The short answer is: it depends on how far you’re willing to go! Everyone has different standards for what they feel constitutes a “dark enough” sky for their needs and comforts. But if you’re on a quest to find that perfect dark sky with NO light pollution in the distance, that adventure is becoming a much harder task the more cities spread due to population growth, the more reliance we have on LED’s, and thus make locations that were once near pristine dark into washed out suburban skies.
Do you live in states like Arizona, Nevada, New Mexico, Wyoming, or pretty much any of the less populated western or mid-western United States of America? Congratulations! You live relatively close to destinations that provide the poetic stellar night sky views our ancestors used to see every night before cities and light pollution ruined it. I can surely envy those who live in or near a a small town, and they only need to drive 15-30 minutes to be completely free of any distant light pollution! I do not have that luxury being a Greater Los Angeles resident.
I was once invited to attend a popular monthly star party in Landers – about 90 minutes from my residence. I didn’t outright decline the invitation, but I said that I felt their spot was “too light polluted” for my taste. The person who invited me then said, “too light polluted?! You must have a pretty high bar for astrophotography standards, which isn’t a bad thing!”
As a Southern California resident, I’ve published an article going over the best sites to stargaze in Southern California, and depending on your place of residence, you can find a rural sky that’s nice but still contain very apparent distant light domes within a couple hours of driving distance. For me, I have to decide “what portion of the sky am I okay with being washed out?” For example, If I want a good view of the more southern features including Omega Centauri or the Sagittarius/Scorpius region of the Milky Way, then I can’t have the southern sky washed out by light domes.
And compared to people who live in New York or anywhere east of the Mississippi, us SoCal residents have it better! But one thing we Greater LA/ San Diego Metro residents have in common with the easterners is that gone are the days where we could drive an hour and be in pristine dark skies, there is always another bright town in the distance!
While they are still options for weekend trips, places like Yosemite, Sequoia, or Death Valley are not geographically considered Southern California destinations. That leaves places like Joshua Tree National Park, Red Rock Canyon State Park, or Anza-Borrego as the nearest locations that have “dark enough” skies for The Inland Empire, Los Angeles, and San Diego residents respectively – at least for MY standards.
So How Dark is “Dark Enough?”
Understand that I refer to locations in Southern California. If you’re reading this and live elsewhere, you can still think of locations that you think or used to think are dark enough locations… but are in fact are NOT based on the Bortle Scale – which you should definitely check up upon if you want a better understanding of most light pollution maps, my references to Bortle numbers, and my own standards.
People have come up to me and said things like “oh yeah, I once drove to Vegas (or Phoenix) at night and pulled off the side of the interstate in the desert – I saw so many stars!”
Yes and No… you need to get AWAY from the major interstates and highways so your eyes can actually adapt to the dark – each time another car passes by, the glare ruins your adaptation. If your only experience is pulling off a highway for a few minutes, even if you’re in the middle of nowhere, then you still have NOT truly experienced a dark sky!
Others have told me, “I went up to the San Gabriel Mountains and it was pitch black up there!” The best you can get over popular locations near Los Angeles like Mt Wilson, Crystal Lake, or even Wrightwood are Bortle 6-7 skies. The same applies for people who live in the western parts of the San Bernardino Mountains like Crestline. Yes, it’s darker than being in the city, and it feels pitch black in comparison at first, but it’s actually still bright enough outside that you can still read a book if your eyes are properly adapted to the night lighting! That is NOT dark!
Bortle 4-5 Locations like Big Bear in the eastern San Bernardino Mountains, Idyllwild, or Lockwood Valley near Frazier Park are much better. However, you can still see a big light dome in the direction from Los Angeles, which washes out a significant portion of the sky. The same applies to if you visited Palomar Mountain, Anza-Borrego (San Diego/Escondido) or the western half of Joshua Tree National Park (Palm Springs and 29 Palms) – sure it may be pretty dark and remote, but you still have significant parts of the sky washed out by light pollution from the nearby metro areas!
The first time I attended a Star Party was at Camp Oakes near Big Bear, and at the time I believed it was going to be pitch black up there. I remember getting excited, and then looking to the west, seeing the huge light dome that never went away, and wondering why I felt the “bright twilight from sunset” wasn’t fading away in the west while the view to the east was clearly dark. Even though I enjoyed the views, that’s when I realized I have higher standards for a dark sky and realized, “Nope, that is NOT dark!”
