Leap Day is February 29.
Without leap years, December would drift into summer in 400 years.
We get a bonus day on Thursday — Leap Day, February 29 — to keep the seasons in check.
O'Donoghue's animation reveals what would happen if we didn't have leap years — after 400 years, our calendar months would drift into new seasons.
That extra quarter of a day, of course, adds up to one full day of drift every four years.
Persons:
—, James O'Donoghue, O'Donoghue, Shayanne
Organizations:
Service, NASA, JAXA