A series of bright glints of light reflecting from Earth puzzled NASA scientists until recently, when their study concluded that the flashes were coming from microscopic ice crystals high above Earth.
For years, any bright flashes of light captured by deep space cameras were typically chalked up to be the sun reflecting over bodies of water, based on the 1993 findings of the late astronomer Carl Sagan.
But NASA fellow Alexander Marshak noticed that the glints appeared over land as well.
“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,” Marshak said in a release.
Marshak and his colleagues also ruled out lightning flashes after conducting a series of tests, which showed the flashes were mirror-like reflections. They recorded 866 flashes over 13 months from 2015 to 2016.
“We were able to prove that little ice crystals in clouds were sending this light back millions of miles away, so that was quite surprising and exciting,” said Alexander Kostinski, a Michigan Tech University professor of physics and co-author of this latest study.
The camera was aboard the DSCOVR satellite, a Deep Space Climate Observatory launched by NASA in 2015. One implication of this finding is in the future of studying climate change and how heat enters Earth’s atmosphere.
“These clouds are cooling us off by reflecting the sun energy back to space, but what we didn’t realize is that they may be reflecting more than we previously thought,” said Kostinski.
“These bright spots are bright because they’re reflecting a lot of energy back. The main idea is that if they’re so bright, then these spots reflect a lot more than the average diffused reflection. It appears that in a single bounce, most of the light goes back and that means none of that portion of light goes through and warms us up,” he said.
Kostinski stressed that it’s an exciting discovery for climate change researchers but “it’s too early to tell” if these ice crystals are actually cooling us down.
Another important implication of these findings, said Kostinski, is the practical application in imaging exoplanets (planets outside of our solar system).
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