Source: Discovery News
By: Joe Rao June 30th, 2015
Every day of school feels like it drags on and on and on and…. but really, it’s only 24 hours long. Same as any other day. Except today. Every 4 years, we have a “leap year” where there is an extra day in February, making the usual 28-day month turn into 29 days long (Question: Why do we even need a leap year?). Today, June 30th, an extra second is added onto the clock Why is this? Well, the Earth is starting to slow down. Our world is constantly spinning which is why we have day and night. However, the moon’s pull on our Earth is causing a very very veeeeeery slowdown of that spinning. So an extra second is added onto the end of June 30th of this year in order to make up for that slowing.
This isn’t the first time we’ve added a second or two onto the clock either. It has happened 25 previous times as well since 1972… wait, the number of years and the number of seconds added don’t add up! Why are there fewer additions to the clock than there are years? Because the Earth is slowing down at such a minuscule rate, only a tiny fraction of a second is being created every year which means there isn’t a need to add the full time to the clock when a year comes to an end and a new one begins.
QUESTION: Why do we have a leap year?
Answer: It takes the Earth 365 and 1/4 days to rotate around the sun once. So every four years, we have an entire day to make up for!