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Naked eye observing questions

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#1 astroaLLL42

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Posted 05 February 2024 - 08:48 PM

I have several questions regarding naked-eye astronomy and light pollution.

 

Question 1:

 

What is the needed level of light pollution(Bortle scale or SQM) so that I can see these without equipment (assuming little observer experience but good eyesight and transparency)?

 

The Milky Way in Gemini and Monoceros
The Milky Way in Cygnus and Aquila
The Zodiacal light
The Andromeda galaxy

 

Question 2:

 

How many stars(approximately) will I see from each Bortle scale class?

 

Question 3:

 

What colours will the Milky Way and Zodiacal Light be when I will see them?



#2 Jethro7

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Posted 05 February 2024 - 09:09 PM

I have several questions regarding naked-eye astronomy and light pollution. 

Hello astroaLL42,

I live under Bortle 8 skies and can make out the stars that make up the major contellations. Here is a link to a graph that explains this.

http://www.bigskyast.../lp_bortle.html

 

HAPPY SKIES AND KEEP LOOKING UP Jethro


Edited by Jethro7, 05 February 2024 - 09:58 PM.

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#3 weis14

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Posted 05 February 2024 - 09:10 PM

I often observe from Bortle 3 or 4 skies with scopes and find myself looking up for hours on end.  Here are my thoughts on your questions.

 

1. The Milky Way is literally an important part of the definition of the actual Bortle scale.  Thus, in order for a sky to be Bortle 6, you need to be able to see the Milky Way near the zenith.  Now, assuming you are new to the hobby, you may not realize that most light pollution maps are garbage.  They use old, obsolete data and are generally based on modelling.  Thus, what many maps say is Bortle 6, is probably closer to Bortle 7 or 8 most nights.  Transparency also can vary due to humidity, smoke, dust and clouds on a nearly hourly basis.  

 

All that said, while the textbook answer for the Bortle scale needed to see the Milky Way and Zodiacal Light are Bortle 6 and Bortle 4 respectively, if you are using light pollution maps, the skies probably need to be at least one or two levels better to account for general degradation of the skies over the last few years.  Experience matters too.  I can sometimes see the Milky Way from my house, which is Bortle 7 most nights, but I know exactly where and when to look.

 

2. I don't have a good answer to this.  Bortle 4 skies have many more stars than I can count (literally thousands) and I've never even bothered to try to count the number visible from my Bortle 7 sky.  When I lived in the Washington DC suburbs (Bortle 9 or worse), there were none except maybe Sirius, Vega and Arcturus, and even then you needed to know where to look.

 

3.  They will be pale white/gray, just like almost everything else except the occasional bright star or the aurora.  Your eyes are not very sensitive to color in the dark.  Some subtle shading is visible to seasoned observers, but we are literally talking about shades of gray.  Structure, including brighter and dimmer areas, will be visible, but color won't be.

 

By no means am I trying to discourage you, but it is important that you have realistic expectations.  Your eyes can't take long exposures, so they cannot hope to match what is visible in photographs.  


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#4 ShaulaB

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Posted 05 February 2024 - 09:33 PM

They are pricey, but night vision viewers can fight light pollution really well. I have had several opportunities to look through friends' NV devices under a Bortle 6 Moonless skies. Usually, only the brightest stars in constellations can be seen naked eye, but with the NV, many more are seen. If you like observing comets, the NV is a tremendous asset.

 

Moonless nights are best. Moonlight is a horrible light pollution source.

 

Fuel for ones vehicle is a great help for naked eye night sky enjoyment. Here is a link to a light pollution map.https://www.lightpol...WNpdHkiOjg1fQ==

 

Folks in your local astronomy club can advise about where the best skies are close to home.


