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Comment by uv-depression | Hacker News Reader

Greenhouses here in the lower mainland of British Columbia have been devastating to the night sky. It's quite depressing how little society values the night sky, something that's been an important part of every human culture for longer than recorded history. I've taken friends out to thoroughly mediocre skies (Bortle 4-5) and they've been very impressed, because they're used to city lights (Bortle 9) where you can maybe see a few of the brightest stars and planets.

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.

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Starlink gets a lot of flax for it but as an avid night sky photographer myself (IG: @dheeranet) who regularly goes to Bortle 1 parts of the world, I haven't found them to be an issue at all.

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.

> They are only visible when they are spinning up to orbit

> 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

I don't see how this can be true especially if you have a fancy telescope tracking something, take 3-5 whatever many shots in succession and stack. It's astrophotography 101.

For professional astronomers, it really sucks if you only have, say, an hour of observing time on a big telescope, and then a few of your precious frames are ruined because of a satellite. And you don't always even know that the frame is ruined until later, or have the flexibility to take more frames if needed (because you submit the full observation plan ahead of time, and just get the results later), in which case one bad frame can mean you don't have enough good frames to get valuable data.

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.

That's what I don't understand, how are they ruined? If you're so deep that you need minutes or hours of exposures, that satellite will blip past the frame so fast it's not going to matter. And if the exposure time is less than that, you stack.

1. The satellite is usually significantly brighter than the thing you are observing. Often bright enough to saturate pixels (which can spill over to adjacent pixels).

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.

Is this what you do? Because I'm at least an intermediate with astrophotography with a camera, and even airplanes are a total non issue. If you're so deep into the sky that you actually need many minutes or hours on the same spot, the teeny tiny time that satellite is there is a non issue and easy to remove with math.

Not any more. But in college I worked in an astronomy research group.

Where is 10% coming from? If you're focused on something far away shouldn't the fraction be <<1%?

As a “night sky enthusiast”, as opposed to a real astronomer, Starlink and other satellites do not bother me much.

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.

Starlink has over 10k currently but has applied for at least 42k. And because it's now a US military technology, every other country is building its own. China is planning on launching over 12k satellites and Russia is working on their own.

It's too much

Deep dusk will be quite a disco ball.

Both are real issues, to be clear. LEO satellites are a real and increasing issue.

Yes, but one is a vastly smaller issue than the status quo issues.

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's an exponentially growing issue. Starlink's current fleet of ~10k is expected to grow to at least 42k. And since its been used for military uses, China and Russia have realized they also need their own competition. China's SpaceSail plans on launching 15k satellites by 2030. The EU's ambitions are much smaller than both of them, but if every developing nation continues to build their own platform, where does it end?

> where does it end

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.

(1) Considering there are now multiple companies planning to launch their own fleets of tens of thousands, satellites need replacing, etc, even if this was completely accurate, this will be a continuous and ongoing issue as it has been for years.

(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).

Some good points. However:

> 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.

My wife's hometown in China used to have two options to reach from Shanghai - high speed rail (top speed ~ 200MPH) that takes about six hours or a roughly one hour flight.

Rail travel has stops and slowdowns in more populated areas that make it a bit slower than the advertised top speeds.

That's a backwards argument. Flights in California between SF and LA will obviously travel a continuous line across California. Yes, the populated areas have light pollution, but that's because they're, y'know, populated areas. HSR itself would add nearly no light pollution outside of the existing population centers, in contrast to flights.

Right, the California HSR route doesn't travel through any really dark sky regions anyway.

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.

> but if there aren't population centers, you'll have to have plans to create them in order to support the rail system itself.

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.

Many cities and settlements have been created intentionally rather than as a result of populations organically reproducing on the spot. Colonies, chartered towns/cities/etc, company towns, etc. It's a very common thing throughout history to the present day.

And... the people? Where do they come from? Mars?

All you're describing is population redistribution, not population creation. Urban centers have very low fertility rates, which actually reduces populations...

Yes, the people come from other places. The "population center" is very often made by people with intention though. The global population is still rising, so conjecture about the effect of cities on fertility rates is irrelevant. Humans aren't going extinct any time soon.

Did you read my previous comment in detail?

People don't live in caves, they will create light pollution everywhere, anyway. Might as well put them in small and dense population centers.

I hate reading comprehension these days :-)

You said: "Nobody "creates" population centers."

That's demonstrably false, population centers are created all the time. The fact that populations don't spontaneously appear is irrelevant.

