The Sun is the closest star to the earth, at a distance of some 150
million kilometers away. Because of this we are able to study the Sun
in great detail using an array of instrumentation both in
space and on
the ground.
With dedicated solar telescopes we are able to identify individual features on the
solar surface
and in the
solar atmosphere.
The average star, however, is many
light years away, the closest being Proxima Centauri at approximately 4.5 light
years distance. The great distances involved in stellar astronomy
means that normal telescopes are not particularly useful in studying
the average star. Instead special observational techniques are
required in order to obtain some information about any particular star.
Before discussing these techniques it is important to understand some
basic concepts about stars, including the Sun.