
Leap years and astrolabes
Since today is 29th February, a leap-year-themed post is in order. This one answers the question you’ve all been asking: how are leap years represented on astrolabes? First, a word about the Julian calendar. Most astrolabes were made before the Gregorian calendar reform (1582), and that made life a bit simpler for instrument-makers. In the Julian calendar, leap years happen every four years, without exception. On the other hand, the Gregorian calendar got rid of 3 leap da