# mean motion

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## mean motion

The constant angular speed that is required for a celestial body to complete one revolution of an (undisturbed) elliptical orbit of a specified semimajor axis.

## Mean Motion

(religion, spiritualism, and occult)

Because celestial bodies move in elliptical orbits, their speed varies depending upon their location. Mean motion refers to their average speed.

## Mean Motion

an element, or parameter, of the orbit of a celestial body that characterizes the dimensions of the orbit. The relation between the mean motion and the semimajor axis of the orbit is given by Kepler’s third law: the larger the semimajor axis, the more slowly the body, on the average, moves in its orbit. (SeeORBIT OF A CELESTIAL BODY.)

## mean motion

[′mēn ′mō·shən]
(astronomy)
The speed which a planet or its satellite would have if it were moving in a circular orbit with radius equal to its distance from the sun or a central planet with a period equal to its actual period.
References in periodicals archive ?
This is a figure-8 pattern that depicts the Sun's mean motion in the sky, which changes due to Earth's axial tilt and orbital eccentricity, throughout an entire year.
Also, the extrasolar system around HD 37124 that consists of two planets with periods of 155 and 31 days shows a 5:1 mean motion resonance, so even the particular commensurability seen for HD 202206 is not new.
By this I mean motion to a place either where the speaker was in the past, or will be in the future.
Ozanne-Rivierre 1997:90) She offers an example where motion 'up' can mean motion towards the place of a person of higher rank than oneself, regardless of the physical location of that place.
Two motions are fundamental: (1) the mean motion and (2) the motion in anomaly.
The motion of the epicycle's center on the deferent is the mean motion of the object, or the average position at which it will be found.
He finally compiles all the data into tables of mean motion and of motion in anomaly, with which the astronomer can calculate any object's position at any date.
These enhancements mean motion and displacement can be applied and removed several times throughout the course of an analysis, as in the application and release of a brake pedal.

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