## Where Does the Leap Year Come From?

In fact the time taken to rotate with respect to the Sun is called a Solar day, and the time taken for the Earth to rotate once on its axis is called a sidereal day.

over a period of

\[\frac{1 \: day}{3 \: 56/60 \: minutes}= \frac{24 \times 60}{3 \: 56/60} = 366.2414\]

days, the Earth will have turned once more on its axis than there are days, so that after 366.2414 days the Earth will have rotated 367.2414 times.We can approximately reconcile this difference between the time the Earth rotates relative to the Sun and the time the Earth takes to rotate on its axis by adding one day every four years to a year. These years where an a day is added are called leap years. 2016, 2020, 2024,... are leap years.