It takes the Earth 365 days, 5 hours, 48 minutes and 45 seconds to rotate around the sun. This is a tropical year, but our Gregorian calendar has only 365 days in it, meaning we’re off by nearly 6 hours every year. That’s why every four years, we add a day to the calendar, in February, the shortest month. When you’re planning what to do with your extra day this year, remember if we didn’t have leap days, after only a century, our calendar would be off by about 24 days! Leap day is a Monday this year, so most of us will be stuck in the office, but if you’re one of the lucky ones, we think you should know about some of the things you could do with the extra 24 hours.