Answer:
I'm a god. I'm a planet. I measure heat.
Which weighs more? A pound of iron or a pound of feathers?
You row in one while you float.
I start in little but I end in full, you'll find me in half and complete.
I'm the source of all emotion, but I'm caged in a white prison.
Special abilities and brightly colored underwear are all you need to be one of these.