“Aren’t we part of the milky way, how can you see it if we’re in it??”
This is a question I’ve heard a surprising number of times when I tell people about the type of photography I do, and it seems silly at first but there was a time when I would have been guilty of asking that same question.
Our Place in the Galaxy
We are living within the milky way. Our own sun is a star within the milky way, and it is but one of several hundred billion other stars making their residence in this galaxy. Look up at the stars at night and you’re seeing around 0.00002% of all those stars. In fact, every single individual star that you’ve ever seen with the naked eye belongs to the milky way galaxy.
The milky way is a spiral disk shaped galaxy, but everything within it doesn’t exactly lie within a flat plane, we see stars that appear condensed within the plane and others that seem to be just above or below it. We can see the milky way in a dark sky region as an almost solid stream of clouds, smoke, or even milk stretching from one horizon to the next, and that’s exactly what we believed to be seeing in the night sky until the early 1600’s when Galileo confirmed by telescope that this stream was in fact light produced from a dense concentration of stars. It wasn’t until the late 18th/early 19th century that it was postulated the milky way might be the arms of a spiral galaxy among other galaxies. In 1923, Edwin Hubble confirmed that Andromeda was a galaxy located outside of our own milky way. More discoveries soon followed and astronomers now put estimates at least as high as 100 billion on the number of galaxies in the known universe.
M81 is a spiral galaxy thought to look nearly identical, at least in shape, to the milky way. Imagine Earth’s location being approximately in the center of one of the spiral “arms” in the picture. Photographers, like myself, prefer to take pictures of the core, or center, of the milky way galaxy because there is a greater density of stars in the center, just like in M81, and these produce the most impressive and dramatic pictures.
Of course, the milky way is visible any time of the year, but the core is only visible during certain times due to the rotation of the earth and its orbit around the sun. If you live in the northern hemisphere, the core becomes visible around February/March in the very early hours just before sunrise and comes up earlier as the season progresses until around September when the core is out only in the day light hours. July/August are the best months because the core is visible around midnight, a much more manageable time, and is highest in the sky on these nights.
Now, to actually find an optimal spot for viewing the milky way requires some understanding of how pervasive light pollution is and how to get away from it.
Escaping Light Pollution
Dial back time to only a century ago and the milky way would have been a common site for most people anywhere in the world. Return to the present day in an age where electric lights are exerting an influence on every piece of civilized land and you will likely find that most people have never seen the milky way in their lifetime. Over 2/3 of Americans live in an area where the milky way is not visible at all.
The further you can find yourself away from these areas, the more the sky will open. There’s actually a measurement that was developed and published in 2001 by John E. Bortle, an amateur astronomer, that describes the level of darkness in an area called the Bortle Scale. The scale quantifies the darkness of a sky on a scale of 9 to 1, from the brightest, most light polluted areas to the absolute darkest. In general, you need to be very far from the center of a city to see the milky way from horizon to horizon, and it’s debatable whether its even possible to find a level 1 sky in the USA.
As an example, lets take a trip out of Las Vegas, one of the absolute brightest spots on the planet where buildings are actually competing with their neighbors to be the flashiest and brightest visible objects around.
With the naked eye we can make out around 2000-5000 stars in a dark sky region. Stand on the Las Vegas strip at night and you might make out 20 stars, perhaps the most recognizable being the brightest stars from the constellation Orion, some of the Pleiades or Sirius, the brightest star in the night sky. Everything else is completely washed out and overwhelmed by the brighter lights of the strip. Welcome to a class 9 sky.
Drive about 15 miles north of the strip to the Las Vegas Motor Speedway and you’ll see a washed out yellow/orange glow in the sky. Some stars are returning but the milky way is still invisible in a class 7-8 sky. Drive another 5-10 miles north on I-15 and you may see hints of the milky way, but only directly over head if you know what to look for. Otherwise light pollution in every other direction at class 5-6. Keep journeying north and merge on to the Great Basin Highway, about 30 miles from the strip to reach class 4. The sky really should be dotted by hundreds of stars by now. The milky way is more visible and you might even see it touching the northern horizon, but one glance back toward Vegas will have you seeing the familiar orange dome of light that you just escaped. Drive for 10-15 minutes longer and the next 20 miles will be through class 3 skies where, on a good night, the milky way may be visible from horizon to horizon and clouds will appear black rather than orange, except on the very edge of the Las Vegas horizon.
At this point there will be some small amount of influencing light pollution from scattered, surrounding sources that may prevent you from ever reaching a class 1 sky. You will have to drive for another 60 miles or more from Coyote Springs, NV, 120+ miles from where we began, in order to even have a chance. However, these class 2 skies will likely contain the most stars you have ever seen in your life. Step out of the car and give your eyes 20 minutes to adjust to the darkness and you’ll discover the dark, which isn’t really all that dark. Go ahead, try walking around a little in the dark, once your eyes have adjusted you’ll be surprised how much you can see by starlight alone. Look overhead, from north to south and you will see that “broad and ample road, whose dust is gold, and pavement stars” as the milky way is described by John Milton in Paradise Lost.
Prepare to find inspiration if you’ve never been inspired by the night sky before, just as Milton had, just as the legions of others who have stood in awe of that same sky before the electric light held dominion over it.
