Posted by defrost 17 hours ago
If you've never seen truly dark skies, do yourself a favour and go see what they look like during true night. Bring binoculars if you have them, maybe get a planisphere and a (dim!) red flashlight.
The lack of respect for the night sky includes starlink and the other internet providers dumping tens of thousands of satellites in orbit instead of building municipal internet, by the way. It's been a huge hit to the field of astronomy. Before someone inevitably says "we should just be putting telescopes in orbit", orbital observatories are obviously a huge deal and I support building more of them, but you simply can't put things like the ELT (40m primary mirror, 2800 tonnes) or the Square Kilometre Array in space.
1. They are only visible when they are spinning up to orbit
2. They are too dim to desensitize your eyes, and are extremely easy to remove with the most basic of outlier rejection techniques; netizens often amplifiy outliers by max-stacking instead of outlier-rejected mean-stacking to make Starlink look much worse than it is
3. Lights from planes have ALWAYS been much, much, much, much worse than satellites. They still aren't particularly a problem for imaging if you know how to outlier reject, and their paths are known, predictable and trackable
I'm not an Elon-fan or anything but just giving a dose of objective reality here.
Not to detract from TFA's real issue which is light pollution from cities -- that's an actual issue as the regions of dark sky are shrinking.
> and are extremely easy to remove with the most basic of outlier rejection techniques; netizens often amplifiy outliers by max-stacking instead of outlier-rejected mean-stacking to make Starlink look much worse than it is
my understanding was that they are a problem on much bigger scale than yours "one dude with mobile telescope (or maybe just a camera?)"
sure, we don't have many film observatories anymore (where max-stacking is literally only thing they can do), but a lot of lower-to-medium scale observatories get polluted observations with not enough funding to clean up easily or too small FoV for cleanup to matter - frame gets ruined, observation needs to be longer for effect
Or more generally, let's say 10% of frames have satellite noise. That means there is 10% less observing you can do in a night. For amateurs, that is annoying. For professionals, that means less science can be done.
2. If you are doing photometry (measuring the brightness of something), even if the relative brightness isn't very much, it can introduce a lot of noise to the data. For many things, even the dimmest satellite is going to add more light than the change in brightness you are looking for.
Now to be fair for scientific research typically you can use the frame if the streak isn't too close to your object(s) of interest. And for pretty pictures you can often edit out the streaks. But even so, it's a problem more than you would think.
There’s certainly more of them than there used to be, but the satellites aren’t bright enough to affect your eyes or distract too much from the stars. If you do see one it’s a fun little exercise to try and figure out what it is!
Ground-based light sources are the real threat to night skies.
It's too much
Starlink gets a lot of attention because it's new, and because it's run by a polarizing guy who sucks.
Meanwhile, the airplane and streetlight situation has been destroying night sky photography for decades, to the point where photographers consult charts and have communities tracking the best times of years to minimize the hours of driving you have to do.
But let's "both are real issues" it, sure.
It still won't be as big of an issue for night sky photography, for reasons mentioned in the parent comment.
However, there are many other severe issues, of course. But for hobbyist and professional photography? Mitigable.
I can see a problem with 100x the current deployment, but the "other severe issues" kick in long before that, anyways.
(2) The standards for astrophotography and for professional astronomical measurements are somewhat different! Also, I think you meant median stacking; mean stacking doesn't handle outliers as well.
(3) Whataboutism. Besides, you'd get no argument from me about replacing the majority of air travel with high speed rail, even without considering lights.
I agree that city light pollution is probably the bigger problem, especially for the amateur/cultural angle, but these are two symptoms of the general cause of our economic system not valuing the sky (or the environment generally).
> replacing the majority of air travel with high speed rail
I absolutely LOVE high speed rail, but I will note that it is correlated with far more light pollution than air traffic. I say correlated because typically high speed rail is routed through high-density population centers, but if there aren't population centers, you'll have to have plans to create them in order to support the rail system itself.
Basically there is nowhere in the world that has both high speed rail AND suitable for astronomy. If you want to find dark skies in China for example you have to get far away from all the high speed rail areas of the country.
Rail travel has stops and slowdowns in more populated areas that make it a bit slower than the advertised top speeds.
