Ooo, this is a fun one. I just got asked to go on my local CBC radio lunchtime show on Feb 29 to talk about the astrophysical reasons why Feb 29 exists. I'll definitely also have to talk about the Catholic church's role in the calendar we use, and how 10 days got removed from the calendar (at different times in different places!) to switch from the Julian to Gregorian calendars. This is going to be very fun!
[edited because I had Julian and Gregorian names swapped oops]