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There is some discussion (and there are some questions on this site) about the impact of Starlink on observational astronomy. I am not an astronomer, but I am amazed by the beauty an immensity of the night sky.

Must I be concerned, from an aesthetical point of view, that Starlink will change the night sky that I and countless people before me have admired? For example, will there be less stars visible to the naked eye, or will the night sky be defaced by a myriad of artificial light sources?

For background: Starlink is a commercial project by SpaceX, a private company, that seeks to launch thousands of small satellites into the earth's orbit.

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    $\begingroup$ Starlink won't obscure stars and the night sky will remain amazing as it is. But the project seems to pose problem to professional astronomers. astronomy.stackexchange.com/questions/43471/… $\endgroup$
    – Alchimista
    Apr 20 at 9:57
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    $\begingroup$ @Alchimista that might be an answer if you could elaborate a bit as to what the implications visible to the naked eye are. $\endgroup$
    – henning
    Apr 20 at 10:01
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    $\begingroup$ @Alchimista amateur astrophotographers making pictures of star trails may see them as well, though I'm not sure about that. $\endgroup$
    – uhoh
    Apr 20 at 16:24
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    $\begingroup$ @Alchimista Many people at least use binoculars to watch the skies, some also more powerful instruments. I wouldn't be so sure that the sky "remains amazing as it is" for people like me. The Starlink train was visible with the naked eye, and even the newer ones are visible with binoculars. $\endgroup$
    – Polygnome
    Apr 20 at 18:41
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    $\begingroup$ @uhoh yes but it usually wanted. I've missed all launches to date. $\endgroup$
    – Alchimista
    Apr 21 at 8:32
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Satellites just add moving lights to the sky, they do not obscure stars. However, some may find that disrupting their view of what a sky should look like.

The visual magnitude of starlink satellites is about 5.92 at zenith, and usually darker (but also sometimes brighter). The new darker satellites are about 0.77 magnitudes fainter. This is in the lower range for naked eye vision under good conditions.

Light pollution is likely to make the satellites invisible to most people, since they already cannot see much of the sky. You need to be outside suburban skies on the Bortle scale to be able to notice them. So if you are concerned with the aesthetics of the sky, city light pollution is a far, far greater problem.

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    $\begingroup$ I think it's a slippery slope, though. Light pollution is indeed a huge problem, but no single light source is problematic : it's the sheer quantity of small light sources which is the problem. And people keep adding them and the night skies are only getting worse and worse. Launching 10 satellites to LEO? Not a problem for visual astronomy. But launching 40000 satellites? $\endgroup$ Apr 20 at 21:29
  • $\begingroup$ @EricDuminil the major problem is not the light per sé, but the fact that professional observation can be hard to be elaborated. $\endgroup$
    – Alchimista
    Apr 21 at 8:39
  • $\begingroup$ Comment was intended to the comment :) $\endgroup$
    – Alchimista
    Apr 21 at 9:19
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A nightmare for star hopping

I can only speak as an amateur astronomer with a 10-inch Dobsonian.

My telescope has no GOTO or tracking, so if I want to find something interesting in the sky, I have to use star hopping:

  • taking bright stars (up to ~mag 5) as reference points, I point the finder in the approximate direction.
  • through the finder, I can see dimmer stars (up to ~mag 9) and use them as reference to point the telescope even more accurately
  • through the eyepiece with the appropriate magnification, I can find the desired object (up to ~mag 12).

This process works really well, and if I know the sequence, I can usually find dim objects in less than 15 seconds, even from my light-polluted suburban skies.

In order to practice star hopping, I need to see the star patterns, I need to recognize them, and I need to memorize them. Having 42000 mag 6.5 satellites in the sky will make those 3 steps really hard.

For reference, here are 42000 evenly distributed points on a sphere, between latitude 60°S and 60°N:

enter image description here

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    $\begingroup$ At such a low altitude, Starlink satellites will be moving roughly 0.5 to 1.4 degrees per second (also here and here). I don't see how one could confuse something moving that fast with a star. And of course chances are low that one will pass through your finder scope's FOV during your star hopping. $\endgroup$
    – uhoh
    Apr 21 at 21:16
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    $\begingroup$ @uhoh when I know the pattern, I really don't need more than a very quick glance to recognize it. It's just an instant look, so angular velocity of the object doesn't play a role. A bright point is there, and shouldn't be. So I need a double take, and then realize the problem. Without horizon as reference, it's also less easy to recognize a moving object. It already happened to me with iridiums, ISS and starlinks. I regularly see satellites in the finder. With 15 times the density, it would be harder to memorize clean patterns. $\endgroup$ Apr 22 at 3:26
  • $\begingroup$ That's amazing! It's been more decades than I care to admit since I've actually looked through a finder scope :-) $\endgroup$
    – uhoh
    Apr 22 at 3:29

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