Part of the fun of amateur astronomy is getting caught up in “rabbit holes”. You see something on Facebook, that gets you looking up articles in the popular press, and then into academic publications, and they lead you in a different direction and everything is so fascinating and time just rushes by…

My current example is looking into the timing of craters on the moon – when they enter and exit the umbra or full shade of the Earth. It was an important way to figure out the time, and therefore one’s longitude, before reliable clocks were made. In the 18th century, astronomers recognized that there is a problem (La Hire, Tabulae Astronomicae, Paris 1707); the earth’s shadow is over 100 km bigger than expected. The anomaly is bigger than can be explained easily with the atmosphere. One would think this is a simple geometric problem that is fully understood, but it is still under study!

Amateur astronomers are helping collect the necessary data. Sky and Telescope publishes predicted times for when the shadow is expected to cross 24 prominent craters, and they request people to email in their observed times. Upcoming May 26, 2021, eclipse online info. Up to 2011, their database includes 22,539 observations by 764 different people. If the sky is clear between 02:52 and 05:48 on Wednesday May 26, I hope to add my name to the list!

The point is, we are a community of interesting and interested people. We set challenges for ourselves. Some are simple; some are very difficult. Get your telescope to track better. Process an image to show more detail. Understand black holes a bit more. Learn another myth of a constellation. And then we get together (virtually, these days) and support each other in these pursuits.