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.