This is a puzzle i came up with earlier, with a few amendments. Work out what the three clues are, and then use the final clue to decide which one is the correct one.
I am three things, but which one am I?
1: The internal temperature North, maybe a half more, and eleven elevens towards apollo's destination. I am almost modest, but not quite there.
2: I am the first of many, the largest and the brightest, but still small in the scale of things; I fit inside a belt.
3: I am plentiful harvest, but the sides of skulls no longer echo my name. Some even use an alternate name.
Of these three, I am one, the one whose period is 1680
I will only accept an answer that fits all of the clues and explains them. Good luck ;)