There are 365 days in a year. That’s it! Just 365. Sometimes, though, we have a leap year. A leap year has 366 days because it has an extra day, February 29th. Leap years happen every 4 years. So, if you were born on February 29th, you’d only have a birthday every 4 years!”
Gregorian Calendar
How many days are in a year? This is a question that has puzzled people for centuries. The answer, of course, depends on which calendar you are using. The Gregorian calendar, which is the most widely used calendar in the world, has 365 days in a year.
Leap Year
There are 365 days in a year, except for leap years. Leap years occur every 4 years, and add an extra day, February 29th. This day is added to keep the calendar year synchronized with the astronomical or seasonal year.
Sidereal Year
A sidereal year is the time it takes for the Earth to complete one full orbit of the sun, as measured by the stars. It’s about 365.25 days long.
Tropical Year
A tropical year is the time that elapses between successive passages of the Sun through the mean solar point of the vernal equinox, which occurs around March 20. Because Earth’s orbital speed is not uniform, a tropical year is not the same length as a sidereal year. The mean tropical year is about 365.24 days long.
There are several slightly different definitions of a tropical year. The International Astronomical Union’s (IAU) definition is based on the position of the Sun at the March equinox. The IAU officially adopted this definition in 2000. It states that a tropical year is: “the period of time for one complete revolution of the mean Sun, measured from March 20th (vernal equinox) to March 19th (the next vernal equinox).”
The United Nations’ World Meteorological Organization’s (WMO) definition of a tropical year is also based on the March equinox, but uses a different starting date: January 1. According to the WMO, a tropical year is: “the period of time between two passages of the Sun through the same sign of the zodiac.”
So, both definitions agree that a tropical
Conclusion
There are 365 days in a year. This is because it takes 365.24 days to orbit around the sun. This 1/4 day discrepancy is resolved through leap years, or by adding an extra day, February 29th, to the calendar every four years.
