Why we have leap years
A leap day is not extra time. It is a calendar repair.
Made with StrokeVideo from a plain text script, no editing.
Make one like thisWhat the video shows
Earth takes about 365 and a quarter days to go round the Sun, so a 365-day calendar falls a quarter day behind every year. The video draws that leftover quarter day piling up, the February 29 that resets it, and the century rule: most century years skip the leap day unless they divide by 400, which is why 2000 was a leap year and 1900 was not.
How it was made
The script was written from the single line "Why do we have leap years?". Its draft got one fact backwards, saying that without leap days spring would arrive earlier on the calendar; it would arrive later. We corrected that sentence in review and drew the rest as written, in the Creative style with the Andrew voice.