My point was that if you want replace, say, San Francisco <-> Las Vegas with HSR you're going to inevitably have to wreck a chunk of Bortle 1 dark skies in the Sierra or Death Valley.
Doesn't mean I'm against HSR but it has to be done thoughtfully.
This is such a misanthropic point of view.
Nobody "creates" population centers. People aren't created out of raw clay, they already exist.
If population centers are "created" it's because people already exist and want to live in a specific place, often time urban.
And if they wouldn't go to these population centers they wouldn't live in caves in the dark. They would be spread over many more places, yes, creating lower levels of light pollution but lots more of them, covering a lot more land.
All you're describing is population redistribution, not population creation. Urban centers have very low fertility rates, which actually reduces populations...
Most people didn't care about dark skys in the first place and still don't.
I would argue that probably not looking up all the time at night with predators around was an evolutionary trait though! (Semi joking)
Most people were never given the opportunity to care.
Or are you suggesting that by the time they are in the Navy, it's after the age where one might be most easily encouraged to care?
There's another aspect to it, though — parent was in a navy ship, surrounded by sailors. That's a very specific population, in a very specific situation, and it's not necessarily true that that's the right crowd or situation to care (though it baffles me how a sailor at sea might look up at the stars without being in awe of the thought "damn, my predecessors navigated based on those")
Some pictures: https://milieufederatie.nl/nieuws/6-op-de-10-nederlanders-wi...
Where I live, it usually impossible due to nights being too cold (okay, you can use sleeping bags/extra blankets etc), clouds, or... mosquitos.
But when/where it's not: highly recommended! "Spaceship Earth" in progress.
> If you've never seen truly dark skies, do yourself a favour and go see what they look like during true night
I think I went from only ever experiencing Bortle 5-6 to Bortle 1 when I visited Merzouga and Erg Chebbi. Blew my mind, made me really appreciate the extent of light pollution almost everywhere else I've been.
When I first learned about the "clouds are noticeably brighter than the sky" part of Bortle 5, it was like it flipped a switch in my brain. I can't avoid noticing it now.
But even here it’s under threat: a recent new retail development on the edge of the town (called “Three Parks”) emits so much light that it illuminates the nearby hills at night. The sad thing is that much of this light seems unnecessary to me: eg a hardware / garden retailer has enormous floodlights to illuminate their inner courtyard constantly at night, even when they’re closed.
The rest of the town has always been pretty good at minimising light pollution, with soft, modest and well designed street lighting in residential areas. But such considerations have been forgotten completely with the new development. Three Parks emits more light pollution than the rest of the town combined!
Considering how little value we put on far more important things (like the climate or biodiversity), I'm not really surprised.
Lunar regolith would probably be quite damaging to optics. It's nasty stuff. I have seen ideas for building liquid mirror telescopes on the moon, though.
As to the dark side of the moon, I would suggest a read of the story "A Walk in the Sun" - https://www.baen.com/Chapters/0671878522/0671878522___1.htm (the dusk terminator moves at about 10 mph (15 kph) at the equator).
Like O'Neill's research group killed off the plan with the big cylinders because you would construct solar power satellites out of plastic films with vapor deposited metal and semiconductors and these would be light enough to send up from Earth and assemble in space.
Radio telescopes only need a wire mesh to deploy (rather than polished optical mirrors). https://www.skyatnightmagazine.com/space-science/arecibo-tel... has a view under Arecibo.
https://www.nasa.gov/general/lunar-crater-radio-telescope-lc...
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The liquid metal mirror telescopes https://en.wikipedia.org/wiki/Liquid-mirror_telescope are interesting in part because you can get liquid mercury temperatures near room temperature on Earth.
It's theoretically possible for the moon - https://ui.adsabs.harvard.edu/abs/2007Natur.447..979B/abstra...
A previously proposed liquid mirror telescope, based upon a spinning liquid metallic alloy, is not appropriate for infrared applications, which will require a liquid below 130K. Here we report the successful coating of an ionic liquid with silver. The surface is smooth and the silver coating is stable on a timescale of months. The underlying ionic liquid does not evaporate in a vacuum and remains liquid down to a temperature of 175K Given that there are ~10^6 simple and ~10^18 ternary ionic liquids, it should be possible to synthesize liquids with even lower melting temperatures.
