Sun spots are locations where the magnetic field is concentrated.
The spots also normally occur is in pairs. These pairs represent the
negative and positive regions of the magnetic field. Between the positive
and negative areas there are magnetic field lines. Plasma gets trapped
and is forced to travel along these field lines. This occurrence is called
a coronal loop. The magnetic field can also store energy. When the field
gets twisted and tangled enough it finally can take no more and releases
its energy. This is a Coronal Mass Ejection (CME). Some of this energy gets
'hooked' by the suns gravity and reeled back into its atmosphere. The rest
is thrown out into space with its own magnetic field. The earth experiences
a constant solar wind, but if a CME is directed towards earth it is like
a sudden huge gust of wind. The earths magnetosphere acts as a blanket or
shield, repelling some of the gust, but some of the particles from the CME
get trapped by the earth's magnetic field and creates Auroras from the particles
inter acting with the atmosphere. Sometimes the result is not quite so pretty
there are dangerous and destructive results from CME s. Astronauts, satellites,
power grids ,and communications can be harmed or destroyed. So we can see
that by studying coronal loops we can get more insight for forecasting the
suns weather and improve the safety of our astronauts, satellites, and communications.
in short:
1. Magnetic field lines fill the corona
2. Coronal loops can be observed when plasma is heated within
a magnetic flux tube, resulting in
ionization
3. The wavelength of the photons observed can be used to determine the ion
formed in the loop, each
ion being formed within a temperature range.
4. The values of temperature so determined are currently the most accurate
temperature diagnostic
tool available to the observer.