Rendered at 23:53:00 GMT+0000 (Coordinated Universal Time) with Cloudflare Workers.
signorovitch 5 hours ago [-]
FWIW, if you actually want to photograph a comet or anything that doesn’t move in the sky, you’d take multiple exposures that would make the moving light sources like satellites disappear. Taking HDR photographs like this has an number other benefits as well.
(telescopes in space looking outside should have happened long ago, lets just get it done man)
ragebol 16 hours ago [-]
Yeah, I kinda get why astronomers are not particularly happy with satellite constellations.
adev_ 14 hours ago [-]
And this is just the visible spectrum.
The situation is one order of magnitude worst in radio-astronomy.
It is fair to state that satellite constellations will certainly be the main obstacle to multiple major scientific discoveries in the next decade.
ultratalk 14 hours ago [-]
Opinion: We need to move our astronomical observation equipment off of Earth and onto other bodies, especially radio astronomy, which, unlike telescopes that operate in other wavelengths, is still affected by Earth's emissions in LEO/near-Earth space. We should put a radio telescope on the far side of the moon [0] to benefit from the thousands of kilometers of lunar material separating Earth's emissions from telescopes.
Unfortunately, that seems to be the only solution.
However, it has serious disadvantages. It will exclude the poorer from astronomical research, except within the limits enabled by whatever cooperation the richer will be willing to do with them.
For the richer, that will make astronomical research much more expensive. When even USA, who claims to be the richest country, cuts a lot of the scientific funding, this makes likely a great reduction in the research targets that could be accomplished, even if a Lunar array of telescopes and radiotelescopes and communication relays for them were approved.
While professionals might still be able to do some work, the amateurs will be able less and less to enjoy the sight of the distant Universe.
There are already many years since I have become unable to see the sky that I enjoyed looking at when young, because it cannot be seen from the city where I live, due to light pollution (and high buildings). To see it again, I would have to go somewhere up in the mountains, far from a city or village, but I have not succeeded to do this recently. Even there now you can hardly look at the sky without seeing satellites, and it will only become much worse.
Nowadays there are many children who have never seen even once the sky that our ancestors were seeing every night, so many passages from old texts that mention the sky are unintelligible for them.
mgfist 10 hours ago [-]
I get what you're saying, but poor people want cheap internet/phone connectivity. They can't afford telescopes anyways.
And starlink (and the like) have more uses beyond good remote connectivity. They're a big reason why Ukraine didn't lose to Russia. They're also a potential avenue for people in oppressed nations to talk to the rest of the world (eg: Iran has a death penalty for starlink usage to counter this point).
adev_ 5 hours ago [-]
> I get what you're saying, but poor people want cheap internet/phone connectivity.
Nope. Starlink is not a tool for poor people. It's first and foremost a tool for middle class living in rural area with poor connectivity.
As a comparison, it is estimated to that there is around 198M people in Nigeria with a Mobile phone connectivity. Compared around 67K Starlink users.
Mobile being around 2-3x cheaper than Starlink there (even without considering the hardware), it remains an upper middle class privilege.
adolph 7 hours ago [-]
> It will exclude the poorer from astronomical research, except within the limits enabled by whatever cooperation the richer will be willing to do with them.
Isn't it the case that most astronomical research uses source data from large telescopes and sky surveys? An example is the Rubin Science Platform [0] which makes available images and metadata from the Rubin Observatory along with compute and APIs?
Its still worth while for every normal human to have access to space if the benefit of this stuff is not relevant for most people.
And with 9 million customers its not.
maxnoe 13 hours ago [-]
Our telescopes actually need the (or at least an) atmosphere to function.
There are some classes of observatories, which you cannot build in space but which are still affected by satellites to some degree.
ultratalk 13 hours ago [-]
> Our telescopes actually need the (or at least an) atmosphere to function.
What about Hubble, Chandra, Spitzer, JWST, etc? As of my understanding, the only reason we haven't built radio and and other long-wave telescopes in space is because of their impractical size preventing them from being deployed in orbit.
> There are some classes of observatories, which you cannot build in space but which are still affected by satellites to some degree.
