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Holiday lights brighten cities in outer space images
City lights shine brighter during the holidays in the U.S. when compared with the rest of the year, as shown using a new analysis of daily data from the NASA-NOAA Suomi NPP satellite. Dark green pixels are areas where lights are 50 percent brighter, or more, during December. - photo by NASA's Earth Observatory/Jesse Allen

Holiday lights are visible even from outer space.

While individual light displays can’t be seen from far above the Earth, cities celebrating the holidays appear much brighter around Christmas, New Year’s and Ramadan,according to NASA. Scientists recently mapped the trend.

“Around many major U.S. cities, nighttime lights shine 20 to 50 percent brighter during Christmas and New Year's when compared to light output during the rest of the year, as seen in the satellite data,” a statement from NASA reads. “In some Middle Eastern cities, nighttime lights shine more than 50 percent brighter during Ramadan, compared to the rest of the year.”

Black Friday marked the beginning of bright lights in the U.S. in past years, according to researchers. The increased light output continued through New Year’s Day. Light intensity increased the most in suburbs and outskirts of major cities, where it grew by 30 to 50 percent, NASA reported. Lights brightened by 20 to 30 percent in central urban areas.

"It's a near ubiquitous signal,” NASA researcher Miguel Román said in a statement. “Despite being ethnically and religiously diverse, we found that the U.S. experiences a holiday increase that is present across most urban communities. These lighting patterns are tracking a national shared tradition."

The data and images come from the NOAA/NASA Suomi National Polar-orbiting Partnership satellite. Using a Visible Infrared Imaging Radiometer Suite instrument and an advanced algorithm, researchers said they isolated city lights on a daily basis by filtering out clouds, moonlight and other airborne particles, according to NASA.

Seventy cities were analyzed for the study. Only data from snow-free cities was used because snow reflects light.