City lights illuminate this night time view of southern California, Mexico's Baja California and the Gulf of Cortez, as photographed by one the Expedition 28 crew members onboard the International Space Station flying at altitude of approximately 220 miles. The Salton Sea can be seen in the lower right quadrant of the frame. A solar panel and part of one of the space station's modules are silhouetted at right. A 15-mm focal length was used to capture the time-lapse image. The thin line of Earth's atmosphere is visible above the horizon.
IN ONE SENSE IT LOOKS PRETTY, but in another it reveals enormous and callous waste. Poorly designed and implemented lighting results in a lot of light being sent straight up into space, instead of down onto the ground where most of it is supposed to go.
This waste light consumes enormous amounts of energy, which ordinary citizens are paying for.
Not only that, but this upward-directed light also bounces around in the air, making the sky glow in a phenomenon astronomers call “light pollution“.
The combined image shows how light pollution affects the appearance of clouds at night. The photo at left, taken by Ray Stinson in Glacier National Park, shows that in pristine areas clouds appear black, because they block out starlight. The photo at right, taken by Christopher Kyba in Berlin, was published as a part of a light pollution research paper, and shows how clouds are lit from below by light pollution, dramatically brightening the night sky. Photo courtesy Ray Stinson and Christopher Kyba, used under the Creative Commons Attribution-Share Alike 3.0 Unported licence.
Light pollution is a major problem, not just for astronomers—who find that many of the faint astronomical objects they want to see are “drowned out” by sky glow—but also for the environment. Wasted energy means more power-generated pollution than there needs to be, and waste light also can affect animal and plant life.
A lot of good work has been done in recent decades to begin correcting this problem, but there is still a long way to go.
As ideal illustrations of the scale of the problem, shown below are some recent nighttime photos taken by astronauts aboard the International Space Station.
International Dark Sky Association
The Nile River and the Sinai Peninsula can be easily delineated in this nighttime photo captured by one of the Expedition 28 crewmembers aboard the International Space Station, flying at an altitude of approximately 220 miles. A 42-mm focal length was used to record the image.
The Nile River Delta and part of the Mediterranean Sea can be seen in this night time photo captured by one of the Expedition 28 crew members aboard the International Space Station, flying at an altitude of approximately 220 miles. A 38-mm focal length was used to record the image.
Sicily is featured in this nighttime image captured by one of the Expedition 28 crewmembers aboard the International Space Station, approximately 220 miles above Earth. The landmass at left edge is part of the "toe" of Italy's "boot." A 38-mm lens was used to record the image.
The "boot" of Italy is featured in this nighttime image photographed by one of the Expedition 28 crewmembers aboard the International Space Station. A tip of Sicily is at top centre of the frame, photographed from approximately 220 miles above Earth. A 35-mm lens was used to record the image.
This nighttime view of northwestern Europe is featured in this image photographed by an Expedition 28 crewmember on the International Space Station. Several of the oldest cities of northwestern Europe are highlighted in this photograph taken at 00:25:26 Greenwich Mean Time (GMT). While the landscape is dotted with numerous clusters of lights from individual urban areas, the metropolitan areas of London (United Kingdom), Paris (France), Brussels (Belgium) and Amsterdam (Netherlands) stand out due to their large light "footprints". The metropolitan area of Milan, Italy is also visible at lower left. This photograph was taken with a short camera lens, providing the large field of view recorded in the image. To give a sense of scale, the centres of the London and Paris metropolitan areas are approximately 340 kilometres distant from each other. The image is also oblique, or taken while looking outward at an angle from the station; this tends to foreshorten the image, making the distance between Paris and Milan (approximately 640 kilometres) appear less than that of Paris to London. In contrast to the land surface defined by the city lights, the English Channel at right presents a uniform dark appearance. Similarly, the Alps (bottom centre) to the north of Milan are also largely devoid of lights. While much of the atmosphere was clear at the time the image was taken, the lights of the Brussels metropolitan area are dimmed by thin cloud cover.
Story by Jonathan Nally, SpaceInfo.com.au. Orbital images and captions courtesy NASA.
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