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

There’s two different types of things we call “days”: solar days, and sidereal days.

A solar day is the amount of time it takes for the sun to reach from one spot in the sky, to that same spot in the sky (24 hours). This is the amount of time we use primarily because it’s the most practical length of time for us to keep track of.

A sidereal day is the amount of time it takes for the Earth to complete a full rotation in regards to some absolute point in space (23 hrs and 56 minutes). This isn’t very practical for us to use (why would we care when we’ve made a full rotation compared to an absolute point in space? That point in space isn’t important to us for any other reason) so we generally don’t.