I really don’t know why this is even a question. We refer to Hashem as “Master of the Universe”. The Universe consists of untold numbers galaxies, stars and planets. Hashem is the creator of all of them. Why shouldn’t beings exist on other planets? Perhaps they acknowledge the existence of Hashem in their own way? Who is to say that WE aren’t the aliens being pondered by beings on other planets?
Hashem is the Master of the Universe. That means Master of everything.