I'm still waiting for an answer to Light Pollution: what is the difference between artificial brightness and brightness and SQM but I'm tired of waiting so I'll just go ahead and ask my follow up question now.

I've already seen the night sky at Bortle Class 3, and I could see 7 stars in Ursa Minor which is quite satisfying. But Wiki lists 13 additional stars in that constellation, and if I could see all of them with the naked eye then that would really be something. And if I can only see those stars in Bortle Class 1 then to me it would be worth driving an extra 3 hours.

Question: beyond this abstract argument, is there any way to describe how much better the night sky view is in Bortle 1 than Bortle 3? Beyond a numerical comparison, will there be some qualitative aspects of night sky viewing that will make the experience more worth the drive than a star count?


I live in San Diego. If I drive one hour I can get Bortle Class 3 light pollution, if I drive 4 hours I can get Bortle Class 1. Fortunately, living on the West Coast I have that luxury whereas there really isn't an area east of the Mississippi which has Bortle Class 1.

Anyway, is there a big difference between the two? I suppose the question is somewhat stupid since the answer is obviously it depends on how badly you want clear skies, but, on the other hand, in music, for example, I really can't tell the difference between notes which are very close to one another. So if Bortle Class 1 and 3 are more similar to a C and D note of the same octave then the answer is: 'no, don't spend an extra 3 hours in your car', but if it turns out that Bortle Class 1 and 3 are more similar to C notes on adjacent octaves, then, yes, it is worth it.

  • $\begingroup$ I unfortunately cannot speak from own experience, but I assume that there is a noticeable difference between Bortle 3 and 1. Whether it's worth it is up to you. $\endgroup$ – Jonas Jan 22 at 8:19
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    $\begingroup$ Since your question already has two close votes and I think it can be answered well, I've adjusted the wording somewhat to better fit the question style for this Stack Exchange site. It's important to ask in such a way that the question won't be easily answered with opinions as much as facts. "Is it worth it?" asks for an opinion whereas "Qualitative differences?" can be answered with facts. $\endgroup$ – uhoh Jan 22 at 16:31
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    $\begingroup$ The difference between Bortle 3 and Bortle 1 is about 1 full magnitude to the naked eye. At this level (around magnitude 6), a full magnitude represents at least 2,000–3,000 more stars, effectively almost doubling the number of stars you see in any given area of the sky. Worth it? It all depends, like @uhoh said, but I’d definitely say yes. $\endgroup$ – Pierre Paquette Jan 22 at 20:41
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    $\begingroup$ @uhoh Thanks to your edit I retracted my close-vote :-) $\endgroup$ – B--rian Jan 22 at 21:20

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