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Sunday, November 26, 2017

Light Pollution Is Increasing

When scientists are disappointed with their results, it's usually because they were following a different hypothesis than where their data leads. In the case of the switch from sodium lights to LEDs, though, it's more than that.

“Honestly, I had thought, assumed, and hoped that with LEDs we were turning the corner,” says Christopher Kyba (German Research Center for Geosciences). Kyba researches the spread of artificial lights and how it affects our nights, and as a former member of the board of directors of the International Dark Sky Association, he also advocates the use of improved lighting practices.

But in the November 22nd Science Advances, Kyba and colleagues show that we are farther from the goal of dark, starry skies than ever.

World maps showing the rates of change of the lit area of the world (left) and the measured brightness of each country (right) during 2012–2016. Warmer colors in each map correspond to higher rates of change. Note that Australia is an odd case: wildfires increased the country's lit area, but this effect was not included in the radiance analysis. Kyba et al. / Science Advances.

More Lights, Brighter Nights

Qatar nighttime lights Outdoor lighting in Doha, Qatar, between 2012 (cyan) and 2016 (red) as seen from the Suomi satellite. Areas newly lit since 2012 appear in bright red. Kyba et al. / Science Advance The team used the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on the Suomi National Polar-orbiting Partnership weather satellite to measure the change in global light emissions between October 2012 and October 2016. The VIIRS instrument is the first-ever calibrated satellite radiometer designed to measure nighttime lights – earlier investigations were often based on uncalibrated sensors on military satellites.

VIIRS observes the Day/Night band (DNB), which picks up visible through near-infrared wavelengths. Each pixel covers ½ square kilometer, a higher spatial resolution than previous instruments, which enables scientists to investigate neighborhood-scale changes, rather than a city or national, for the first time.

The researchers’ findings will not please astronomers: Earth’s nights are becoming brighter.

Read the Full Article by Jan Hattenbach at http://www.skyandtelescope.com/astronomy-news/lost-led-revolution-light-pollution-increasing/

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