Capturing stunning images of the night sky has become much easier in recent years. The low-light performance of modern cameras (and even my six-year old Nikon D750) far outpaces the capabilities of cameras made even a decade ago. Recently, I was flipping through some old astronomy magazines from the early 2000s and was shocked not only by the (low) quality of the wide-field astrophotography of the day, but also by the incredibly expensive gear used to produce those images at the time. 20 years ago, it was extremely difficult to capture a detailed image of the Milky Way without a high-end camera and an expensive tracking mount.
Today, even some phone cameras can capture passable images of the Milky Way. Stunning panoramas of our galaxy stretching from horizon to horizon are now a dime a dozen on social media. Given the advanced abilities of today’s cameras, it is natural to wonder: “Does the Milky Way really look like that?” Do the spectacular Milky Way images we see plastered across the internet accurately represent what the human eye can see? Or is this incredibly rich detail only visible to a high-tech camera sensor? Or, more nefariously, could these images simply be the result of some Photoshop trickery? The answer, perhaps not surprisingly, is a combination of all three!
Let’s begin by discussing one way in which most Milky Way images are not representative of what the human eye would see: color. The Milky Way will always look monochromatic to the naked eye. However, the reason why has to do more with the physiology of the human eye than any deception on the part of the photographer. Let me explain.
Some photographers do like to crank up the saturation of their Milky Way images beyond belief. Night sky photos with vibrant blues, purples, oranges, and pinks are the tell tale signs of digital embellishment. Rather than point fingers, I’ve created my own version below to illustrate:
To be clear, these colors aren’t real. This is Photoshop trickery, pure and simple. Here’s what the same image looks like without the saturation increase:
Much more subdued, certainly, but look closely and you’ll see that there is still some color there! Here’s the good news: those colors ARE real! Notice the pale green sky behind Mt. Adams. That’s airglow, a phenomenon caused by gas molecules in our atmosphere re-emitting energy they absorbed during the day in the form of ultraviolet radiation from the Sun. If you open the photo full screen and look really closely, you can also see some small pink-ish blotches along the plane of the Milky Way. These are hydrogen gas clouds—stellar nurseries if you will—glowing with the characteristic ruddy hue of ionized hydrogen.
Now for the bad news: while these subtle colors are “real”, you’ll never actually see them with the naked eye. Why not? To sum it up, our eyes suck at seeing colors at night. We see using two different sets of cells in our retinas: rods and cones. The cones are what allow us to see color. Unfortunately, the cones only work when there is lots of light entering our eyes, like during the day. Our rods are mostly responsible for our night vision and they are, sadly, colorblind. This is why the night sky (and low light scenes in general), always appear in shades of gray. Only a few of the brightest stars and planets emit enough light to trigger our color-seeing cones. The diffuse glow of the Milky Way does not.
Cameras on the other hand don’t have rods and cones. They are much better at picking up color in low light, so they naturally produce images that are more vibrant than what we actually experience…no editing necessary!
With this in mind, let’s remove the color entirely from our Milky Way image:
With the color out of the picture, is this now what the Milky Way actually looks like to the naked eye? Yes…under certain circumstances.
Look closely at the Milky Way in the image above. Notice the detail. It’s complex. It’s interesting. Some parts are brighter, others fuzzier, with dark blotches and voids winding sinuously from upper left to lower right. The Milky Way is a complex place, and this manifests itself in our view of it from Earth. In this regard, this photo actually does a pretty good job of depicting what the Milky Way actually looks like. You CAN see this detail and complexity with your own eyes…provided that a few things are true:
#1: You have a dark sky. For most people, light pollution prevents the Milky Way from being seen in its full glory. If you want to see the kind of detail shown in a photo like this one, you need to be somewhere dark. Not “turn off the porch light” dark. Not “drive out to the edge of town” dark. Not even “drive an hour up into the mountains” dark. Light pollution is incredibly pervasive and the view of the Milky Way can be degraded for literally hundreds of miles from a major city. Even some of the most remote wilderness areas in the United States are still awash in the glow of artificial light. Places like eastern Oregon, central Idaho, northern Nevada, and southern Utah are among the few locales where you can still experience a pristine night sky. A view of the Milky Way from anywhere else simply doesn’t compare.
