📅 Today in History: In 1610, Italian astronomer Galileo Galilei, through improvements he made on a homemade telescope, first observed Jupiter’s four Galilean moons: Ganymede, Callisto, Io and Europa.
Jupiter's volcanic moon Io doesn't appear to ... a moon-wide ocean of molten rock. In the 1990s, NASA's Galileo mission performed magnetic induction measurements that suggested there was such ...
1610: Astronomer Galileo Galilei observed four of Jupiter’s moons for the first time. 1955: Singer Marian Anderson became the first Black American to sing ...