Question about Right Ascension

frbee · #1 (**permalink**) 02-July-2009, 11:23 PM

so the stars on the Meridian at midnight would have a Right Ascension value of about how many hours away from the Right Ascension of the Sun?

can someone answer this and then explain?

thoth II · #2 (**permalink**) 02-July-2009, 11:34 PM

Quote:

Originally Posted by frbee

so the stars on the Meridian at midnight would have a Right Ascension value of about how many hours away from the Right Ascension of the Sun?

can someone answer this and then explain?

RA is angle measured eastward from vernal equinox in hours 0-24 hrs. The sun's RA can be looked up for today's date (the sun starts with RA = 0 at vernal equinox and increases by 2 hr/month after that) .

The stars on meridian would be approx. = RA(sun) + 12 hr.

(because at midnight, the sun is 180 degrees = 12 hr. around from the meridian).

frbee · #3 (**permalink**) 02-July-2009, 11:36 PM

then it is 12 hours away?

thoth II · #4 (**permalink**) 02-July-2009, 11:38 PM

Quote:

Originally Posted by frbee

then it is 12 hours away?

yes, it is 12 hrs. away

frbee · #5 (**permalink**) 03-July-2009, 05:24 AM

thanks thoth.

Amber Robot · #6 (**permalink**) 03-July-2009, 05:25 AM

Now he can score that 100% on his quiz!

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