Knowra Galileo Galilei Galileo Galilei Galileo Galilei (1564–1642) was an Italian astronomer, physicist, and mathematician whose telescopic observations challenged established cosmology and whose experiments advanced the study of motion.
Galilean moons : The four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto. Their orbit around Jupiter showed that not every celestial body circles Earth.
Kinematics : The study of motion that describes positions, velocities, and accelerations without addressing their causes. Galileo helped establish mathematical ways to describe motion over time.
University of Pisa : An Italian university founded in 1343, where Galileo studied medicine before turning to mathematics. His early studies there preceded his appointment as a mathematics lecturer.
Galileo affair : The conflict between Galileo and the Catholic Church over his support for heliocentrism, culminating in his 1633 trial. The trial made his astronomical arguments a major institutional controversy.
Phases of Venus : The changing illuminated shapes of Venus as seen from Earth during its orbit around the Sun. Their full range contradicted the traditional Ptolemaic arrangement of the planets.
Inclined plane : A flat surface set at an angle, often used to study motion while reducing an object's acceleration. Rolling balls down slopes let Galileo investigate falling motion more slowly.
Aristotelian physics : A natural philosophy based on Aristotle's accounts of motion, elements, and the cosmos. Galileo's studies and experiments increasingly challenged its explanations of motion.
Heliocentrism : The astronomical model in which Earth and other planets orbit the Sun. Galileo's observations supplied evidence consistent with this model, though they did not prove it alone.
Galileo's telescope : An early refracting telescope Galileo improved and used for astronomical observations beginning in 1609. It made his discoveries of Jupiter's moons and lunar irregularities possible.
Pendulum : A suspended object that swings under gravity around a pivot. Galileo studied its regular oscillations, a clue to measuring time.
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