Astronomy Amphitheater is an outdoor venue below the Lehman Caves Visitor Center, built for ranger astronomy programs. A typical session is about two hours: a 30-minute talk, then 90 minutes looking through telescopes at planets, star clusters, satellites, meteors and other deep-sky sights. Programs are free and don't need reservations, but capacity is limited and the visitor-center lots can fill on program nights. If you want a guided introduction to the sky, this is a good evening stop; you can stargaze from almost anywhere in the park without attending a program.