Planetary Body

A Planetary Body in Universe Sandbox is a simulated object that is massive enough to be spherical and to have a significant gravitational effect on other objects, but is not massive enough to qualify as a Star or a Black Hole. Planetary Bodies can represent a variety of actual celestial objects, including exoplanets, planets, moons, and larger Solar System objects.

Planetary Body objects may be further subcategorized as Terrestrial Planets, Gas Giants, and Planetoids.

Properties Panel
The properties panel for a Planetary Body object will include the following tabs:
 * Overview
 * Motion
 * Composition
 * Temperature
 * Actions

The Earth and Mars will have a Climate tab in place of the Temperature tab.

Characteristics
Planetary Body objects have the following sets of characteristics:
 * They are attracting objects, meaning that they exert a gravitational force on other objects in the simulation.
 * They are attracted objects, meaning that they feel the effects of gravity from other attracting objects in the simulation.
 * They have calculated orbital elements, and their orbit can be displayed.
 * They can collide with other objects, and produce fragments.
 * Their surface properties, including surface temperature, are simulated in two dimensions.
 * They have a simulated composition.
 * They may have an atmosphere.
 * They may have a magnetic field.