Galileo Galilei: The First Telescopic Astronomer

In 1609, Galileo built his first telescope, improving Dutch designs.
He was the first to use a telescope systematically for astronomy.
Galileo discovered craters and mountains on the Moon.
He observed four moons orbiting Jupiter, now called the Galilean moons.
His discoveries challenged the geocentric worldview of the cosmos.
Galileo spotted the phases of Venus, proving it orbited the Sun.
He observed sunspots, showing the Sun was not perfect and unchanging.
His findings strongly supported Copernicus’ heliocentric model.
Galileo faced trial by the Inquisition and was forced to recant.
Today, he is celebrated as the “father of modern observational astronomy.”