Tuesday, September 10, 2019

STEVE Puts on a Labor Day Show Over Canada

Have you met STEVE? Steve isn't a person, but rather a mysterious light in the sky that sometimes
The violet streamer in this photo is a STEVE (Strong Thermal
Emission Velocity Enhancement) seen over Canada on
September5. The green streamer is an auroral display.The two are
different even though they sometimes occur in tandem.
. (Photo by Chris Lahoda, via Spacewather.com)
accompanies aurora, but isn't an auroral display itself. STEVE stands for Strong Thermal Emission Velocity Enhancement and, according to Spaceweather.com, "(t)he phenomenon is caused by hot (3000°C) ribbons of gas flowing through Earth's magnetosphere at speeds exceeding 6 km/s (13,000 mph). These ribbons appear during some geomagnetic storms, revealing themselves by their soft purple glow." The source, it says may be "(m)agnetic explosions called 'substorms' more than 22,000 km above Earth's surface (that) hurl streams of hot plasma toward Earth. When the material reaches an altitude ~250 km above Earth's surface, it begins to emit a mauve light."
Several STEVE sightings were reported and photographed in Canada over Labor Day weekend during an auroral event linked to a geomagnetic storm.