Astrophysics (index)

Eccentricity

(e)
(degree to which an orbit is non-circular)

Eccentricity (e) is a number indicating the degree to which an orbit is non-circular, 0 meaning circular, between 0 and 1 being Elliptical, 1 being parabolic, and greater than 1 being hyperbolic.

The eccentricity of an elliptical orbit is:

    ra - rp
e = ———————
    ra + rp

Where

  • e is the eccentricity
  • ra is the radius at apoapsis (furthest distance)
  • rp is the radius at periapsis (closest distance)

Earth's orbit has an eccentricity of 0.0167. The Moon's is 0.0549.


(orbits,celestial mechanics,measure)
http://en.wikipedia.org/wiki/Orbital_eccentricity

Referenced by:
Apsis
DQ Tau
Hill Radius
Kozai Mechanism
Libration
Moon
Orbital Element
Precession
Laplace Radius (rL)
Semi-Major Axis (a)
Titan

index