How to find a darker sky

One of the most dramatic improvements you can make in the quality of your visual observing is by getting to a darker sky. Most of us live in or near big cities, or at least larger towns. Getting away from all those lights will allow our eyes, binoculars, and telescopes to see more in the night sky. Today, being mobile is more important than ever. Even imaging and electronic assisted astronomy benefit from darker skies, despite the ability to counter light pollution to an extent through technology. Some amateur astronomers say that the best filter for your telescope is the "car filter." Get in a car and drive somewhere darker.

(Above: The sky at Arizona Sky Village. Photo by Astronomerica)

If you are new to astronomy and you are lucky enough to live in a reasonably dark sky without neighbors who try to banish the evil darkness with all-night lights, you may be able to do most if not all of your observing at home. But most of us aren't so lucky, and home observing must contend not only with pervasive sky glow but neighbors' lights, streetlights, parking lot lights, headlights, building lights, etc. I only observe the Moon, bright planets, and occasional double stars from home. Everything else means driving somewhere else to get better views.

Contact a local astronomy club

The best way to find observing sites that are reasonably dark, have little or no glare from local lights, are safe, and have decent horizons is to locate and contact your local astronomy club. Chances are that someone has already done the hard work of finding suitable locations and negotiating with the powers that be for the use of that land at night for observing. I am lucky to belong to the Northern Virginia Astronomy Club, one of the largest amateur astronomy clubs in the United States. We have numerous sites from suburban to dark sky, depending on how far you are willing to drive.

Being a member of a club usually gets you access to sites that the general public may not be allowed in at night. It will also give you information about members' favorite sites that may not be official club sites, but are still viable places to observe.

Do your own research

If you don't have a nearby club, you can do your own research, or ask on the various fora such as Cloudy Nights, Stargazer's Lounge (for the U.K.), The Sky Searchers, or various Discord servers what others might recommend. This also works if you are traveling and want to know where a good place to observe might be. For your own safety, never tell anyone except relatives and trusted friends where you are going to observe, but make sure someone knows where you are.

The most accurate light pollution map is the one developed and maintained by David Lorenz, called Light Pollution Atlas. The most recent data is from 2023 and the satellite data and methods he uses to determine sky brightness seem to be more accurate than other light pollution maps. If you click on a point, it will tell you the year of the data, the latitude and longitude, and the sky brightness measured in magnitudes per square arcsecond, close to what you would get if you used a sky quality meter (SQM) to measure the sky (shown above), as well as a ratio of artificial/natural brightness. These are all approximations in the map, and tend to still be overly optimistic especially while we are near solar maximum, but give you plenty of information to see how skies compare relative to each other.

Left: It's a long drive to a dark sky from the Northeastern U.S. megalopolis. The dark blue near the top is the area around Cherry Springs State Park in north-central Pennsylvania, a favorite observing spot for those in the region. The other blue area in the lower left is in the mountains of West Virginia, home of the Almost Heaven Star Party.

(David Lorenz, Light Pollution Atlas)

You may hear people say that they live in an orange zone, or in Bortle 5, for example. The color refers to the color scale of more basic maps, which ranges from white (brightest) to black (darkest). The Bortle Scale was invented by amateur astronomer, comet observer, and contributor to Sky & Telescope magazine John Bortle, and is a scale to measure the brightness of the sky in a particular place and time based on what can be seen in the sky. More people will refer to their site using the Bortle Scale than with an SQM reading, so it's good to know what both mean. Scroll to the bottom of this page to see a rough comparison chart. (Your browser may warn you the site is not secure. Proceed only if you trust those nefarious amateur astronomers!) 

Lorenz's atlas appropriately does not use the Bortle Scale because it is dependent upon observations on a specific night by a specific individual, assuming they didn't just read it off a map. However, if someone who has a reasonable amount of observing experience tells you he or she estimated that a site was Bortle 2, you can be pretty certain it's nice and dark and you will not be disappointed observing there on a good night. But most people don't actually bother trying to make Bortle Scale observations. I prefer looking at the Atlas or just staying away from population centers.

Here is the color scale from David Lorenz's atlas, calibrated to the brightness readings:

Although the SQM readings are more precise, I personally find it much more difficult to remember how good a sky is based on the SQM number. For example, my usual semi-dark site is listed at 21.01 (greenish-brown). The site I camp at is 21.28 (green). My home is a sickening 18.42 (red bordering on light gray). 