#2: Your eyes are dark adapted. Remember the rods from earlier? While our rods allow us to see fairly well in low light, they need at least 20-30 minutes of darkness in order to reach peak sensitivity. This period is known as “dark adaptation” and it is a key ingredient of a successful stargazing session. Gazing at the Milky Way before your rods have had time to fully dark adapt is like looking at a Van Gogh or Monet with dark sunglasses on; you miss many of the finest details. If you walk out of a brightly lit RV or tent and look skyward expecting to see the Milky Way like it appears in a photo, you’ll be quite disappointed. Even using a headlamp or checking the time on your phone while waiting for your eyes to dark adapt can inhibit the process. For this reason, astronomers typically use red lights at night because our rods are less sensitive to that color, making it easier to preserve night vision.
#3: You are in the right place at the right time. We live in the suburbs of the Milky Way galaxy. When we look toward the center of the Milky Way (downtown), it looks brighter, because we are looking at a greater concentration of stars, gas, and dust. When we look away from the center, it looks dimmer. Images like the one I’ve been using in this post are taken looking downtown…toward the galactic center. This portion of the Milky Way is only visible during certain times of year. In late fall, it’s behind the Sun, making it rather difficult to photograph or see. Late evening in the summer and early fall, or early morning in the Spring is the ideal time to catch it. At other times of year, when the galactic outskirts grace our sky, the Milky Way is much more ho-hum. You’ll also want to avoid the Moon, whose glow will mostly overwhelm the diffuse and relatively faint Milky Way.
If all three of these things are true, then yes, the black and white image above is a good representation of what the Milky Way looks like to the naked eye. Sadly, only about 20% of North Americans can even see the Milky Way from their homes, much less see it under ideal circumstances. Light pollution has masked the view of our home galaxy to the point that most of us no longer know what it should look like. Ecologists call this “shifting baseline syndrome”, a phenomenon in which each successive generation comes to regard the state of the environment around them as “normal”. In other words, as we degrade our environment, we gradually forget what things used to be like, or, in this case, look like.
While increasingly rare, such a view of the Milky Way is one of the most spectacular sights in the natural world. I vividly remember a backpacking trip I took over a decade in Aoraki/Mt. Cook National Park in New Zealand. The Milky Way appeared so bright that it cast shadows on the ground, and I was able to read a book (albeit barely…) by its light. Oddly enough, sometimes the “darkest” skies are actually the brightest because so many stars are visible.
Fortunately, light pollution is an easy problem to fix. Many outdoor light fixtures are poorly designed and allow light to escape upward into the night sky. While our modern lives certainly require light at night, that light is almost always needed on the ground, not up in the sky. Illuminating the sky or the crown of a tree makes no one safer or more secure from hazards real or imagined. Light fixtures that direct light downwards (known as “fully shielded” fixtures) eliminate much of the problem. Cities that use such lights, like Flagstaff, Arizona (where I grew up), produce substantially less light pollution than other cities of comparable population. You can see the summer Milky Way from downtown Flagstaff…a city of nearly 100,000 people. Simple actions can go a long ways toward preserving the view of the Milky Way for future generations. (For more on what you can do to combat light pollution, check out the great work being done by the fine folks over at the International Dark Sky Association.)
