[Chaos-l] Skywatching canceled

[Robert Nielsen]

I usually think the background glow is because of moisture in the air 
... reflecting WHATEVER light there happens to be (moon below the 
horizon, campfires, streetlights).   Has anyone noticed a difference 
based on humidity or temperature?   For me, the night skies are usually 
more "contrasty" than summer skies ... which I think means the same 
thing you noted, Mark.

Robert

Mark South wrote:
> Thanks John!
> This is a good article to explain the phenomena-- a combo of airglow, 
> indirect scattering of sunlight, stars, minimal light pollution, and 
> twilight.  I know it was dark there with no light domes, but seeing 
> gray sky as well as being able to walk around made me think... is 
> space the only way to get that "Morehead Planetarium" black sky??
> Mark
>
> On Sep 21, 2009, at 8:45 AM, john.6.miller at gsk.com 
> <mailto:john.6.miller at gsk.com> wrote:
>
>>
>> I have read that there is a natural luminescense or "airglow" that 
>> arises from air molecules being excited by the sun during daylight 
>> hours and then slowly decaying with a weak emission of visible light 
>> that persists throughout the night.  However, I don't know if the 
>> intensity of this phenomenon is sufficient to account for the 
>> observed sky brightness you guys are talking about.  See: 
>> http://en.wikipedia.org/wiki/Sky_brightness.
>>
>> John Miller
>>
>>
>>
>>
>> *"Mark South" <md_south at mac.com <mailto:md_south at mac.com>>*
>> Sent by: chaos-l-bounces at rtpnet.org <mailto:chaos-l-bounces at rtpnet.org>
>>
>> 21-Sep-2009 07:48
>>
>> 	       
>> To
>> 	"Michael Hrivnak" <mhrivnak at hrivnak.org <mailto:mhrivnak at hrivnak.org>>
>> cc
>> 	"CHAOS" <chaos-l at rtpnet.org <mailto:chaos-l at rtpnet.org>>
>> Subject
>> 	Re: [Chaos-l] Skywatching canceled
>>
>>
>>
>> 	
>>
>>
>>
>>
>>
>> I suspect that a truly dark place is somerwhere like austrailia or  
>> antartica.
>> Mark
>>
>> Sent from my cell phone
>>
>> On Sep 20, 2009, at 9:46 PM, Michael Hrivnak <mhrivnak at hrivnak.org 
>> <mailto:mhrivnak at hrivnak.org>>  
>> wrote:
>>
>> > You mentioned that the weather wasn't great a lot of the time.  When  
>> > the sky
>> > was completely clouded over, were the clouds lit up at all, or was  
>> > the sky
>> > black?  My experience at Almost Heaven was that the sky was actually  
>> > a bit
>> > brighter when it was completely cloudy.  That tells me that even in  
>> > a very
>> > dark place, there is some light pollution reflecting off of the  
>> > clouds, and thus
>> > the same light brightens a clear sky at least a little.
>> >
>> > Although, I suspect that stars which are too faint for us to resolve
>> > individually with the naked eye could collectively cause the whole  
>> > sky to seem
>> > less-than-black.  It would be interesting to look at a part of the  
>> > sky with
>> > the least number of stars, and compare its blackness to other parts.
>> >
>> > Michael
>> >
>> > On Sunday 20 September 2009 02:32:09 pm Mark South wrote:
>> >> I know this is slightly off topic but I had a question
>> >>
>> >> I noticed at okie Tex one of the darkest star parties in the us that
>> >> the sky as never truly black.. sort of how it looks at the
>> >> planetarium.  Why is that?  I think it was quite clear but the sky
>> >> still was grayish.  Is it possible to find a black sky with stars on
>> >> earth with an atmosphere and light adaptation.  Greg Dillon theorized
>> >> that it is truly darker than we realize but he thinks the stars light
>> >> the sky up some.  Has anyone ever thought of this or been to a truly
>> >> black sky?
>> >>
>> >> Mark
>> >>
>> >> Sent from my cell phone
>> > _______________________________________________
>> > Chaos-l mailing list
>> > Chaos-l at rtpnet.org <mailto:Chaos-l at rtpnet.org>
>> > http://rtpnet.org/mailman/listinfo/chaos-l
>> _______________________________________________
>> Chaos-l mailing list
>> Chaos-l at rtpnet.org <mailto:Chaos-l at rtpnet.org>
>> http://rtpnet.org/mailman/listinfo/chaos-l
>>
>>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Chaos-l mailing list
> Chaos-l at rtpnet.org
> http://rtpnet.org/mailman/listinfo/chaos-l
>