Did you know if you looked through this you could see what the Universe is made of?
A spectrum is the result of splitting up this light into its constituent colours and it is by studying spectra that astrophysicists have been able to make their most important discoveries.
Much of what we know about the composition of the Universe has been gleaned from the astronomers studying spectra with instruments like this one.
This is a brass laboratory spectroscope. When dismantled it consists of three tubes which screw into one another.