Comet C/2020 F3 (NEOWISE) continues to put on a stellar show for skywatchers in the northern hemisphere. Over the past week, the comet has moved into the evening sky, making a trip out to see it somewhat more palatable than it was when I first highlighted the comet 11 days ago. Last week, I had the pleasure of viewing the comet twice in one night while camping on the east flank of Mt. St. Helens. High clouds prevented a great view at sunset, but had mostly cleared just four hours later when the comet rose again in the northeast. Just below and to the left of the comet was the distant cone of Mt. Rainier. Low clouds in the river valleys below us made for a spectacular view:
Unfortunately, the comet has dimmed noticeably over the past few evenings. While we still have a few days until its closest approach to Earth, the comet has receded from the Sun enough that its activity is likely beginning to wane. The next few nights will likely provide the final chance to see this comet and its tail with the unaided eye (until it returns ~6,800 years from now that is!) The waxing moon will begin to interfere by later this week and by the time the moon leaves the evening sky a few weeks from now, the comet will likely have faded from naked eye visibility. To see it, look northwest 1-2 hours after sunset. The comet will appear a little below the bowl of the Big Dipper, and is far enough north now that viewing is significantly better from more northerly locations. More details on spotting the comet can be found here: https://earthsky.org/space/how-to-see-comet-c2020-f3-neowise
Naked-eye comet alert! Comet C/2020 F3 (NEOWISE), discovered back in March, has brightened to the point where it is visible to the naked-eye in the pre-dawn sky. Both the comet and its tail were easily visible to the naked eye about one hour and fifteen minutes before sunrise this morning:
This is the first time in ~20 years of skywatching that I can recall seeing a comet and its tail with the naked eye. (Western Washington’s persistent clouds and 49°N latitude stymied my attempts to see Comet PANSTARRS in 2013.) Such comets are relatively uncommon, making it well worth the effort to get up to see this one.
Here’s how to see it yourself:
Look northeast 75-90 minutes before local sunrise. You’ll need a relatively clear horizon in that direction. For most locations in the United States, the comet will be no more than 10 degrees above the horizon at this time. A large tree 200 yards away was enough to block the view of the comet from my patio, forcing me to take a short stroll through the neighborhood to find a better vantage point. The comet is small, but for at least the next few mornings should be readily visible. Here’s a wide field view to give you a better sense of the comet’s apparent size:
Timing is key. My experience is that the comet is best seen about 75-90 minutes before local sunrise. Too much earlier and the comet will be too low in the sky to see clearly. Too much later and the brightening dawn sky will render it invisible. This morning, by about one hour before sunrise, the comet had become much more difficult to pick out and the tail was barely visible to the naked eye. By 45 minutes prior to sunrise, the comet was no longer visible to the naked eye at all (although it was still visible in binoculars or a camera).
Since you’ll be observing in twilight, light pollution conditions shouldn’t make much of a difference here; this comet should be visible even from urban areas, provided you have a clear northeast horizon and time your attempt correctly. A pair of binoculars greatly enhances the view. For more detailed information on viewing Comet NEOWISE, check out https://earthsky.org/space/how-to-see-comet-c2020-f3-neowise
Now for a bit more on what you are seeing and how the comet’s appearance might change over the coming days and weeks:
Comets are city-sized “dirty snowballs” made mostly of ice and rock. They are leftovers from the formation of our Solar System and orbit the Sun on highly elliptical paths. Comet NEOWISE takes several thousand years to complete one orbit of the Sun. While comets spend most of their time in the cold outer solar system, when they approach the Sun they are heated by solar radiation, causing ices on the comet to begin sublimating (turning from a solid into a gas). This creates a temporary atmosphere surrounding the comet nucleus known as the coma. That’s the bright part of the comet you see in the close-up below. A stream of ionized gas “blown” off the comet by the solar wind can form a tail, while dust particles left behind the comet can form a second tail. As you can see in the close-up, Comet NEOWISE does appear to have two distinct tails at the moment.
NEOWISE made its closest approach to the Sun back on July 3rd and is now on its way back into the outer solar system. Typically, as comets move away from the Sun’s heat, they dim. So far though, NEOWISE appears to be bucking the trend. This is exciting because while the comet is moving away from the Sun, it is moving closer to us. It will reach its closest point to Earth by about July 22nd. If the comet can maintain its brightness for just another week or two, the show could get even better. Now is still the time to look though. The comet will be visible in the morning sky for just a few more days before it disappears into morning twilight. It will reappear in the evening sky by mid-July. Here’s hoping it is still bright enough to see by then. If so, we can all enjoy its presence without having to get up at 3:30 AM!