With the sun's final habitable zone dangerously close to the star, what will a dwarf planet like Ceres need to balance?
a. being far enough from Pluto to avoid collision while
keeping behind it to avoid the sun's rays
b. being far enough from the sun to maintain its own gravity
while not getting too cold
c. being close enough to take in the sun's heat without
being sucked in by its gravity
b. being large enough to maintain organisms without
creating dangerous bacteria