Examples?
voidUpdate 12 hours ago [-]
I believe we haven't built radio telescopes in space because we don't need to, and building them in space would be a lot more expensive.
This shows that wavelengths between ~10cm and ~10m are largely unaffected by the atmosphere, so you wouldn't gain much from putting receivers of those wavelengths in space. Spitzer and JWST (IR), and Chandra (x-ray) operate in bands that are generally blocked by the atmosphere, and Hubble gets better images than a similarly sized earth-based telescope because of the atmospheric distortion (stars don't "twinkle" when you're in space), however there are still earth-based visible light telescopes because you can more easily build a massive one on earth than in space
BenjiWiebe 11 hours ago [-]
What? The atmosphere gets in the way. Ever heard of an (amateur/)astronomer talking about 'good seeing'? That's when the atmosphere is hindering you less than usual.
The limiting factor of passive optical telescopes on earth is the atmosphere.
SiempreViernes 11 hours ago [-]
They are talking about very high energy gamma-ray telescopes, the Imaging Cherenkov Telescopes.
christophilus 14 hours ago [-]
Agreed. It’s the only solution short of a ban on constellations.
silon42 7 hours ago [-]
IMO, everyone that launches/operates a constellation should pay for launch of large telescope every 5-10 years (assuming science organizations can fund/build them).
NegativeLatency 7 hours ago [-]
Or even out past the heliosphere/heliopause
Aboutplants 12 hours ago [-]
Any chance of CubeSat style of telescopes at some point?
SiempreViernes 11 hours ago [-]
Sure, there have already been some launched and predictably they are only adequate to look at the bright stuff we already knew about from the big telescopes.
A small telescope is just a small telescope even when you put it in space.
iso1631 12 hours ago [-]
> . We should put a radio telescope on the far side of the moon [0] to benefit from the thousands of kilometers of lunar material separating Earth's emissions from telescopes.
Do you really think a starlink style installation won't be put in orbit of the moon before such a telescope could be funded?
adev_ 12 hours ago [-]
> Do you really think a starlink style installation won't be put in orbit of the moon before such a telescope could be funded?
There are ITUs rules that forbid that and the far side of the moon is declared as radio quiet.
bluGill 11 hours ago [-]
Those rules won't last long once (IF) there are significant numbers of people on the moon. The rules are easy to agree to today (50 years ago) because nobody could do anything otherwise anyway. Once the rules are getting in the way of a significant number of people they will change.
I make no predictions how they will change, but the current rules are obviously unworkable if significant numbers of people live in space. I also make no predictions on if we will ever get significant numbers of people living in space - there are a lot of hard/expensive problems that may not be solvable.
adev_ 5 hours ago [-]
> Those rules won't last long once (IF) there are significant numbers of people on the moon.
Maybe. If you believe we are heading to a situation with large numbers of colonies on the moon.
For now we are no way there and already struggle to just get back there.
SiempreViernes 11 hours ago [-]
Starlinks are already spewing out into supposedly protected radio bands on Earth, good look getting these rules respected on the Moon when they aren't here.
chris_va 10 hours ago [-]
Not to disagree, but stacking a series of exposures with a sigma-clipped mean (or similar) should still get a nice image.
oofbey 9 hours ago [-]
Exactly. It’s not that hard to remove the satellites. It’s almost easier than whining about it. But whining is more fun.
oofbey 9 hours ago [-]
Computational photography has long been table stakes for astronomers. They just need to up their game on satellite rejection algorithms. Satellites look nothing like stars, and as such are pretty easy to remove with software. Pictures like this which leave them in are just there to make a point.
HumblyTossed 11 hours ago [-]
Doesn't matter. We, as a society, have said we're willing to give up nature in exchange for money machines the go brrrrr.
MagicMoonlight 9 hours ago [-]
So what? Astronomy doesn’t actually produce anything meaningful.
Hell, astronomers were telling us the sun orbited the earth for 99% of human history. Shoot forward to the present day and they can tell us… the universe started at some point somehow. Great job guys. Really earning those billions in grants.
