Light Pollution: Time to Turn On the Night?

Astronomer Mark Thompson discusses a project in the UK that will have the side effect of darker skies. But is it a realistic venture?

One of my most memorable shoots for the BBC's "The One Show" was when I traveled up to to the UK's first "Dark Sky Park," Galloway Forest Park in West Scotland. When the sky finally cleared, we were treated with the most amazing sight of a velvety black star-filled sky with the Milky Way brighter than I have ever seen before.

There are eight registered Dark Sky Parks in the world, but is light pollution really that much of a problem for those of us in less rural locations? Is the only solution to turn all the lights off?

For astronomers, light pollution is a major problem and along with the turbulent currents in our atmosphere, it drives professional astronomical observatories to the top of the most remote mountains. For the rest of us though, we have to be content with the skies above our homes.

The problem is that a vast proportion of light fittings shine light above the horizontal and up into the sky. The resulting stray light bounces off particles and industrial pollutants in the atmosphere straight back down to Earth as the characteristic orange color of sky glow. The effect on the astronomer is that it lowers the contrast between it and objects in the sky, making them hard -- if not impossible -- to see.

Lights Off

In a recent shoot for the One Show (which aired Monday night in the UK), I was invited along to a small town called Needham Market, in Suffolk, UK to turn the street lights off!

The driver for this activity wasn't for TV, or to reduce light pollution, but it was about CO

Suffolk Council owns 55,000 street lights and where appropriate, by April 2012, they will be switching most off after midnight and reducing the output by 60 percent on others. In doing so, they will reduce CO

A lot of the filming was done under the glare of 450 street lights, but as the night closed in, we waited until 11:30 p.m. when the big switch-off was going to happen. Although it was cloudy unfortunately, it was incredible. The sky had some broken cloud, so occasionally we glimpsed the sky behind was noticeably darker. The effect of just turning off the street lights was significant.

I'd taken along a "sky quality meter" which measures how dark the sky is. The darkest skies in the UK have been recorded with one of these devices. For example, the Galloway Forest Park has a reading of 22.72 and at the island Sark (the UK's first "Dark Sky Island") comes in at 21.53 (the higher the reading, the darker the night sky).

The Needham Market reading, although tainted by cloud, showed an increase of almost one, from a little over 18 to a little over 19. This happened just by turning off the streetlights, obviously a great ally in the fight against light pollution, cost savings and CO

Darkness = Crime?

Of course, perception is still one of the biggest challenges as people 'feel' safer when it is lighter. The jury is still out as to whether security lighting is as effective as we think at reducing crime levels.

So it seems that while a reduction of lighting is a good thing -- bringing financial savings, pollution reduction, reduction in energy usage, wildlife benefits (birds can become confused with dusk-to-dawn lighting in built-up areas) and of course, better viewing of the night sky -- the one remaining problem is to challenge the belief that lighting prohibits crime.

In some areas of the UK, studies have even shown that better lighting has very little effect on levels of crime. But, as a rule, people feel safer with lights on. Unfortunately, I think that's an instinctual thing and something that will take a very long time to overcome.