[AZ-Observing] Re: Jupiter Events
- From: "William R Wood" <wmrwood@xxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Sat, 12 Apr 2003 06:26:46 -0700
Frank,
Maybe you (or anyone else who was watching or knows about these things) can
help me on this. I watched Jupiter's moon transits on 4/10/03 from about
8:15pm local time to about 10pm. I was using a 5" refractor and seeing was
terrible here in Fountain Hills, 4/10 at best. I was only able to use 138x.
Jupiter looked like it was shimmering in heat waves, the turbulence was so
bad.
In any event what I saw at about 8:15pm was 2 perfectly round black shadows
in the equatorial zone, one on the east side and one on the west side of
Jupiter. The shadows were both about the same size and both were jet black.
They made it look like Jupiter had 2 black eyes staring back at me because
they were just about equidistant from the planet's limbs :o).
These 2 shadows both looked exactly like the moon shadows that I have seen
many times watching moon transits on Jupiter in the past.
The mystery is that Sky Map Pro 9 (SMP9) shows only one moon shadow as of
that time (8:15pm local 4/10/03 or 3:15 UT 4/11/03) and that shadow
corresponds exactly with the shadow that I saw on the east side of Jupiter.
SMP9 shows Callisto on the west side exactly where I saw the second black
shadow. Your post said that Callisto was a dark spot - not unlike a
shadow - at 7:50pm local time. At that time, 7:50pm, there was no moon
shadow on Jupiter's surface.
My question is did you continue to observe the event and see Io's shadow
which appeared beginning about 7:56pm. If so did Callisto itself and Io's
shadow look the same to you? Or, in other words, is it possible that I was
seeing Callisto itself and mistaking it for a moon shadow???
If I was seeing Callisto itself and not a shadow how is it that Callisto
could look like a black shadow while transiting then look like a bright star
as soon as it completed its transit and moved off the globe into space? It
seems odd that it could look black against a bright background and bright
against a dark background.
Thanks for your help.
Regards,
Bill Wood
Fountain Hills, AZ
-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx
[mailto:az-observing-bounce@xxxxxxxxxxxxx]On Behalf Of Frank Kraljic
Sent: Thursday, April 10, 2003 7:54 PM
To: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Re: Jupiter Events
I probably should have left my 10-inch to equilibrate earlier,
but at both 400x and 560x, Callisto is a dark featureless
spot--not unlike a shadow--and Io is a pale spot just about to
cross the central meridian at 7:50pm. There is a festoon north
of Callisto which may effect Io's visibility, as they appear
close to same albedo--I think Io may be darker, though.
-FRANK
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