The Bortle scale is a nine-level numeric scale that measures the night sky’s brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution. John E. Bortle created the scale and published it in the February 2001 edition of Sky & Telescope magazine to help amateur astronomers evaluate the darkness of an observing site, and secondarily, to compare the darkness of observing sites. The scale ranges from Class 1, the darkest skies available on Earth, through Class 9, inner-city skies.
Visit Black Canyon of the Gunnison National Park in Colorado and see some of the steepest cliffs, oldest rock and craggiest spires in North America. Pictured here is a stunning shot of the park at night with the Milky Way rising above the Black Canyon. Photo courtesy of Greg Owens
Until recently, for all of human history, our ancestors experienced a sky brimming with stars – a night sky that inspired science, religion, philosophy, literature and art. Unfortunately, we’ll never know the great art we’ve lost to light pollution.
Enjoy these beautiful pieces of art inspired by starry night skies and learn how you can help inspire future generation to invent, create and dream.