American Geophysical Union, GeoSpace Blog, December 18th, 2009.
I can imagine Galileo sitting in the dark, peering through his telescope and taking careful notes on the objects he saw orbiting Jupiter. Or maybe I saw it in some Space Channel documentary. Either way, the fact that in 1610 Galileo used a 30 times magnifying telescope to discover these moons blows my mind. The insights on the structure and atmosphere of these moons presented at P53B: The Galilean Satellites: 400 years of Discovery II blew my mind all over again.
The Galilean satellites, or Jupiter’s moons as they are known to lay-folk like myself, were the first objects found orbiting something other than Earth or the Sun. The four Galiean moons, seen from top to bottom in NASA image at the right, are Io, Europa, Ganymede (the big daddy of the bunch) and Callisto. All are more than 3000 km in diameter. Though they may be large for moons, Jupiter dwarfs them, weighing in at five thousand times more massive and causing them extreme tidal stress. Jupiter is also radioactive, bathing its moons in high-energy electron beams and radio emissions. Read More >