Expert: Jayendra Upadhye - 3/23/2005

Question
How can I calculate the rotation peroid of a celestial body (planet). Is there a fmla?

Is it possible to calculate the inclination of the axis of a planet

Also I need a fmla for the time period of an elliptical orbit.

Answer
Hi Mark,
there is no fixed formula for rotational periods of celestial bodies. These periods are the inheritance from thier history! Some turn fast, some slow, some not at all, about their axes.

It is possible to calculate the inclination of the axis of a planet, provided you take prolonged visual exposures of the planet. then determine the poles, and their inclination to the orbital plane of the planet.

I will not be able to tell you any such formula off hand.
A search of the web might yield you a site for that.
Some interesting sites:
1 - http://www.windows.ucar.edu/tour/link=/our_solar_system/planets_table.html
2 - This site is excellent for you as it gives the famous kepler's equations of orbiting planets namely that orbital period squared is proportional to the cube of the semi-major axis of the elliptical orbit.
http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Gravity/KeplersLaws.html
Hope this suffices.
Jayen