What’s Up: Satellite Constellations and Light Pollution

Apr 12, 2021 | Daily Space, Sky Watching, Spacecraft, Starlink

IMAGE: Trails caused by the fifth deployment of satellites making up the Starlink constellation. CREDIT: Andreas Möller

I have been an astronomy nerd pretty my entire life. I really started out as a dinosaur nerd who loved sci-fi, but between an asteroid being responsible for the demise of the dinosaurs, and my ability to see the sky from my backyard while dinosaurs remained out of reach, I became an astronomy nerd. 

Back when I was fifteen, I got to go to the USSR on an astronomy exchange. This was on those People-to-People programs that were designed to build peace by bringing, as it turned out, the young nerds of opposing countries together. Through this, I got to go to the six-meter telescope in the Caucasus mountains, and as part of a weekend trip, I got to go hiking at the foot of a glacier from a location so far from civilization that no lights could be seen in any direction in the valley below our campsite. 

This campsite was the darkest place I’ve been in my life, and one night, I went off by myself and just sat on a rock staring at the too many stars. This was the 1980s, so there were a lot fewer satellites than we have today, and the Hubble Space Telescope, the ISS, and the bright grid of Iridium satellites weren’t yet launched, or in some cases, even imagined. Nevertheless, as I sat there on my rock, I was able to catch the faint light of a satellite streaking across the sky, and it kind of felt like I was seeing something magical.

Today, I can go outside, and while the lights from my small town’s street lights make many things a challenge to see, I can easily make out satellites any night I want, and last summer a Starlink pass blared bright across the sky, startling Annie and I away from watching marshmallows roast in a fire. 

Satellites now make regular appearances in photos and science images. If you want to purposely see them, websites like Heaven’s Above can help, and there are even web apps that will notify you when a bright object like the ISS is about to go overhead. While these myriad new satellites are improving our weather forecasting, our Earth science, our communications, while they are technologically improving our ability to live on and understand our world, a new study makes it clear that they are also blocking the light of the stars. In a new paper, led by Miroslav Kocifaj in the Monthly Notices of the Royal Astronomical Society: Letters, scientists find that the scattered light of satellites makes our sky 10% brighter.

According to John Barentine of the International Dark-Sky AssociationUnlike ground-based light pollution, this kind of artificial light in the night sky can be seen across a large part of the Earth’s surface. Astronomers build observatories far from city lights to seek dark skies, but this form of light pollution has a much larger geographical reach.

As came up in yesterday’s Rocket Roundup, nations around the world are launching mega and minor satellite constellations. With the largest hosting thousands of satellites and the smallest on the order of ten, we’re just creating more things to brighten the sky. According to Barentine: Our results imply that many more people than just astronomers stand to lose access to pristine night skies. This paper may really change the nature of that conversation.

We here at the Daily Space have extremely conflicted emotions about this issue. We both want everyone to have access to the internet and communications networks like Starlink, and we want to study the universe beyond that network of satellites is making it hard to see. For now, we recommend everyone go out and enjoy the skies whenever they can, and that you try and find magic in viewing the occasional passing space station or Hubble Space Telescope. We’ll link to websites and apps you can use to find both stars and satellites on our website, DailySpace.org. Go find yourself a dark spot, a nice rock, and maybe remember the bug spray. This is the perfect time of year to look up.

More Information

RAS press release

The proliferation of space objects is a rapidly increasing source of artificial night sky brightness,” M Kocifaj et al., 2021 March 29, Monthly Notices of the Royal Astronomical Society: Letters

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