Galileo Galilei, Pisa

Galileo Galilei (1564–1642) was a pioneering Italian physicist, astronomer and philosopher who is regarded worldwide as the founder of modern astronomy and experimental natural science. Through his improvements to the telescope and his revolutionary observations, he changed our view of the cosmos forever.

Key contributions and discoveries

• Improvements to the telescope: He modified existing designs to create a powerful instrument with twentyfold magnification.
• Cosmic discoveries: He discovered Jupiter’s four largest moons (Io, Europa, Ganymede and Callisto), the phases of Venus, craters on the Moon and sunspots.
• Evidence for heliocentrism: Through his observations, he provided visual evidence that the planets revolve around the Sun, rather than around the Earth (the Copernican model).
• Founder of mechanics: He formulated early laws concerning inertia and the period of a pendulum, and discovered that objects of different masses'fall with the same acceleration.

His defence of the heliocentric world view brought him into direct conflict with the Roman Catholic Church, which at the time maintained that the Earth was the immovable centre of the universe. Following the publication of his famous book *Dialogue Concerning the Two Chief World Systems* (1632), he was tried by the Inquisition. In 1633, Galileo was forced to recant his views and spent the rest of his life under strict house arrest. More than 350 years later, in 1992, he was officially rehabilitated by the Church.

The poster is based on a photograph I took on 6 September 2026.