René Descartes said "Cogito ergo sum" which means "I think, therefore I am". Meaning that, life and what we see and hear might very well be an illusion, but at least we think, and that proves in and of itself that we do in fact exist. I've had the exact same thoughts as you before but this quote has helped me to at least find some footing, I think it's a great quote.
Oddly enough, that was something I was going to say. More context for that quote is that Descartes decided he needed to doubt everything, but realised that the one thing he couldn't doubt was that he was doubting (which means he was thinking, and so cogito ergo sum).
I feel like you're on track not to be an astrophysicist, but the next great crazy modern philosopher or something. Pull a Nietzsche or something and shape the thought of mankind for the next 200 years.
On the positive side it's better for you to wonder about the meaning of the sun and moon, and question your existence. Philosophy begins with wonder, wonder at the universe around them. It's much more interesting and open-minded to look into the meaning of things than to say "well we have empirical evidence that such and such is so, but that's about it."
I'm a Philosophy major about to graduate :P
This! The uncertainty and immensity of existence is one of the, if not the most, exciting things in life for me. Really recommend reading philosophy if you're interested, once you start it's really life changing.