Across the span of 1671 through 1684, Italian-French astronomer Giovanni Cassini discovered four moons of Saturn while working under the patronage of King Louis XIV. Cassini collectively named the four “Sidera Lodoicea” – the “Stars of Louis.” But they’re better known as Iapetus, Rhea – his second find, discovered Dec. 23, 1672 – Tethys, and Continue reading "Dec. 23, 1672: Saturn’s moon Rhea is discovered" The post Dec. 23, 1672: Saturn’s moon Rhea is discovered appeared first on Astronomy Magazine .