Juan Carlos Casado
Of all the changes brought to the environment by human activity, the loss of the night sky may not be among the first most people think of.
But some research suggests it should be.
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The brightening of the sky by light pollution can interfere with sleep patterns, disrupt animal behavior, and even hide the cosmos.
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In 2016, it was estimated that a third of Earth’s population can no longer see the Milky Way, and 80 percent are affected by light pollution.
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Now, a team from the Instituto de Astrofísica de Canarias has completed a study on the natural brightness of the night sky, revealing the darkest places left on Earth.
The team analyzed 11 million photometer measurements from 44 of the darkest locations around the globe.
These photometers took measurements during a phase of the solar cycle when the Sun has the least effect on the brightness of the night sky.
Juan Carlos Casado and Petr Horálek
The measurements revealed the Roque de los Muchachos Observatory as the darkest place on Earth, where artificial light only brightens the night sky by 2 percent.
Located at an elevation of 7,860 feet above sea level, the Roque de los Muchachos Observatory on the island of La Palma in the Canary Islands is an important site for astronomy.
The Roque de los Muchachos Observatory is home to dozens of telescopes and other instruments used by astronomers, including the largest single aperture telescope in the world.
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The autonomous community of Extremadura in Spain, the Montsec commune in France, and the Sierra Nevada mountain range in the U.S. were also found to be among the darkest spots on Earth.
Even in these exceptionally dark areas, the brightness of the night sky can vary, thanks to luminescence from the upper layers of the Earth’s atmosphere.
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According to the study’s authors, a more complete map of nighttime darkness could be made by installing photometers in remote places and comparing their findings with images taken by satellites.
Read more stories on astronomy here.
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