Scientific Revolution II - Galileo Galilei
Galileo Galilei (1564-1642)
Born in Pisa to a cloth merchant-musician father
Studies medicine and mathematics
Serves as professor of mathematics at Universities of Pisa (briefly) and Padua (1589-1609)
1609 - learns about newly invented telescope, builds his own
1610 - publishes The Starry Messenger at 46, gains fame and recognition as a scientist
Galileo the icon
Remembered as first true modern scientist, or at very least, one of the first
Seen also as martyr for science against ignorance and religious dogma
Reality is more complex than that, however
The Starry Messenger (Siderius nucius), 1610
The beginnings of telescopic astronomy
Galileo seems to be the first person to point his telescope at the stars - at least the first to publish
40 page pamphlet announces a number of extraordinary discoveries
Mountains and craters on the moon
Four new "planets" circle around Jupiter
There were many stars could not be seen with the naked eye
While the moon and planets appeared larger in the telescope, the stars only seemed brighter, implying enormous distance
Proof of Copernicus?
Ptolemaic system said everything in the heavens was perfect - but Moon clearly was not
Many had expressed doubts that the Moon could circle the Earth while the Earth circled the Sun
but here were four moons around Jupiter
Clearly, not everything directly circled the Earth
New stars and moons meant the ancients didn't know everything
If the stars were circling the Earth, yet they were so extraordinarily distant, then they would have to be going unfathomably fast
Galileo, Renaissance career man
Starry Messenger is a classic example of how scholars and artists advanced their careers in the Renaissance
Galileo dedicated the book to the powerful ruler of Florence, Cosimo de Medici, Duke of Tuscany
Named the new moons of Jupiter the "Medician stars" - we call them the Galilean satellites (Io, Europa, Ganymede, and Callisto.)
Parlayed this flattery and his new fame into a job as court mathematician and philosopher to the Medicis
Left the University behind for a more lucrative and individualistic position as an independent researcher working for a patron - the ideal Renaissance career path
Further telescopic discoveries - Letter on Sunspots, 1613
Sums up various discoveries made from 1610 to 1613
Venus goes through phases like the Moon - hard to explain under Ptolemy, easy under Copernicus (and Tycho)
Another observer, David Fabricus, beat him to publication
Implied that the Sun was not unchanging, unlike the claims of the Aristotelian-Ptolemaic system
Some critics suggested these were only small planets near the Sun - would take some time to resolve
Rings of Saturn
In Galileo's weak telescope, he saw "twins," two small globes attached to Saturn (1610)
Again, this demonstrated that not everything in the heavens was a perfect sphere
By 1612, the "twins" had disappeared!
Would not be till 1659 that Chrstiaan Huygens shoed that they were rings, not globes, that "disappeared" when they were edge on to the Earth
Conflict with the Church
By 1616, Catholic Church had decided heliocentrism was a problem, and Galileo narrowly avoided being condemned.
Galileo ordered not to "hold or defend" a belief in heoliocentrism, but he could still discuss it.
Publishes Dialogue Concerning the Two Chief World Systems in 1632, as a conversation between a supported of heolicentrism and geocentrism.
The geocentric defender was called Simplicus, seemed foolish, and used some wording the Pope himself had used.
Galileo convicted of heresy in 1633, condemned to house arrest
Would do important wok on gravity, inertia, mechanical physics and number theory before his death in 1642.