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A cosmic census

Posted: Wed Apr 17, 2019 9:59 am
by brian livesey
The Campaign to Protect Rural England ( CPRE ) has carried out a "cosmic census" to find out the visual affects on the night sky caused by light pollution.
A star count revealed that fifty-seven per cent of participant stargazers had difficulty in seeing more then 10 stars, while only two per cent, located in "truly dark skies", counted 30 or more stars.
Participants in towns and the countryside were asked to count the number of stars they could see in the constellation of Orion. The star count was supported by the British Astronomical Association ( BAA ). The census showed how light pollution affects "one of the countryside's most magical sights - a dark, starry night sky," said campaigners.
CPRE dark skies campaigner, Emma Marrington, said: "Without intervention, our night sky will continue to be lost."
In this area, the worst culprits for light pollution seem to be local councils. They insist on putting lamps everywhere, including setting them into the ground to shine vertically. A recent addition to light pollution is the Victorian Town Hall, which is now lit up like a Christmas tree at night.

Re: A cosmic census

Posted: Thu Apr 18, 2019 10:37 am
by stella
Using the unaided eye as the observing 'equipment' makes these results
very questionable. Standing side-by-side, a eagle-eyed youngster could
count around 20 stars when I could make out 7 stars - tau, iota, eta and
sigma plus the belt. I don't suppose the survey asked the age of the observer?

Re: A cosmic census

Posted: Thu Apr 18, 2019 2:43 pm
by brian livesey
The age range wasn't mentioned, Stella, in the original press report.

Re: A cosmic census

Posted: Thu Apr 18, 2019 6:50 pm
by JohnM
I would agree with Stella, I have had experiance of a young person who was able to observe 12+ stars in the Seven Sisters when the older people could resolve 6. The person concerned drew a diagram of the stars she could see which agreed pretty well with images.

The other variable that is not controlled is how long people waited to get dark adapted before they observed Orion.

I gave a talk to the SPA about vision for astronomy, I am not sure if it is still available in the meeting video archive.