Galileo’s telescopic observations in 1610 established that four moons orbit Jupiter. Watching their positions change supplied a clear example of motion centred somewhere other than Earth. We include this finding for its conceptual force: not every celestial body revolves around our planet. It supported challenges to an Earth-centred cosmos, but alone did not settle every question about the Solar System. The montage shows spacecraft-era views, not Galileo’s telescope images.
Source: Jupiter’s four large moons orbit another world.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute · Public domain. Resized and JPEG compressed.
