The Belt of Venus over the McMath-Pierce Solar Telescope

The McMath-Pierce Solar Telescope, located at Kitt Peak National Observatory (KPNO), a Program of NSF NOIRLab, is captured here beneath the full moon just after sunset. This is the perfect time of day to witness a phenomenon known as the anti-twilight arch, nicknamed the Belt of Venus. The belt forms directly opposite the rising or setting Sun — in this image, the Sun is setting in the west behind the camera. Rays of light from the Sun hit the eastern atmosphere at the antisolar point, the point directly opposite the sun from an observer’s perspective. The light is then backscattered off of the atmosphere and reflected back to the observer at a longer wavelength, changing the typically blue-appearing light into pink. The band of dark blue sky below the anti-twilight arch is actually the Earth’s shadow!

You can find a diagram representation of this phenomenon here.

This photo was taken as part of the recent NOIRLab 2022 Photo Expedition to all the NOIRLab sites.