An astronomical experiment YOU can contribute to

One reason often giving for studying archaeoastronomy is that the sky hasn’t really changed much since ancient times. There’s some problems with this, like precession of equinoxes shifting the position of all the stars, but these can be accounted for. What we tend to skip over is a much bigger change. In the photo below the image on the left is Orion as it might be seen in ancient or prehistoric times. It’s a photo from place where there are still dark skies. The image on the right is a photo from Orem, UT.

Photo: Light Pollution. (cc) jpstanley

The difference is due to light pollution. There’s various reasons why it’s a bad thing, from loss of heritage to preventing scientific research but there’s economic costs too. It costs money to light up the night sky and that’s money that could have been spent lighting the streets or – to be more realistic – funding a banker. The haze you see stretching above your head is a big sign that someone is burning money on your behalf. How bad is the situation? This is where you can help tonight.

GLOBE at Night is running an experiment between March 16 to 28. About an hour after sunset (7pm in the UK) they’d like you to go outside and look at Orion. Then you pick the best match for what you saw against their charts. Then you can report your observation and see how your home compares to other people. In perfect conditions you should be able to see stars down to around Magnitude 6 or 7, but this will vary on your eyesight as well as sky conditions. By picking up enough observations the Globe at Night team will be able to make allowances for that and get a better idea of what the sky is like. Once you’ve made your observation, you’ll be able to compare your own findings with past years and see if light pollution is improving or getting worse.

It’s an experiment which anyone with an internet connection in any hemisphere can contribute to. I’d guess it would take 5-10 minutes of your time. Hat-tip to the Jodrell Bank twitter feed.