Astronomy Cast 1.2: Giovanni Cassini (Episode 228)

This podcast is a brief biography of Giovanni Cassini and his major contributions of the discovery of Saturn's moons, the gap in Saturn's rings (known as the Cassini Division), Jupiter's Red Spot, and the speed of light. Cassini lived at the time when gravity was discovered, and, believe it or not, he did not accept the truth of gravity at first.  However, Cassini was a very smart person: he obtained his PhD at the age of 25, determined the rotation rate of Jupiter, and his observations lead the calculation of the speed of light.  That is crazy:  it is an amazing thing that he was able to come to the conclusion of the speed of light by observing the accelerations and lags in the planets' moons' phases.  His contribution to our understanding of the universe was a grand one: he developed complex ideas that made a huge impact on the growth of calculations of the universe.  Giovanni Cassini's work lead to an accurate understanding of the scale of the solar system, and the distance of the planets.