After years of describing red sprites as “rare” and “elusive,” astronauts on the International Space Station are out to prove me wrong. They photographed two entirely unrelated sprites above thunderstorms in the Midwest and Mexico within minutes. What’s going on?!
Red sprite over Missouri or Illinois as seen from 2,200 kilometers away over Mexico. Image credit: NASA/Earth Observatory
If this photograph of a red sprite over the Midwest looks eerily familiar, it’s not déjà vu. We previously squealed an entirely unrelated red sprite over a thunderstorm in Mexico photographed by the same astronauts just moments later. If the timing seems implausible, it is certainly a very rare occurance: we only got our first photograph of a red sprite in 1989, and our first colour photograph in 1994. While these aren’t the first photographs of red sprites we’ve ever seen from space, the total number is still countably small enough to be a very scanty gallery.
Both sprites were photographed by astronauts aboard the International Space Station on August 20, 2015. NASA’s Earth Observatory explains:
Viewing from a point over northwest Mexico, astronauts aboard the International Space Station looked northeast and shot this unusual photograph of a red sprite above the white light of an active thunderstorm. In the top image, the sprite was 2,200 kilometers (1,400 miles) away, high over Missouri or Illinois; the lights of Dallas, Texas appear in the foreground. The sprite shoots up to the greenish airglow layer, near a rising moon.
Two minutes and 58 seconds later, as the ISS was over the coastal Mexican resort of Acapulco, the crew documented another red sprite (lower image) over a brilliant white thundercloud and lightning discharge near the coast of El Salvador. The shorter distance to the storm—about 1,150 km (710 miles)—makes it somewhat easier to see details of the sprite. City lights are a diffuse yellow because they are shining through clouds.
Along with the new image of the Midwestern sprite, they’ve also released an annotated version of the Mexican red sprite we were cooing over last week:
Red sprite over Mexico as seen from 1,150 kilometers away over El Salvador. Image credit: NASA/Earth Observatory
For a long time we thought red sprites were a form of lightning, but thanks in part to our slowly-growing collection of photographs we’ve learned they’re actually cold plasma electrical discharges. Red sprites are usually associated with thunderstorms, with clusters of tendrils stretching up to one hundred kilometers tall.
This is starting to feel a bit like public transit: after waiting for ages, a pair sprites show up within minutes of each other just where the astronauts happen to be looking. If someone wants to start in on the conspiracy theory connecting these sprites, we’re listening!