(I'm not a botanist or a farmer but I grow greenhouse veggies for fun)
Starlink is intended and used as solution for places and uses for which municipal internet is not an option at all
(is it usable at all as replacement for municipal internet? I would guess that you would overcrowd connection quite quickly)
I've been in some place with very dark skies, like Death Valley or Teide in the Canaries (https://www.teidebynight.com/tenerifes-dark-sky-reserves-hav...). It was great, but also not that much better than what I've seen closer to home in French countryside or in the alps. Maybe I didn't get the best conditions though.
Ah yes, that municipal internet in the Pacific Ocean. The municipal internet in the 1 person per square mile rural area. The municipal internet to mountain villages. The municipal internet running to airplanes. The municipal internet to the Antarctic research stations.
Tell me you don’t know the point of satellite internet without telling me.
If you want to make arguments against sat constellations so people can make long exposure photos, go for it. But don’t pretend there are actual viable alternatives to LEO sat internet.
Yet that person can receive mail, is within a few miles of a major highway, and is likely connected to or close to the electric grid.
Infrastructure is expensive. LEO Satellite internet is only cheaper because the environmental cost is not being accounted for.
Not an expert, but I would think greenhouse light pollution is not necessary for agriculture? It seems like obvious waste (money spent generating light that isn't going to photosynthesis), but I assume it's cheaper not to shield the lights than to shield them, so it's a matter of ROI and requiring people take care of their externalities.
Is there an economic argument that light shields will make agriculture in that area too expensive?
(FYI, it's a solved problem: https://de.made-in-china.com/co_zenong/product_Agriculture-P...)
Light pollution has dramatic negative consequences for wildlife and thereby our ecosystem we so heavily depend upon.
Would you rather have 2x the wilderness 80% degraded or 1x the wilderness 90% degraded? Unless your plan is to decide who starves to death, it's far better to have greenhouses where we already have farms!
Therefore I fully agree with you!
> instead of shutting down agriculture in the only marginal spot on the west coast you can grow food.
The Okanagan will be shocked to hear they can't do agriculture! Perhaps we could just turn off the greenhouse lights for a couple hours, or install retractable shields/mirorrs on top of the greenhouses.
lightpollutionmap.info/#zoom=8.01&lat=49.6027&lon=-122.7672&state=eyJiYXNlbWFwIjoiTGF5ZXJCaW5nUm9hZCIsIm92ZXJsYXkiOiJzYl8yMDI1Iiwib3ZlcmxheWNvbG9yIjpmYWxzZSwib3ZlcmxheW9wYWNpdHkiOiI2MCIsImZlYXR1cmVzb3BhY2l0eSI6Ijg1In0=
Just install light shields.
But what if someone were uncomfortable briefly? Did you ever consider that? Technology exists to infantilize us while slowly ruining everything that makes us human. Shame on you for attempting to interrupt human progress.
(I find it odd; dark-adapted eyes see a lot, including movement in shadows or low-contrast obstacles - after all, our bodies know how to see well at moonlight levels of illumination. Why are we so keen to kill this ability?)
As an example, in the UK, councils are expected to light commonly-traveled paths, both so path users can see where they're going, and to reduce crime. Unlit paths in city parks are still traversed, and are often a haven for crime.
"Dead of night" isn't the right image. 5PM in winter with clouds (as is typical in the UK) has roughly the same level of natural light as 2AM. People are still coming home from work in conditions where natural light is low enough to lead to accidents and crime.
Powerful lights are known to actually increase safety risks. Our nightvision is reduced and the shadows of the lights are the most dangerous parts. Perhaps more dangerous than no light at all.
Once city (I can't recall which) had a really cool solution to this where they installed string lights. Lots of small, dim lights don't negatively impact your nightvision, keep the path pretty visible, and don't cause too much light pollution
I would say that going from no lighting at all, to some lighting, on urban paths, improves safety (not tripping over unexpected obstacles) and reduces crime (presuming there was any crime while it was unlit). The article doesn't refute that. I would suggest that if a major city decided to eliminate all street lighting, it would be absolute chaos.