I figure anything around 21.0 and higher is usable for deep sky observing and I can get some decent views that are worth driving an hour or so. Anything about 21.7 and higher is going to be very good to excellent, and there are only two big areas in the eastern United States like this—in the mountains of West Virginia and in north-central Pennsylvania—that have suitable observing places, unless you own private property in the Adirondack Mountains and have cleared some trees. But these are difficult number ranges to remember, so I get why people use the color scale or Bortle rating. Looking at the map, it's much easier to see where you need to head for dark skies because of the color scale.

Other considerations

A dark sky is not the only criterion. There is the weather, dust, and wildfire smoke. Also avoid hours where the Moon is up. You need a good horizon. As noted, the Adirondack Mountains in upstate New York get as dark as 21.91 (see above), if you believe the map readings, but good luck finding some open sky. 

You want to avoid parks that close at dusk (almost all local and state ones) unless you like talking to the police, stay off private property without the owner's permission, and avoid dangerous places. An airport runway might seem like a great place until a Cessna flies out of the darkness and tries to land on your head. (Cessna 152 by Ramon FVelasquez, CC BY-SA 3.0, via Wikimedia Commons, with edits)

You also need to be away from nearby lights, which is a much more difficult endeavor than it might seem at first, as many people absolutely LOVE all-night "security" lights. I've always thought this was odd, because no one is out there in the middle of the night to see prowlers moving around. Well, except for astronomers, who unfortunately won't be there to scare off the prowlers because YOUR LIGHTS ARE TOO ANNOYING! I will leave you with one of my "poems" from the Redneck Patio (see link at right):

Criminal

Porch lights

Garage lights

Whitewash the suburban wasteland

And kill the sky

As I draw chalk emojis

On the driveways,

Unseen.

🙉🙈🙊 

An inexpensive hand controller for your SynScan mount

I have a Sky-Watcher Virtuoso GTi 150P 6-inch collapsible tabletop telescope, which has become my go-to scope (pun most certainly intended) since I am no longer able to heft my 10-inch Dobsonian around on a regular basis. 

This scope uses the SynScan app to control the mount, which appears to me to be a cheaper version of the AZ-GTi mount. My particular scope's go-to works poorly, so I use the mount strictly for tracking when viewing the Moon and brighter planets from my Bortle 8-ish home. I built a more reliable alt-az tabletop mount that I use for everything else.

The SynScan app (shown at left), in my opinion, is rather poorly rendered and clunky. Beyond that, though, my main dislike is the fact that with any app controlling your mount, you have to look down at your cell phone and use the touchscreen to move the scope around. This makes it difficult to see the effects in the eyepiece and I have found it very frustrating.

To solve that problem, I did some google-fu and found that several people have used game controllers to replace at least some of the commands on the app. All I was looking for was one that would let me control the altitude and azimuth movements with actual buttons that I can feel at night without taking my eye from the eyepiece. 

I didn't want a full size game controller, and found a little mini one that someone mentioned on this Cloudy Nights thread that will indeed work for movement control with my scope. For $5 shipped from Aliexpress (you won't get that low price now), I picked up an 8BitDo Zero 2 keychain-sized mini controller. Its Bluetooth paired easily with both of my cell phones (Google Pixels). 

Now I can control the scope without taking my eye from the eyepiece. What a difference this makes for frustration-free viewing! Because the tracking on my scope is rather poor, I frequently need to recenter the object in the field of view, and this makes it much easier than using the touchscreen on the phone. Panning around on the Moon is much more pleasant. Also, my mount has a tendency every once in a while to go slewing off into the ether somewhere on its own, and this way I can quickly stop it and bring it back under control without fumbling with my cell phone. 

I use it one handed, and it works even if I have thin gloves on or hold it inside my pocket. It does have a steady blue light when connected to the phone's bluetooth, so you might need to keep it in your pocket or tape over the light if you use it around other folks in a darker environment. In my light polluted yard, it makes no difference.

While I can't comment on how well this works with other mounts and apps, for $20 (now the lowest price on Amazon), it might be worth a try. Or if you already have a game controller, try that one. It has made a big difference in the usability of my tracking mount.