This is a graph of the relative flux of a star in Draco, close to the boarder of Cygnus and Lyra. The measured light dips because a planet around that star is transiting the star blocking some of the light, I'm still amazed that modest equipment (8" MakNewt) in a back garden in light polluted Bexleyheath can detect the presence of exo-planets. 

Whilst graphs are quite 'dry' when you think about what's being detected it is quite wonderous...

I only just got the start of transit as the star was behind the warm room of my observatory (see here for details of my observatory https://crayfordmanorastro.com/2019/02/11/a-crayford-type-roll-off-roof-observatory/ ) it took about an hour before the guide scope cleared the warm room!