The most important rule of star parties is to keep it dark. No white flashlights, no Coleman lanterns, no using cellphones or PDAs as a flashlight, no camera flashes, and especially no car headlights.
Here's why: when it gets dark, your eyes change gradually to help you see better in the dark. It's not just your pupils expanding -- there are changes happening in the retina, too, and it can take over an hour to become fully dark adapted. (Google for "dark adaptation" if you want all the details.) So astronomers try very hard to avoid turning on lights once they become dark-adapted.
If you need light, a dim red light is best -- that's what astronomers use to read their star charts. A small red LED flashlight (the kind that costs $1.99 at Fry's) is great. But any dim flashlight with a piece of red cellophane or a red balloon stretched over the front works fine.
Turn off any dome lights in your car before you get to the star party, so opening your door won't flood the area with light. Turn off your headlights and drive slowly with parking lights. If you need help, ask -- someone will be happy to guide you to a parking spot if you're having trouble seeing.
When you're about to leave, if you need to use backup lights or brake lights when you're leaving the star party, or (horror of horrors) if your car has "daytime running lights" that are always on, please warn people first. Announce "I'm about to leave, and my backup lights will come on." That gives astronomers a chance to cover their eyes or turn away.
If you can park somewhere away from where the telescopes are, that's sometimes the easiest solution.
Remember, these rules on light help you as well as everyone else. If you use a white flashlight and the dome light in your car, you won't be able to see anything through the telescopes either!
Most astronomers love to let people look through their telescopes -- feel free to ask! But don't touch somebody's scope without asking first. Remember, these are expensive instruments and some of them may be delicate ... or they may be so easy to move that by touching it, you'll bump it away from that galaxy that the owner just spent half an hour finding. Or, worse, you might jiggle the telescope while it's taking a photograph.
If you have kids, this is especially important. We love showing the universe to kids. We don't love having kids running through the area grabbing at our telescopes.
Of course, common sense applies. If someone is busily consulting charts, typing on a laptop (perhaps setting up a photograph), seemingly glued to the eyepiece, or just seems a bit anti-social, that person may be too busy to offer any views right then. Don't take it personally -- try the next scope.
And if you have something in particular you'd like to see, or any other questions about astronomy, ask!
Few people realize just how chilly it gets late at night, even in summer. So bring about twice as much warm clothing as you think you'll need. In summer, a light and heavy jacket, warm shirt, jeans. Winter calls for warm boots, gloves, heavy coat, thermal underwear, and, very important, a warm cap! The greatest heat loss is from your head, so a cap or a coat hood helps a lot, especially if there's a breeze.
It's fun to have the radio or stereo on in the car as you drive down the highway, but once you arrive at the site, turn it off. You'll be pleasantly surprised at the variety of night sounds that you can't hear in a noisy city. And tastes in music differ so violently that it's usually best to avoid it -- chances are that your favorite band isn't the favorite of everybody else in the parking lot.
If you really want to listen to music, use headphones.
Aside from bringing a dim red flashlight and warm clothes, bring binoculars if you have any -- you'd be amazed at how much you can see through cheap binoculars.
You may want to bring along snacks to keep you going through the cold night, and coffee or soft drinks. (Be sure to dispose of wrappings, cans, bottle caps, etc. properly so that we continue to be welcome in the various parks, and allowed to use them after hours.)
We hope you have fun at the star party! After all, that's what it's all about.
You can also read what other clubs have to say on this topic.