The list - for this Answer - is quite lengthy: in fact everything that we know about Stars and all other celestial entities comes from the spectrums of the observed Light.
Telescopes are used for observing stars.
Astronomy, from the greek astra, meaning stars.
You Can Learn About The Stars
By observing stars and nature, as we do today.
Scientista started to gather information by observing the stars and learnt from here. First they used parallax to get the distance, then the apparent brightness, but after a while they can get luminosity, size/mass, what fuel they use (eg.helium), and then from that the learnt about the starts lifetime. Hope this is helpful
A place for observing stars and planets is usually called an observatory.
By observing the stars.
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You use a telescope to observe stars, and sometimes also use a star map.
It means that you're observing them through a turbulent atmosphere.
An observatory is a location used for observing terrestrial and/or celestial events
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