This year, we’ll have an extra day of February — the 29th. We get this extra day every four years, during a leap year. Like daylight savings time, you might think the leap year is a confusing disruption that our modern world could do without. But think again. That extra day augments three years’ worth of slowly shifting time, readjusting our calendars to stay in-sync with the seasons.
Why do we have a leap year?
Contrary to what we learn as kids, the earth takes longer than 365 days to orbit the sun. And so, we start every new calendar year with just a little bit of extra time left on our solar clock — 0.242 days, to be exact. By adding that extra day every fourth year, we use up the 0.242 days that accumulated each of the three years before that. In this year’s case, we’re using up the extra time left over from 2013, 2014 and 2015.
How does a leap year keep us in season?
If we didn’t have leap years, our calendar year would fall behind the solar year by one full day every four years. Over the course of 120 years, our calendar year would be one full month askew of the solar year. That could mean warmer winters and cooler summers, eventually leading to a complete overhaul of how we define our seasons.
The leap year is an over 2000-year-old tradition first started by Julius Caesar, but it isn’t antiquated. The next time you experience a warm spring thaw or a white Christmas, thank the leap year for keeping our seasons, and our lives, in harmony with nature.