BTW: I have finalized by Size classification system for worlds:
R - Rock - a term for an asteroid smaller than 1km in diameter (from Wikipedia)
S - Small - a term for an asteroid that is larger than 1km but too small to for hydrostatic equilibrium.
0 - Planetoid - Worlds from about 600km to 1600 km in diameter (hydrostatic equilibrium but not SIZ 1)
Small - SIZ 1-6 (1D6)
Large - SIZ 7-C (1D6+6) - this add two new world sizes to the UWP
SGG - Small Gas Giant (10-60 earth masses) (Uranus and Neptune)
MGG - Medium Gas Giant (50-300 earth masses) (Saturn and Jupiter - although Jupiter is right at the upper limit)
LGG - Large Gas Giant (500 - 3000 earth masses) - Upper limit is at the lower limit of a Brown Dwarf
The reality is that MGG and LGG are actually about the same size physically, but the term allows for a nice range to get you from Jupiter to a Brown Dwarf with regards to mass and energy output. The possible moon sizes also goes up with the mass of the GG, so having this extra category lets you have Earth-sized worlds orbiting a GG which is a SciFi staple without breaking our current theory of moon formation around gas giants. EDG had a nice write up on this a few years back.
I would love to get your feedback before I publish.
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