Same for the years. If a year actually is 365.24219 days (tropical year) and we’re adding 1 day every 4 years (.25 per year) there’s a difference of 0.00781 days or ~11 minutes per year. After a few years, aren’t we actually shifting hours? Is there a mechanism to adjust it?
In: Physics
The day with reference to the sun is 24 hours. This used to be used in the exact definition of hours, minutes, and seconds, but since the Earth’s rotation is very gradually slowing over millions of years, more precise definitions have been created that rely on things like atomic vibtations. So it is no longer exactly 24 hours, just extremely close to it.
Since the earth revolves around the sun, the relative position of the sun in the sky changes by about 0.998° per day.
A *Sidereal Day* is 23 hours, 56 minutes, 4.0905 seconds. This is the amount of time it takes the earth to rotate exactly 360 degrees. This is the day with reference to the background of stars.
If you do the math and add this up, it works out to be 365.256 days, minus about 3 seconds. The former figure is accounted for by leap days.
The latter number of seconds requires an additional leap day every 26,000 years.
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