Holiday Lights Actually Can be Seen From Space

The holidays shine bright even from space.

NASA scientists and colleagues have identified how patterns in nighttime light intensity change during major holiday seasons. Around major U.S. cities, nighttime lights shine 20 to 50 percent brighter during Christmas and New Year's compared to light output during the rest of the year, according to NASA satellite data.

In some Middle Eastern cities, nighttime lights shine around 50 percent brighter during Ramadan, compared to other times of the year.

Suomi NPP, a joint NASA/National Oceanic and Atmospheric Administration mission, carries an instrument called the Visible Infrared Imaging Radiometer Suite (VIIRS). VIIRS is capable of observing the dark side of the planet and detecting the glow of lights in cities and towns around the world.

In 2012, NOAA scientists released "Earth at Night" maps, created from VIIRS data, accoridng to NASA. These images are composites, based on monthly long-term averages of data collected on nights with no clouds or moonlight.

The new analysis of holiday lights uses an advanced algorithm, developed at NASA's Goddard Space Flight Center in Greenbelt, Maryland. The algorithm filters out moonlight, clouds and airborne particles in order to isolate city lights on a daily basis.

The data from this algorithm provided satellite information on light output across the globe, which allowed scientists to track when and how bright people illuminate at night.

In the U.S., the lights get brighter on "Black Friday," the day after Thanksgiving, and continue through New Year's Day, said Miguel Roman, a research physical scientist at NASA Goddard and member of the Suomi NPP Land Discipline Team, who co-led this research.

Roman and his colleagues studied the light output in 2012 and 2013 in 70 U.S. cities, as a first step in determining patterns in urban energy use.

In most places, light intensity increased by 30 to 50 percent. Lights in central urban areas didn't increase as much as in the suburbs but still brightened by 20 to 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," Roman said. "These lighting patterns are tracking a national shared tradition."

Researchers could only analyze snow-free cities since snow reflects so much light. They mainly focused on places in the U.S. West Coast from San Francisco and Los Angeles and cities south of a rough imaginary line from St. Louis to Washington, D.C.

"Overall, we see less light increases in the dense urban centers, compared to the suburbs and small towns where you have more yard space and single-family homes," said Eleanor Stokes, a NASA Jenkins Graduate Fellow and Ph.D. candidate at Yale University's School of Forestry and Environmental Studies, New Haven, Connecticut, who co-led the study with Roman, according to NASA.