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A study of nighttime illumination during holidays shows that in many cities, lights are up to 50 percent brighter during the festive season. Scientists at NASA decided to investigate it after noticing a major discrepancy in data describing the average brightness of the lights in Cairo. The boost turned out to correspond to the Muslim holiday of Ramadan, in which observers fast during the day and shift many activities to the nighttime. A similar pattern was found in the U.S. during December, especially in suburban areas where single-family households fill their lawns with decorations.

"Despite being ethnically and religiously diverse, we found that the U.S. experiences a holiday increase that is present across most urban communities," said NASA's Miguel Román, who co-led the study. "These lighting patterns are tracking a national shared tradition." The data isn't just for fun, either: Understanding patterns of consumption and how they relate to culture, weather and other factors is essential to any effort to reduce energy use.



—Devin Coldewey