Tagged: light pollution
25 May 2022 at 9:13 am #610472
Interesting they claim the skies are darker for a greater percentage of people than last year, in 2021 they said over 7000 participated yet this year only 2500 took part which is a huge drop. Personally where I live in South Wales there has been a huge increase in LED streetlights and security lighting which has had a detrimental effect on the limiting magnitude, for instance 2021 I counted 12 stars in Orion on several nights, this year 8 in similar sky conditions?
One interesting thing I’ve noticed is you can zoom in to house level on the results, this shows where people have an interest in astronomy and usually expensive equipment, nice indicator for thieves.
I’m a bit skeptical how valid the results are and agree with a recent letter in the BAA journal.25 May 2022 at 9:45 am #610473Andy WilsonKeymaster
I had thoughts along similar lines.
I have already pointed out to them it appears you can zoom in on individual houses. They responded to say the postcodes cover many houses and they don’t think anyone looking at the map would assume everyone taking part has a telescope. None the less I wonder if it might discourage those with expensive equipment from contributing.
I have not seen evidence their conclusions are rigorous. I do think it is encouraging those recording severe light pollution has fallen, though my concern is whether this might be due to differences in participation. It would take quite a detailed analysis of their results, looking at individual locations. In particular comparing locations where results are reported from the same or nearby locations over several years.
25 May 2022 at 10:53 am #610475
- This reply was modified 1 year, 6 months ago by Andy Wilson.
That’s interesting they claim the postcodes cover many houses, where I live there were 4 results close by, when I zoomed in on my red dot it was over my house as it was last time in 2021. When I zoomed on the nearest one to me it also zoomed in to their house and the person concerned has an observatory and did indeed take part, the next closest one was the same as it zoomed in to their house and the person concerned also has quite expensive equipment. So their response about the postcodes don’t agree with the graphic on their website, at least that’s where I live, it would be interesting if anyone else who took part has the marker over their house.
I think it’s a bit naïve of them to assume most taking part hasn’t got expensive equipment, 3 of those near me, myself included has expensive equipment but the 4th person I’m not sure about.
Personally it’s put me off contributing in the future.
I totally agree if they want their results taken seriously they should publish detailed analysis, going from 7-8000 in 2021 ( there website give both figures so how many did take part?) to 2500 is quite a drop and was this taken into account when they reached their conclusions.
I like the letter in the last journal, the author does raise some interesting points.
25 May 2022 at 11:25 am #610478
- This reply was modified 1 year, 6 months ago by Daryl Dobbs.
Looking back at how many people CPRE claim to have submitted results;
2021- 7-8000 as their website mentioned both figures depending on what part of it you looked at
Further back I haven’t got the figures, but this does raise concerns about their conclusions, is the drop in light pollution due to fewer people contributing this year when compared to 2021. I’ve lived here for 6 years and in that time Caerphilly council has replaced most of the streetlights with LED from the sodium and mercury lights and they switch them off between midnight and 5am, plus security lights have increased dramatically.
The change in the colour of the skyglow from Bristol, Newport and Cardiff has noticeably changed now LED lighting is commonplace.
Daryl25 May 2022 at 11:29 am #610479Alex PrattParticipant
To check the level of light pollution at a specific location in the British Isles (or overseas) I use
I find that its SQM readings and Bortle Scale estimates are in good agreement with my own obtained on my travels.
to click on a location and generate a plot of the trend in light level.
Alex.25 May 2022 at 11:48 am #610480
What interesting links, very useful, the light trends was interesting for the area I live, it did show a drop since 1992 which was a surprise.
Daryl25 May 2022 at 2:15 pm #610481Alex PrattParticipant
The light trends feature suggests that conditions have improved a little at some of my light-polluted locations and worsened at my rural sites. Hmmm. I leave it to others to investigate and comment on this.
Alex.25 May 2022 at 3:18 pm #610482
Very interesting when I play around with the light trends where I live from 1992 to the present the light pollution has seen a slight drop, however over the past 3 years it has risen slightly. Recently Caerphilly Council has replaced the sodium and mercury lights with LEDs, they just replaced the heads and not adjusted the distance between the lamp posts, this has resulted in quite a few areas being a lot brighter, we don’t need to put the bathroom light on anymore! We moved here 6 years ago and the light trends over that time frame showed a slight rise which seems to have been reflected in my observations. It makes the CPRE results even more odd.
Thanks for the links, very useful.
Daryl25 May 2022 at 3:45 pm #610483Richard MilesParticipant
Alex – Yes exactly that. Urban areas that are badly light polluted (i.e. counting 10 or less stars is the criterion) seem to have improved somewhat.
I suspect that the darkest skies may have deteriorated slightly.
I have some peripheral involvement with the CPRE Star Count and we know that the weather badly affected reporting in 2022 cf. 2021.
I know that National CPRE used paid ads on Facebook to help spread the word in 2021 and several local groups also promoted it.
I intend to get actively involved in promoting the 2023 effort.19 June 2022 at 8:39 pm #611087Brian MillsParticipant
As the writer of the letter to the BAA Journal perhaps I could comment.
I had contacted CPRE for each of the last three years taking issue with their campaigns and claims about data validity. They have at times suggested carrying out the count with the Moon above the horizon and with the Sun less than 18 degrees below it. This year their advertising material showed participants carrying out the count from indoors with the light on. They also suggested that it was only necessary to allow ones eyes to adapt for “… a few moments…” all of which immediately renders any results worthless.
The response from the CPRE was that the count was simply intended to get people “looking up” which, in the right context, would be creditable. However, it is not possible to encourage such a cursory approach to data collection and at the same time expect that it be taken seriously.
Yes, by all means encourage everyone to look up at the night sky, but if they do it in such a casual manner, they ought not to be surprised when governments fail to act on their results.
Brian Mills19 June 2022 at 9:20 pm #611088Dr Paul LeylandParticipant
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