Actually going to space has far more value.
ragebol 9 hours ago [-]
Have you heard of Kessler Syndrome?
More satellites means higher risk on that happening and not going to space until all the debris of a collision deorbits.
albert_e 13 hours ago [-]
Why are satellite trails not continuous lines
Is the camera exposure taking a few seconds of break between takes that get stacked later with some "missing" moments in between?
max-m 10 hours ago [-]
My time to shine! I've spent yesterday morning to track the photo down and answer this question.
The APOD description is lacking.
Yes, this was an exaggerated stack of 153 four-second exposures (the rejection map of the satellite trails was added on top of the image), and the gaps happened when the camera took its time to save between two exposures.
Probably exactly that. If you take a single 10 minute exposure (or really, anything more than a few seconds) you'll get noticeable star trails if you don't put your camera on a rotating mount. Stacking multiple exposures also has other nice benefits such as noise canceling itself out and being able to remove satellite trails.
Last time I did astrophotography was a few years ago, before Starlink made the problem considerably worse, but satellite trails were relatively easy to remove with stacking. I'm sure it's harder now but definitely still possible, so I'm assuming in this case leaving them in was done on purpose to highlight the problem.
EDIT: Looking better at the picture, I belive this was taken with a star tracker and then composited with a shorter exposure of the foreground. Notice how the foreground, even far away, looks considerably blurrier than the stars, and how the tower in the background has some light streaks. This is exactly what you'll see if you use a star tracker. Rather than star trails, you'll have "foreground trails". This would explain why there are relatively few gaps in the satellite trails, since the exposures can be much longer.
pta2002 2 hours ago [-]
Update: I was wrong, check max-m's sibling comment! The satellites just move really fast across the camera because they're in LEO, so they can traverse rather large distances before there's a new exposure and a small gap.
debugnik 13 hours ago [-]
My guess is the camera itself was taking photos of shorter exposure and the final image was composed in post-production, yes.
goodcanadian 11 hours ago [-]
I am guessing, but I think it likely has to do with the shape and orientation of the satellite with respect to the sun and the camera. Depending on the relative positions, the brightness reflected off the satellite and reaching the camera will change over time.
pedvide 12 hours ago [-]
I've taken long exposures using film (analog, so no stacking or any other funny business) and saw the same thing. I always thought they were planes but now it seems they may have been satellites. I'm curious if someone knows why this happens
mark-r 12 hours ago [-]
I'm not aware of a digital camera that can take a 10 minute continuous exposure, but maybe there are special astronomy cameras that can?
nayuki 9 hours ago [-]
Pretty much every DSLR/DSLM camera out there has a "bulb" mode that keeps the shutter open as long as you hold down the shutter button. I think my personal record is a 20-minute exposure.
As for actually holding down the button, you can either use an external wired shutter button that has a mechanical lock to hold it down, or you use a wired controller that has an electronic timer, or you use a software feature in the camera to set the bulb timer.
jlarocco 8 hours ago [-]
For anybody wondering, the reason not to do a single ultra-long exposures is noise.
There's an equilibrium between exposure duration, aperture, and ISO that gives the best results for the conditions with a minimum amount of sensor noise, and getting close to the equilibrium and stacking the images typically gives better results than one massive exposure.
nayuki 8 hours ago [-]
I believe your claim about noise and long exposures is false. To start, I posit that there are three sources of noise:
0) Photon shot noise from the object that you want to photograph. This is an inherent and unchangeable quantum-mechanical fact.
1) Sensor read noise per photo taken. This increases with the number of subexposures.
2) Dark current noise per time and per temperature.
#0 and #2 only depend on the total exposure time, not the number of subexposures. #1 actually gets worse with more subexposures, but what you gain are the ability to reject satellite trails, bad mount tracking, cosmic rays, wind gusts, rolling clouds, and other transient artifacts. Whereas if you took a single hour-long exposure, it's essentially guaranteed to be ruined by something.
