# semimajor axis

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## semimajor axis

(sem-ee-may -jer) Symbol: a . The distance from the center of an ellipse to the edge, through the intervening focus. It is half the greatest distance across the ellipse, i.e. half the major axis. The semimajor axis of an elliptical orbit is one of the orbital elements.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

## semimajor axis

[‚sem·ē¦mā·jər ′ak·səs]
(mathematics)
Either of the equal line segments into which the major axis of an ellipse is divided by the center of symmetry.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
And the inner PML boundary has a semimajor axis of 3.5 m.
The average value of the minimal detectable deformation along the semimajor axis is equal to 42.3 mm, with an estimated standard deviation of displacement of 7.5 mm.
The microstructure was observed to lengthen along the semimajor axis [r.sub.3], semimajor axis [r.sub.1], and semiminor axis [r.sub.2].
(i) The estimation of the BC is tailored for reentry predictions by comparing the decay of the mean semimajor axis according to TLE data and according to a high-fidelity propagator considering all perturbations.
(2) If the semimajor axis does not satisfy [[alpha].sub.min] [less than or equal to] [alpha] [less than or equal to] [[alpha].sub.max], then drop [e.sub.i], where [[alpha].sub.min] and [[alpha].sub.max] are the maximum and minimum of the semimajor axis, respectively.
Time Evolution of Semimajor Axis, Eccentricity, and Inclination.
For particular, [??], [mu] will be maximum and value of [mu] will be semimajor axis of an ellipse.
A wide range of orbital periods will be possible for the pulsar, from around 107 per year for a semimajor axis of 0.1 AU to only about one orbit every year and a half for a semimajor axis of 3 AU.
The extension length L of an elliptical ILA is L = e x a, where [[epsilon].sub.r] is the relative permittivity of the lens material and a the semimajor axis of the ellipse.
where a, e, i, [OMEGA], [omega], and f are the usual Keplerian orbital elements, semimajor axis, eccentricity, inclination, longitude of the ascending node, and true anomaly, respectively, p is the semilatus rectum, [mu] the gravitational parameter, and n is the orbital mean motion.
The point that will be deemed as (X([t.sub.0]), Y([t.sub.0])) is chosen as the leftmost point that lies on the semimajor axis. For the linear interpolation in the profiles, measurement of the arc length starts from [t.sub.0] and t increases counterclockwise.
a is the semimajor axis (average heliocentric distance), and b is the semiminor axis of the ellipse.

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