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On March 17 , 2015 , a bloodline - red bow of twinkle cut through the sky hundreds of mile above New Zealand . Over the next half hour , an amateur skywatcher observed that arc as it transmute before his eyes into one of Earth ’s most puzzling atmospheric whodunit — the eery ribbon of light known as STEVE — freshly released images reveal .
STEVE , short for " strong thermal velocity sweetening , " is an atmospheric oddity first described in 2018 , after amateur aurora chaser interpret a narrow stream of gauzy purple light arc across the sky over northern Canada . scientist who studied the phenomenon before long substantiate that STEVE was not anaurora — the multi - colored freshness that appears at high latitudes when solar particle collide with atoms high inEarth’satmosphere . Rather , STEVE was a separate and unique phenomenon that ’s " completely unknown"to skill .
Auroral images taken over New Zealand, showing a red auroral arc (left), the skyglow called STEVE (middle), and a partial arc with green picket fence structures (right).
Unlike the northern lights , which tend to shimmer in broad band of green , disconsolate or cherry light count on their altitude , STEVE typically appears as a single ribbon of purple - white Christ Within that stabs directly upward for hundreds of mile . Sometimes it is accompanied by a broken green note of lighting nicknamed the " lookout man fence " phenomenon . Both STEVE and its picket fence acquaintance look much lower in the sky than a typical cockcrow does , in a part of the atmosphere known as the subauroral region , where charge solar particles are unlikely to trespass .
Now , newfangled research publish in the journalGeophysical Research Lettershas tie in STEVE to another subauroral body structure , known as stable auroral red ( SAR ) arcs , for the first time .
In the newfangled cogitation , the authors liken the New Zealand skywatcher ’s March 2015 footage with contemporaneous satellite observations and data from an all - sky imager at the nearby University of Canterbury Mount John Observatory . Combining these three sources give the researchers a comprehensive look at STEVE ’s unexpected coming into court that night .
The complete set of auroral images taken by a citizen scientist, showing the auroral objects through a range of color filters.
That evening ’s sky show begin with the appearance of a roue - red SAR arc that swooped at least 185 miles ( 300 klick ) over Dunedin , New Zealand . artificial satellite data point showed that the arc ’s appearance coincided with a firm geomagnetic storm — a showering of charged solar subatomic particle into Earth ’s upper atmosphere — that lasted for approximately half an hour .
As the violent storm subside , the red arc step by step collapse way to the theme song mauve bar of STEVE , which slashed through the sky in almost the exact same spot . Just before STEVE fade , the fleeceable picket fence structure shimmered into view . According to the researchers , this is the first recorded occurrent of all three structures appear in the sky together , one after the other — possibly revealing new clues about the geological formation and phylogeny of STEVE .
" These phenomenon are decided from auroras , as their optic signatures look to be trigger by extreme caloric and kinetic muscularity in Earth ’s atmosphere , rather than produced by energetic particle rain down down into our aura , " the investigator wrote in the newfangled study .
Satellite observations of the event evoke that the Nox ’s geomagnetic violent storm may have played a key role in this parade of sky lights .
During the storm , a fast - moving reverse lightning of charged mote appear alongside the red SAR arc , the researcher write . Known as subauroral ion drift ( SAID ) , these streams of red-hot , riotous particles typically come out in the sky ’s subauroral zone during geomagnetic tempest . The planet observations also showed that the current ’s heat and swiftness escalate when STEVE look about 30 minutes after .
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According to the researchers , a " plausible generation mechanism " for STEVE could be the interaction between these fast - motivate ion stream andnitrogenmolecules in the subauroral zone ; when the charged , spicy particles whop against nitrogen molecules , the molecules become excited , emitting mauve light to combust off their extra energy .
The new study illuminate part of the mysterious phenomenon , but more observations of STEVE — from citizen scientist and professional researchers alike — are need to further trap down this theory .
earlier published on Live Science .
