Hipparchus of Nicaea, an ancient Greek astronomer and mathematician, was the first to calculate that a calendar year (the amount of time it takes Earth to make one complete orbit around the sun) was actually 365.246 days. If we ignored this fact, the calendar would shift by approximately 6 hours each year. After 100 years, January 1st would effectively come at the time that January 25th comes now. After 1000 years, it would arrive in September!
Another option would be to add a six-hour day to the end of each year. The problem with this is that sunrise would come closer to noon in the second year, around dinnertime in the third year, and near midnight in the fourth year before returning to its "regular" time.
Approximately a century after Hipparchus' discovery, Julius Caesar came up with a solution. In 45 BC, Caesar rounded the year up to 365.25 days and established the Julian calendar, which added a Leap Day every fourth year. However, science needs to be precise. Since he rounded up, the Julian calendar was essentially losing days. To make up for it, the entire world (at least those still using the Julian calendar) completely skipped 10 days in 1582 and the calendar jumped from October 4th to October 15th!
So in this year, we began using the Gregorian calendar, which skips three leap years every 400 years. So the year 1600 was a leap year, but 1700, 1800, and 1900 were not. The year 2000 was a leap year, but 2100, 2200, and 2300 won't be. Confused? It gets worse!
The Earth's rotation is slowing down ever so slightly. We lose a second about every 500 days. Since the 1970s, leap seconds have been added from time to time to our clocks. This is important because GPS satellites and other systems are designed to match the Earth's rotation.
Do something unique and special to celebrate Leap Day! How about ...
- Play leapfrog! Or make origami frogs! Or learn about frogs! Frogs are unofficially the Leap Day mascot.
- Have everyone in the family write letters to themselves. Open them on Leap Day 2020.
- Print pictures of things that leap — like rabbits, jumping beans, and children — and make a collage.
- Find out if any of your friends are Leap Year babies, then have a birthday party!
- Have a dance party using only songs with "Leap," "Jump," "Day," or "Time" in the title. Start with "Jump, Jive, and Wail" by Brian Setzer Orchestra, "Look Before You Leap" by Suicide Machines, "Jump Around" by House of Pain, "Time After Time" by Cyndi Lauper, and "One Day" by O.A.R.
- Spend 24 hours sleeping, reading, watching movies, or hanging out with your friends. You can completely ditch your to-do list and still accomplish as much as you did last year.
- Watch the movie Leap Year, starring Amy Adams, Matthew Goode, Adam Scott, and John Lithgow.
- If you're an unmarried woman in love, propose! According to Irish legend, St. Brigid convinced St. Patrick to allow women to propose to men every four years. (Actually, I think it's a great idea anytime you're in love ... Leap Day not required!)
