|It was a quiet day on the
The above image shows, however, that even during off days the
Sun's surface is a busy place.
Shown in ultraviolet light, the relatively
cool dark regions have temperatures of thousands of degrees
Large sunspot group AR 9169 from the last
solar cycle is
visible as the bright area near the horizon.
The bright glowing gas flowing around the
has a temperature of over one million degrees
The reason for the high temperatures is
but thought to be related to the rapidly changing
magnetic field loops that channel solar plasma.
sunspot group AR 9169 moved across the
Sun during 2000 September and decayed in a few weeks.