Answer:
I'm a god. I'm a planet. I measure heat.
With pointed fangs it sits in wait. With piercing force it doles out fate, over bloodless victims proclaiming its might. Eternally joining in a single bite.
The more of them you take, the more you leave behind. What are they?
Goes over all the hills and hollows. Bites hard, but never swallows.
Round as a button, deep as a well. If you want me to talk, you must first pull my tail.
I will disappear every time you say my name.