As for ISO, it is very commonly misunderstood. ISO amplifies photon noise and dark current noise, and changing the ISO doesn't make your images better or worse in these aspects. ISO in the form of analog gain can help boost the signal above the analog-to-digital converter noise, and that's what it's useful for. The MinutePhysics video explains excellently: https://www.youtube.com/watch?v=ZWSvHBG7X0w . More and more sensors these days approach "ISO invariance", where analog amplifier gain has about the same effect as digital gain (i.e. multiplying the measured numbers on a computer).
Exactly what I'm refuting:
> exposure duration
In astronomy, more is better. Get as much total exposure time as you can afford (e.g. time being at a suitable location, time spent monitoring the equipment, time under clear skies).
> aperture
In astronomy, more is better. Buy the biggest aperture you can afford - obviously, subject to constraints such as cost, weight, mountability, focal length. Also, telescopes don't have adjustable aperture blades, unlike general photographic lenses. You could put a disc cut-out in front of the telescope to close down the aperture, but that's just a waste of light.
> minimum amount of sensor noise
You get the least amount of sensor noise by reducing the exposure time and reducing the temperature (dedicated astro cameras have Peltier cooling). Note that although noise increases with time, signal increases with time faster, so the signal-to-noise ratio is proportional to the square root of time. So 100× more exposure time gives you a 10× better SNR.
> stacking the images typically gives better results than one massive exposure
This is the main falsehood that I wanted to address. Taking multiple images actually gives more noise overall, even if it's a tiny bit. But multiple images gives you much more processing flexibility and the ability to selectively reject things.
tejtm 5 hours ago [-]
Exposure time (in digital imaging) is directly
related to sensor well saturation.
It does not mater how much water you pour into a full bucket.
zimpenfish 10 hours ago [-]
Do iPhones count?
I've taken multi-hour continuous exposures on my iPhone + iPad (both "normal" and "light trail" variants.)
By the looks of [0], you can do at least 90 seconds on the Olympus E-M5 MK II - which is what I have and I'll see if it can do 10 minutes tonight.
My Canon can do this without modification and its 8 years old. Switch to bulp and have an external mini device which you connect with a microphone cable and it creates the signal for shutter off after x minutes.
For extra long exposre its recommended to use also a stable powersource.
10 hours ago [-]
adolph 7 hours ago [-]
How is a 10 minute continuous exposure functionally different from 10 minutes of video with every frame stacked? In the former, each photodiode acts as a compositor for each pixel instead of whatever algorithm is chosen to combine frames in the latter?
nayuki 7 hours ago [-]
You pay the read noise every time you read out the sensor and digitize the values. Also, you lose a tiny bit of time between exposures as the sensor resets itself. And you might have a bottleneck in moving the data off the sensor and saving the image. Furthermore, if you perform lossy compression on the video, then your digitally stacked image will differ significantly from analog stacking on the silicon sensor.
13 hours ago [-]
rcxdude 12 hours ago [-]
Maybe, but also a lot of satellites rotate and so their brightness changes over time.
12 hours ago [-]
raldi 11 hours ago [-]
Passing clouds?
AlgorithmicTime 12 hours ago [-]
[dead]
originalvichy 15 hours ago [-]
I fear this is only the start of it. A minimum of 3-4 constellations more will probably be launched in the near future (Russia, China, EU).
Their obvious dual-use nature makes them tempting, and a military target if a large conflict will take place in the near future. I hope their lower orbit will help any space junk burn up fast.
gorgoiler 11 hours ago [-]
Add a black umbrella to each satellite: when they pass through the critical region where they are visible in the night sky while still being sunlit, pop the brollies up. We will fly them in the shade!
You could paint them black but they’d probably get quite hot.
fluoridation 10 hours ago [-]
Won't the shade then reflect the light instead? It's nighttime, so sunlight will be aimed up, from the Earth-based observer's point of view, so the shade will need to be pointed down in order to shade the satellite.
mark-r 12 hours ago [-]
If you blow up a satellite, half of it will end up going slower and half will go faster. The slower bits will probably burn up nicely, but the faster bits will just elevate their orbit.
bluGill 11 hours ago [-]
I doubt they will elevate their orbit by enough to be a problem. Some bits will come down in hours, some will come down in a year - even in the worst case where it takes out everything in low earth orbit in 5 years everything will be clear and we can start over. Higher orbits are the real worry, even the things slowed down mostly stay in orbit for centuries - but higher orbits are mostly a lot higher.
