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

Remember that 1 year is about 364 days.

That means that each time a day of rotation happens, the earth *also* moves about 1/364th of the way around the sun.

So “noon” today isn’t exactly where “noon” was yesterday. It’s now about another 0.98 degrees further “east” than it was before.

So the Earth has to rotate a little bit further for the same spot to reach the “noon” position again. That “little bit further” to move about another 1 degree or so takes about 4 more minutes.

Thus the “length of a day”, measured as the time it takes to go from “noon” today to “noon” tomorrow, is 4 minutes longer than the time it takes to actually rotate the Earth back to the same exact spot.

That’s the reason the rotation is short of 1 day by about 4 minutes.