WASHINGTON — www.exploratorium.edu What: Take an online tour of San Francisco's "Exploratorium," a museum of science, art, and human perception. The museum itself has about 650 interactive exhibits. On the site you'll find four - "Exploring Chocolate," "Memory," "Sport Science" and "Observatory." Each exhibit covers its topic with essays, photos, graphics, and some corresponding activities. There's also a digital library with an archive of past exhibitions and an impressive list of Exploratorium-recommended links. Best points: It might not be like touring the museum in person, but the creators have done a good job of organizing the site, packing it with information, and incorporating plenty of attention-grabbing visuals to keep the learning interesting. And best of all, there's no jostling for position in the ticket line. The exhibits are easily accessible on the main page. Click on "Observatory," for example, and you'll find color and graphic-rich presentations on sunspots, solar eclipse, and auroras. Then there's a build-your-own solar system activity where kids (and adults) can practice making distance and speed calculations and another page that will calculate your weight on other planets for you. Each exhibit is similarly modeled. What you need to know: Founded in 1969 by physicist Frank Oppenheimer, the Exploratorium is located in San Francisco's Palace of Fine Arts. Further information about the museum's history and mission is easily located on the left side of the main page.