spaceSpace and Physics

NASA Sees Your Holiday Lights From Space

304 NASA Sees Your Holiday Lights From Space
Dark green pixels are areas where lights are 50 percent brighter, or more, during December / NASA's Earth Observatory/Jesse Allen

Illuminate that rooftop! Whether you’re putting up a single string of twinkly reds and greens or if you’re creating a spectacle of lights that’s sure to create a bottleneck on your street…NASA is watching. By analyzing data from the NOAA/NASA Suomi National Polar-orbiting Partnership satellite, scientists have identified how patterns of light intensity in our night skies change during the holidays. 

Compared with light output from the rest of the year, U.S. cities shine up to 50 percent brighter during Christmas and New Year’s. And it starts as early as Black Friday. Most of the light intensity increases are thanks to suburbs and the outskirts of major cities where there’s more yard space and more single-family houses. Lights in the middle of big cities don’t seem to increase as much, but they still brightened between 20 and 30 percent. 


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

In the Middle East during the month of Ramadan—when meals and social gatherings might be pushed into the nighttime hours—lights in several cities shine more than 50 percent brighter. In fact, light use in Saudi Arabian cities increased by about 60 to 100 percent through the month of Ramadan. And while light use didn’t increase in many areas, during the Eid al-Fitr celebration that marks of the end of Ramadan, it soared across all the neighborhoods they studied. 

Suomi NPP carries an instrument called the Visible Infrared Imaging Radiometer Suite (VIIRS). You might remember the Earth at Night maps in 2012 created from VIIRS data; those images are composites of monthly averages collected on nights without clouds or moonlight. The new holiday lights analysis filters out moonlight, clouds, and airborne particles to isolate city lights daily. The high resolution can see variation at the neighborhood level. But they could only analyze snow-free cities, since snow reflects light so much. 

Besides being festive, the dataset helps researchers better understand what impacts our energy decisions. "More than 70 percent of greenhouse gas emissions come from urban areas," Román says. "If we're going to reduce these emissions, then we'll have to do more than just use energy-efficient cars and appliances. We also need to understand how dominant social phenomena, the changing demographics of urban centers, and socio-cultural settings affect energy-use decisions."


These new illustrations were presented at the American Geophysical Union's fall meeting in San Francisco this week. You can see more (and maybe find your city) on their Flickr page. And here’re the lights from where I’ll be for Christmas:

Images: NASA's Earth Observatory/Jesse Allen


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