The Iridium-Kosmos collision fragments have been up there since 2009, and that's a massive spray of junk just from one disintegration in LEO.
zamadatix 1 hours ago [-]
"LEO" is a big place, those satellites collided ~1.5x higher than e.g. the maximum Starlink altitude and the debris lifetime relationship is not a linear one.
zamadatix 10 hours ago [-]
It'll elongate the orbit, which is a bit better of a scenario than elevating it wholesale.
marcosdumay 9 hours ago [-]
In either case, you will increase the section area / volume ratio, what makes the fragments fall from LEO faster.
aaron695 15 hours ago [-]
[dead]
mlmonkey 5 hours ago [-]
Why doesn't the comet "streak" also, given the Earth's rotation? 10 minutes is a long enough window to have an appreciable impact on the comet's image. Or is it the case that the telescope is stabilized to the Earth's rotation?
advisedwang 5 hours ago [-]
Low earth orbit satellites orbit about once per 90 minutes, so in 10 minutes they go about 40 degrees across the sky. The comet is not even orbiting the earth, it's essentially fixed in the sky. The earth only rotates about 2.5 degrees in 10 minutes. So the satellites streak is 16 times longer than the comets.
dangond 2 hours ago [-]
Given that the moon is about 0.5 degrees in diameter from Earth, shouldn't we expect to see the stars and comet much more blurred than they are here though? Or the ground if it's stabilized against the rotation?
NooneAtAll3 4 hours ago [-]
40 degrees around Earth (central angle)
but it increases to much more when you are much closer to the arc
max-m 3 hours ago [-]
https://www.facebook.com/groups/Nachtfotografie/posts/264063...
Here is the original photo description in German.
See also my other comment in this thread.
But the tl;dr is that this was a stack of 153 four-second exposures with some gaps in the timelime when the camera took its time to save between exposures.
ciroduran 15 hours ago [-]
I'm rebuilding my RSS feed collection, and having pretty astronomy pictures is a fine addition. Thanks!
if i could imagine what a Sophon from 3 body problem would look like. this is kind of it.
khazhoux 14 hours ago [-]
Is this all / mostly Starlink?
vednig 14 hours ago [-]
It's a set of network satellites for sure either by Eutelsat or Starlink in 70:20 ratio 10% being other providers
But all of them being LEO for sure.
oofbey 9 hours ago [-]
70% of all satellites are Starlink. So probably.
aa-jv 13 hours ago [-]
Hot take: We're in the first stages of building our own Dyson sphere and therefore comets are only useful in the context of capturing them for that purpose.
;)
AntiUSAbah 9 hours ago [-]
We do not need Starlink! It only provides service to 9 Million! People
We are a planet with 8 Billion People.
Do i want cheap and reliable internet everywhere and perhaps work remote? Yes. Should someone like Musk destroy our look into space for just me and my use case? No.
signorovitch 5 hours ago [-]
Not to play the musk’s advocate, but there is a case to be made that proving internet access in remote places is more valuable than a perfect night sky. If you live in the cities you can barely see the stars anyway, so you’re not missing much. But in an austere environment, connectivity can be the difference between life and death. It also lowers the bar, encouraging more people to visit wild places and make them more likely to support their protection in more meaningful ways.
giancarlostoro 8 hours ago [-]
I do wonder if in 100 or 200 years if we do become interplanetary as a species, and technology advances if many of these satellites will just disappear from the night sky and it would be long since forgotten or if remembered only as a steppingstone towards an interplanetary future.
In the meantime, Starlink is the only thing that gives my sister in Puerto Rico access to the internet when the grid gets completely nerfed by a hurriance so she can tell us she's alright, well, that and landlines if she gets a power generator, otherwise, we're left to wonder how my sister and nephews are doing.
