Thursday, September 7, 2023

Difference between a Stellar Day and a Solar Day

It is hard to wrap my head around this, but the Earth actually rotates once every 23 hours, 56 minutes, and 4 seconds. If you compare the position of the stars in the sky, they will be in the same place 23 hours, 56 minutes, and 4 seconds later. However, the Earth is moving around the Sun in what is called prograde motion (the same direction as the rotation of the Sun, not that this matters), so consequently, the Sun appears in the same place in the sky roughly every 24 hours. It is a difference of 4 minutes. It is the difference between a Stellar day and a solar day.

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