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# mass of extra-solar planet from M, r and R

sspickle.mass of extra-solar planet from M, r and R

The ** Mass of an Extra-solar Planet** calculator computes the mass of a planet based on the mass of the star (**M**), the distance to the star (**R**) and the distance to the planet (**r**).

**INSTRUCTIONS:** Choose the preferred units and enter the following:

- (
**M**) This is the mass of the star. - (
**R**) This is the orbital radius of the planet. - (
**r**) This is the orbital radius of the star about the center of mass.

**Planet Mass (m):** The calculator returns the mass of the planet in Jupiter_Mass units (multiples of the mass of Jupiter). However, this can be automatically converted to other mass units (e.g. Earth_Mass or kilograms) via the pull-down menu.

#### The Math / Science

If you know the mass of a star, and the orbital radius of the star and the planet, you can compute the mass of the planet using the fact that the center of mass obeys the relation: m•R = M•r.

##### Example:

Consider Jupiter in our own solar system:

- (M) The mass of our star (the Sun) is 1.0 Solar_Mass
- (R) This orbital radius of Jupiter is 5.2 ua
- (r) The orbital radius of our Sun around the solar system's center of mass is 0.005 ua

If you enter the above, the calculator returns an exoplanet mass of approximately 1 Jupiter Mass which fits the model and describes our solar system.

**mass of extra-solar planet from M, r and R**, is used in 3 calculators.

**Calculators**