Eclipse!

 I've seen a few lunar eclipses, but my only memory of a solar eclipse when I lived in Florida in the 90s, and only a tiny chunk of the sun got eaten by the moon.  Yesterday in England we had another one, and while we didn't reach totality, the moon still covered something like 90% of the sun!  Quite a different experience.

We made cameras obscura out of a shoebox and a coffee mug box to view it, which worked pretty good.  When it reached its peak, it was kind of surreal -- noticeably darker outside, though not so much that the birds seemed affected or anything.  The most visible effect was all the crescent-shaped projections as the light passed through small openings -- including in light reflected off of our windows.

I'm both amazed and not amazed that eclipses can be predicted so well.  Amazed because I wouldn't begin to know how to do it, but not amazed because we've been to the moon and so obviously know a thing or two about orbital mechanics.