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In which I learn about clear skies

14 March 2009

Imagine my delight to look out my living room window after sunset to see that the Astroforecast clear sky prediction was coming true, and that the usual grey dome of sky was actually a reddish purple. Stargazing! So once the sun had set properly I placed the telescope outside – to allow it to acclimatise to the temperature difference – and worked out a list of Messier objects to view, as I quite like the idea of doing the Messier Marathon.

I went out to join the telescope 45 minutes later but my timing may have been off, as both my neighbours had their kitchen/dining room lights on, the back neighbour had every single light on (inside and outside!), and the sky had quite a bad orange glow. At first I thought the latter was something to do with the sun, but I saw it was a dome that went all around the horizon and at least 45° up from it – leaving just a small darkened cap with stars coming through. I couldn’t see the Pleiades or nebulae around Orion’s belt, Betelgeuse was okay, Aldebaran was barely visible, and Procyon was washed out.

An hour later I was becoming increasingly frustrated, my neighbours still had their lights on (I can’t blame them, of course), and the orange half-dome had no intention of going away. It was bad enough that Orion’s belt effectively set 20° before it went below my roof line. I did get a nice view of Saturn and Titan, but that was it – time to call it a night.

It turns out that clouds are not the only thing that matter when you’re viewing the night sky. Clarity of the atmosphere seems to make a huge difference, as does the time of day (and potentially day of week) in terms of the human factor – at least when not at a dark sky site. This may be obvious to you, but I grew up on the outer edge of suburbia in a Mediterranean climate where there weather and skies are clear 300 days a year. Careful night viewing planning is uncharted territory for this antipodean…

Light pollution is a truly appalling blight for the urban or suburban stargazer, particularly as it’s the easiest of all pollutants we emit to prevent. I accept it’s unreasonable to expect our neighbours to contain their indoor lighting (it really is their right to use inefficient lighting and waste power, though is something of which I’ve always been conscious), but my crime-free neighbourhood and the large town I live on the edge of is lit up like an orange Christmas tree from sunset to sunrise. Why? The oft-quoted reason is crime prevention and safety, and I concede there are places where that does apply – particularly in pedestrianised urban areas – but there is a growing body of evidence to show that it makes little if any difference in the majority of suburbia and rural areas.

I’m beginning to think the British Campaign for Dark Skies (CfDS) and International Dark-Sky Association (IDA) are worthy organisations, and will be looking into them in detail. I intend to bring it to the attention of my local residents’ association, and write to my council and member of parliament. My MP may well disagree with me (he has in the past), but at the very least it will raise his awareness of the issue.

There has to be a better way of using public lighting (and non-renewable resources) than floodlighting the planet during darkness. Anyone?

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