Dawning of Venus at Cerro-Tololo

Dawn breaks behind the mountain of Cerro Tololo, bringing with it another day full of discoveries. This Image of the Week captures a panoramic view of the Belt of Venus rising behind instruments of the U.S. National Science Foundation Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF NOIRLab, in Chile. Contrary to the name, the Belt of Venus has nothing to do with the planet Venus. It refers to an atmospheric effect occurring before sunrise and sunset. The sky opposite the rising or setting Sun is illuminated by limited sunlight. As the light travels through the atmosphere, its bluer wavelengths are scattered and diffused more than its redder ones. The red light is then reflected back towards the viewer, leaving the reddish belt seen across the sky. While the planet Venus (also known as the ‘morning star’ or the ‘evening star’) is often seen at the same time as the belt, the bright object in the sky near the center of the image is actually the waning Moon.

CTIO has over 40 telescopes that are used to investigate a wide variety of research topics, including exoplanets, the Sun, Earth’s atmosphere, meteors, supernovae, gamma-ray bursts, and dark energy. The largest of these telescopes, the Víctor M. Blanco 4-meter Telescope (second from the left), was instrumental in the discovery of dark energy. Some of the telescopes are also used for educational purposes. Daytime guided tours of the facilities on Cerro Tololo are available on Saturdays all year round. 

This photo was taken as part of the NOIRLab 2022 Photo Expedition to all the NOIRLab sites. Petr Horálek, the photographer, is a NOIRLab Audiovisual Ambassador.