A New Type of Aurora Ripples Across the Sky in Horizontal Green ‘Dunes’
By Katherine J. Wu/Smithsonianmag.com
Since time immemorial, people around the world have been beguiled by the wonders of the night sky. But even after millennia of study, the cosmos keeps hitting us with surprises. Reporting this week in AGU Advances, a team of researchers has discovered a brand new type of aurora, thanks to the help of some intrepid citizen scientists.
Described as “dunes,” the spectacular light show manifests as a series of rippling emerald ribbons that extend toward the equator. Unlike typical aurorae, which are oriented vertically like fence posts, the dunes hang horizontally like blinds in a window, giving off the appearance of hills of sand cascading across a beach.
The dunes also occur at an unusual altitude, about 60 or so miles off the Earth’s surface, in a layer of the atmosphere too high to access by balloons and too low to explore with satellites—a sort of scientific no man’s land. This strip of sky, technically known as the mesosphere, is so poorly understood that physicists jokingly dub it the “ignorosphere,” study author Minna Palmroth, a physicist at the University of Helsinki explains in a statement. But sussing out what gives the dunes their dazzling gleam might help researchers ….Read More: