[AZ-Observing] Re: Cloudy Nights

At 12:31 PM 3/21/2004 EST, Bill Ferris wrote:

(good stuff about shadow transits of Jupter)


Early in the evening at the Arizona City site, we had pretty decent seeing,
which enabled a good view of Jupiter at 365x through my 20-inch.  Not
knowing when the shadow was going to enter the disc of Jupiter, I was
impressed by the separation between the moon and its shadow, even though
Jupe is only a couple weeks past opposition, and the phase angle is quite
large.  Comparing the separation to that of the innermost moon and its
shadow later on gave a good feel for the distances of the moons from the
planet.  Here's an illustration I put together using Voyager III software
that illustrates the geometry.  The perspective is from a bit above the
ecliptic plane to show the shadow cones.

http://www.psiaz.com/polakis/jupiter_shadow_cones.jpg

Okay, time for some sleep...

Tom



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