Join the IDA. The IDA produces useful fact sheets and educational materials (including sources for good lighting fixtures), lobbies the lighting industry, and has worked for state, local, and international light-pollution control initiatives. As of 2006 it boasts more than 11,000 members. Dues from members are essential to pay for staff to handle this work and carry out the IDA's numerous programs.

Supporting the IDA financially is the most effective thing you can do to turn the light-pollution tide. Basic membership is$30 per year ($15 for students, seniors, and those on limited incomes); the address is 3225 N. First Ave., Tucson, AZ 85719, U.S.A. The IDA maintains a Web site, which includes its fact sheets and newsletters, at www.darksky.org. Every amateur astronomer should be eager to help.