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Thursday, March 08, 2007


How many stars can you see? An International Survey

Western horizon as seen from the Southern Hemisphere an hour and a half after sunset. Click to enlarge. Orion is top right, marked by Rigel and Betelguese.

How many stars can you see? It depends on whether you are living in the bush, the suburbs of the heart of town. Light pollution is so bad in some places, you can only see the brightest stars.

There is a world wide survey of star visibility going at the moment, Globe at Night. DaveP has the details, but basically, between now and March 21, go outside at around an hour and a half after sunset, possibly a bit later, let your eyes adjust for a few minutes (or more, after looking at the computer screen it can take up to 5 minutes for my eyes to adjust), compare what you see of the constellation Orion (see map above, or print out the maps in the Family Activity pack) to their starcharts, and submit your observations. If you are using a torch to read the Family Activity Pack maps, remember to put some red cellophane over the end so as to not destroy your night vision.

Simple as that, and you are contributing to our understanding of light pollution as well a doing a bit of amateur science.

It's funny, I know I should know better. I know there's no real "up" or "down". But, looking at the image you've produced here, I know I could never get used to the idea of looking at Orion upside down. ;)
It was freaky to see Orion standing on his head in the southern hemisphere. I found the best solution (in real life) was to face south and tip your head right back (or lay down on the ground). Then he is the right way up again!
When I was in the northern hemisphere, seeing Orion "right way up" (on the rare occasions I could see it through the light pollution) was not a bother. But the Moon upside down really bothered me.
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