Don't forget important discoveries are also made by or with the help of amateurs, who permanently observe the night sky and measure the coordinates, i.e. the relative positions, of luminating objects. This allows others, mostly professionals, to calculate their motions and obtain information about the (hidden) masses, i.e. luminating and non luminating objects, inducing and influencing them. By this means, black holes, 'dark' masses, or asteroids, 'fast' moving illuminated objects, have been discovered.