The Buddha spoke about the “world Systems” and other humans in them. This is a remarkable subject for myself as someone thinking about astronomy. Here are some links discussing world systems and related topics.
The Dhamma is sort of like the laws of mathematics and physics that govern this universe, universal to all sentient beings, everywhere. This is why we spread our metta out into deep space. I usually go one step even more and spread out metta out to the multi-verse.
What Buddhists Believe Venerable K. Sri Dhammananda Maha Thera: Other World Systems
The Buddhist Idea of World Bhikkhu T. Seelananda
The Buddha once explaining the world system said,” Monks, as far as sun and moon revolve and brighten all directions by their brilliance, so far does the thousand-fold world system extend. And because thousand-fold world system, there are thousand moons, a thousand suns, inhabited planets … This thousand-fold world system is called culanikā-loka-dhātu or Minor World-System, which is the tiniest unit in deep space (However all these modification takes place, change occurs. When seeing this the instructed honorable disciple is disenchanted, dispassion.)
I also discover this sutta interesting in which the Buddha seems speaking about a black hole.
http://www.accesstoinsight.org/tipitaka/sn/sn56/sn56.046.than.html Andhakara Sutta: Darkness
“There is, monks, an inter-cosmic  void, an unrestrained darkness, a pitch-black darkness, where even the light of the sun & moon– so mighty, so effective– doesn’t reach.”