# Re: Yes, I'm back

From: | John Cowan <jcowan@...> |

Date: | Tuesday, January 21, 2003, 6:39 |

James Landau wrote:
> (This leads to another question: is there anyone here who knows
> how to find out how fast a planet will rotate on its axis or complete a
> year, given its volume, mass and distance from the sun?)

The parameters of mass/volume, day length (rotation on axis), and year
length (revolution around sun) are absolutely unrelated. The year
length is related to the distance from the sun by the following
relationship (Kepler's 3rd or harmonic law): Y^2 = D^3, where Y is
measured in years and D is measured in astronomical units (Earth's
distance from the sun, about 150 million km).
--
John Cowan jcowan@reutershealth.com www.ccil.org/~cowan www.reutershealth.com
"In computer science, we stand on each other's feet."
--Brian K. Reid