I said a lot more than that and this entire discussion is in the context of high speed trains and light pollution.

Again, reading comprehension, context, and I guess, typical techie obtuseness.

It's not that big a deal for MOST people. I was on navy ships transiting the Pacific it's as dark as it can get on deck and sure, it's magical and spectacular (especially the NUMBER OF SHOOTING STARS!) but even in the middle of the ocean 99% of my fellow sailors could not have given less of a shit. I'd sit out there for hours and they all though I was a weirdo for it. So, while amazing, most people don't understand or care to understand the enormity of what's going on around them.

Most people didn't care about dark skys in the first place and still don't.

> Most people didn't care about dark skys in the first place and still don't.

Most people were never given the opportunity to care.

Very true, but isn't that exactly what the parent is suggesting? That even a ship full of sailors given the opportunity to care, very few do?

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?

Mostly the latter.

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")

I'm just one experience but my view was aside from a passing comment on a shooting star no one cared. Much more inteted in playing PlayStation, porn and seeking liquor on board.

Had s similar experience in the saharah desert.. I love all things space and have a teleclscooe I use regularly but seeing it in person and just laying down and watching for hours was another experience.

I would argue that probably not looking up all the time at night with predators around was an evolutionary trait though! (Semi joking)

In parts of The Netherlands is simple never gets dark due to light pollution. It feels like it is always dawn. Pretty bad for your sleep cycle.

Some pictures: https://milieufederatie.nl/nieuws/6-op-de-10-nederlanders-wi...

There are a lot of Muggles in the world.

Depends how far back we go for "first place". Stars are an interesting intersection of social sciences, hard sciences, and even some woo for a very long time. We must consider their interaction between religion, astronomy and astrology going as far back at least as history lets us.

I hadn't been out to a dark sky in years so I went out to a deep part of Joshua Tree (Bortle 2-3) one night not too long ago just to see some stars. Wow, I was not expecting that many Starlinks up there.

National parks in California are indeed amazing. One time during a group trip to Death Valley, people were so amazed by the night sky that half decided to sleep outside the tents just to experience falling asleep while looking at the stars.

> people were so amazed by the night sky that half decided to sleep outside the tents just to experience falling asleep while looking at the stars.

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.

Wanaka, in the South Island of New Zealand, still has pretty good views of the night sky. You can see an awful lot more stars than you can from major cities.

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!

Today I learned about the Bortle scale. I was completely ignorant about it.

> 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.

> Today I learned about the Bortle scale

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.

> instead of building municipal internet

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)

Putting astronomy on the dark side of the moon would probably work better than putting it into space because you can use some local material for construction.

There isn't a single "dark side" of the moon that's always in darkness, the "dark side" of the moon is the side that always faces away from us (poor choice of name). It's fully illuminated during a new moon.

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.

Of course the dark side of the moon is illuminated by the sun at times. But it has minimal human illumination, so that's pretty nice.

human illumination is nothing compared to the giant fusion reactor that would be lighting it up for 2 weeks at a time. At least on terra firma, you can view the sky nightly.

Er.. on the moon you can also view the sky nightly.

It's just that both the days and the nights are a lot longer.

The far side of the moon would be useful for a radio observatory where one can block the noisy Earth while taking advantage of the ability to construct large collection area dishes (think Arecibo in a crater - https://en.wikipedia.org/wiki/Lunar_Crater_Radio_Telescope )

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).

In space though you can do extremely lightweight construction because structures don't need to support their weight against gravity unless they are huge enough that tidal forces matter.

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.

I have read elsewhere that spinning mercury would be used as the mirror.

The suggestions that I've seen for astronomy on the far side of the Moon have largely been about radio astronomy rather than optical. The lack of the ionosphere which otherwise blocks and distorts 10 meter and longer radio and using the Moon itself as a shield from the radio noise of Earth makes it more interesting.

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...

---

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.

... But this seems a bit more speculative. It wouldn't be mercury and requires a yet to be discovered liquid metal that is stable for months at 175 °K.

> other internet providers dumping tens of thousands of satellites in orbit instead of building municipal internet

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.

Maybe it's okay for there to be places on the earth where high sped internet is not available?

Always easy to say as the person with internet on the internet where the people stuck in those locations can’t speak.

Maybe it’s okay for you to not have internet.

> The municipal internet in the 1 person per square mile rural area.

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.

It’s cheap to deliver mail and even then many of those places don’t get mail to their home. It’s to a shared mailbox.

> LEO Satellite internet is only cheaper because the environmental cost is not being accounted for.

