Dark Skies and Satellites in the News

[Dr Paul Leyland]

Robin Leadbeater wrote:

Shouldn’t it possible to extract useful information from the sky background in the photometrically calibrated images and spectra we take ? If so there could already be a huge (untapped ?) historical source of data covering a range of passbands, locations, air mass and atmospheric conditions

Cheers
Robin

That is a damned good idea! I alone have over 30,000 images neatly catalogued, most of which contain little but stellar images so determining the background sky brightness should be possible.

The FITS headers of mine not only have RA, Dec and time recorded, they also have altitude and azimuth (admittedly easily computed from the first three) so more than just air mass is available – the distribution over the sky, such as city lights, can also be determined. About the only thing I don’t have recorded is the weather condition at the time of exposure but perhaps there are other public records of that too.

[Howard Lawrence]

This is a very interesting question Robin and one that needs investigation. I suspect that there will be scientific reports on this subject somewhere,

[Howard Lawrence]

https://www.bbc.com/travel/article/20231123-the-last-places-on-earth-to-see-truly-dark-starry-nights
These amazing images by Jordi Busqué illustrate what dark sky campaigners are working for. Very few people will experience these conditions today.
With the rise of satellite constellations, will it be possible in future to make similar images, for instance those made near dusk and dawn?

[Howard Lawrence]

Here is what looks like a useful publication from the EU office of the Director General for the Environment: https://op.europa.eu/en/publication-detail/-/publication/5727bc7c-843c-11ee-99ba-01aa75ed71a1/language-en/format-PDF/source-296551457
I have only skimmed it so far.

[Howard Lawrence]

Coming to your local sky soon maybe? Apparently this event was the result of a malfunction in a “green” house blackout blind system. But shouldn’t the rules be no blinds then don’t switch on the lights? These vertical farms are likely to be increasingly common in future. The story comes via contributors on the Dark Sky International forum.
https://www.kwtx.com/2023/12/04/researchers-weigh-pink-glow-sky-coming-lettuce-farm-temple/

[Robin Leadbeater]

Howard Lawrence wrote:

Coming to your local sky soon maybe?

Also seen here
https://www.bbc.co.uk/news/uk-england-humber-67095602

There it seems to imply the decision to draw the blinds is temperature dependent not to reduce light pollution and is likely to occur again under certain circumstances

[Howard Lawrence]

The International Union for Conservation of Nature has published World at Night, Preserving natural darkness for heritage conservation and night sky appreciation.
This looks like an excellent general guide to global light pollution issues. It is 160 pages so I’ve not read it yet, but the page (7) on amateur astronomy and stargazing is particularly good. I especially like the opening sentence.
Thanks to John Barentine, one of the authors, for announcing this.

https://portals.iucn.org/library/sites/library/files/documents/PAG-033-En.pdf

[Howard Lawrence]

Reflectors in space could make solar farms on Earth work for longer every day. Is this a sensible idea?

https://www.space.com/reflectors-in-space-increase-solar-farm-capacity

[Dr Paul Leyland]

Not obviously cost effective. It’s much cheaper to double the collecting area on the ground than to do so in space.

[Robin Leadbeater]

There could be some financial advantage to extending the time over which power can be generated rather than increasing capacity on the ground. For a region heavily dependent on solar power, the price of night time electricity must presumably attract a high premium due to the high cost of storage or alternative generating capacity.

[Dr Paul Leyland]

Robin: true.

I question whether it is cheaper to put large structures in space or whether to put large structures (such as transmission lines) on the ground at a range of longitudes.

Or, for that matter, to install storage mechanisms to convert daylight solar energy into nighttime electricity. Batteries, in the general sense of the word, are relatively cheap. Raising a cubic kilometer of mass a hundred metres stores a lot of energy and uses technology which has been well understood and implemented for a hundred years. Melting and re-solidifying a phase-change material, such as NaCl, likewise.

[Howard Lawrence]

A new paper sheds fresh light on a subject that CfDS have used in past campaigns – the disruption caused by artificial light to the lives of insects. The new science has been featured on various news outlets. A straightforward article about it can be found on the Conversation website.. https://theconversation.com/the-surprising-reason-why-insects-circle-lights-at-night-they-lose-track-of-the-sky-221387 There is a link to the original paper from this article and a video compilation showing insects in flight.

[Robin Leadbeater]

I have just been listening to one of the scientists involved in that study on BBC world service Science in Action
https://www.bbc.co.uk/sounds/play/w3ct4sdl
starting at 22:40

Robin

[Howard Lawrence]

Thanks Robin. I will listen to it later.

[Howard Lawrence]

This is an interesting article about the prospect of an artificial plasma shield being generated by the high masses of future de orbiting satellites. It is little studied at present but the potential impact on planet Earth could be enormous. So, another reason to campaign against satellite constellations until this and other issues are resolved.

https://spaceweather.com/archive.php?view=1&day=03&month=02&year=2024

[Robin Leadbeater]

Interesting. I don’t think the comparison between the mass deorbited and the amount of material in the Van Allen belt is particularly helpful as the two are not comparable (We already receive ~ 40T/day of metals from meteorites) but at the future projected rate of 23 satellite deorbits a day (in the paper) the amount of additional material would appear to be comparable.

[Mr Giovanni Di Giovanni]

I have carefully viewed the articles posted by Mr Christopher. They are very interesting, well laid out and equally well developed topics. I am interested in their content, and for this I thank the author for making them available in this forum. For a few years now, I have been interested in sky transparency and observing sunrise and sunset light in order to detect the ‘optical depth’ parameter. I have a small archive of data from about 300 observations. I will try to identify the possible existence of a correlation between the theory Christopher applies and the one I use for my observations. I hope this will provide good guidance for further experiments and studies. Thank you Christopher.

[Howard Lawrence]

The UN is now talking about the issue of satellite constellations (at last). Will it result in anything positive in time? We must hope so. https://www.iau.org/news/pressreleases/detail/iau2401/

[Mr Giovanni Di Giovanni]

I always hoped for their title.

https://www.youtube.com/watch?v=P8Xk2e3ApiA&ab_channel=JORGEC

What a beautiful sky, all black. Back then, the sky was filled with clusters of stars, which you could touch with your hands, even from the cities. Remember?

Unfortunately today our starless sky is all white. I see white, it’s over!

[Howard Lawrence]

This article is a comprehensive critique of the satellite swarm issues, conveniently in one place. https://bigthink.com/starts-with-a-bang/outer-space-human-pollution/
So the notion that satellites are just the latest lies are true!😀

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