This is a completely irrational (though commonplace) fear. Criminals aren’t hiding out in bushes in desolate parks to mug or rape random people. Muggings most commonly happen in side paths off of busy high streets because criminals, being people, like to hang out in stimulating places where they won’t get bored. They’re not going to be donning ghillie suits and lying patiently in wait for however long in uncomfortable brush for a hapless victim to cross their path. The muggings are crimes of opportunity. Rapists are most commonly somewhat trusted friends or acquaintances who have access to people when they’re in vulnerable states in private, protected spots.
Thinking parks and parking lots need to be lit up like Christmas to deter crime is just a veneer of rationalization to cope with the standard childhood fear of the dark. It is not backed by data or evidence. The actual main public safety concerns when it’s dark out are trip-and-fall hazards or collisions with or vehicles who can’t react fast enough when things pop out at them, not muggers and rapists. Having the nighttime environment overly lit actually makes shadows starker and blows out people’s night-vision so they can’t find things. If anything, it makes the edge case where Sam Fischer is hiding in the bushes more dangerous rather than less.
Criminals hide out in the dark parts of urban parks, mere minutes away from well-lit, more populated areas of the city. They're not going to get bored. Victims walk through the parks and get jumped, occasionally dragged off into the darker parts.
To give a example: The Meadows in Edinburgh: https://www.openstreetmap.org/way/233760765
A park between the university and student accomodation. Very popular with students going home at night. Apart from a few lit paths, entirely dark. Most paths are lined with trees, like so: https://www.edinburghnews.scotsman.com/webimg/b25lY21zOjAxYz...
Here's a small sample of incidents. There are genuinely criminals who hang about in the dark parts of this park, late at night, in order to attack victims. They don't have to wear ghille suits, they need only stand behind the trees.
- 2011: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-1... "Two men who grabbed a young woman before one sexually assaulted her in an Edinburgh park are being sought by police. The 19-year-old woman was walking through the Meadows at 03:30 on Tuesday when she was attacked at a spot north of Melville Drive."
- 2011: https://www.scotsman.com/news/charges-over-sex-assaults-in-m... "Lothian and Borders Police issued an open letter to students and residents in response to the incidents, advising them not to walk alone in the Meadows at night"
- 2012: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-2... "The 30-year-old was walking through Middle Meadow Walk at about 22:30 when two men approached him. One of the men punched the victim in the face, knocked him to the ground and continued assaulting him before taking his personal belongings."
- 2014: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-2... "The 25-year-old was walking near the tennis courts at the east end of the park at about 04:30 on Saturday when he was approached by two men. After asking the man for money, the two attackers punched him several times, causing minor facial injuries, and also tried to steal his watch."
- 2014: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-3... "Steven Davidson, 24, attacked the 19-year old as she made her way home through the Meadows in November 2014. [...] Davidson ran up and grabbed her from behind. [...] The woman had been making her way home just before 07:00 [...] she passed out and came round to find him lying on top of her. He then raped her."
- 2016: https://archive.news.stv.tv/east-central/1374940-three-assau... "Police are investigating after three assaults were carried out on the Meadows in Edinburgh within 15 minutes of each other. In each of the incidents, which took place between 3.10am and 3.25am on Sunday, the attackers robbed or attempted to rob the victims of cash or possessions."
- 2020: https://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-5... "The attack on the 37-year-old took place on The Meadows at about 23:15 on Saturday"
- 2023: https://www.edinburghlive.co.uk/news/edinburgh-news/edinburg... "The incident took place at around 4am on Sunday, January 29."
I'm not saying we should floodlight the park. What has helped most is regular police patrols of the park. But I'd be lying if I said the criminals don't hang out in the dark parts of this park, waiting for victims. They do.
Those nights are the safest in my experience. Simply because no thief or mugger would bother to venture out into the middle of nowhere, in the off-chance there's something to be had there. That's assuming they'd even know someone/something to be there! And even if they would, chances are I'd be quickly aware of their presence, or some geese/other birds would announce their presence.
TLDR; Be careful in areas with lots of people, or on the edge of such areas. Places that lack people tend to be safe.
