It evolved out of some weird interaction someone was smartassing me that the moon wasn't full when I was pointing to how pretty the full moon was. After that, between a friend and myself, it became a bit of a running gag how full (or not full) the moon actually was. This was my first real project I kind of "vibe coded": https://moon.masca.teide.cloud/ - showing you how full the moon is to the 10th decimal