Planet Types
Planet Types
Biology, Geology, and Meteorology require you to specialize by "planet type," as does the "Physical" specialty of Geography. If you do not specify a planet type, your native planet type is assumed – so if the campaign will never leave your home world, save space and just write "Geology," "Biology," etc. GURPS sorts planets into six broad categories for these purposes.
Earthlike: Essentially, all habitable worlds.
Gas Giants: Jupiter/Uranus types.
Hostile Terrestrial: Venus types.
Ice Dwarfs: Comets and small moons composed almost entirely of snow or ice.
Ice Worlds: Rock worlds covered by a frozen "ocean."
Rock Worlds: Most moons, asteroids, etc.
Unless otherwise specified, all planet-type specialties for a given skill default to one another at -4.