NASA scientists believe they have discovered the origins of the strange lights that the EPIC instrument caught reflecting off of Earth a few years ago.
The Deep Space Climate Observatory first uncovered this strange phenomenon during a space weather satellite launch in 2015. Over that year, researchers observed hundreds of different flashes of light in different spots across the world. This prompted to NASA to further investigate.
The agency found that the reflections were the same ones Carl Sagan uncovered in 1993 while studying Galileo spacecraft images. Though the agency initially thought the flashes were caused by sunlight reflecting off the surface of the ocean, the new study suggests they are actually caused by high-altitude ice crystals.
Initially, the team thought the light may have been the result of the sun hitting the ocean. However, the flashes also appeared on land. This stumped researchers because the glints — which could be viewed from space — were much too big to come off smaller bodies of water.
“We found quite a few very bright flashes over land as well,” said lead author Alexander Marshak, DSCOVR deputy project scientist at NASA’s Goddard Space Flight Center, in a statement. “When I first saw it I thought maybe there was some water there, or a lake the sun reflects off of. But the glint is pretty big, so it wasn’t that.”
This led the team to focus on water in other places, specifically turning their attention to ice particles situated high up in the atmosphere. They then conducted a number of different experiments that confirmed the small crystals were indeed the source of the glints.
To prove this, the scientists took an inventory of flashes that sparked up over land between June 2015 and August 2016. If the flares were caused by reflected sunlight, they would have only been in certain spots where the angle between the Earth and the sun is the same as the angle between the satellite and the planet. The angles matched in every instance, suggesting the lights were the result of a reflection, Tech Times reports.
Then, to prove the light originated on the ground, the team plotted all of the points. This revealed that all of the locations where the flashes occurred had cirrus clouds, which are made up of ice crystals.
“The source of the flashes is definitely not on the ground,” said Marshak. “It’s definitely ice and most likely solar reflection off of horizontally oriented particles.”
The team next plans to see how common the horizontal ice crystals are. If they are common enough to impact the amount of sunlight that reaches Earth there is a chance they could one day help scientists create more accurate computer models that show how much heat enters and leaves the atmosphere.
The recent findings were outlined in the journal Geophysical Research Letters.