PMThis guide provides a comprehensive tour of the famous Kitt Peak telescopes and an introduction to the important research accomplished with them. For more than 45 years, astronomers have used the telescopes at Kitt Peak National Observatories (KPNO) to make many remarkable discoveries about the Universe. KPNO supports the most diverse collection of astronomical observatories on Earth for nighttime optical and infrared astronomy and daytime study of the sun. It is currently the most visited astronomical observatory site in the world, including over 50,000 visitors a year from all 50 states and over 51 countries. With over twenty optical and radio telescopes, the site reveals to visitors modern astronomy's great diversity. Leslie Sage is a Senior Editor at Nature magazine and Research Associate, Department of Astronomy, University of Maryland. ^lGail Aschenbrener is a Public Affairs Officer, USDA Forest Servi