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Página creada con '{{traducción}} The '''semi-major axis''' of any ellipse is one-half of the axis of symmetry that passes through the foci of that ellipse. In astrophysics, the semi-maj...'
{{traducción}}
The '''semi-major axis''' of any [[ellipse]] is one-half of the axis of symmetry that passes through the foci of that ellipse.
In [[astrophysics]], the semi-major axis of an orbit is the distance between the geometric center of the orbit and either [[apsis]]. It is a commonly reported orbital element that can determine the size and shape of an orbit.
== Calculations ==
The semi-major axis, usually labeled ''a'', is the arithmetic mean of the two apsides:
a = (Q + q)/2
For this reason the semi-major axis is often cited as a "mean orbital radius."
The semi-major axis, together with the [[orbital eccentricity]] (''e''), can predict the periapsis and apoapsis:
Q = a(1+e)
q = a(1-e)
See [[orbital eccentricity]] for a detailed derviation.
{{Astronomy portal}}
[[Category:Astronomy]]
[[Category:Orbital mechanics]]
[[en:Semi-major axis]]
[[fr:Axis semi-majeur]]
[[pt:Semieixo maior]]
The '''semi-major axis''' of any [[ellipse]] is one-half of the axis of symmetry that passes through the foci of that ellipse.
In [[astrophysics]], the semi-major axis of an orbit is the distance between the geometric center of the orbit and either [[apsis]]. It is a commonly reported orbital element that can determine the size and shape of an orbit.
== Calculations ==
The semi-major axis, usually labeled ''a'', is the arithmetic mean of the two apsides:
a = (Q + q)/2
For this reason the semi-major axis is often cited as a "mean orbital radius."
The semi-major axis, together with the [[orbital eccentricity]] (''e''), can predict the periapsis and apoapsis:
Q = a(1+e)
q = a(1-e)
See [[orbital eccentricity]] for a detailed derviation.
{{Astronomy portal}}
[[Category:Astronomy]]
[[Category:Orbital mechanics]]
[[en:Semi-major axis]]
[[fr:Axis semi-majeur]]
[[pt:Semieixo maior]]
