If Earth makes one complete rotation on its axis every 23 hours and 56 minutes, how does day and night not being flipped on our clocks after six months? (6monthx30dayx4min/60=12hour)

Question

And why leap year happens once per 4 years only to address this?

In: 1081

Answer 1

>If Earth makes one complete rotation on its axis every 23 hours and 56 minutes,

It doesn’t really, that’s just a kind of colloquial thing we say because the exact precision isn’t required most of the time. What a day (in common usage) *actually* represents is how long it takes for a given spot on the surface of the Earth that is facing the Sun to be facing the Sun again. That’s closer to 24 hours. This isn’t simply 360 degrees of rotation later, because the Earth will have moved along its orbit around the Sun during that time. Measuring a day based on the time between a spot on the Earth facing the Sun takes into account both the rotation of the Earth, and its movement along its orbit. If we measured a day based on exactly 360 degrees of rotation, then you’re correct, exactly what you said would happen would happen.

Edit to add: [The Wikipedia page](https://en.m.wikipedia.org/wiki/Earth%27s_rotation) does a surprisingly good job at explaining all the ways you can calculate a day and how they’re all different, pretty good read if you’ve got the time!