Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Yellow zone

  • Please log in to reply
11 replies to this topic

#1 André 123

André 123

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 13 Oct 2019

Posted 30 November 2021 - 06:17 PM

I live in a light red zone and I'm going to travel to a yellow (nearly dark yellow) zone. My telescope is an Orion (14"). Will it change a lot? Will the DSO be seen much better?

#2 Bowmoreman

Bowmoreman

    Clear enough skies

  • *****
  • Posts: 9,772
  • Joined: 11 Sep 2006
  • Loc: Wimberley, TX

Posted 30 November 2021 - 06:22 PM

It will be most noticeably better in every regard, especially in your 14”…

 

enjoy and report back


  • Kimbo_2112, jcj380, Jethro7 and 1 other like this

#3 DaveL

DaveL

    Vostok 1

  • -----
  • Posts: 199
  • Joined: 30 Sep 2009
  • Loc: Madison, WI, USA

Posted 30 November 2021 - 08:54 PM

Yes, for sure.

 

Let's say you go from the edge of light red to edge of light yellow: that's 20.91-18.95 = 1.96 magnitudes difference. So the total sky brightness will go down by a factor of 6.08 (2.51 raised to the 1.96 power = 6.08, where 2.51 is the definition of one magnitude). That's a big, big deal. If you're in the middle of light red, then the difference is even bigger.

 

-Dave


  • George N likes this

#4 jcj380

jcj380

    Mercury-Atlas

  • *****
  • Posts: 2,587
  • Joined: 08 Jul 2014
  • Loc: Hellinois

Posted 04 December 2021 - 06:43 PM

Around here, yellow is considered a dark site.  wink.gif


  • ShaulaB and Kimbo_2112 like this

#5 Ptarmigan

Ptarmigan

    Lagopus lagopus

  • *****
  • Posts: 5,059
  • Joined: 23 Sep 2004
  • Loc: Arctic

Posted 05 December 2021 - 02:15 PM

Yellow zone is a major improvement over red zone. cool.gif wink.gif waytogo.gif



#6 MEE

MEE

    Viking 1

  • -----
  • Posts: 554
  • Joined: 10 Jul 2010

Posted 08 December 2021 - 11:23 PM

This is assuming the yellow zone does not have significant local light pollution, and you’re looking at objects high above the light pollution domes (which will still be visible, and prominent)

#7 Tony Flanders

Tony Flanders

    ISS

  • *****
  • Posts: 20,387
  • Joined: 18 May 2006
  • Loc: Cambridge, MA, USA

Posted 09 December 2021 - 05:49 AM

This is assuming the yellow zone does not have significant local light pollution, and you’re looking at objects high above the light pollution domes (which will still be visible, and prominent)

That is correct. On the other hand the Original Poster was asking us to compare the light red zone versus dark yellow, and even the worst part of the sky in dark yellow is much darker than the best part of the sky in the light red zone.

 

This was brought home to me when comparing the sky at my astronomy club's observing field in the exurbs of Boston, MA (USA) versus my country home.

 

At the club field northwest there's a huge light dome to the southeast from Boston itself and pretty big domes to the north and south from Lowell and Framingham, respectively. Northwest, directly away from Boston, appears strikingly dark, with no obvious light sources at all.

 

At my country home northwest -- toward Albany, NY -- is startlingly bright, a vast light dome covering a whole quadrant of the sky. But guess what? Measurements with sky quality meter and camera confirm that the very worst part of the sky there, 15 degrees directly above Albany, is darker than the zenith at my club's field. And my astronomy club is in the orange zone, not the red zone.

 

So the only reason that the northwestern sky at the club site appears dark is because the rest of the sky is so bright. Or, looking at it a different way, northwest at my country home appears bright only because the rest of the sky is darker than most suburbanites can imagine -- though still very, very far from being truly dark.

 

Put yet another way, the difference between deep-sky observing in the dark yellow zone and the light red zone is bigger than words can properly convey.


  • George N and DaveL like this

#8 zach__

zach__

    Lift Off

  • -----
  • Posts: 21
  • Joined: 13 Nov 2021
  • Loc: DFW

Posted 12 December 2021 - 09:30 AM

Hello fellow darker sky seekers. Newbie here.

So, the light pollution rating at my home per the "Good To Stargaze" app, is an 8.6. The rating at another spot I can use about 1/2 hour away is rated at 5.6. Will there be a significant difference in my viewing experiences at each location? The "lightpollutionmap.info" shows white at home, and border yellow/red at my remote location. I plan on trying the remote location at my first opportunity either way.

 

Clear skies...



#9 osbourne one-nil

osbourne one-nil

    Mercury-Atlas

  • -----
  • Moderators
  • Posts: 2,824
  • Joined: 03 Jul 2006
  • Loc: Cumbria, England 54.5ºN 2.5ºW

Posted 12 December 2021 - 12:29 PM

Personally, if you’re only talking about half and hour’s drive, I’d think you were far more likely to be impacted by local things like presence of street lights or nearby houses, than general light pollution.

#10 DaveL

DaveL

    Vostok 1

  • -----
  • Posts: 199
  • Joined: 30 Sep 2009
  • Loc: Madison, WI, USA

Posted 14 December 2021 - 11:12 PM

Personally, if you’re only talking about half and hour’s drive, I’d think you were far more likely to be impacted by local things like presence of street lights or nearby houses, than general light pollution.

I disagree, in half an hour I can drive from my house (red zone, SQM = 19's) to a site in the green zone (SQM=21.2-21.4). Local lights do matter for glare, but a half hour drive matters a lot if you are on the edge of a city. If you are driving, use your car to block local lights if they are in one direction.

 

-Dave



#11 Tony Flanders

Tony Flanders

    ISS

  • *****
  • Posts: 20,387
  • Joined: 18 May 2006
  • Loc: Cambridge, MA, USA

Posted 15 December 2021 - 08:08 AM

A half hour drive matters a lot if you are on the edge of a city.


Indeed it does. And it matters even more if you're near the center of a city -- at least a concentrated city of the type that's the norm in most of the world.

Mind you, the person who posted this is from Cumbria, which first of all has no cities worthy of the name and secondly has no roads where you can drive a whole lot faster than 40 km per hour.



#12 osbourne one-nil

osbourne one-nil

    Mercury-Atlas

  • -----
  • Moderators
  • Posts: 2,824
  • Joined: 03 Jul 2006
  • Loc: Cumbria, England 54.5ºN 2.5ºW

Posted 16 December 2021 - 02:42 AM

40kmh? Do you think I'm Lewis Hamilton?!

 

You're both quite right!




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics