Night Light

At first glance, it might appear as though this image was taken during the day, with the deep blue sky arching over Vera C. Rubin Observatory, a Program of NSF’s NOIRLab. On closer inspection, however, a sprinkling of stars is visible throughout the sky, revealing that it was actually taken at night, by the light of the Moon. The brightening of the sky is due to the artificial light from areas densely populated by humans, which can be seen as clusters of bright lights on the horizon. The light from the cities is so obvious in this image because the photographer used a long exposure time. If you were to visit this spot in person then the night sky would actually be very dark, and the stars would be far more visible. In fact, one of the reasons why Rubin Observatory’s location on the Cerro Pachón ridge in north-central Chile is so ideal for astronomical observations is the lack of light pollution in the area. 

Rubin Observatory is a joint initiative of the National Science Foundation and the US Department of Energy (DOE). Once completed, Rubin will be operated jointly by NSF’s NOIRLab and DOE's SLAC National Accelerator Laboratory to carry out the Legacy Survey of Space and Time.