angle E, between the perihelion B, the centre of the ellipse at C, and the point Pā², which is located by drawing a perpendicular to AB passing through the planet and intersecting a circle of diameter AB.
Read MoreThe eccentric anomaly is the angle E, between the perihelion B, the centre of the ellipse at C, and the point Pā², which is located by drawing a perpendicular to AB passing through the planet and intersecting a circle of diameter AB.
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celestial mechanicsKeplerās laws of planetary motionThe angle u, called the eccentric anomaly, also locates G relative to P but with the centre of the ellipse as the origin rather than the focus S. An angle called the mean anomaly l (not shown in Figure 1) is also measured from P with S as the origin;ā¦
Read MoreThe angle u, called the eccentric anomaly, also locates G relative to P but with the centre of the ellipse as the origin rather than the focus S. An angle called the mean anomaly l (not shown in Figure 1) is also measured from P with S as the origin;ā¦
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