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I have often wondered what the sky was like

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#1 orionn1

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Posted 21 April 2013 - 12:02 AM

I have often wondered what the view of the sky was like back when messier was viewing the sky. What was the limiting naked eye magnitude. The light pollution had to be almost nil with not having electricity.
Are there any articles on that

#2 Dave O

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Posted 21 April 2013 - 04:09 AM

Here is a neat sight that shows what a dark sky might look like in several of the largest cities ... pretty neat. :)
Darkened Cities

#3 Tony Flanders

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Posted 21 April 2013 - 05:13 AM

I have often wondered what the view of the sky was like back when messier was viewing the sky. What was the limiting naked eye magnitude.


Same as it is today over most of Earth's surface.

Light pollution is a big deal because most people live in light-polluted surroundings. That's almost true by definition -- every individual who lives on the grid and/or owns a car makes his or her own light pollution.

However, perhaps a quarter the land area of the U.S. is so far from any artificial light that light pollution has no effect at all on the limiting magnitude at the zenith. Exactly what that is depends primarily on the individual and secondarily on the clarity of the air. Anywhere from about 8.0 to 6.0 -- or worse for people with uncorrected vision defects.

Messier lived in Paris, so his skies were a good deal worse than modern skies in, say, the middle of Utah.

#4 bunyon

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Posted 21 April 2013 - 08:40 AM

Not to mention that, at the time, all heat was generated by fire in the home. Paris in messier's time probably had pretty lousy sky.

#5 vsteblina

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Posted 21 April 2013 - 10:25 AM

I not so sure that the skies were that bad. The population of Paris in 1770 was around 500,000. This is the population of Boise or Spokane today!!

Spring, Fall and Summer probably had pretty good skies. Winter during inversions might have smokey skies, but remember very few people would have had access to firewood in Paris. Only the very rich.

Wood that was burned was probably used for cooking rather than heating. Most people just froze in their homes.

The prevailing winds and living on the edge of Paris probably blew the the smoke away.

Does anybody know when coal came into common use? Coal packs a lot more energy than wood and that probably did change the sky.

The above is the opinion of a professional Forester....use with extreme caution on this issue!!!

#6 Tony Flanders

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Posted 21 April 2013 - 06:53 PM

I not so sure that the skies were that bad.


This subject just came up in a different group.

No, I'm sure that Messier's skies would be considered excellent by a modern urban or suburban observer. But not like the skies in the American West. Even without light or air pollution, humid, low-altitude Paris would be no match for the West.

#7 orionn1

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Posted 21 April 2013 - 09:40 PM

cool website dave o

good point vesteblina

#8 vsteblina

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Posted 21 April 2013 - 11:12 PM

[/quote]



No, I'm sure that Messier's skies would be considered excellent by a modern urban or suburban observer. But not like the skies in the American West. Even without light or air pollution, humid, low-altitude Paris would be no match for the West. [/quote]

I am not so sure.

I live in eastern Washington where the relative humidity is 10% in summer and 99% in winter.

I have a cabin up in the mountains and in the winter eastern Washington gets blanketed with a low lying fog. The cabin at 3000 feet is above the fog layer. Those skies are dark!!

I can see the fog swirling in the meadow just below me, yet the night sky is totally dark. The key is the meadow is off-grid and there are NO lights to scatter in the aerosols.

So in a completely dark area, even high humidity, has an impact I am sure, but not like an area with both high humidity AND lights!!

BTW I worked in the southwest in National Park areas in the mid-1970's and recently returned as a snowbird. It is sad what has happened to SW skies over that period of time.

#9 Kraus

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Posted 22 April 2013 - 11:42 AM


I'm sure Messier's telescope was a piece of junk so his skies had to be the most excellent in his days. And I'm inclined to agree with Herr Orioon1. There was no electricty thus no light pollution.

#10 bunyon

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Posted 22 April 2013 - 12:30 PM

I not so sure that the skies were that bad.


This subject just came up in a different group.

No, I'm sure that Messier's skies would be considered excellent by a modern urban or suburban observer. But not like the skies in the American West. Even without light or air pollution, humid, low-altitude Paris would be no match for the West.



Tony, can you share a link or any details? Obviously, I don't know what it was like in Paris, but I have read a lot about London and the skies there - independent of weather, etc. - were lousy with smoke. I may also have my centuries mixed up.

#11 StarStuff1

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Posted 22 April 2013 - 05:06 PM

Tony, overall sky glow is much worse today, especially in the USA. The last time I went to the Winter Star Party was 2005. Amost sickening with the skyglow. You could easily read a newspaper headline without a flashlight. Of course the stripping of vegetation by a couple of hurricanes and inceased lighting by humans did no good.

#12 BrooksObs

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Posted 26 April 2013 - 07:49 AM

A truly depressing fact is that excellent skies were available almost universally, save for the interiors of the largest cities, anywhere in America prior to about 1960. For example, back then one needed to drive no more than 15-20 miles outside the boundaries of even NYC in any direction to see 7th magnitude stars...about as faint as the average observer can detect under the best of circumstances and identical to what Messier would have seen from 18th century Paris.

Most of folks here were born simply a generation, or two, too late to experience what the sky looked like for 90% of the population from their own backyards.

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#13 Jon Isaacs

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Posted 28 April 2013 - 06:58 PM

Wood that was burned was probably used for cooking rather than heating. Most people just froze in their homes.



Coal...

Jon

#14 Retentive

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Posted 28 April 2013 - 08:14 PM

having been a prescribed fire manager and been around a lot of smoke deep into the night for quite a few years,I have contemplated this issue, my thinking is that Messier's skies would have surely benefited from inversion as the night sky cools and smoke lays down low. But who really knows.food for thought,

Phil






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