The important factors in an astronomical telescope are the range, the resolution and the
magnification. We have already talked about the latter when we studied the way the telescope works, if you want to know more about the range and resolution, click on the corresponding word.
RANGE
It is the weakest stellar magnitude that we can observe with the telescope. A bright star can have a magnitude of 1 (a few are even brighter).
The weakest that we can see with the naked eye have a magnitude of
6. A telescope can let you view much weaker stars. In some cases up
to a magnitude of 21 or more. In order for you to compare, we can
say that a heavenly body is 100 times brighter than another which
is 5 magnitudes weaker (a star with a magnitude of 6 is 100
times weaker than one with a magnitude of 1).
It
is the smallest angle at which we can observe two stars of the same
magnitude as distinct. If we are observing stars S1 and S2 from
point O, then the resolution would be the minimum angle S1OS2 at
which they do not look like a single star. This magnitude is very
important in order to distinguish objects on planets, the sun (always
use an adequate filter) or the moon.
RESOLUTION
