I created a new astronomy presentation last weekend. I'll be presenting it to my club, the Temecula Valley Astronomers, tonight at 7:00 at the Temecula Library on Pauba Road -- nothing like the last minute, as working on it this weekend suggests, but it's based on observations of pinhole projections, also called the camera obscura, that I've been interested in for many years.
I believe the pinhole projection provides all the information to intuitively understand how telescopes work and how focal ratio affects depth of field:
To complete the analogy, I add prisms, which lead me to contemplating William Herschel's discovery of infrared. To resolve a discrepancy, I examine black body radiation curves, which leads me to understanding the green house effect, and for the first time I think I can explain why nearly every illustration of the greenhouse effect is wrong by over simplification.
I'd write more, but it's, as I said, last minute and I have preparation to do.
My presentation (which severely lacks annotations) can be found at this location:
2 days ago