Yeah - that's what I was trying to say! You put the words right into my
mouth! =)
RPD
On Tuesday, Dec 30, 2003, at 19:18 US/Pacific, Peter Natscher wrote:
> I think the seeing plays tricks with planetary detail at the eyepiece.
> The
> HST images aren't affected by the earth's atmosphere. The two "ears"
> are an
> optical illusion in the area of the Cassini Division meeting the
> darkened
> limb of Saturn's globe.
>
> Peter Natscher
>
>> From: Raymond Duval <rpduval@No-Spam>
>> Reply-To: The Astronomy Connection <sf-bay-tac@No-Spam>
>> Date: Tue, 30 Dec 2003 17:09:42 -0800
>> To: The Astronomy Connection <sf-bay-tac@No-Spam>
>> Subject: Re: [TAC] Saturn's Shadow On Its Rings At Opposition Time?
>>
>> I still think it was just an optical illusion - the Cassini division
>> was in just the right place to make it look like shadows just below
>> where it meets the planet's outer edge. IOW, just an apparent bending
>> of the light. Not sure if my opinion counts, being a rookie and all,
>> but that's what I saw through Dave's scope.
>> RPD
>>
>> On Tuesday, Dec 30, 2003, at 16:21 US/Pacific, Peter Natscher wrote:
>>
>>> In further response to the conversations between me and David
>>> Kingsley
>>> on
>>> Saturday night at Fremont Peak when we were observing Saturn, whether
>>> Saturn
>>> was showing a shadow from its globe onto its rings, I don't see any
>>> shadow
>>> when carefully examining Hi-res HST mages of Saturn at opposition.
>>> During
>>> the days around Saturn's opposition, the visually observed darkening
>>> that's
>>> noticed at the junction of the globe and rings behind the globe is
>>> only the
>>> darkened limb of the globe and not a shadow. Like Jupiter, Saturn
>>> exhibits a
>>> darker limb as compared to the brighter central area of the globe.
>>> Take a
>>> careful look at a HST Saturn image taken during opposition time at
>>> the
>>> HST
>>> Saturn Image website.
>>>
>>> http://hubblesite.org/newscenter/newsdesk/archive/releases/2001/15/
>>> image/a
>>>
>>> What do you think?
>>>
>>> Peter Natscher
>>> Monterey
>>> ______________________________
>>> David Kingsley wrote:
>>> ......
>>> Saturn was
>>> absolutely beautiful last night at magnifications up to 450x The
>>> crepe ring was very obvious all around the planet, with lots of other
>>> structure and brightening in the A and B rings. Beautiful banding
>>> was also visible on globe. While soaking in the views, I was
>>> surprised to see two dark ears poking out behind the planet where
>>> Saturn's edge was superimposed over the ring behind it. Each small
>>> black ear almost identical in size. While looking at this, I thought
>>> it must be the shadow of the planet projected on the rings. However,
>>> a shadow could only produce symmetric black ears if Saturn was very
>>> near opposition. I subsequently checked Karkoschka's handy atlas,
>>> and sure enough Saturn last night was only a few days away from its
>>> opposition on December 31st, 2003. I have previously watched the
>>> shadows of Jupiter's moons switch from the preceeding to following
>>> side of the tiny moons as Earth caught up with and passed the king
>>> of planets near opposition
>>> (http://www.observers.org/reports/2000.11.27.html). Saturn's rings
>>> make it possible to see a similar effect with the shadow of an entire
>>> planet. The two symmetric black ears were an interesting bonus to a
>>> wonderful view. I suspect that by the time that I get a chance to
>>> look again, the shadow on the following side will start to grow as
>>> the earth pulls away from Saturn after opposition.
>>>
>>> (for anyone who wants to see an image of the symmetric black ears
>>> effect, there happened to be a post today by someone on the AP-user
>>> Yahoo group who imaged Saturn imaged last night with an 8 inch F/15
>>> AP. The views through both the 14.5 inch and 20 inch starmaster last
>>> night at Fremont Peak, were actually somewhat sharper than what was
>>> recorded in the image, but it gives you some idea of the detail
>>> visible in moments of good seeing last night , and the two black
>>> ears. Unfortunately, you may have to joint the yahoo group to see
>>> the file
>>> http://groups.yahoo.com/group/ap-ug/files/17Saturn12-27-03.jpg )
>>> ......
>>>
>>> Happy new year, and best wishes to both new and old observers in
>>> 2004.
>>>
>>> David Kingsley
>>>
>>>
>>
>>
>
>
