STEVE over Copper Harbor
Image Credit & Copyright:
MaryBeth Kiczenski
What creates STEVEs?
Strong Thermal Emission Velocity Enhancements
(STEVEs) have likely been seen since antiquity,
but only in the past five years has it
been realized that their colors and shapes make them different from
auroras.
Seen as single bright streaks of pink and purple, the origin of
STEVEs remain an active topic of research.
STEVEs may be related to
subauroral ion drifts (SAIDs), a supersonic river of hot atmospheric
ions.
For reasons
currently unknown,
STEVEs are frequently accompanied by green
"picket-fence" auroras.
The featured STEVE image is a combination of foreground and background exposures taken consecutively in mid-March from
Copper Harbor,
Michigan,
USA.
This bright STEVE lasted several minutes, spanned from horizon to horizon,
and appeared in between times of
normal
auroras.