Across the United States, natural darkness is an endangered resource. East of the Mississippi, it is already extinct; even in the West, night sky connoisseurs admit that it's quicker to find true darkness by flying to Alice Springs, Australia, than traveling to anywhere in the lower forty-eight.
Ever since the nation's first electric streetlight made its debut in Cleveland, on April 29, 1879, the American night has become steadily brighter. In his new book, The End of Night: Searching for Natural Darkness in an Age of Artificial Light, Paul Bogard aims to draw attention to the naturally dark night as a landscape in its own right -- a separate, incredibly valuable environmental condition that we overlook and destroy at our own peril.
Venue took the opportunity to visit Bogard in his office on the campus of James Madison University, in Harrisonburg, Virginia, to learn more about nocturnal America and its dark skies -- and what we have lost by dissociating the two.
Our conversation touches on the difficulty of measuring and preserving such an ephemeral quality, as well as the ecological and health consequences of endless artificial light, with speculative detours into evolutionary shifts in human vision and the possibility of preserving Las Vegas (the brightest pixel in the world in NASA photographs) as a "light pollution park."
Nicola Twilley: Darkness is easy to overlook, if you'll excuse the pun. How did you go about structuring the story of such a familiar, yet intangible quality?
Paul Bogard: People think they know darkness, and that they experience darkness everyday, but they don't, really. That's one of the reasons I borrowed the Bortle scale for the table of contents. I think John Bortle's point, when he created this tool for measuring the darkness of skies, was that we have no idea what darkness really is. We think night is dark -- full stop, end of story. But, on the Bortle scale, cities would be a Class 9 -- the brightest. Most of us spend our nights in what he would call a 5 at best, or more likely a 6 or 7. We rarely, if ever, get any darker than that.
Until the coming of electric light, people experienced a darkness that Bortle would classify as 2 or 3, every night. What I tried to do in the book is to show that difference, by working my way down from places that are bright to those that are less bright, but also by talking to people who are living and working in those places.
Twilley: It's interesting that, in order to see the nuances in darkness, we need to measure and name it. It was certainly a revelation to me to read in your book that twilight has three stages -- civil, nautical, and astronomical, with civil being when cars should use headlights, nautical meaning that enough stars are visible for navigational purposes, and astronomical referring to the point at which the sky is dark enough for the faintest stars to emerge. Previously, I had thought of twilight as a single condition on the light-to-dark spectrum, rather than a multiplicity.
Bogard: For sure. For me, one of the reasons why identifying different depths of darkness is so important is that we don't recognize that we're losing it, unless we have a name to recognize it by. It's also a way to talk about what we might regain.
That's also what the National Parks Service Night Sky team, who I describe in the book, is trying to do with their sky quality index. If you're charged with preserving darkness as natural resource, unimpaired for future generations, then you need to be able to put a number on the level of darkness. You need to be able to see and measure any losses before you even know what you're trying to protect.
Twilley: It's astonishing to read the description of a Bortle Class 1, where the Milky Way is actually capable of casting shadows!
Bogard: It is. There's a statistic that I quote, which is that eight of every 10 kids born in the United States today will never experience a sky dark enough to see the Milky Way. The Milky Way becomes visible at 3 or 4 on the Bortle scale. That's not even down to a 1. One is pretty stringent. I've been in some really dark places that might not have qualified as a 1, just because there was a glow of a city way off in the distance, on the horizon. You can't have any signs of artificial light to qualify as a Bortle Class 1.
A Bortle Class 1 is so dark that it's bright. That's the great thing -- the darker it gets, if it's clear, the brighter the night is. That's something we never see either, because it's so artificially bright in all the places we live. We never see the natural light of the night sky.
Geoff Manaugh: There are a few popular urban legends about the extent to which people no longer experience true, natural darkness. One is that, even though telescopes sell really well in New York, no one has seen a star over Manhattan since 1976 or something like that. The other one, which I have to assume is also at least partially an exaggeration, is that, after the Northridge earthquake in 1994, the L.A.P.D. was flooded with worried phone calls because people were seeing all these mysterious lights in the sky -- lights that turned out to be stars.
Bogard: I've heard that one, too -- that people were seeing the Milky Way for the first time, and they didn't know what it was.