A 1610 da Italiyanci polymath Galileo Galilei gano hudu mafi girma da watã na Jupiter (yanzu da aka sani da Galilean watã) ta amfani da wani madubin hangen nesa; zaton ya zama na farko telescopic lura da watã wanin Duniya ta. Wata rana bayan Galileo, Simon Marius da kansa gano watã a kusa da Jupiter, ko da yake bai buga da discovery a cikin wani littafi har 1614. Yana da Marius sunaye ga hudu manyan watã, duk da haka, cewa makale <unk> Io, Europa, Ganymede da Callisto. Wadannan binciken sun kuma kasance na farko da gano na Celestial motsi ba a fili centered a kan Duniya. The discovery was a major point in favor of Copernicus's heliocentric theory of the motions of the planet; Galileo's outspoken support of the Copernican theory under the threat of the Inquisition.
Ole Rømer