A NASA camera launched in 2015 one million miles from Earth was capturing mysterious flashes of light on Earth in images that had researchers perplexed since they began turning up. On May 15, NASA announced the culprit of these light flashes: crystals of ice floating above the Earth’s surface.
In a paper published in Geophysical Research Letters by Alexander Marshak, DSCOVR deputy project scientist at NASA’s Goddard Space Flight Center, Tamas Varnai of the University of Maryland, and Alexander Kostinski of Michigan Technological University, the scientists proved the origin of the light flashes over land discovered in these images. “We construct a yearlong time series of flash latitudes, scattering angles and oxygen absorption to demonstrate conclusively that the flashes over land are specular reflections off tiny ice platelets floating in the air nearly horizontally,” wrote the scientists. The flashes of light only occur at certain latitudes where the angle of the sun and Earth matches with the Earth and spacecraft where the observing instrument is located. Mapping out possible latitudes where these flashes could occur and areas where the flashes were observed over land matched, eliminating other possible explanations like lightning strikes. To prove the flashes of light were caused by ice crystals in clouds, the scientists deciphered the wavelengths of light in the images to determine their estimated origin due to oxygen in the atmosphere absorbing certain wavelengths of light. The absorption matched the rate expected from an object three to five miles above the ground. “These glint observations also support proposals for detecting starlight glints off faint companions in our search for habitable exoplanets.”
The latter observation demonstrates that their findings could prove pivotal in the search for Earth-like exoplanets throughout the universe, as astronomers search for possible harbors of life within habitable zones of foreign stars. Some of the flashes observed were so bright they overwhelmed the instruments reading them even at 1 million miles away, giving researchers hope that these flashes could be used by astronomers to determine if observed exoplanets have water on the surface. Researchers also hope this effect could be applied to other chemical compositions, changing the way exoplanets in the universe are studied.
According to NASA, as of May 18, 3,488 planets have been scientifically confirmed, with 21 exoplanets less than twice the size of Earth in the habitable zone confirmed. These planets are just the tip of the iceberg of what scientists estimate exist in the universe. In our galaxy alone, a 2013 study estimated there are 20 billion Earth-like planets. Discovering mechanisms to deduce which of these planets could potentially harbor life, like using light flashes from reflections of water or other elements, could be the key to discovering a potential Earth twin.