intergalactic: planetary

Currently, Britt has nightmares about aliens. He ran into our room at 3:00 this morning and said, "mom...I hear aliens outside..." I mumbled some response about how if there were aliens outside, our big scary guard dog would be barking like crazy to warn us. "Well..." he responded, "he can't hear them because he's snoring too loud."
Fair enough.
I walked him to his bed, re-tucked him in, laid down next to him, and asked which song he wanted me to sing to him. Instead, he asked me to explain (for the 45th time) why we don't need to be afraid of aliens. I told him the facts all over again (for the 45th time) and explained that scientists have found no evidence that any of the other planets in our solar system can sustain life, because of their lack of oxygen, lack of water, heat or subzero temperatures, etc.
Then, he blew my mind. He said,
"yeah, I know all that, but remember how our sun is just a star that's a lot closer to Earth?...well, what if all the other stars in outer space are actually suns in their own solar systems?...and they each have a planet that's just right for living on, like Earth?"
WOW. Is this kid seriously only five? We talked about it a little more, then I dressed his teddy bear in the shirt I had worn the day before (so he could smell me and feel comforted, even while I was cozy in my own bed) and he dozed off. And that's why I'm sleepy today...and why I might start having nightmares about aliens.