Terrestrial wireless and wired had decades to do something and failed. Trenching fiber for 30km is insanely expensive and requires tons of time to get easements to do it.

Also, it’s a pretty old trope to say “X only works when cost Y I’ve invented and not even quantified is not imposed”. If you want to make the argument that Starlink should pay for something, do that. Otherwise it’s meaningless crap that can be used to argue against literally anything.

Humans have been looking at the stars every night for tens of thousands of years and we've essentially occluded the night sky to most in the matter of about 50 years, I don't even think most people know what we've lost anymore.

> It's quite depressing how little society values the night sky,

Considering how little value we put on far more important things (like the climate or biodiversity), I'm not really surprised.

Check out southwestern Ontario as well. I've driven through there on my way to Michigan a couple times. It's purple at night. The sky is purple.

I would have assumed that most plants need a daily light/dark cycle but maybe not?

Most fruit crops need 8-12 hours of darkness but it changes depending on which point they're at in their life cycle. 20 hours of light is usually fine during the initial stages, then they require 8-10 hours of darkness to bloom, then back to 18-20 hours of light during the fruit growth.

(I'm not a botanist or a farmer but I grow greenhouse veggies for fun)

The world record holder vegetables are all grown in Alaskan summers, up north... where they get 20+ hours of daylight per day. Dunno, maybe the CAM plants would do bad (pineapples) but just about everything else benefits.

Are there places in EU that are dark and easy to visit?

In the EU, the canary islands are known to have great skies. You check this map https://www.lightpollutionmap.info

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.

Dude your country is 98% desolate and unsuited to agriculture. If you want night sky go to a cabin literally anywhere in your unending and cold mountains instead of shutting down agriculture in the only marginal spot on the west coast you can grow food.

> instead of shutting down agriculture in the only marginal spot on the west coast you can grow food.

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?

I mean it's not easy to have greenhouse walls that let sunlight in but don't let grow light out. You can direct the light but you are going to have loss.

Yeah, let's not inconvenience companies.

(FYI, it's a solved problem: https://de.made-in-china.com/co_zenong/product_Agriculture-P...)

Sunlight and grow light generally happen at different times.

This is not only about being able to see a nice night sky (although I admit I love seeing one), it's a very much more fundamental issue.

Light pollution has dramatic negative consequences for wildlife and thereby our ecosystem we so heavily depend upon.

Yes it has negative consequences for wildlife, which is why it is FAR BETTER FOR THE ENVIRONMENT to put all the agriculture in one place at high efficiency rather than spread farmland out over otherwise virgin wilderness.

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!

Stop with the false dichotomies. I would rather have no wilderness 90% degraded at all. There are better alternatives than spreading out the farmland. Like better greenhouses that don’t blast grow lights all over the night sky. We have the technology, it’s just cheaper to destroy the environment.

OK, looks like I misunderstood what you were trying to say.

Therefore I fully agree with you!

I can't just casually hop up to the Yukon for an evening of astronomy. It's about a thirty hour drive. Even relatively small towns have exurbs now because of our terrible city planning, so light pollution extends shockingly far. Alberta's probably the worst, almost the entire province (about the same land area as Texas) has light pollution.

> 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.

What are you on about? Literally drive north a bit towards Whistler, you can get out of the light pollution in an hour or two

lightpollutionmap.info/#zoom=8.01&lat=49.6027&lon=-122.7672&state=eyJiYXNlbWFwIjoiTGF5ZXJCaW5nUm9hZCIsIm92ZXJsYXkiOiJzYl8yMDI1Iiwib3ZlcmxheWNvbG9yIjpmYWxzZSwib3ZlcmxheW9wYWNpdHkiOiI2MCIsImZlYXR1cmVzb3BhY2l0eSI6Ijg1In0=

Have you never been there? This light pollution map wildly underestimates light pollution outside of cities. I can tell you from experience you're not getting nearly 22 mpsas skies anywhere near Pemberton.

The entire world’s agriculture “shut down” at night before we decided we want every crop to be available everywhere year-round.

Just install light shields.

Yes we also had a population of 50 million and 10% of them starved to death every time a volcano burped, they were great times.

And 9 million starve to death annually because it isn't profitable to feed them, what's your point?

The point is that we don't need to increase 0.11% back to 10%. Specially when the base numbers have significantly increased.

or you know, just adjust the lights a little

>It's quite depressing how little society values the night sky, something that's been an important part of every human culture for longer than recorded history.

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.

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