digplanet beta 1: Athena
Share digplanet:


Applied sciences






















In celestial mechanics, mean anomaly is a parameter relating position and time for a body moving in a Kepler orbit. It is based on the fact that equal areas are swept in equal intervals of time by a line joining the focus and the orbiting body (Kepler's second law).

The mean anomaly increases uniformly from 0 to 2\pi radians during each orbit. However, it is not an angle. Due to Kepler's second law, the mean anomaly is proportional to the area swept by the focus-to-body line since the last periapsis.

The mean anomaly is usually denoted by the letter M, and is given by the formula:

 M =  n \, t =  \sqrt{\frac{ G( M_\star \! + \!m ) } {a^3}} \,t

where n is the mean motion, a is the length of the orbit's semi-major axis, M_\star and m are the orbiting masses, and G is the gravitational constant.

The mean anomaly is the time since the last periapsis multiplied by the mean motion, and the mean motion is 2\pi divided by the duration of a full orbit.

The mean anomaly is one of three angular parameters ("anomalies") that define a position along an orbit, the other two being the eccentric anomaly and the true anomaly. If the mean anomaly is known at any given instant, it can be calculated at any later (or prior) instant by simply adding (or subtracting) \sqrt{\frac{ G( M_\star \! + \!m ) } {a^3}} \,\delta t where \delta t represents the time difference. The other anomalies can hence be calculated.


The mean anomaly M can be computed from the eccentric anomaly E and the eccentricity e with Kepler's Equation:

M =  E - e \cdot \sin E

To find the position of the object in an elliptic Kepler orbit at a given time t, the mean anomaly is found by multiplying the time and the mean motion, then it is used to find the eccentric anomaly by solving Kepler's equation.

It is also frequently seen:

M =  M_0 + nt,

Again n is the mean motion. However, t, in this instance, is the time since epoch, which is how much time has passed since the measurement of M0 was taken. The value M0 denotes the mean anomaly at epoch, which is the mean anomaly at the time the measurement was taken.

See also[edit]


  • Murray, C. D. & Dermott, S. F. 1999, Solar System Dynamics, Cambridge University Press, Cambridge.
  • Plummer, H.C., 1960, An Introductory treatise on Dynamical Astronomy, Dover Publications, New York. (Reprint of the 1918 Cambridge University Press edition.)

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Mean_anomaly — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
57249 videos foundNext > 

True Anomaly vs. Mean Anomaly

This video explains what the Mean Anomaly is, how it relates to the True Anomaly, and how to use the Mean Anomaly to propagate a simple 2-body orbit. In case...

True anomaly

How true anomaly affects satellite position.

10-Year Mean Anomaly

Begins with 1881-1890 mean meteorological year anomaly and ends with 1998-2007. Nasa.

Lecrae - "What Does a Real Man Look Like?!" #ANOMALY

Download Lecrae's #ANOMALY: https://itunes.apple.com/us/album/anomaly/id897749424 Download my album: https://itunes.apple.com/ca/album/rise/id910099839 ○ SEN...

Lecrae Anomaly | The Definition

iTunes: http://lecrae.cta.gs/01r Amazon: http://lecrae.cta.gs/01s Merchline: http://lecrae.cta.gs/01t Google Play: http://lecrae.cta.gs/01w Lecrae's seventh ...

Anomaly Definition - What Does Anomaly Mean?

Go to http://www.corporatevocabulary.com for the complete lesson on Anomaly and a full course to give you the vocabulary and communication skills of a six-fi...

Baltic sea Anomaly take five updated 2014 HD

http://www.alwaysmoving.com.au/ Edited to removed media source information owned by the greedy and distributed to no body of interest that would be willing t...

KB Anomaly (@KB_HGA) HD

BUY IT ON ITUNES NOW! Tracklist Below Join teamunashemed: http://goo.gl/7FhGJ Our lives are not meant for self-exaltation or self-preservation. Our lives are...

Anomaly - Second Wind (Track 1)

Track 1 - "Second Wind" off the new record 'Different Shade, Same Color' now available through iTunes, Spotify, Amazon and many more! @AnomalyPA www.facebook...

Lecrae - Say I Won't (Christian Dance Video) @Lecrae @AndyMineo @Reachrecords #Anomaly

I do not own Rights to this song!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Buy the Song/Albulm here: iTunes: http://lecrae.cta.gs/01r Amazon: http://lecrae.cta.gs/01s...

57249 videos foundNext > 

We're sorry, but there's no news about "Mean anomaly" right now.


Oops, we seem to be having trouble contacting Twitter

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!

Searchlight Group

Digplanet also receives support from Searchlight Group. Visit Searchlight