Which Italian scientist used telescopic evidence to support Copernicanism?

Galileo Galilei used telescopic evidence to support Copernicanism.

Beginning in late 1609, Galileo improved the newly invented telescope and turned it toward the sky. He observed mountains and valleys on the Moon, countless previously invisible stars, sunspots, and four bodies orbiting Jupiter. These observations challenged the Aristotelian-Ptolemaic picture of perfect heavens revolving around a stationary Earth.

The phases of Venus were especially important because they showed that Venus orbits the Sun, though they did not by themselves prove that Earth moves. The moons of Jupiter demonstrated that not everything revolves around Earth, weakening a central assumption of geocentrism. Galileo presented many of these findings in Sidereus Nuncius in 1610.

A common mix-up is calling Galileo the originator of heliocentrism: Nicolaus Copernicus had proposed the Sun-centered model decades earlier. Galileo was its most famous observational defender, while later physics and measurements supplied stronger evidence for Earth’s motion.