# Calculators

## Planetary Parameter Calculator

Written: 1998.12.30

This form will calculate numerous planetary parameters for a planet of
given diameter and surface gravity (expressed as a multiple of Earth's surface
gravity). The parameters are:

- Volume, in m³.
- Surface Area, in m².
- Distance to horizon in km. This value is determined by the observer height.
Note that typical human eye-level is roughly 1.6m, while a large armoured troop
transport like an AT-AT walker has an observer height of roughly 20m.
- Mass in kg.
- Average density in kg/m³.
- Surface escape velocity in m/s.
- Death Star blast yield lower limit in joules, based on the gravitational binding
energy lower limit. This is in turn based on the assumption that the planet's density
is uniform (method #2 in the Death Star Firepower page). This represents an absolute
lower limit for the energy required to hurl the planet's mass outwards at sufficient
speed to permanently reduce it to space rubble.
- Death Star blast yield upper limit in joules, based on the energy requirement for
hurling the planet's entire mass outwards at roughly 5 planetary diameters per second.
This is the approximate speed of the fastest-moving debris in ANH.

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