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`T = ({4\pi^2 R^3}/{MG })^{1/2}`

Enter a value for all fields

The **Period from Mass and Separation** calculator uses Kepler's 3^{rd} law to compute the orbital period (**T**) of a system based on the distance (**R**) between astronomical bodies (e.g. a star and exoplanet) and the mass of the system (**M**).

**INSTRUCTIONS:** Chose units and enter the following:

- (
**M**) This is the mass of the system. - (
**R**) This is the separation between the bodies.

**Orbital Period (T):** The calculator returns the period in Earth days. However, this can be automatically converted to other time/duration units (e.g. seconds, years) via the pull-down menu.

In a binary system the separation between the objects in the system depends on the mass of the system and the period of the orbit (Kepler's Third Law). This equation computes the separation given the other two values. Kepler's formula for orbital period is:

`T = sqrt( (4π^2 • R^3)/(M•G) )`

where:

- T is the period of the orbit.
- M is the total mass of the system
- R is the separation distance between the two objects.
- G is the universal gravity constant

- Hubble's Law
- Kepler's 3
^{rd}Law formula T² = (4π • R³)/(G • M) - Small Angle Formula
*Small Angle Formula**α = S / D* - Flux and Magnitude formulas
- Telescope formulas
- Mass formulas
- Relative Size Formulas
- Wavelength Formulas
- Luminosity and other Formulas

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