(WORLDWIDE SPACE PARTY) Forty-five years ago, Russian cosmonaut Yuri Gagarin became the first person to survive a trip into orbit. (Rumor has it he murmured: "I don't see any god up here.") Tonight, revelers in scores of cities, on every continent, and even on the International Space Station will celebrate Yuri's Night. Seattle will party with NASA astronauts and UW professors, mission films, and music by Optimus Rhyme, Plan B, and others. (Museum of Flight, 9404 E Marginal Way S, 764-5720. 7 pm, $25–$30, all ages.)