"Currently there's a medium-sized coronal hole on the Sun's visible disk…"

31 OCTOBER 2002:
“Currently there’s a medium-sized coronal hole on the Sun’s visible disk…”

 

FROM CNN.COM:

Spooky auroras light up autumn nights

By Richard Stenger

Thursday, October 31, 2002
Posted: 12:07 PM EST (1707 GMT)

(CNN) — Green ghosts, wispy
witches and other glowing phantoms are dancing and darting around in the
night skies of October, which has proved a particularly productive month
for aurora hunters the world over.


    Sky watchers
photographed everything from a floating fairy ring in Norway, multicolor
spires in Arizona and pulsating swirls in Australia.


    In Finland,
Juha Kinnunen captured a glowering witch face with a considerable schnozzle
and two greenish ghosts looming over the Lapland.

    “Of those
three images, only one looked like a ghost with my own eyes as well, for
a brief moment. The other two turned up that ‘spooky’ during the exposure,
which was 4 to 6 seconds,” Kinnunen said Wednesday.


    “This
shows you how an active aurora changes shape continuously. The ghost I
photographed appeared for one horrifying moment only.”


    Auroras,
also known as the northern and southern lights, emit light as highly charged
particles from the sun excite atoms and molecules high in Earth’s atmosphere,
which creates a glow in the same manner as neon lights.


    While
concentrated in the most northerly and southerly regions, particularly
strong aurora displays can extend down into the mid-latitudes. Northern
lights, for instance, occasionally creep down to Mexico.


    The seasonal
lights tend to perk up in the autumn and spring for reasons that are not
entirely clear. What scientists do know is that the strength and scope
of the sky shows are directly tied to solar activity.


    From
time to time the sun unleashes powerful salvos of ionized gas that, if
they collide with Earth’s magnetic field, can spark nocturnal aurora displays
as well as disrupt satellites and power grids.

    Moreover,
coronal holes in the solar disk can leak out strong gusts of solar wind,
which can produce the same striking results if headed in our direction.


    Earth
is now exiting a solar wind stream that sparked numerous auroras since
October 23, according to NASA’s Spaceweather.com, which regularly posts
aurora images.


    “There
is a slim chance that trick-or-treaters in the northern United States and
Canada might see some ghostly auroras of their own on October 31st,” the
Web site said.


    There
could be more eye candy in the works in November too.


    “Currently
there’s a medium-sized coronal hole on the Sun’s visible disk,” Kinnunen
said. “It probably will create auroras within less than a week.”