A spectroscope is and instrument used by spectroscopists and they use the instrument to look at light from stars and tell what the star is made out of. Stars are made up of many different elements. With a spectroscope you can identify what type of element they have inside of it and is used to measure the properties of light. As light passes through object's or gasses in space it changes. When it changes they can identify which gas it is by the lines in the spectroscope. From the different line patterns you an tell what gasses are in front of the light.