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The origin story behind cosmic phenomenon STEVE

In this image, STEVE is a glowing pink streak across the dark starry purple sky. There are a row of black pine trees.
STEVE glows pink. Photo: Ryan Sault/AGU

The Internet's favorite light in the night sky finally has an origin story.

What's new: Scientists have figured out what causes the cosmic phenomenon affectionately known as STEVE — a mauve-colored streak that appears farther south than where auroras typically are visible.

Details: A new study published in the journal Geophysical Research Letters suggests that STEVE — short for Strong Thermal Emission Velocity Enhancement — isn't an aurora at all, but is in fact a "skyglow" created by heated and shining particles in the ionosphere.

  • STEVE's glow is produced when particles in the ionosphere are heated through friction, causing them to glow, according to a news release accompanying the study from the American Geophysical Union.
  • Auroras, on the other hand, are caused by charged particles from the sun slamming into neutral particles in the upper atmosphere, creating their distinctive glow.
  • The study drew on satellite data collected when STEVE was aglow in April 2008 and May 2016, and then matched them against photos of the phenomenon.
  • A 2018 study showed that STEVE wasn't an aurora, but it was still unclear exactly what caused the glow.

Background: STEVE rose to prominence in 2018, when news of the new kind of skyglow with the funny name spread on the internet. The unique glow was first noted by a sky-watchers' Facebook group, with one of the members, Chris Ratzlaff, naming it STEVE, according to NASA. It wasn't until later on that STEVE received its acronym.