議論は果てしなく
Another option would split planets into subcategories.
Mercury, Venus, Mars, and Earth could be known as terrestrial planets, while Jupiter and Saturn could be formally termed gas giant planets. Pluto and UB313, along with thousands of other Kuiper objects, could be grouped as ice dwarfs
"Tenth Planet" Larger Than Pluto, Study Confirms (National Graphic News)より抜粋