That’s where I eventually “settled” with Cottonwood Campground in Joshua Tree National Park. Located in a Bortle 3 zone – 2 hours from my current residence. The light pollution in the distance from Indio and Mexicali is still evident, and some portions are still washed out, but it’s a huge difference versus the Bortle 4-5 skies. This gives me a “dark enough” sky for my standards especially when it comes to imaging.
It remains my go to spot for convenience and ease, but is it truly a dark sky? No. When my eyes are properly adapted, my surroundings are still vaguely visible, and I can still safely move around open spaces without too much trouble – though I would still use a red light to navigate around foliage and avoid sharp plants. I have also noticed the Cottonwood sky slowly getting brighter compared to a decade ago thanks to the Coachella Valley and Imperial County towns/ Mexicalli growing in population – thanks a lot, urban sprawl!
Because it’s a very popular camping site that fills up, I’ve had plenty of nights where attempts at serious observing or imaging were made almost impossible by nearby campers constantly shining lights at me, cars passing by long after dark, or people who constantly keep their campfires going – which ruin my exposures and dark adaptation. I don’t fault people for it; they just don’t know any better!
So when I am more than willing to drive even longer (almost 3 hours) to Bortle 2 locations like Amboy Crater or Rice, the payoff is the darkest possible skies in Southern California! Even from anywhere within this “patch” of Bortle 2 skies in Southern California, there will ALWAYS be small light domes evident in the distance. But the main difference is they don’t affect your general view! In these skies, I’ve seen shadows cast by the Milky Way on brighter surfaces, and bright planets like Jupiter and Venus feel like annoying glares, So at their best they can be considered a “typical dark sky.”
One of the best reactions I heard under such a sky was a guest remarking an hour after sunset how she had never seen so many stars before. Knowing there was still 30 minutes of twilight left, I said, “it’s not completely dark yet,” and her jaw dropped, replying, “wait, you’re telling me it gets better?!” That’s a testament to how great these skies look do look, especially when you give your eyes the proper time they need to adapt to the dark, and you can see details you never thought were possible!
But are they the best possible dark skies a human on Earth can experience? No.
That is where Bortle 1 skies are. Where can they be found? Geographically, not in Southern California, that’s for sure. When it comes to Death Valley, believe it or not, the distant glow from Las Vegas’ (over 100 miles away) is still visible from the park; and it’s only going to get brighter the more the location keeps growing in population. But for now, if you want a Bortle 1 sky in Death Valley, the northwestern sections of the park are your best bet, and the closer you are to Vegas, the more you’re back in a sky that’s no better than Bortle 2 – still amazing by all means but not quite perfect.
The best Bortle 1 skies are pretty much entirely free of light pollution with no light domes from cities in the distance or nearby villages. There are things that are ONLY visible in such skies with properly adapted eyes to the dark, such as direct naked eye visibility for M33 (which is used as the measuring stick), several other Messier objects, and the Gegenschein glow. You’ll never get a perfectly pitch black sky from horizon to zenith because of the Earth’s atmosphere, but under these skies. your surroundings are only visible as silhouettes even when your eyes are adapted. It can be so dark that you may not see your hand in front of your face, and you cannot navigate the landscape at all without using a red flashlight pointed to the ground.
So the question is where can you go? In the continental USA, you have a better shot at finding them far away from all the major interstate highways in central and northern Nevada, southwestern New Mexico, northern Arizona, eastern Oregon, central Utah, parts of Wyoming, Idaho, South Dakota, western Texas, Montana… just think of the most remote locations in the western United States and you have a good shot at finding one! What about the central and eastern states? You might find large pockets of Bortle 3 and tiny pockets of Bortle 2, but for the most part the best you can get is a 4-5 between all the large cities and towns nearby!
Of course you can always go to central Australia… or find a spot in Africa… good luck if you dare!
So What Can I Do To Find A “Dark Enough” Location That Suits Me?
With all the sites and apps that use these color coded maps, they all reflect the same Bortle Scale that I’ve been mentioning all article. And if using numbers doesn’t help, then let’s use Letter Grades:
|Bortle Scale||Sky Type||Color||Letter Grade|
|3||Rural||blue||A – / B +|
|4||Suburban/ Rural Transition||green||B / B –|
|6||Bright Suburban||orange||D +|
|7||City/Suburban Transition||red||D –|
|8||City||darker white||F +|
You can easily look online for sites that have light pollution maps, such as https://www.lightpollutionmap.info/
For smartphone apps, I personally use Dark Sky Finder by Skidmore Apps which works on my iPhone, and I’m sure you can find a version that works for other types. Whenever I get asked in person by a visitor what’s a good location near their hometown, I bring it up and show them on a map what places are “dark enough” to my standards, and what places are not.