A 365.25-day period is like having a year that’s just a little bit longer than 365 days, almost like having an extra day every four years.
Imagine you have a calendar with 365 pages, and each page is one day of the year. But if you count very carefully, the Earth takes about 365.25 days to go all the way around the Sun. That extra 0.25 is like having a quarter of a day, or 6 hours!
Why 365.25?
If we only counted 365 days every year, our calendar would slowly get out of sync with the seasons. To fix this, we add an extra day, February 29, every four years. That’s why we have a leap year.
It’s like when you're playing a game and count steps: if you only take 365 steps each time, but you need to go all the way around a track that's just a little bit longer, you’ll need an extra step now and then to stay on the right path.
Examples
- Imagine Earth takes about 365 days to go around the Sun, but it's actually a tiny bit more, that extra 0.25 day is why we have leap years.
- If you had a year that was always exactly 365 days, your birthday would be a little earlier each year, but thanks to the 365.25-day period, it stays on track.
- A year isn't perfectly divisible by 4, which is why we need the 0.25 day to keep our calendar accurate.
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See also
- What is 365.2422 days?
- What is 31 days?
- What is 30.44 days?
- Perihelion: What Will Happen on October 29?
- What is equinox, aphelion and perihelion?