8 hours ago [-]
AntiUSAbah 8 hours ago [-]
You don't need starlink to get a message out of Puerto Rico.
We also don't need starlink as a stepping stone.
What we need is food for the planet, resiliance infrastructure, proper health care, stable energy grids.
giancarlostoro 8 hours ago [-]
I sure hope you never have to wonder if your relatives are safe and doing well after they have no way to communicate with you for weeks.
newer_vienna 5 hours ago [-]
It is obvious that the 9 million current customers are just the beginning of where SpaceX wants to take Starlink access. Easy to imagine Starlink serving 1 billion + customers in the near future.
renerick 15 hours ago [-]
That looks so cool, ngl!
1970-01-01 11 hours ago [-]
I, a taxpayer, would rather have a cellphone signal in a remote location than lots of amazing pictures of a comet. And I just don't see a solution or compromise that could work. The utility of neat picture vs full cell signal in a Montana canyon cannot be won by taking more pictures and showing me the problem. I made my decision already.
hrldcpr 11 hours ago [-]
Why gaze up at the vast cosmos when we can stare down at a little screen
1970-01-01 11 hours ago [-]
Why have cheap radio safety when you can die under the stars?
projektfu 10 hours ago [-]
I, a taxpayer, wish that we could significantly reduce light pollution so we could see the stars on a typical clear night.
MagicMoonlight 9 hours ago [-]
Then give up streetlights. Although crime and road accidents will massively increase and women won’t feel safe outdoors. So is it really worth it?
joshmoody24 5 hours ago [-]
We don't need to give up streetlights to make huge progress. 20 to 50 percent of outdoor lighting is wasted. Just shielding streetlights would go a long way.
Well, isn't that good for you? The other seven and a half billion of us just get to deal with having our skies skidmarked like this with no choice on the matter.
gowld 6 hours ago [-]
You can use satellite Internet too.
It's strange to call it "skid marked" when the "skid marks" only appear when you apply complicated technology setups, and those setups can easily remove the "skid marks" also.
"Now, the orbiting satellites themselves only appear as streaks because of the long camera exposure, over 10 minutes in this case. On the contrary, to the eye, satellites appear as points that drift slowly across the night sky and shine by reflecting sunlight -- primarily just after sunset and before sunrise. "
(telescopes in space looking outside should have happened long ago, lets just get it done man)
The situation is one order of magnitude worst in radio-astronomy.
It is fair to state that satellite constellations will certainly be the main obstacle to multiple major scientific discoveries in the next decade.
[0] https://doi.org/10.1109/AERO50100.2021.9438165
[1] https://en.wikipedia.org/wiki/Lunar_Crater_Radio_Telescope
However, it has serious disadvantages. It will exclude the poorer from astronomical research, except within the limits enabled by whatever cooperation the richer will be willing to do with them.
For the richer, that will make astronomical research much more expensive. When even USA, who claims to be the richest country, cuts a lot of the scientific funding, this makes likely a great reduction in the research targets that could be accomplished, even if a Lunar array of telescopes and radiotelescopes and communication relays for them were approved.
While professionals might still be able to do some work, the amateurs will be able less and less to enjoy the sight of the distant Universe.
There are already many years since I have become unable to see the sky that I enjoyed looking at when young, because it cannot be seen from the city where I live, due to light pollution (and high buildings). To see it again, I would have to go somewhere up in the mountains, far from a city or village, but I have not succeeded to do this recently. Even there now you can hardly look at the sky without seeing satellites, and it will only become much worse.
Nowadays there are many children who have never seen even once the sky that our ancestors were seeing every night, so many passages from old texts that mention the sky are unintelligible for them.
And starlink (and the like) have more uses beyond good remote connectivity. They're a big reason why Ukraine didn't lose to Russia. They're also a potential avenue for people in oppressed nations to talk to the rest of the world (eg: Iran has a death penalty for starlink usage to counter this point).
Nope. Starlink is not a tool for poor people. It's first and foremost a tool for middle class living in rural area with poor connectivity.
As a comparison, it is estimated to that there is around 198M people in Nigeria with a Mobile phone connectivity. Compared around 67K Starlink users.
