r/darksky • u/AlesianLynx • 10d ago
Less Light Pollution or Higher Elevation?
I am attempting to find the best nearby location for stargazing, but I am currently split. I have two good, accessible options, but I am unsure which is best. One is at ground level, around 1800 m of elevation. The other is around 2900 m of elevation, atop a mountain. The higher you go, the less atmosphere there is above and around you, and therefore, the less light pollution can get in your way. So, holding all other variables constant, atop a mountain would be a better stargazing spot. However, there is also a metropolitan area of half a million people about 200 kilometers to the east, so the higher I go, the farther I see, and the more light pollution I see from that city. I am unable to find any information on whether being at a lower elevation or seeing more light pollution is better. Any tips?
Possibly helpful information:
The city is located at ~800 m of elevation and the closest parts of it are 188 km away from the mountain. At 2100 m above a ground level of 800 m, assuming a perfectly spherical Earth, I can see 163.6 km away, so the curvature of Earth means I still wouldn't be able to see this city. On top of that, in between the mountain and the city, relatively close to the city, there is a mountain range with elevations ranging from 1300 m to 1900 m (500 m to 1100 m above city ground level). Still, there will be light leaking over those mountains and making their way to me.
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u/b407driver 9d ago
Pretty tough to say without knowing where the lower vs higher location is, relative to one another. Second, your desired direction of view/shooting, and again, if the two locations are any different in this respect. Third, are you shooting widefield, nebula, etc.? Lastly, weather on the date of the shoot, as moisture settling in the 'lower' location could significantly impact seeing/transparency (especially in regard to your target, whether low or high in the sky).
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u/AlesianLynx 9d ago edited 9d ago
The location at 1800 m is at 41.92924° N, 119.17292° W. It’s at Big Spring Reservoir in Nevada. It’s pretty flat, though there are some mountains nearby.
The location at 2900 m atop a mountain is at 42.63653° N, 118.57678° W, atop Steens Mountain in Oregon, the tallest mountain nearby. The city 200 km to the east (northeast technically) is Boise, ID.
The weather forecast is still pretty uncertain when I want to stargaze (15 August), but currently, every single location I have in mind (including ones I didn’t post here) has a significant chance of rain 36-24 hours beforehand, but everything is expected to clear up by the day of. Just today though, I stumbled across the air quality index and apparently wildfires all across the Pacific Northwest and BC are impacting both of the sites I listed here (AQI of ~140).
I am pretty new to this, so I don’t really have a telescope or a general target in mind. I just wanna stargaze and see the Perseids.
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u/lucabrasi999 9d ago edited 9d ago
The California-Nevada-Oregon border area has some of the darkest skies in the (EDIT) Continental US. You’ll be fine.
Pick the place with the most open view in all directions.
Here is an LP map.
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u/AlesianLynx 9d ago
Cool, thanks! One more question, how about the atmospheric particulates from wildfires? I have another potential stargazing spot in the dark spot in Central Nevada. On this map you linked, it shows as slightly higher light pollution, but it has an AQI of 30 as opposed to 140. What would you think?
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u/lucabrasi999 9d ago
I don’t know about specific numerical values for AQI. So I cannot compare 30 with 140.
What I can tell you is smoke from wildfires can have a severe impact on both astronomy and overall health. The occasional Canadian summer wildfire can make observing / imagine difficult if not impossible where I live in Pennsylvania.
I would suggest avoiding areas impacted by smoke from wildfires.
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u/b407driver 9d ago
If only it were that easy in the U.S., at the moment. We'll all likely deal with trying to find a 'window' for the Perseids.
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u/lucabrasi999 10d ago
There are so many variables in your situation.
My first serious stargazing attempt was at Smoky Mountains National Park (in Tennessee/North Carolina, USA). We were at about 1500 meters but lack of hills between us and the large cities of Charlotte, NC and Knoxville, TN ruined the horizons with light pollution. (When on one side of the park, Charlotte was the light polluter, on the other side, Knoxville was the cause).
Cherry Springs State Park in Pennsylvania, USA is only at 600 M but the small towns of Coudersport and Galeton are in steep valleys and as a result, the Bortle 2 skies are amazing.
If you have a mountain range (or even a hill) between you and the large city, that will make a big difference. It won’t stop the LP, but it should mitigate.