Galileo's Galilean Moons: A Cosmic Revolution Begins
Published: January 12, 2026
Duration: 1:43
# Astronomy Tonight Podcast
This is your Astronomy Tonight podcast.
Tonight, we're celebrating a truly cosmic milestone that occurred on January 12th! On this date in 1610, the legendary astronomer Galileo Galilei discovered the four largest moons of Jupiter – what we now call the Galilean moons: Io, Europa, Ganymede, and Callisto.
Picture this: Galileo points his primitive telescope toward the night sky, and suddenly, the universe expands in ways no human had ever witnessed before. These four pinpricks of light orbiting Jupiter weren't just pretty dots – they fundamentally changed our understanding of the cosmos! Here was proo...
This is your Astronomy Tonight podcast.
Tonight, we're celebrating a truly cosmic milestone that occurred on January 12th! On this date in 1610, the legendary astronomer Galileo Galilei discovered the four largest moons of Jupiter – what we now call the Galilean moons: Io, Europa, Ganymede, and Callisto.
Picture this: Galileo points his primitive telescope toward the night sky, and suddenly, the universe expands in ways no human had ever witnessed before. These four pinpricks of light orbiting Jupiter weren't just pretty dots – they fundamentally changed our understanding of the cosmos! Here was proo...