I vaguely remember that studies showed that lack of streetlights does not create crime, but the crime that happens anyways prefers badly lit areas. But from a pedestrian's perspective that's not much relief, you'd still avoid those areas. Which is not what a city planner has in mind for a park
Amber LEDs could provide a similar experience.
I know if I was trying to sleep a constant source of light is easier to get used to than a randomly flashing source of light. And for nocturnal animals I'd imagine randomly losing the cover of darkness from time to time is probably a lot more stressful than just avoiding the brighter areas.
I'd be interested in seeing data. I really wonder which is better.
This actually isn’t true. Having done physical security work before, a weird fact is that one of the best physical deterrents is lighting; even over CCTV.
I don’t say that to take away from this, this is great work and I’d love to see the lighting toned down for multiple reasons. However, this should be framed as a security tradeoff not an outright win.
Source: The Impact and Policy Relevance of Street Lighting for Crime Prevention: A Systematic Review Based on a Half-Century of Evaluation Research (https://www.crimrxiv.com/pub/wl9zqxga/release/1)
You need much less light on the ground if the eyeball itself has no direct line to the hottest part of the lights. Instead, the night-blindness caused by excessive bare lighting is "fixed" by adding more fill lights for the shadows caused by the first lights. Classic addictive behaviour.
The thing was, the roads of this city were arranged as a footpath, then a grassed area with trees, then the lights, then the roadway. Only after the city had rolled out thousands of these lights did someone notice the footpaths were now much darker. And also the footpaths were quite uneven, due to the trees' roots - a problem the lights had previously been keeping under control.
It's now common, in winter, to see groups jogging on the road.
Alas when running in a group, the runner in front of you can not just obstruct your line of sight of the pavement, but also the light of your torch. His retroreflective vest becomes the brightest thing in your view. And he's not happy either; backlit by your torch, he casts a shadow forwards and the road ahead is illuminated everywhere except where he's about to step. And of course the tree-lined pavement, while very beautiful and shaded in the summer, isn't very wide. So you can't always run beside the guy.
My personal 'solution' is not to run fast enough to keep up with the guy ahead of me, giving me a clear view. But you don't win medals with my attitude.
1. Red light preserves your dark adaptation
2. It doesn't have as much of an impact on your circadian rythm
3. Not using phosphorescence can increase the lifetime of the light, since you don't have to worry about the coating degrading
4. Red light is less energetic, so could potentially use less power.
5. Since an LED without phosphorescence is a single wavelength, telescopes (and binoculars) can use a narrow band filter to filter out the light pollution, without blocking most of the light from celestial objects.
That’s a weird thing to include. That sounds like an argument _for_ more aggressive lights. I didn’t expect to see a “think of the surveillance system”
One of the biggest excuses for ultra-bright streetlights is crime prevention (usually shortly followed by CCTV). I'm not really sure why we continue to indulge that point of view, but if one is indulging it...
Dare I argue even I would choose 6500k LED street lights with decent CRI over poor CRI 2700K LED lamps any day.
What makes you say that the CRI causes the lack of soul? I'm not saying that you're wrong, but given that CRI is objectively better than it ever was now, why?
The sodium lamps we used previously had a CRI of 25-35. The absolute worst white LEDs we have have a CRI of at least 60.
Having my environment reflect the patterns of nature has really been a nice change.
Note that bulbs exist that automatically warm as they dim - so in my case the switches are smart, but the bulbs themselves are all dumb.
* Smart switches: Lutron Caseta. (With the dimmer for ELV lighting so I can use the middle button for specific brightness/warmth levels.)
* Outdoor bulbs: Philips warm glow bulbs. (2200K-2700K warm dimming, 95 CRI - these ramp from 0% at 2200K to 100% at 2700K)
* Outdoor recessed lights: Globe Electric DuoBright LEDs (2000K-5000K warm dimming, 96 CRI - these ramp from 0% at 2000K to full lumens at 3000K at 80% the dimmer, but then will continue to ramp from 3000K to 5000K at full lumens if the dimmer is turned up.)
* Motion sensors: Philips Hue Outdoor sensors.
Non-smart bulb availability is kinda weird, my specific bulbs may be discontinued or unavailable outside of Canada, but I'd expect local alternatives to be available.
