Galileo Galilei

On February, 15th we celebrated 452nd anniversary of Galileo Galilei’s birthday. Is it fair to say that he’s the person that influenced modern astronomy the most? How much more would he accomplish if he wasn’t seen as a heretic by the Church?

Fraser Cain (publisher at, co-host of Astronomy Cast)

Galileo was one of the very first people to see the wonders of the night sky though a telescope, and identified many of the things we take for granted now in a small telescope: the moons of Jupiter, the rings of Saturn, craters on the Moon, phases of Venus and the stars in the Milky Way. Right place, right time, right direction to point the telescope. I don’t know if it would have been possible for Galileo to not have ended up in trouble with the church. Even though he had many opportunities to keep his mouth shut and follow the party line, he kept finding new ways to enrage the church. I think he saw it as a badge of honor.

Andrew Rader (SpaceX engineer, MIT PhD, author)

That’s a tough question to answer, but certainly Galileo’s contribution to astronomy was enormous. He provided evidence to support the Sun-centered solar system by demonstrating that not everything revolves around Earth – if the four large moons of Jupiter revolve around that planet, clearly there is no hard and fast Earth-centered (or Sun-centered) rule. In addition to other scientific contributions (especially going a long way towards Newton’s law of Universal Gravitation), Galileo mapped the features of the Moon and sketched the phases of the Moon and Venus. This demonstrated that these were not perfect celestial spheres but worlds in their own right, complete with detailed features. This was probably the biggest step in going from a concept of Earth as the entire Universe to a system of many worlds – which would later be expanded into many Suns and then ultimately many galaxies. It would be hard to argue that Galileo’s accomplishments wouldn’t at least give him a strong contention for most influential astronomer ever.

Antonio Paris (Astronaut Candidate, Astronomy Professor, Planetary Scientist, Space Science Author)

I would argue that Galileo Galilei was one of many great scientists, whom collectively, shaped the scientific revolution. Through the use of a refracting telescope, Galileo was able to finally put the geocentric model to rest. His observations of the moon’s of Jupiter and the phases of Venus led to direct evidence for the heliocentric model. Thereafter, using his work, others such as Kepler, Newton, and as recent as Einstein, collectivley shaped modern astronomy. One can say, therefore, that Galileo started it all.

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