Las Vegas is a unique situation. The city is surrounded by desert and the Great Basin area is considered to be one of the darkest places in America. If you want to experience a true class 1 sky in the USA, chances are better than most that it will happen here. The fact remains that you will only find more light pollution if you drive 150 miles in any given direction from most other cities. This makes finding the milky way a surprisingly difficult task for most of us. Fortunately for me and where I live, I can still drive 2-4 hours away to see a class 2 sky in West Virginia, one of the very few places on the East Coast where this is still possible. A good resource for finding dark skies that I like to use is Dark Sky Finder. The data it is based on is quite old at this point but it is still a good, easy to use map for reference. EDIT: There is slightly more updated site that I’ve found that includes worldwide data on light pollution: Dark Site Finder. The scale here is based on color, with white representing class 9 skies and dark/clear representing class 1 (white, red, orange, yellow, green, blue, gray, clear). To photograph the milky way, ideally you want to be within the blue or non-colored areas marked on the map.
Planning the Shot
Did you think the planning was over once you’ve found a dark sky region? Nope, that’s just the starting point!
As I discussed previously, for the most dramatic milky way shots, you’ll want to look for the milky way galactic, center, or “core” as I’ll be referring to it henceforth. In the northern hemisphere it rises in the south beginning late February in the predawn hours until around October when it’s just visible above the southern horizon briefly at dusk before disappearing. You can still get a shot of the milky way that doesn’t include the core at any time of the year and get great results depending on the scene, but the core is where the fun is and that is why photographers refer to the time period I outlined above as “milky way season.”
The core doesn’t come up exactly due south either, it depends on the season and time of night. Early in the milky way season the core will come up in the Southeast and as the season progresses will eventually begin setting in the Southwest early at night.
There are a number of apps that you can use to predict the position of the milky way and timing. By far the best, the one I use and the one used by many amateur astronomers is Stellarium, a free app that you can download on the PC, Mac or mobile phone. On a computer, just plug in the location (it doesn’t have to be the exact location, just search for a town or city that is near where you plan to shoot), and adjust the time to get a preview of what the sky will look like. The core moves with the stars Antares and Altair if you have trouble identifying the core in the program, look for those stars in the south. If you use Stellarium on a mobile device, you can actually use it to see what’s happening in the sky in real time. This is what I use to help me plan on location, especially when I’m trying to learn when and where the milky way will be in relation to a foreground object of interest. If you have an iPhone you can also use Photopills, which I’m told is another great program, possibly an even better option as it allows you to see the landscape in real time as well using your phone’s camera. In fact, this is probably what I would use if I wasn’t an Android user.
In addition to being at the right place at the right time of night, you also need to be aware of the moon. The moon essentially serves as a giant reflector for the sun and as such, it’s bright enough to blot out the milky way and many stars. So before you go out, check the moon phase and moonrise/moonset times. You don’t want to be out when the moon is out, unless it’s during a moon phase called the “new moon,” a time when the moon is completely eclipsed by the Earth. When I first began astrophotography I was very confused by online sources that would claim that the new moon is the only good time to shoot the milky way. However, I eventually learned that this ignores the long periods of time we have when the moon is only out during the day. So to be clear, you will be fine and see the milky way to be just as brilliant as it might be on a new moon, as long as the moon is not in the sky during the time you’re shooting the milky way.
There is one more element of planning that should not be ignored. The milky way is fine to shoot on its own, especially if it’s your first time, but having nice foreground objects or silhouettes in the background can make your photo even stronger and really inject some life into a scene. Try to think about composition in the same way you would think about any other landscape photo, the rule of thirds is still a good rule to follow here and you may want to think about the story you want the image to tell.
The best thing you can do in terms of planning is to visit the area you want to shoot during the day and visualize your shot in advance. This isn’t always possible, however, and the next best thing you can do is to search potential areas on Google Earth, or use Dark Sky Finder to find areas marked by pins on the map in a dark sky region, and hope that you can find an interesting shot once you get there. Wondering around in the dark is not fun and can be unsafe if you plan to be far from your vehicle. When I shot at Arches National Park, I visited every place I wanted to shoot during the day first, not only because I wanted to visualize and plan the shot in advance but I had never been there before and it’s very easy to get lost, even on the popular, established trails. I actually encountered several people lost in the dark on my way to some of my destinations at Arches. Always use GPS to get around at night, even familiar places can appear alien and disorienting at night, and everyone carries a smart phone these days, so there’s no excuse not to use it. I like to use Backcountry Navigator on my android phone.
Forecasting the Skies
This last point is an obvious one but is just as important as any others: if the skies are not clear you will not be able to see the milky way. It would be a waste of time to travel so far to escape light pollution only to arrive at your destination and still have the stars obscured.
Simply checking the weather forecast should be enough, but its good to be aware of just how cloudy it might be. Clear Sky Chart is an excellent resource for this purpose. Simply look at the maps for the state that you plan to be viewing and find an area that’s near your destination. This is also another good way of finding dark sky viewing areas as most of the areas listed are included because they are popular dark sky regions for astronomers. For each chart, just check the cloud cover measure during the time you plan to be out. The rest of the measures given are more important to astronomers viewing deep sky objects through the lens of a telescope. We’re just looking for the milky way which can be seen with the naked eye, so for our purposes, cloud cover is all we’re interested in. Personally, I won’t bother going out if there is not a large window of time with 30% or less of cloud cover. NOAA is also a good resource as it where many weather services obtain their weather data, but the information is dense and can be difficult to find what you need. Most times, I simply like to use Intellicast because they give a very quick and easy to read cloud cover prediction and I find them to be just as reliable as NOAA. You should also make sure that you’re not going out in 100% humidity since this will likely create foggy conditions.
Now that we know where to look, I’ll give you some tips on photographing the milky way in my next post, just in time for milky way season!