Red Lights and Starlight at Kitt Peak

Set against the rolling background of starlight, the red lights of the Visitor Center 0.5-meter Telescope at Kitt Peak National Observatory (KPNO) is a curious sight. Why is the telescope glowing red? To observe effectively during the night, astronomers need their eyes to be well-adapted to the dark. To preserve this adaptation, they use red light which doesn't disrupt their night vision capabilities as much as other colors of light would.