Dark Skies

Gran Canaria, Tenerife, La Gomera and La Palma seen from orbit  at 10:15 pm.  La Palma is much harder to see.
NASA photo of Gran Canaria, Tenerife, La Gomera and La Palma at 10:15 pm

It’s pretty hard to see La Palma on this photo – it’s the dim outline, right at the top of the frame.   Gran Canaria and Tenerife shine out like beacons, you can see the outline of the  little island of Gomera, but La Palma?  Well you can see the capital, Santa Cruz, and if you really try, you can see the faintest line of light up to Los Sauces.  And you can see Los Llanos on the west of the island, sort of, but where’s the rest of the island?  It’s invisible.  And please note – this photo was taken before midnight.  They turn off floodlights at midnight.

One of the reasons that La Palma has such dark skies is a local law known as the Sky Law, which covers aviation routes, atmospheric pollution, electromagnetic radiation and crucially, exterior lighting. A lot of this is achieved simply by using street lights which send all the light downwards – which is where you want it anyway – instead of wasting on the clouds.  In spite of the islanders initial fears, it actually saves so much money that we’ve had people from elsewhere asking for advice.  Why spend good cash on dazzling the owls?

Speaking of owls, it’s very easy for humans to forget that many species, perhaps most species, are nocturnal. Light pollution affects them too. For example, newly hatched turtles instinctively head for the brightest horizon. For millennia, that was the sea shore. Now, all too often, they wind up in a tourist resort.  The problem is particularly acute in Florida, where all the local turtles are threatened with extinction.

But on La Palma, we don’t drown out the night sky.  All you have to do is move away from street lights, and you’ll see thousands of stars.  If you live in a city, it may take some time before you remember to shut your mouth.

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