Mobile being around 2-3x cheaper than Starlink there (even without considering the hardware), it remains an upper middle class privilege.
Isn't it the case that most astronomical research uses source data from large telescopes and sky surveys? An example is the Rubin Science Platform [0] which makes available images and metadata from the Rubin Observatory along with compute and APIs?
https://data.lsst.cloud/
And with 9 million customers its not.
There are some classes of observatories, which you cannot build in space but which are still affected by satellites to some degree.
What about Hubble, Chandra, Spitzer, JWST, etc? As of my understanding, the only reason we haven't built radio and and other long-wave telescopes in space is because of their impractical size preventing them from being deployed in orbit.
> There are some classes of observatories, which you cannot build in space but which are still affected by satellites to some degree.
Examples?
https://commons.wikimedia.org/wiki/File:Atmospheric_electrom...
This shows that wavelengths between ~10cm and ~10m are largely unaffected by the atmosphere, so you wouldn't gain much from putting receivers of those wavelengths in space. Spitzer and JWST (IR), and Chandra (x-ray) operate in bands that are generally blocked by the atmosphere, and Hubble gets better images than a similarly sized earth-based telescope because of the atmospheric distortion (stars don't "twinkle" when you're in space), however there are still earth-based visible light telescopes because you can more easily build a massive one on earth than in space
The limiting factor of passive optical telescopes on earth is the atmosphere.
A small telescope is just a small telescope even when you put it in space.
Do you really think a starlink style installation won't be put in orbit of the moon before such a telescope could be funded?
There are ITUs rules that forbid that and the far side of the moon is declared as radio quiet.
I make no predictions how they will change, but the current rules are obviously unworkable if significant numbers of people live in space. I also make no predictions on if we will ever get significant numbers of people living in space - there are a lot of hard/expensive problems that may not be solvable.
Maybe. If you believe we are heading to a situation with large numbers of colonies on the moon.
For now we are no way there and already struggle to just get back there.
Hell, astronomers were telling us the sun orbited the earth for 99% of human history. Shoot forward to the present day and they can tell us… the universe started at some point somehow. Great job guys. Really earning those billions in grants.
Actually going to space has far more value.
More satellites means higher risk on that happening and not going to space until all the debris of a collision deorbits.
Is the camera exposure taking a few seconds of break between takes that get stacked later with some "missing" moments in between?
Here is a link to the original photo and it's description (German) by Uli Fehr: https://www.facebook.com/groups/Nachtfotografie/posts/264063...
Last time I did astrophotography was a few years ago, before Starlink made the problem considerably worse, but satellite trails were relatively easy to remove with stacking. I'm sure it's harder now but definitely still possible, so I'm assuming in this case leaving them in was done on purpose to highlight the problem.
EDIT: Looking better at the picture, I belive this was taken with a star tracker and then composited with a shorter exposure of the foreground. Notice how the foreground, even far away, looks considerably blurrier than the stars, and how the tower in the background has some light streaks. This is exactly what you'll see if you use a star tracker. Rather than star trails, you'll have "foreground trails". This would explain why there are relatively few gaps in the satellite trails, since the exposures can be much longer.
As for actually holding down the button, you can either use an external wired shutter button that has a mechanical lock to hold it down, or you use a wired controller that has an electronic timer, or you use a software feature in the camera to set the bulb timer.
There's an equilibrium between exposure duration, aperture, and ISO that gives the best results for the conditions with a minimum amount of sensor noise, and getting close to the equilibrium and stacking the images typically gives better results than one massive exposure.
0) Photon shot noise from the object that you want to photograph. This is an inherent and unchangeable quantum-mechanical fact.
1) Sensor read noise per photo taken. This increases with the number of subexposures.
2) Dark current noise per time and per temperature.
#0 and #2 only depend on the total exposure time, not the number of subexposures. #1 actually gets worse with more subexposures, but what you gain are the ability to reject satellite trails, bad mount tracking, cosmic rays, wind gusts, rolling clouds, and other transient artifacts. Whereas if you took a single hour-long exposure, it's essentially guaranteed to be ruined by something.