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#5 Jethro7

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Posted 05 February 2024 - 10:11 PM

They are pricey, but night vision viewers can fight light pollution really well. I have had several opportunities to look through friends' NV devices under a Bortle 6 Moonless skies. Usually, only the brightest stars in constellations can be seen naked eye, but with the NV, many more are seen. If you like observing comets, the NV is a tremendous  asset.

Hello ShaulaB,

Night Vision Astronomy is my game. With my light intensifier, I essentially bring dark skies to my Bortle 8 skies. You are correct that this these night vision set ups are pricey, I have about $5000.00 USD wrapped up in my night vision kit. If you live under heavy light pollution like I do, these night vision devices are game changers and the best money that I have ever spent for my Backyard Astronomy Project.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

 

I  go from views like this. 

20210925 193500

 

To views like this, with a night vision device. It hard to believe that these two images are from the same point in the sky

20210924 201712

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#6 Tony Flanders

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Posted 06 February 2024 - 06:22 AM

Curious, I was just about to post something on this subject. I'm going to make a big push on Cloudy Nights to standardize on SQM as a way of expressing sky quality, since for the first time in history David Lorenz's 2022 Light Pollution Atlas makes predictions that are quite a good match to what people actually obtain when they measure their own skies with a Sky Quality Meter.

 

The tenor of these questions makes me think that you live somewhere between latitude 30N and 50N, so I will answer on that basis. Obviously you would need darker skies to see the Cygnus Milky Way from Australia, where it grazes the horizon at best.

 

The Milky Way is pretty obvious all the way south to Gemini at SQM=20.5 or 21.0, but I would say that it's vague at best in Monoceros even under pristine skies. That's definitely the least visible part of the Milky Way. Odd, since it's incredibly rich in deep-sky objects.

 

I can see the Cygnus Star Cloud when it's overhead at SQM=19.0. Other people might need somewhat darker skies.

 

The visibility of zodiacal light depends greatly on your latitude and the time of year. And also on how low your eastern and western horizons are, since it's strongest by far near the setting or rising Sun. I cannot see it from my country home at SQM=21.0, but that's because I have hills and my two major light sources to the west and east. With unobstructed views and no light sources in the appropriate direction it should be obvious at SQM=21.0 at the appropriate time of year.

 

I start to see the Andromeda Galaxy naked-eye around SQM=18.0.

 

I will answer the question about star visibility in my forthcoming post. I do not see either the Milky Way or the zodiacal light as colored. Your mileage may vary.


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#7 rjacks

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Posted 16 February 2024 - 10:28 AM

Even in the darkest skies, the only colors apparent to the naked eye are the colors of bright stars (yellow, orange, red, blue) and of Saturn (yellow-ish) and Mars. 

 

Even the brightest emission nebulae (Eta Carina nebula, Tarantula nebula, and M42) don't show color to the naked eye. Nor do the brightest galaxies (LMC and SMC and Andromeda). The photon density is too low for the human eye to see color.



#8 Tony Flanders

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Posted 16 February 2024 - 03:11 PM

Even in the darkest skies, the only colors apparent to the naked eye are the colors of bright stars (yellow, orange, red, blue) and of Saturn (yellow-ish) and Mars.


I might add Jupiter to that list; I find it distinctly bluish. Or maybe that's my imagination from knowing what it looks like through a telescope ...

I have never seen any color in the Milky Way or the zodiacal light, but other people apparently do.

 

Obviously the Northern Lights can be quite colorful, but that's a special case.



#9 Dave Mitsky

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Posted 16 February 2024 - 03:23 PM

<p>

Even the brightest emission nebulae (Eta Carina nebula, Tarantula nebula, and M42) don't show color to the naked eye.

<br />
I can't speak for their veracity but I've read a few reports over the years from people who say they can see color in M42 without optical aid.</p>

#10 Phil Cowell

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Posted 16 February 2024 - 07:39 PM

Might be beverage or gummies assisted.

 

<p><br />
I can't speak for their veracity but I've read a few reports over the years from people who say they can see color in M42 without optical aid.</p>




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