February 29 is a date that usually occurs every four years, and is called leap day. This day is added to the calendar in leap years as a corrective measure, because the Earth does not orbit the sun in precisely 365 days. The Gregorian calendar is a modification of the Julian calendar first used by the Romans.
In this way, how often does leap year come around?
Learn what a leap year is, why we have leap years, and how often we have a leap year. The Earth orbits the sun every 365.2422 days (0.2422 days is equal to 5 hours, 48 minutes and 46 seconds, roughly 1/4 of a day). Every 365 1/4 days (not exactly 365 days), the Earth returns to the same exact spot in its orbit.
Why every 100th year is not a leap year?
A year is a leap year if it is divisible by 4, but century years are not leap years unless they are divisible by 400. So, the years 1700, 1800, and 1900 were not leap years, but the year 2000 was, which is why in a given 100 years, there are 24 leap years and 76 ordinary years.