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.
