Louis Ferdinand Cruls, Belgian-born Brazilian astronomer and geodesist (Diest 21 January 1848 - Paris 21 June 1906)
Determined the rotation period of Mars and measured apparent semi diameter of this planet.
Saw the Great Comet of 1882 that was known as Cruls Comet
Described an original method to graphical predicting of observation elements for stars occultation by Moon.
Invented a differential barometer.
Organized Dictionnaire Climatologique Universelle reckoning on scientists of world renown.
Valz Medal, Academie de Sciences de Paris (1882) for his work on spectroscopical analysis in the study of comets
Cruls Crater (in Mars)