SQM sky darkness during a power outage!

[Ships and Stars]

Hi all,

I'm in NE Scotland which as you may have heard, has had back to back storms recently - Storm Malik on Saturday and Storm Corrie which hit late Sunday night.

My town near Aberdeen escaped power outages from Malik, but around 11pm Sun night, Corrie knocked everything out locally, the lights from Aberdeen were the only thing visible in any direction, it was incredibly striking, just a huge glow on the horizon. Aberdeen vaguely reminded me of Mt Etna in Sicily or something on that level, it was so bright in contrast to my surroundings.

The sky cleared and I stood in the centre of the town, with all the constellations in a jet black sky framing the taller structures. This is the brightest part of town, normally bathed in LEDs and any other number of street/commercial and residential lights. Incredible. Not a single light to be seen anywhere.

I immediately took SQM-L readings with the unihedron from home. My best reading ever during lockdown on a very clear moonless night was a 20.38, with 19.9 to 20.1 more the norm after local shops turn off their lights.

I managed to quickly obtain a 21.4 early Monday morning from the exact same spot, and that was with some small patches of faint wispy cloud reflecting light from Aberdeen in the distance.

If sky conditions had been the same as my old 'best' reading of 20.38, then I think it would have easily surpassed 21.5. I think a jump from say 20.00 to 21.00 represents a sky ten times darker, if memory serves me right? Logarithmic scale perhaps? 

I didn't have time to set up either dob, but did easily bag M51 with a pair of handheld 15x70 Apollos. It was a small faint smudge, but directly observable. 

Just goes to show the huge leap between normal and lights out!

My house was freezing the next day with no heat, but was slightly disappointed when power came back on Monday afternoon, as I was going to set up one of the dobs. However, I did enjoy a hot bath!

Edited February 1, 2022 by Ships and Stars

[tomato]

Interesting post, if it happened to me I think I would always be thinking back to what my sky could be…

So how do we get everybody within a 20 mile radius to turn off every light after midnight?😏

[Ships and Stars]

16 minutes ago, tomato said:

Interesting post, if it happened to me I think I would always be thinking back to what my sky could be…

So how do we get everybody within a 20 mile radius to turn off every light after midnight?😏

The sqm numbers only tell a small part of the story, the difference was really incredible. It would take me 40 minutes to an hour plus normally to drive to an equally dark spot in the Cairngorms.

I've been thinking of ways to convince local businesses and homes to switch off as a pilot project, but that's a very hard sell!

I have managed to get one local business to switch off a 7pm and the other at 9pm, long after either are closed, and that literally took a couple of years. Their lights were shining directly at my house though. 

There is a dark sky village in rural Arizona, they only have one rule, 'turn off your g-- ---- lights!'.  I'd like it there! Imagine going over to a neighbour, could I borrow your collimator? I've misplaced mine.

Edited February 1, 2022 by Ships and Stars
typo

[scarp15]

The skies were indeed clear around the periods of those named storms, that is a stark account for what could be possible if only change would happen. We did not experience a power cut, although Towns and villages through Northumberland were knocked out again.   

[Ships and Stars]

1 hour ago, scarp15 said:

The skies were indeed clear around the periods of those named storms, that is a stark account for what could be possible if only change would happen. We did not experience a power cut, although Towns and villages through Northumberland were knocked out again.   

At one point, a lot of the NE here was out - something I probably won't see again! I was the only fool out walking around at 1am in the town carpark, laughing at how dark it was and how brilliant the stars were. 

The change is beyond striking, really a special moment. 

[saac]

On 01/02/2022 at 22:09, tomato said:

Interesting post, if it happened to me I think I would always be thinking back to what my sky could be…

So how do we get everybody within a 20 mile radius to turn off every light after midnight?😏

It may be poor consolation but with the oncoming hike in energy prices we may see one or two security lights being turned off. 

Jim 

[Gfamily]

On 01/02/2022 at 21:04, Ships and Stars said:

my old 'best' reading of 20.38, then I think it would have easily surpassed 21.5. I think a jump from say 20.00 to 21.00 represents a sky ten times darker, if memory serves me right? Logarithmic scale perhaps? 

If the SQM reading is based on astronomical magnitude, a difference of 1 represents a 2.512 difference - as 5 magnitudes represents a 100 fold difference in brightness.

Edited February 5, 2022 by Gfamily

[Ships and Stars]

On 05/02/2022 at 15:43, Gfamily said:

If the SQM reading is based on astronomical magnitude, a difference of 1 represents a 2.512 difference - as 5 magnitudes represents a 100 fold difference in brightness.

Two and a half times probably makes more sense, I've never fully got my head around sqm, readings vs other night sky yardsticks, but the difference between say 20.2 (home on a dark night in town) and 21.2 (a dark night 15-20 drive outside of town) make a massive difference. I've been under 21.9, about an hour and a half away, and that was incredible.