Any astronomers around?
05-30-2014, 04:03 PM (This post was last modified: 05-30-2014 04:10 PM by Dale Reed.)
Post: #2
 Dale Reed Junior Member Posts: 34 Joined: Dec 2013
RE: Any astronomers around?
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)
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 Messages In This Thread Any astronomers around? - HP67 - 05-29-2014, 05:17 PM RE: Any astronomers around? - Dale Reed - 05-30-2014 04:03 PM RE: Any astronomers around? - everettr - 05-30-2014, 06:08 PM RE: Any astronomers around? - HP67 - 05-31-2014, 06:41 PM RE: Any astronomers around? - HP67 - 06-01-2014, 11:37 AM RE: Any astronomers around? - NetMage - 06-02-2014, 07:11 AM RE: Any astronomers around? - HP67 - 06-02-2014, 09:44 AM RE: Any astronomers around? - Bill (Smithville NJ) - 06-04-2014, 01:54 AM RE: Any astronomers around? - HP67 - 06-04-2014, 06:40 PM RE: Any astronomers around? - htom trites - 06-04-2014, 09:01 PM RE: Any astronomers around? - HP67 - 06-05-2014, 01:09 PM RE: Any astronomers around? - CosmicTruth - 06-07-2014, 01:33 PM

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