surface of the sun as observed from outside regions).
(See fig. 1-2).
Solar Prominences/Filaments
Solar prominences/filaments are injections of gases
from the chromosphere into the corona. They appear as
great clouds of gas, sometimes resting on the Sun’s
surface and at other times floating free with no visible
connection. When viewed against the solar disk, they
appear as long dark ribbons and are called filaments.
When viewed against the solar limb (the dark outer
edge of the solar disk), they appear bright and are called
prominences. (See fig. 1-2.) They display a variety of
shapes, sizes, and activity that defy general description.
They have a fibrous structure and appear to resist solar
gravity. They may extend 18,500 to 125,000 miles
(30,000 to 200,000 km) above the chromosphere. The
more active types have temperatures of 10,000°K or
more
and
appear
hotter
than
the
surrounding
atmosphere.
Sunspots
Sunspots are regions of strong localized magnetic
fields and indicate relatively cool areas in the
photosphere.
They
appear
darker
than
their
surroundings and may appear singly or in more
complicated groups dominated by larger spots near the
center. (See fig. 1-2).
1-4
AGf0102
SOLAR PROMINENCES
PLAGE
FLARE
SUNSPOTS
(FILAMENTS)
Figure 1-2.—Features of the solar disk.