The trade-off in how many / how long subexposures to take has been analyzed and discussed to death by astro imagers. To cite a few videos I enjoyed: https://www.youtube.com/results?search_query=astrophotograph... , https://www.youtube.com/watch?v=T_k9B01AeFM , https://www.youtube.com/playlist?list=PLaDi49CzWbrYhWEKxWiwB... , https://www.youtube.com/watch?v=mj5zn_Jz3dE , https://www.youtube.com/watch?v=n1RbyswFUqs
As for ISO, it is very commonly misunderstood. ISO amplifies photon noise and dark current noise, and changing the ISO doesn't make your images better or worse in these aspects. ISO in the form of analog gain can help boost the signal above the analog-to-digital converter noise, and that's what it's useful for. The MinutePhysics video explains excellently: https://www.youtube.com/watch?v=ZWSvHBG7X0w . More and more sensors these days approach "ISO invariance", where analog amplifier gain has about the same effect as digital gain (i.e. multiplying the measured numbers on a computer).
Exactly what I'm refuting:
> exposure duration
In astronomy, more is better. Get as much total exposure time as you can afford (e.g. time being at a suitable location, time spent monitoring the equipment, time under clear skies).
> aperture
In astronomy, more is better. Buy the biggest aperture you can afford - obviously, subject to constraints such as cost, weight, mountability, focal length. Also, telescopes don't have adjustable aperture blades, unlike general photographic lenses. You could put a disc cut-out in front of the telescope to close down the aperture, but that's just a waste of light.
> minimum amount of sensor noise
You get the least amount of sensor noise by reducing the exposure time and reducing the temperature (dedicated astro cameras have Peltier cooling). Note that although noise increases with time, signal increases with time faster, so the signal-to-noise ratio is proportional to the square root of time. So 100× more exposure time gives you a 10× better SNR.
> stacking the images typically gives better results than one massive exposure
This is the main falsehood that I wanted to address. Taking multiple images actually gives more noise overall, even if it's a tiny bit. But multiple images gives you much more processing flexibility and the ability to selectively reject things.
It does not mater how much water you pour into a full bucket.
I've taken multi-hour continuous exposures on my iPhone + iPad (both "normal" and "light trail" variants.)
By the looks of [0], you can do at least 90 seconds on the Olympus E-M5 MK II - which is what I have and I'll see if it can do 10 minutes tonight.
[0] https://www.olympuspassion.com/2019/08/26/long-exposures-wit...
For extra long exposre its recommended to use also a stable powersource.
Their obvious dual-use nature makes them tempting, and a military target if a large conflict will take place in the near future. I hope their lower orbit will help any space junk burn up fast.
You could paint them black but they’d probably get quite hot.
The Iridium-Kosmos collision fragments have been up there since 2009, and that's a massive spray of junk just from one disintegration in LEO.
but it increases to much more when you are much closer to the arc
But all of them being LEO for sure.
;)
We are a planet with 8 Billion People.
Do i want cheap and reliable internet everywhere and perhaps work remote? Yes. Should someone like Musk destroy our look into space for just me and my use case? No.
In the meantime, Starlink is the only thing that gives my sister in Puerto Rico access to the internet when the grid gets completely nerfed by a hurriance so she can tell us she's alright, well, that and landlines if she gets a power generator, otherwise, we're left to wonder how my sister and nephews are doing.
We also don't need starlink as a stepping stone.
What we need is food for the planet, resiliance infrastructure, proper health care, stable energy grids.
https://www.nps.gov/subjects/nightskies/sources.htm
It's strange to call it "skid marked" when the "skid marks" only appear when you apply complicated technology setups, and those setups can easily remove the "skid marks" also.
"Now, the orbiting satellites themselves only appear as streaks because of the long camera exposure, over 10 minutes in this case. On the contrary, to the eye, satellites appear as points that drift slowly across the night sky and shine by reflecting sunlight -- primarily just after sunset and before sunrise. "
See https://apod.nasa.gov/apod/ap191014.html for example