Galileo Galilei Quote

I therefore concluded, and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury about the Sun; which at length was established as clear as daylight by numerous other observations. Referring to his pioneering telescope observations.

The sidereal messenger of Galileo Galilei and a part of the pref. to Kepler's Dioptrics (ed. 1960)