
Ken Vanlew, retired astronomy & physics teacher, joins us via Zoom to discuss the four largest moons of Jupiter, discovered by Galileo in 1609. Originally called Medicean Stars, they range from volcanic, spewing geysers to cold Callisto with ice hundreds of miles thick. The moons orbit Jupiter in times that range from fewer than 2 days to more than 16 days and influence each other with tidal pulls.