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Re: Venus
From: Bill B
Date: 2005 Dec 8, 17:30 -0500
From: Bill B
Date: 2005 Dec 8, 17:30 -0500
>> Does anyone know the Apparent diameter of Venus viewed from the central USA > On 2005-12-08 00:00 UT1 > > Diameter 40.1" > Phase Angle 117 deg (...meaning that less than half of the diameter > is illuminated) > Phase 0.27 George and Herbert Thank you for your replies. Given the apparent size, and guess that only 26% of the right side is illuminated, it could make lunars with Venus very interesting. Herbert: Did you calculate your results, or is there a web site to look up such information? It would look like the 0.26 phase may correspond to the area illuminated? I'm at a loss at how one derives illumination from the 117d figure. Any help would be appreciated. I also wonder, if like the moon, the line/arc between illuminated and dark portions can be other than vertical. If so, where can one find/determine that information? OPTIONAL READINGI did find that maximum eastern elongation was on Nov 3 2005 at 47d. Inferior conjunction will occur on January 13. Using that I was a able to roughly calculate the angle between earth, the sun, and Venus on the 6th. Using 93,000,000 earth to sun, and 67,000,000 Venus to sun I calculated the earth-Venus distance. Using 7521 as Venus diameter I calculated 38.5d as apparent diameter. I am guesstimating about 25% of the surface was illuminated. A long way to go ;-) It was an interesting exercise. Once a had an estimate of Venus's daily (earth day) angular velocity relative to earth, and earth's angular velocity relative to the sun, I added the two and calculated Venus's velocity and year length (in Earth days). Came up with 218.5 days, so close considering I was playing slop pool. Thanks again bill