Any astronomers around?

[Dale Reed]

360 degrees / 24 hours = 15 degrees per hour (by division).

One hour = 60 minutes.

60 minutes / 15 degrees = 4 minutes/degree (by division).

But that only works for the sun. In one day, the earth has gone around in its orbit about the sun by 1 day motion / 365.2425-ish days per year. You need to account for this, at least for the "fixed" background of distant stars.

360 degrees / 365.2425 days = 0.9856465... degrees per day = 0.0410686... degrees per hour = 0.002737907... degrees per 4 minutes.

Now if I could only remember which way to apply this offset -- add or subtract. Sorry, I'm not an astronomer. If I were, I would know which way the earth rotates with respect to which way it orbits the sun.

Perhaps a google search of "sidereal day" would help...
Maybe see Sidereal Time at Wikipedia.
Dale

(edited to fix an oops in copying a number from calculator to post)