Answer:
I occur twice in eternity. And I'm always within sight.
The thinkers usually hold this body part
They are Dark, and always on the run. without the sun, would be none!
I'm a god, a planet, and measurer of heat. Who am I?
They are two brothers. However much they run, they do not reach each other.
I touch the Earth, I touch the sky, but if I touch you, you’ll likely die. What am I?