Why does a star a

A star appears to rise four minutes earlier in the sky every day than the previous day

We know the earth takes 24 hours to complete one rotation around its axis and 365 days to revolve around the sun. By the time the earth completes a rotation, it moves about 1° on its orbit. The position of a star though fixed but with respect to the position of the sun, the position of star shifts by 1°.

Now, for a complete rotation (360°), the earth takes 24 hours.

Therefore, for a 1° shift, it will take () hours

= 4 minutes.

So we calculate the time with respect to the position of the sun, and thus we see a star 4 minutes early from the previous day.