Parked one million miles away from Earth, a NASA space camera has been taking photographs of our blue planet for the last twelve months.
Now given that humans first sent a satellite to space half a century ago, in 1957 when the Soviet Sputnik first orbited the earth, you would have thought we’d know what to expect from the images.
But turns out, NASA’s EPIC View has spotted something a little out of the ordinary.
The homeward-facing instrument, attached to NOAA’s Deep Space Climate Observatory, has spotted hundreds of flashes of light radiating from hundreds of different locations on our planet.
Alexander Marshak, DSCOVR deputy project scientist, first noticed these flashes occasionally appearing over oceans as he looked through the reel.
He said: “Large expanses of blue ocean and apparent coastlines are present, and close examination of the images shows a region of [mirror-like] reflection in ocean but not on land.”
And he proposed a simple explanation that this could just be sunlight reflecting off the water, back on to the sensor. That was until, they noticed them also appearing over land.
“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,” said Marshak.
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 team instead now believes that ice particles suspended high up in the earth’s atmosphere are to blame.
“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,” Marshak said.
The ability to detect glints, such as these, from further away, could be used by other spacecraft to study exoplanets.