This year, February is feeling a little extra special and gets 29 days instead of the usual 28! We all know about leap years, but let’s dive into the cosmic, complicated reasoning behind this phenomenon. What’s going on, and why do we have leap year?

A calendar year is typically 365 days, but Earth takes about 365.242190 days to complete its journey around the Sun – 365 days, 5 hours, 48 minutes, and 56 seconds to be exact. That’s a lot of time unaccounted for in our usual calendar. Without this year’s bonus day, the seasons would start playing musical chairs with the months – summer would start in December, and winter would start in June! By throwing in an extra day every four years, we keep our calendar in sync with Earth’s sidereal year.

But here’s the twist: The sidereal year doesn’t add exactly 24 hours over four years – it’s 23.262222 hours. Adding a leap day every four years seems like a solid plan, but it turns out we’re overshooting a bit. We’re making the calendar longer by over 44 minutes. Those extra minutes might seem small, but over time, they’d push the seasons into different months. So, not every four years gets the leap year treatment. The party skipped a beat in the years 1700, 1800, and 1900 to account for it.

Don’t stress about missing the next leap year, though – the next time we hit pause on the leap year is in 2100. Until then, we have plenty of leap year fun coming our way.