Citizen scientists looking at NASA photos of the Earth must have all shared something like a moment of “Uh, what was that?” when they spotted flashes of light coming from our planet.
So, they — those “keen observers from outside NASA” — collectively clicked the contact info of the scientist responsible for the photos taken by NOAA’s Deep Space Climate Observatory (DSCOVR) from about a million miles away and asked him, “Uh, what are those bright flashes of light coming from Earth?”
The scientists had seen them too, NASA said in a news release, but you know they had other priorities.
Nevertheless, spurred on by those keen observers (some of whom, let’s be honest, undoubtedly thought of giant spaceships either signaling compatriots in deep space or unwittingly reflecting sunlight) believe they have determined the cause of the flashes of light.
“The source of the flashes is definitely not on the ground. It’s definitely ice, and most likely solar reflection off of horizontally oriented particles,” said Alexander Marshak, DSCOVR deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Basically, the agency explained, the scientists figured it was ice reflecting the light from high cirrus clouds because the glints were clearly not coming off of the surface of the Earth, like from a lake or flat bit of ocean, and because of the angle the spacecraft was to the Earth each time it captured the glints.
What the agency said on Monday:
First, the researchers cataloged all of the prospective sunlight glints over land in images from the EPIC camera. The flashes show up in three distinct colors because the camera takes the red, green and blue images several minutes apart. In all, the scientists found 866 bursts between DSCOVR’s launch in June 2015 and August 2016.
The scientists reasoned that if these 866 flashes were caused by reflected sunlight, they would be limited to certain spots on the globe – spots where the angle between the sun and Earth is the same as the angle between the spacecraft and Earth, allowing for the spacecraft to pick up the reflected light.
When they plotted the locations of the glints with where those angles would match, given Earth’s tilt and the spacecraft’s location, the two matched.
The agency’s scientists also determined that these glints were the same phenomena discovered in 1993 by Carl Sagan and his fellow scientists working with the Galileo spacecraft as it sped toward Jupiter. Source: seattlepi.com