Why light needs darkness

TIG

http://www.ted.com/talks/rogier_van_der_heide_why_light_needs_darkness.html

Mike Lucey

Thanks TIG for reminding me that TED is still around.

That was a great 20 minutes of viewing! Rogier explains how we currently (mis)use / waste light and how we could be using it to better enhance our lives and the wellbeing of the planet. His demo model of an LED light was brilliant! I have been hearing a lot lately how LEDs will be coming more and more into everyday use and now understand the reasons why this needs to be the case.

Attached are a couple of images that 'caught my eye'

Sunrise - Sunset.jpg

Inner City to Excellent Dark Sky.jpg

cosycat

When I taught science in a large inner sity school, we had an astronomy topic for the 14 year olds.
One question I always posed was
'How many stars do you think there are altogether'

So what do think the largest number that the students ever guessed ?
10 million ? 100 milliom ? 1 billion ?

No...

10
(not 10 million or 10 thousand ) just 10

Because from that light polluted estate that was (and still is) all you could see, even on a good night.