Earth's Rotation Day

Most everyone knows from science class in school that the earth rotates on its axis and one full rotation takes 24 hours to complete.

It would be very surprising if there was someone who didn't already know this! But what some people may not know is that the speed of the earth's rotation changes slightly from day to day and year to year.

So a true solar day is not exactly 24 hours, but the variations are a matter of seconds. A mean solar day is based on the yearlong average, but the basic concept of a solar day itself is the length of time for the earth to complete one full rotation on its axis. And that's one of the reasons that Earth's Rotation Day is celebrated!