Can you teach yourself math and science?

I’ve had some luck teaching myself new skills, but in every case I’ve had some sort of knowledge base first. Like, teaching yourself a new foreign language from scratch is difficult. But understanding the basics of grammar and pronunciation, and then teaching myself more advanced vocabulary, is pretty easy. Right now I’m trying to learn French from books and videos. I took a couple years of Spanish, and so far the grammar seems nearly identical, so it’s going ok. I’m also teaching myself insanely detailed minutiae of the wine world, pretty successfully, and that’s what got me thinking about this.

My last math class was probably high school algebra, and I don’t even remember that much of it. I think my last science class was high school chemistry. (I was an art major.) It feels like unfinished business- like the most advanced book I ever read was Twilight, and then I stopped there. That sucks!

I can’t really afford community college classes right now, but I’d like to find something with some instruction or explanations to it. Do you have any specific recommendations for my (kindergarteny) knowledge level? I’m especially interested in astronomy and physics.