Five planets revealed after 20 years of observation. To confirm the presence of a planet, it is necessary to wait until it has made one or more revolutions around its star. This can take from a few days for the closest to the star to decades for the furthest away. Only a telescope dedicated to the search for exoplanets can carry out such measurements over such long periods of time, which is the case of the EULER telescope of UNIGE. Source 3a.