Sidereus Nuncius (The Starry Messenger) (1610)
Short book announcing telescopic discoveries: lunar mountains, many new stars and four moons of Jupiter
Science · Physics
Galileo Galilei
1564–1642 · Italian (Tuscan)
Physics and astronomy; Scientific Revolution
Galileo Galilei, born in Pisa, turned the newly invented telescope on the heavens and reported mountains on the Moon, the four largest moons of Jupiter and the phases of Venus, powerful evidence for the Copernican system. His studies of motion, falling bodies and the pendulum laid foundations for Newtonian mechanics. His Dialogue of 1632 led to his trial by the Roman Inquisition in 1633 and house arrest for the rest of his life.
How to spot them
- ▸Sidereus Nuncius (The Starry Messenger); the 'Medicean Stars' Io, Europa, Ganymede and Callisto
- ▸Trial by the Inquisition in 1633; 'Eppur si muove' (a later legend)
- ▸Dialogue Concerning the Two Chief World Systems with Salviati, Sagredo and Simplicio
- ▸Dropping balls from the Leaning Tower of Pisa (probably apocryphal); the swinging lamp in Pisa Cathedral
- ▸Born in 1564, the year Shakespeare was born and Michelangelo died
Key discoveries & works
Discovery of the four largest moons of Jupiter (1610)
Named the Medicean Stars in honour of the Medici; now Io, Europa, Ganymede and Callisto
Observation of the phases of Venus (1610)
A full set of phases showed Venus orbits the Sun, contradicting the Ptolemaic system
Il Saggiatore (The Assayer) (1623)
Polemic on comets containing the claim that the book of nature is written in the language of mathematics
Dialogue Concerning the Two Chief World Systems (1632)
Italian dialogue comparing Ptolemaic and Copernican systems, which led to his trial
Discourses and Mathematical Demonstrations Relating to Two New Sciences (1638)
Published in Leiden while under house arrest; covers strength of materials and the laws of motion
Key ideas
- Falling bodies accelerate uniformly, with distance fallen proportional to the square of time, regardless of weight (air resistance aside)
- A projectile follows a parabolic path
- Principle of inertia in early form, and Galilean relativity: uniform motion cannot be detected from inside a moving system
- Isochronism of the pendulum: period roughly independent of the size of the swing
- Nature should be studied through experiment and mathematics rather than ancient authority
Quick-fire facts
- •Born in Pisa on 15 February 1564; died at his villa in Arcetri, near Florence, on 8 January 1642
- •Taught at Pisa and then at Padua (1592–1610) before becoming court mathematician and philosopher to Cosimo II de' Medici
- •Did not invent the telescope, but built much improved instruments after hearing of the Dutch invention in 1609
- •Condemned in 1633 for 'vehement suspicion of heresy'; forced to abjure and kept under house arrest until his death
- •In 1992 Pope John Paul II formally acknowledged that the Church had erred in its treatment of Galileo
- •Buried in the basilica of Santa Croce, Florence, where a monumental tomb was erected in 1737
- •The simpleton in the Dialogue, Simplicio, was taken by some to mock Pope Urban VIII
- •NASA's Galileo spacecraft orbited Jupiter from 1995 to 2003; the Galilean moons bear his name
Drill it — 9 cards
1 / 9new card
Sources
- MacTutor History of Mathematics, University of St Andrews — Galileo Galilei
- Dava Sobel — Galileo's Daughter