Ice in the Air Makes Earth Sparkle From Space

A satellite orbiting Earth has captured images of our planet seemingly studded with flecks of gold glitter—the result, scientists say, of sunlight reflecting off ice particles in our atmosphere. They published their findings in the journal Geophysical Research Letters.

Alexander Marshak helps direct the Deep Space Climate Observatory (DSCOVR), a joint venture between NASA and NOAA. Tucked aboard that observatory is an instrument called EPIC, or the Earth Polychromatic Imaging Camera. As DSCOVR passes between Earth and the Sun, EPIC takes photo after photo, like a proud parent on prom night.

And just like an eager teen dressed for the dance, our planet is apparently just decked out in sparkles.

Astronomers have known about the little gold flashes of light for decades; legendary cosmos-gazer Carl Sagan even described them in a journal article three years before his death. In reviewing images from the Galileo telescope, Sagan and his colleagues developed a reasonable theory: The flashes were the ordinary reflections of sunlight bouncing off flat stretches of the ocean. After all, they said, there were no flashes over land.

But there were. Marshak and his colleagues first noticed a few tiny glints over landmasses in EPIC’s images. Then they went back to Galileo’s snapshots and found even more.

“When I first saw I thought maybe there was some water there,” Marshak said in a statement, “or a lake the sun reflects off of. But the glint is pretty big, so it wasn’t that.”

The flashes are also too big, and too significantly positioned relative to the Sun, to be the result of electric storms. “Lightning doesn’t care about the sun and EPIC’s location,” Marshak said, and “The source of the flashes is definitely not on the ground.”

That leaves only our atmosphere, which is sprinkled with a layer of fine ice particles. When the ice particles are floating horizontally and the Sun hits them just right, those particles coruscate better than a tiara under a disco ball.

And while Earth will always be the prom queen of our hearts, Marshak says we may not be the only bedazzled planet out there; in the future, researchers may be able to use these flashes to study exoplanets.