The Earth fully rotates in 23 hours and 56 minutes. Where do those extra four minutes go??
I know the answer is supposedly leap day, but I still don’t understand it from a daily time perspective.
I have to be up early for my job, which right now sucks because it’s dark out that early. So every day I’ve been checking my weather app to see when the sun is going to rise, and every day its a minute or two earlier because we’re coming out of winter. But how the heck does that work if there’s a missing four minutes every night?? Shouldn’t the sun be rising even earlier, or later? And how does it not add up to the point where noon is nighttime??
It hurts my head so much please help me understand.
In: Earth Science
It’s not leap day.
If the earth weren’t spinning at all, the sun would still move across the sky because the earth is going around the sun — a day would be the same length as a year. The sun would move about 1 degree East per day, so it’d be going backwards.
We spin the same direction we orbit the sun (counter clockwise if you’re looking down from the north pole), so in the time we’ve made a full rotation, we’ve also moved about 1/365^th of our orbit around the sun. That means the sun is about a degree “back” from where we’d expect it to be. So we need to rotate an extra degree, which takes about 4 minutes.
Or another way to look at it… In a year, we spin ~366.25 times, not 365.25. But moving around the sun “unwinds” one of those spins. That unwound day is spread across the days of the year. 1440 minutes in a day, split among 365 days, is about 4 minutes.
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