Monday, April 13, 2009

Wasted light, no stars

Astronomers battle 
light pollution
Rob Klovance,
If you're thinking that an astronomer's battle against light pollution is just a tad self-serving, think again -- wasted energy, wasted money, dangerous glare for drivers and detrimental effects on wildlife, including birds and fish.

'I think most of us are very keenly aware of the fact that we're using up energy, and that there's a cost to it,' says John McDonald, fresh off a trip to Costa Rica in which he shot a mind-blowing time-lapse video of the sky throughout the night. 'And the amount of energy that is wasted in lighting up the bottoms of clouds and sending light off into space to do nothing is a considerable expense.' ...

There are three types of light pollution:
* Light trespass, which occurs when light crosses property lines. Poor outdoor lighting shines onto neighbours' properties and into bedroom windows, reducing privacy, hindering sleep...
* Glare, which comes from an overly bright source of light compared to background lighting levels. Glare is light that beams directly from a lamp into your eye. It serves no purpose and hampers the vision or pedestrians, cyclists, and drivers. If you can see the bright lamp from a distance, it's a bad light. With a good light, you see lit ground instead...
* Sky glow, which spills upward from urbanized areas and blocks the view of the stars.

Reducing light pollution has a variety of benefits, including energy savings and helping eliminate light exposure that disrupts sleep cycles, causes fatigue and strains the immune system. What we can do to help.

The Sky Tonight (over Vancouver)
Image: Detail of a photo of the Pelican Nebula taken by John McDonald through a telescope at Astronomy Hill near Victoria in 2007. (W.J. McDonald photo)