15 years ago, I co-authored my first paper in the field of #LightPollution studies: https://doi.org/10.1371/journal.pone.0017307

Up to that point, work on artificial brightening of the sky had been done almost entirely by astronomers, who (for obvious reasons) weren't really interested in cloudy nights. But because I was involved closely with ecologists from the Leibniz Institute of Freshwater Ecology and Inland Fisheries @LeibnizIGB, we realized that it's also important to measure the extent to which overcast and clear nights differ.

Through a bunch of twists and turns I now work on #RemoteSensing using nighttime light, but that was the paper that launched me into this direction.

Most people in brightly lit countries probably take for granted that clouds are bright at night, but this is completely unnatural. You can see it better in this pair of photos we published in a later paper (titled "Red is the new black"): https://doi.org/10.1111/j.1365-2966.2012.21559.x

This probably matters a great deal for nocturnal animals, because it's a reversal of an environmental condition that existed during the hundreds of millions of years that life evolved.

@skyglowberlin I teach large university science courses. Hundreds of fairly privileged students in the room. It has been my habit to ask them to raise their hands if they have ever seen the Milky Way.

The results have always been disappointing. Over the past 20 years it has gotten worse and worse. Recently many students don't even know what I mean by the question, and I have to explain what a dark sky looks like.

"Raise your hand if you have ever been awed by a clear dark sky full of countless, countless stars." Always less than 5%.

@jameshowell Yeah, it's rough to hear things like that. I remember hearing from some people from (I think) the US NPS that they created a scene with virtual reality goggles to show people what a natural sky looks like when you are dark adapted, and a lot of the people who experienced it didn't believe that it could be real ๐Ÿ˜ฅ

@skyglowberlin When I teach about retinal physiology, it breaks my heart. Often there isn't a single student who has ever experienced vision after true dark adaptation.

It turns out thatโ€”it takes time, but it's realโ€”you can see by starlight. And the faintest stars you see? That's a single rod cell detecting A SINGLE PHOTON. Your retina is that sensitive.

Before 1879 this was an absolutely universal human experience. Now it's exotic, unimaginable.

@[email protected] @[email protected] I grew up in a rural area in the late 1970s. The Milky Way was vivid in the sky at night and I remember many nights standing outside watching for meteors and taking the presence of the Milky Way for granted. By the time I left for college, there was usually too much light pollution to see it. In the late 1990s I went on a camping trip in Australia and was astonished by how many stars were visible at night, and of course the Milky Way was prominent in the sky. It reminded me of what my hometown's sky had been like. Till then it hadn't sunk in that I'd lost it.

I feel a sense of loss and grief that the Milky Way is effectively gone for so many people, and will be gone for so many more as time passes. And when/where it is visible, it'll be streaked with satellite trails because of the apparent arms race to fill low Earth orbit with as many satellites as possible. What a terrible loss.
@abucci @skyglowberlin Yeah, it's not a happy story. The nice stories are exceptional, and we should cherish them, in the context of a heinous collective loss.