The tiny island of Sark is a window back to the Middle Ages - and that's good for science

Sark is a tiny, car-free island in the English Channel that didn't fully get rid of feudalism until 2008. Its nights are so reliably dark that it's just been named the world's first "dark sky island", making the island one giant observatory for looking up at the night sky without any light pollution to get in the way.

For much of the modern world, the lights of the night sky are confined solely on the ground, with the stars completely washed out by light pollution on the ground. Indeed, I'm pretty sure the first time I ever saw actual stars was during a camping trip in Wyoming when I was 17, and I can't remember the last time I've seen them. This is where the International Dark-Sky Association, or IDA, enters the picture with their plan to create "dark parks", places where darkness is protected just like nature preserves seek to protect animals.


The tiny, self-governing island of Sark is perfect for this initiative. Though technically speaking a part of the United Kingdom, Sark has pretty much been left to its own devices for centuries, as evidenced by the fact that they were still technically practicing feudalism until three years ago. Cars are banned on the island, which means there's no need for streetlights, and all electricity comes from a single, oil-fired power station that is very expensive to operate, meaning most islanders conserve power as much as possible.

Taken together, these factors mean there's almost no light pollution created on Sark, and there's very little else to disturb the nightly darkness. There are no large population centers on any of the islands or landmasses nearby, and the main island is shield from the reflected light kicked up by its cave-dotted cliffs. It's dark enough that the island has been officially granted dark-sky status by the IDA, which the islanders hope will boost astro-tourism.

So how dark is Sark? A good way to look at this is limiting magnitude, which is the magnitude of the faintest stars visible in a given night sky. At the center of a major city like New York, the limiting magnitude is about 2.0, meaning only about a dozen stars are visible at any one time. Staying in New York, a trip to the outer boroughs like Queens or Brooklyn will boost the magnitude to 3.0, meaning maybe 50 stars will be visible. Out in the New Jersey suburbs, the magnitude gets up to 4.0, meaning 250 stars can be visible. (Although, as a former resident of that area, I'll say that that's a pretty optimistic estimate.)

But even 250 stars is just a tenth of the night sky, and it pales in comparison to what's visible on Sark. The limiting magnitude there is a whopping 6.5, meaning even the dimmest stars are visible, and near-Earth objects like the International Space Station can actually be disturbingly bright, particularly to people (like yours truly) who didn't even realize it was really possible to clearly see satellites from Earth.


The entire island is arguably now one giant observatory, but the islanders hope to boost tourism still further by building their own little observatory. Until then, they can bask in the glow of this unlikely title: they're officially the darkest place on Earth.

[via New Scientist]


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