Helpful Hints

Planetary Calculator Help File

This program allows you to apply astronomical formulas to all nine of the planets in our Solar System at the same time.

In the space provided enter equations using the constants and planetary variables in the two tables below or you can select an equation from the menu. Remember the box must be empty if you are using the menu.

Once you hit submit, your answers will be displayed in MKS units (meters, kilograms, and seconds) and degrees, unless you multiply them by one of the unit changing variables like "m2AU" which converts meters to AU.

Sample Equations:

For Escape Velocity enter: sqrt(2*G*M/R)

To change Spin Period from seconds to hours enter: Ps*s2hr

DEFINITIONS
Planet Mass: The Mass of a planet is the total amount of matter contained in the planet. The units of mass are kilograms.

Planet Radius: The Radius of a planet is the distance from its center to its edge. The radius is given in units of meters.

Planet Density: The Density of a planet is the ratio of a planet's mass to its volume. The units of density are kilograms per meters cubed.

Planet Oblateness: The Oblateness of a planet is how much is has been flattened by its rotation. Oblateness is unitless.

Spin Period: The Spin Period is the time that it takes the planet to spin once on its axis. The Spin Period is given in units of seconds.

Surface Gravity: The Surface Gravity is the acceleration due to gravity on the surface of the planet. The units of surface gravity are meters per seconds squared.

Escape Velocity: The Escape Velocity is the velocity a body needs to escape the gravity of the planet and get out into space. The units of escape velocity are meters per second.

Synchronous Orbit: The Synchronous Orbit is the distance from the planet where the Kepler period of the orbitting body equals the spin period of the planet. The units of the Synchronous Orbit are meters.

Planet Tilt: The Tilt of a planet is the axial tilt with respect to the orbital plane. The units of tilt are degrees.

Semimajor Axis: The Semimajor Axis is the longest diameter of the orbital ellipse. The units of semimajor axis are meters.

Orbit Eccentricity: The Eccentricity is how elliptical an orbit is. Eccentricity is unitless.

Orbit Inclination: The Inclination is how much a planet's orbit is tilted with respect to the Earth's orbital plane. The units of inclination are degrees.

Orbital Velocity: The Orbital Velocity of a planet is how fast it orbits the Sun. The units of orbital velocity are meters per second.

Orbital Period: The Orbital Period is the time it takes for a planet to go once around the sun. The orbital period is given in seconds.

Hill Radius: The Hill Radius is the distance within which satellites around a planet will have stable orbits. The units of the Hill radius are meters.

DEFINITIONS
Planet Mass: The Mass of a planet is the total amount of matter contained in the planet. The units of mass are kilograms.
Planet Radius: The Radius of a planet is the distance from its center to its edge. The radius is given in units of meters.
Planet Density: The Density of a planet is the ratio of a planet's mass to its volume. The units of density are kilograms per meters cubed.
Planet Oblateness: The Oblateness of a planet is how much is has been flattened by its rotation. Oblateness is unitless.
Spin Period: The Spin Period is the time that it takes the planet to spin once on its axis. The Spin Period is given in units of seconds.
Surface Gravity: The Surface Gravity is the acceleration due to gravity on the surface of the planet. The units of surface gravity are meters per seconds squared.
Escape Velocity: The Escape Velocity is the velocity a body needs to escape the gravity of the planet and get out into space. The units of escape velocity are meters per second.
Synchronous Orbit: The Synchronous Orbit is the distance from the planet where the Kepler period of the orbitting body equals the spin period of the planet. The units of the Synchronous Orbit are meters.
Planet Tilt: The Tilt of a planet is the axial tilt with respect to the orbital plane. The units of tilt are degrees.
Semimajor Axis: The Semimajor Axis is the longest diameter of the orbital ellipse. The units of semimajor axis are meters.
Orbit Eccentricity: The Eccentricity is how elliptical an orbit is. Eccentricity is unitless.
Orbit Inclination: The Inclination is how much a planet's orbit is tilted with respect to the Earth's orbital plane. The units of inclination are degrees.
Orbital Velocity: The Orbital Velocity of a planet is how fast it orbits the Sun. The units of orbital velocity are meters per second.
Orbital Period: The Orbital Period is the time it takes for a planet to go once around the sun. The orbital period is given in seconds.
Hill Radius: The Hill Radius is the distance within which satellites around a planet will have stable orbits. The units of the Hill radius are meters.

Advanced Functions:

Planet Mean Motion: n

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