Telescopes show that Venus displays phases like the moon while Mars and Jupiter don't, which is important evidence for heliocentrism and the order of the planet

Telescopes show that Venus displays phases like the moon while Mars and Jupiter don't, which is important evidence for heliocentrism and the order of the planets relative to Earth. Telescopes also show that Jupiter's satellites experience eclipses, which isn't direct heliocentric evidence, but does tell you that Jupiter and its moons shine by reflected sunlight rather than intrinsic luminosity. Telescopes also show sunspots, leading towards the discovery that the Sun is an active body, and to some notion of its size and mass. Telescopes can also show Venus transiting the Sun giving you a great idea of their sizes, which happened in 1639. http://en.wikipedia.org/wiki/Transit_of_Venus#First_scientific_observation http://en.wikipedia.org/wiki/Transit_of_Venus#First_scientif... The switch to heliocentrism didn't happen overnight or as the result of a single observation or event, but telescopes brought in many different streams of evidence for it.