What does it mean that God's wrath is infinite and what is its relation to existence of life on other planets?

I heard on the first episode of Cosmos that astronomer [Giordano Bruno](https://en.wikipedia.org/wiki/Giordano_Bruno) was punished because he believed there are other planets with life on them. The Roman inquisition sentenced him to execution because they thought this belief violated the fact that 'God's wrath is not eternal'. I would be appreciate it if you provide me a resource to read about it, or give me an explanation. I am not Christian and this idea is so new to me.