Our holiday lights are so bright, NASA can see them from space

All those strings of lights you're decorating your house with are contributing to a brightening effect in cities around the world, and a satellite can see the difference.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser
2 min read

Darker green areas in this image of California show where lights are at least 50 percent brighter during December. NASA's Earth Observatory/Jesse Allen

I'm a lazy holiday decorator. I leave my Christmas lights up year-round and turn them on for holidays. When Thanksgiving arrives, those sparkly blue lights start to get a workout with a timer running them from dusk until dark. I'm not alone in my LED festiveness. Looking down from space, NASA has noticed a distinct holiday brightening effect in cities across the globe.

Images captured by Suomi NPP, a satellite that is a joint mission between NASA and the National Oceanic and Atmospheric Administration, show a seasonal increase in light coming from US cities.

"It's a near ubiquitous signal. Despite being ethnically and religiously diverse, we found that the US experiences a holiday increase that is present across most urban communities," says Miguel Román, a NASA scientist and member of the Suomi NPP Land Discipline Team. "These lighting patterns are tracking a national shared tradition."

NASA was able to isolate and analyze this seasonal change, thanks to an advanced algorithm that removes factors like moonlight, airborne particles and clouds from the data. The result is a clear view of city lights. Román notes that the trend begins around Black Friday and continues through New Year's Day.

It's not only the US that enjoys lighting up for special occasions. Suomi NPP also noticed brighter city lights in several Middle East cities during the Muslim holy month of Ramadan. Researchers studied three years of data before reaching this conclusion, noting that the change in lights synched with the Islamic calendar each year. The satellite team reports this is likely due to more active nights of social gatherings and markets -- and therefore more lights -- during the period of fasting.

This fascinating satellite data isn't solely about NASA getting into the holiday spirit. The information will help researchers track energy use across the globe.

"What's really difficult to do is to try and track people's activity patterns and to understand how this shapes the demand for energy services. We can now see pieces of these patterns from space -- when, where and how often we turn on the lights," says Román.