Kitt Peak National Observatory, Tucson

High above the Sonoran desert, on the Tohono O'odham Reservation, the Kitt Peak National Observatory studies the universe with one of the world's largest collection of telescopes from one of the most beautiful mountaintops in southern Arizona. Throughout the day, volunteers lead tours of three of the telescopes, including the world's largest solar telescope. The Groupon discounts are only for the daytime tours. On clear evenings, visitors can choose from one of three different nighttime programs according to interest level. All feature views of celestial objects such as the Moon, distant planets and far-off galaxies through 20- and 16-inch telescopes. Advance reservations are required for all nighttime programs. Visit www.noao.edu/kpvc for details.