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> 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.