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
A nominal solar day (say sunrise to sunrise) is 24 hours. If you time when a star rises each day it’s 23 hours, 56 minutes. That’s called a sidereal or star day. A given star will rise 4 minutes earlier every day, or about 1/2 hour a week, or 2 hours a month. This is why the sky shifts and changes over the course of the year–if you look at the sky before sunrise in winter, it’s the same stars you’ll see 6 months later in the evening sky (12 hours timewise), because we’ll have gone halfway around the sun.
Conversely the bright stars of winter you see now in the evening sky will be in the morning sky come summer. And as mentioned, it’s all because of Earth’s orbit around the sun, and our point of view shifting that tiny bit day by day over the course of the year.
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