Mass of a planet!!!?

Question

How ca you calculate the mass of a planet?

Answer 1

The mass of a planet can be calculated via third Kepler's law that can be derived from Newton's law of gravitation, providing this planet has got one or more satelites.
3rd Kepler's law in this case is:
r^3 / T^2 = G x M / 4π^2
where r is the radius of the satelite's path, T is its period, G is the gravitational constant and M is the mass of the planet.
For instance, we know that the Earth's satelite Moon has got the period
T = 27.3 days = 2 358 720 s and its average distance from the Earth is r = 384 000 km. We can solve for M, which, in this case, is the mass of the Earth:
M = 4π^2 x r^3 / G x T^2 = 6 x 10E24 kg.
This is also the way the Earth's mass was determined for the first time, after Cavendish had measured the value of the gravitational constant.
In this way, you can not calculate Venus' mass, because Venus hasn't got any natural satelites.

Answer 2

there will be a reasonable results of the extra advantageous massed planet, yet not sufficient to extremely result orbital velocity. Earth orbits a lots, lots extra advantageous mass - the sunlight. in basic terms whilst the mass of a planet is interior a similar scale because of the fact the sunlight (examine: a million/3 the mass, a million/2 the mass or equivalent the mass of the sunlight), can we hassle approximately having a planet's mass affecting it is velocity. extra often than not, a feather orbiting the sunlight at an equivalent distance that Earth is would have an same velocity; it is actual in case you doubled, tripled or quadrupled Earth's mass. it is once you initiate up getting up there - previous the mass of Jupiter, do you start to calculate how that mass would impact orbital velocity.

Answer 3

http://en.wikipedia.org/wiki/Planets

hope it helps