
Unfortunately, Google’s Advanced Image Search doesn’t allow you to filter on usage rights (at least not yet). There, you might try searching for your subject plus "photos" or "images" (or "pictures"). Someone has put up a Google Custom Search page to take its place. Note: Google used to offer a US government search (which was known as the Uncle Sam search engine) but they killed it off. Be aware, though, that the works of state governments may be protected by copyright. The result will include a bunch of US government produced images that will be copyright free, so long as government employees produced them as part of their jobs. Type in the subject you’re looking for and.The only reliable way to use Google Images to find public domain images is to restrict your picture search to government web sites. You might end up deciding to pay to use a specific image, anyway - but it can’t hurt to see what’s out there first.

But when you have time to search, here’s a short list of picture search engines, and some tips for using them. There are times when paying a fee might beat spending more time searching. (By the way, you can find several NASA sites, plus more, listed here.)

even though NASA photos are in the public domain. If you wanted to use that photo, it would cost 210.00 USD for editorial use on a web site, for a duration of up to one month.

You could find one very quickly at Corbis - in fact, the Bettmann Archive (which Corbis owns) includes a beautiful NASA photo of the space shuttle orbiting Earth. Let’s say you were looking for a photo of the space shuttle.
