Explanation:
This aurora was a bit of a surprise.
For starters, on this Friday morning in August 2002, no intense
auroral activity was expected at all.
Possibly more surprising, however, the
aurora appeared to show an usual structure of green
rays from some locations.
In the above image, captured from
North Dakota,
USA, a picket fence of green rays stretches toward the horizon.
Mirroring the green rays is a
red band, somewhat rare in its own right.
Lights from the cities of
Bismarck and Mandan are visible near the horizon.
Large sunspot groups indicate that activity from an
active Sun
is relatively likely, possibly causing
other streams of
energetic particles to cascade onto the Earth
and so causing more
auroras.
