Perpetual calendar
This activity belongs to the GeoGebra book Earth and Sun.
What day of the week were you born on? Did Columbus discover America on a Tuesday? What day does the 6th of the 6th of the year 6666 fall on? And what about Saint Fermin's Day in 7777? Choose the year you want to display. This calendar supports ten thousand years, from the year 1 to the year 10000..
- Leap years are multiples of 400 or, starting from year 8, multiples of 4 that are not multiples of 100 (year 4 was not a leap year, by order of the first Roman emperor, Augustus, to correct previous discrepancies).
- In 1582 (90 years after the discovery of America) the Julian calendar was changed to the Gregorian calendar, eliminating 10 days from October.
Author of the construction of GeoGebra: Rafael Losada