Moonset from La Palma

© Cees Bassa

On occasion, radio astronomers observe with, and get to go to, telescopes operating at other wavelengths. When those wavelengths are optical, this usually means remote or exotic mountain tops.

Last December I had the joy of observing with the Isaac Newton Telescope on La Palma, and took my camera and tripod to photograph the night sky. On one of the nights the young Moon was setting, and this image shows a sequence of individual exposures. Moonlight is reflected in the dome of the William Herschel Telescope. Atmospheric refraction dramatically alters the shape and color of the trails of the stars, the Moon and also Mars (in the bottom center), as they near the horizon.