Assuming the only creation God engaged in was planet earth, how he is described (as never changing) means that his revelation of himself in Christ (who was both human and God, in order that his death would be like our deaths, ((wages of sin is death)), but whose divinity would allow him to rise from the dead ((thereby proving the penalty of sin - death - had been paid for _eternally_ {{being God}})) means that any other creation in the universe would need to be in a similar situation as humanity on earth...otherwise Christ as God/Human is totally senseless and useless on these other planets...which can not be since God does not change. Thus, no aliens, anywhere.
Now before ppl go off screeching about religion, this is in no way an attempt to convert. It is just a perspective made possible by someone who reads the Bible and likes to try to place any modern idea against it, and maybe the same might help someone else grapple with the immensity of It All. It also doesn't mean that there is no need for humanity to keep searching and exploring the stars.