NavList:

   

Reply

Bill,

The Nautical Almanac incorporates corrections for Venus' phases, so
if you use their ephemerides, etc, in your calculations, you should
be fine.  Perhaps you ought to tell us why you're interested in the
diameter of Venus.

Fred
------------------------------------------------------------------------
Frederick V. Hebard, PhD                      Email: mailto:Fred@acf.org
Staff Pathologist, Meadowview Research Farms  Web: http://www.acf.org
American Chestnut Foundation                  Phone: (276) 944-4631
14005 Glenbrook Ave.                          Fax: (276) 944-0934
Meadowview, VA 24361


On Dec 8, 2005, at 5:30 PM, Bill wrote:

>>> 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 READING 
>
> I 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

   

Reply