To test their theory, the researchers reasoned that if the flashes were caused by sunlight bouncing off ice particles, then the shots would have to be occurring when DSCOVR was in such a position that sunlight would be reflected directly at it when it hit the crystals. This camera is taking these images from a spot which is between the Sun and the Earth. Alexander Marshak, DSCOVR deputy project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, noticed light flashes occasionally appearing over oceans at first as he looked through the EPIC images.
Marshak and a team of researchers discovered that similar reflections were noticed over the ocean in 1993. Alexander Marshak said, "When I first saw it I thought maybe there was some water there, or a lake the sun reflects off of".
While it was initially thought that the odd flashes of light only appeared over oceans, scientists have now discovered that they could also be seen over land. Enthusiasts who were looking at the database of images from DSCOVR began pointing out the flashes, too.More news: Trump threatens Comey, suggests possible leaks of 'tapes'
In 1990, the Galileo spacecraft captured some of these flashes in Earth's atmosphere while it was studying Jupiter. Initially, the land flashes were attributed to smaller water bodies like lakes or ponds but the flashes were too big and bright, scientists realised.
Tasked with explaining this weird phenomenon, Marshak and his team catalogued all known flashes over land from the Galileo and EPIC images, and mapped out their locations. This camera is set to take the image after every hour.
First, they cataloged all prospective sunlight glints over land in images from the EPIC camera and found 866 bursts between DSCOVR's launch in June 2015 and August 2016.
If these unusual phenomena were caused by reflected sunlight, the researchers suspected they would be concentrated to distinct locations on Earth, where the angle between the sun and Earth is the same as that between the spacecraft and Earth.More news: Senior White House officials tout Trump's first foreign trip as president
About 25 years ago, astronomer Carl Sagan and his team noticed something a little odd about images coming back from the Galileo spacecraft: They showed glints of light seemingly coming from Earth.
This helped confirm that it wasn't something like lightning causing the flashes, Marshak said: "Lightning doesn't care about the sun and EPIC's location". Two channels on the instrument are created to measure the height of clouds, and when the scientists went to the data they found high cirrus clouds, 3 to 5 miles (5 to 8 kilometers) where the glints were located.
Another feature of the EPIC data helped confirm that the flashes were from a high altitude, not simply water on the ground. But as they continued their work plotting the angles, they came to another conclusion: the flashes were sunlight reflecting off of horizontal ice crystals in the atmosphere.
In addition to the implications for Earth, scientists say glints such as those spotted by DSCOVR could even be used to study exoplanets.More news: UNSC, Turkey condemn North Korea missile test
Plotting the position of the flashes against the position of horizontally floating ice particles in the air finally gave the scientists the answers they sought.
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