Gian Domenico Cassini (continued)
Cassini's scientific activities covered various fields of astronomy, as well as
hydraulics, art of war, entomology and even medicine – he took part in some of
the very first blood transfusion experiments.
Cassini measured the rotation of Mars to within a 3-minute accuracy and he established the distance of Mars from Earth. He could therefore then work out the Earth-Sun distance (the basic Astronomical Unit of measurement within the solar system) with a 7% accuracy.
He also measured the rotation of Jupiter and discovered on it the "red spot", the eye of a gigantic hurricane which has raged in the planet’s atmosphere for centuries.
He discovered four satellites of Saturn and the division between the rings of the planet, known today as the Cassini Division. He sensed that the rings were not a rigid body but rather a myriad of small particles.
The astronomical community has remembered Cassini and all his important
discoveries by naming after him the Cassini Crater on the moon, the Cassini
Crater on Mars and the Cassini Region on the satellite of Saturn, Iapetus.