Mean motion
McGraw-Hill Science & Technology Dictionary:
Top
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.
Wiley Book of Astronomy:
Top
mean motion
The constant angular velocity that an object, such as a planet, would have if it were moving in a circular orbit (instead of an elliptical one) of radius equal to its mean distance from the Sun, and equal to its actual revolution period. This is a hypothetical concept used in celestial mechanics.
Wikipedia on Answers.com:
Top
Mean motion
 |
This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2009) |
Mean motion, 
, is a measure of how fast a satellite progresses around its elliptical orbit. Unless the orbit is circular, the mean motion is only an average value, and does not represent the instantaneous angular velocity.
In the databases of satellite orbital parameters the mean motion is typically specified in revolutions per day.
Calculation
where:
is the gravitational constant,
and 
are the masses of the orbiting bodies,
is semi-major axis.
Related Formulae
Mean motion can also be expressed in radians or degrees, respectively, per unit of time; where P is the Orbital Period.
Or,
Where M1 and M0 are the Mean Anomalies at particular points in time, and t is the time elapsed between the two. M0 also frequently denotes the Mean Anomaly at Epoch and t the time since epoch.
See also
 |
This astronomy-related article is a stub. You can help Wikipedia by expanding it. |
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
Post a question - any question - to the WikiAnswers community:
Copyrights:
McGraw-Hill Science & Technology Dictionary
McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.
Read more
Wiley Book of Astronomy
Copyright © 2004 by Wiley-Blackwell. Wiley and the Wiley logo are registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and other countries. Used here by license. Read more
Mentioned in
mean solar time
(astronomy)
ephemeris second
(astronomy)
circulation flux
(meteorology)
Ananke
(astronomy)
Carme
(astronomy)
» More