What Did Galileo Discover?

By Staff WriterLast Updated Mar 25, 2020 8:54:42 AM ET
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After Galileo built his first telescope in 1609, he observed and described the landscape of the moon, discovered four of the moons of Jupiter, discovered the phases of Venus, and discovered sunspots. Galileo's discovery of sunspots supported the idea of heliocentrism, a model that places the sun at the center of the universe with the planets orbiting around it.