Globe at Night
. . .While avoiding Fall at Night and Fight at Night
Imagine a night sky without any stars. No moon either. A sky that’s just dark and blank with not one speck of light, not one single bit of intrigue up there at all, nothing to suggest what’s beyond our home planet.
Close your eyes and think about it.
I get a creepy and sad feeling when I do this. Ever since I was a kid growing up on a Tennessee farm, I’ve loved looking at the night sky and just wondering about it, and really just wondering about everything about life. There are so many unknowns in our world, especially to the whole night sky situation. Infinity, a great example. What is infinity? How does it keep going? Can you get past it? What would happen if you could? And then what? Most of us have grown up comfortable with the idea that we can marvel at our heavenly nighttime sky and the celestial objects in it, at least on some nights in some places. But in reality, we are losing more of our night sky to light pollution. You probably won’t like the image below from Globe at Night, the community science project I will introduce this week. But study all four boxes anyway. Most of us, tucked into our beds under these skies night after night, were unaware as these monumental changes took place.
I was born in the late 50s. It feels heavy when I see the differences between the first box, my box, and the 2025 projection. What a massive change! Last week when I visited my mom in Tennessee, the Nashville Tennessean was writing about how extreme weather events––the stifling droughts and the sizzling wildfires they put on the news––get our undivided attention about a changing planet. But other indicators, like the gradual loss of a glossy dark sky sprinkled with stars, are sly. These transformations creep up on you.
It feels heavy AND mournful.
What can we do? On a community basis, there are systemic policies we can support and changes we can advocate for, in an effort to reduce light pollution. Individually, there are also changes we can make. See resources below. For us as community scientists, there is Globe at Night, a project established in 2006 that encourages people all over the world to record and report the brightness of their night sky. This project is web-based, you don’t even need to register or have an account. You do need to go outside after dark and look up at the sky, decide a few things, then come back in and put information in the Globe at Night website. It is not necessary, but it is useful to have (and use) a Sky Quality Meter (SQM) app on your phone.
The six basic steps for using Globe at Night
I’ve entered Globe at Night reports on five occasions by now, two times in a rural area, three times near my first-ring suburban home in Atlanta. It is so easy! You basically put in date and location information, rank how dark the sky was, how cloudy it was, enter a Sky Quality Meter (SQM) meter reading, and hit submit. (More on SQM later.)
There are Globe at Night videos and website pages available to help you go beyond these six basic steps, including great resources to help you find constellations.
Four things I learned from participating in Globe at Night:
How a Sky Quality Meter (SQM) can be used. My SQM is in a free app called Dark Sky Meter. To use it, you open the app and lift your phone screen to the sky so the app can measure the sky’s darkness and give you a SQM rating. I now know that a SQM reading of 20 or 21 indicates a fairly good dark sky where the stars of the Milky Way are clearly visible. A reading of 17 or 18 indicates a light sky that is impacted by either artificial light or bright moon light.
The sketches of a full moon and street lamps on the left remind us how much they wash out the night sky. Source: Globe at Night.
How small differences in SQM ratings actually represent vastly different views of the night sky. Last week, in rural Tennessee we received SQMs of 20.89 and 21.30 on two different clear nights. Back in Atlanta a few days later, we went to a dark park and got a SQM of 19.30. However, the Tennessee sky beat the city sky by a country mile with many more stars and constellations on display. At her website, one astronomer I consulted explained it like this: SQM readings measure magnitudes per arcsecond which is a logarithmic measurement which means that a large change in night brightness is equal to a relatively small numerical change on the scale. So, be aware: small SQM number changes mean big sky changes.
How far the glow from cities (and small towns) travels. In Tennessee at my mom’s farm, we were 38 miles north of Nashville (population 670,000), and since city glow travels from 20 to 30 miles, we were supposedly outside the range of urban light. However, one night as Fred and I stood out behind her farmhouse, there was no way to miss the wide bleary blur of brightness at the southern horizon. “What are they doing down at Nash-Vegas? On a regular Sunday night?” I asked him. “Bachelorette parties run late, I guess,” he said. “The ladies need the light. Glow sticks too maybe.” I harrumphed at that, and we headed back inside. Thinking it over later, I decided the distinct wash of light was likely a mix of big-city lights and a handful of urban sprawl communities and suburbs. Development typically comes with high wattage.
How a nocturnal walk will challenge you. I’d gotten the idea to try a nocturnal walk after learning about Globe at Night, and reading about all the nighttime animals that use the stars and moon to navigate their worlds. I wanted to sample nocturnal life, too. Fred? Reluctant yet willing. Reluctantly willing? Yep, works for me, I thought. All the night hiking guides cautioned things like, “you won’t believe how much you depend on your eyesight once you are in the dark," and “be ready to feel lost.” All true, all true, I discovered after we had ventured forth on two short walks, barely avoiding one pitfall that I knew to worry about, “Fall at Night”1and another pitfall that popped up unexpectedly, “Fight at Night”2. Overall, though, it was refreshing to be a night owl, and we even heard a real owl once, one with a deep hoot that dominated the woods that surrounded us.
I hope you’ll try Globe at Night. Thousands of people already have, and I’ve found research articles based on Globe at Night data from prestigious sources, such as Harvard and the National Institutes of Health. The final word this week on the harm light pollution is doing to our planet comes from the World Economic Forum:
Light pollution robs us of our heritage. Our ancestors experienced a night sky that inspired science, religion, philosophy, art, and literature. Now, millions of children across the globe will never know the wonder of the Milky Way.
Resources:
Turning off the porch light at night is the suggestion that sits at the beginning of most lists of what individuals can do to help with light pollution. Also, I’ll share this from Popular Science, and this from Saving our Stars.
Upcoming:
I’m headed to the Hornyhead Fish Festival this weekend in Newborn, Ga. Yes, there will be community science there, for I plan to meet up with Phil Delestrez who I featured in The Everyday Scientist on March 9. He’s a butterfly man. An artist. And more.
City Nature Challenge is going on around the world this weekend. It’s going to be big! In Atlanta, we have the Atlanta Nature Challenge, sponsored by Fernbank, but you can take observations anywhere you are in the city. Download iNaturalist and look for the Atlanta City Nature Challenge project page. I’ll see you there.
Fall at Night. On our walk at the farm, I took these little mincing steps in the dark, yet despite the care I took, I left the road, mince-stepping myself right off into a ditch. Country road ditches are deep. Yikes, the ground is falling away! Luckily, I avoided all harm by braking with the little steps and backing out of there. Nocturnal nosedive avoided.
Fight at Night: During our nighttime hike in an Atlanta park, I miscalculated Fred when I viewed his reluctance to TAKE the hike as a sign he wouldn’t be serious about it. But he was quite serious about getting his night vision on, with his pupils dilated as much as possible. Anyway, an accident happened when suddenly out of nowhere all 40 lumens of my phone’s flashlight beamed him smack-dab, full-force in the face. His eyes! His shrinking pupils! My dear, caught in the headlights, was none too happy but my apologies helped us avoid a dreaded Fight at Night.