Participate in a world-wide event to measure light pollution. No equipment is necessary. If you can find the constellation Leo, you can participate. If you can't find it, the Globe at Night website will show you how. Go to http://www.globeatnight.org to get all the details and instructions on how you can participate in this effort. it would be particularly helpful to get lots of data points from all over the Hudson Valley, so your backyard or wherever you are at 8-10 PM (an hour after sunset, and before the moon comes up) will produce a useful reading.