--- "Mark J. Reed" <markjreed@...> wrote:
> I'm trying to calculate the orbital period of an Earth-sized planet
> at
> 15 AUs out from a star that's about 7.5 times the mass of the Sun.
> I'm
> guestimating around 50 years, but Kepler's laws don't seem to be much
> help when looking for absolutes; you need a known quantity within the
> same solar system to compare against. Can anyone point me at the
> correct formulae?
>
> Thanks.
>
About 21 earth years, if I did that right.
Psuedocode:
sqrt((m1^2 * G) / (r * (m1 + m2)))
m1 = sun mass (kg)
m2 = planet mass (kg) *
r = radius of orbit (m)
G = gravitational constant
It gives you the orbital period in seconds.
* Not that planet mass makes much difference here.
JC