Leap Year 2020 February 29 question marks

Category : Science

The Science Behind Leap Year

Friday , February 28 , 2020

Earth, years and nuber of days in each yearThis article was written by Michael Vargas, a Physics teacher at Pinnacle High School

Ah yes, it is a leap year, which means at the end of this month we will add a day to the February calendar. If you were lucky enough to be born on February 29th, then you probably know the story of leap year more so than the rest of us.  

When I was asked to explain leap year, my next question was how many pages do I get? You see, leap year is actually a lot more complicated than most people believe. So, in my few short sentences, I will try to help you make sense of it. 

You see, the planet earth does not move in a perfect circle of an orbit contrary to popular belief. There is wiggle room in the orbit. Many, many years ago, during the Roman-time period, astronomers realized that the earth year is not exactly 365 days. As we know today, the earth year is actually 365.256363 days. As a science teacher, I immediately recognize that those numbers after the decimal point are not numbers I can forget about.  

The Romans who first understood this were followed next by the Popes Gregorian Calendar committee 900 years later who realized that the only way to fix this problem was to add a day every four years to the calendar. If we didn’t do this, we would be off by a lot in as little as a century.  And since a good amount of the calendar relies on stars and the sun and their respective positions during the course of the year, if we didn’t add the additional day, we would be way off.  

Make no mistake, even with the addition of the full day, every four years that still does not make our calendar perfect. At the end of each century, we still have to adjust for remaining decimal numbers. Hence, that is what I meant by we would need additional pages to explain in great depth. 

But for most regular folks like you and me, the story of leap year is simply that we add an additional day on February 29th every four years to help reset the calendar and make sure our solstices and equinoxes are for the most part lined up and accurate.


About the Author

Michael Vargas

Michael Vargas has been teaching for 19 years and has been a teacher at Pinnacle High School for 8 years. Prior to teaching at Pinnacle, he lived in Europe and taught at SHAPE American High School in Mons Belgium. Mr. Vargas is a graduate of Northern Arizona University.

Mr. Vargas received the 2019 Air Force Association/Rolls Royce National Aerospace Teacher of the Year Award.  In 2015, he was a finalist for the Arizona Educational Foundation Teacher of the Year Award. In 2014, Mr. Vargas was named Science Teacher of the year by the Arizona Science Teacher Association. He is a board member for the Arizona K12 Center, and he has two daughters who attend school in the Paradise Valley Unified School District.