The History of Astronomy Part 5 The Debate Concludes Copernicus is Confirmed A Whole New awareness...

The History of Astronomy

Part 5The Debate Concludes

Copernicus is ConfirmedA Whole New awareness of the Universe

Galileo Galilei (1561-1642)Galileo was an Italian professor of mathematics and

astronomyHe …• transformed science by developing and using the

scientific method • demonstrated errors in Aristotle’s theories

regarding falling objects, & motion• Developed the concept of inertia In 1609 he heard of the invention of the telescope.He soon had built several of his own and turned them

on the sky. He discovered:

Mountains on the Moon

Galileo’s lunar observations showed him that the moon was a world like ours,

• It had Mountains, valleys, & great plains • It had new features, craters and rays.It also implied that the other planets might

also be worlds like ours.

The Phases of Venus

Galileo found that Venus has phases like the moon.

Oddly it is brightest when it is a mere crescent.

The Ptolemaic model of the universe could not explain it.

The Copernican model not only could but predicted its brightness accurately.

“Its full of stars!”The fact that the Milky Way was made of faint stars

established without any doubt that stars were at vastly different distances .

The Celestial Sphere was shattered. It was reasonable to believe Diggs and Bruno that

stars were Suns at a vast distance away…Far away enough that…

…parallax can’t be seen with the naked eye!The parallax problem is solved. There was new awareness of the vastness of the

Universe

Jupiter’s MoonsGalileo discovered the four largest moons of

Jupiter He kept track of their orbits, which ran like

clockwork • This observation led Galileo to doubt

Aristotle’s principle of motion and come-up with the idea of inertia.

• Eventually the motions of Jupiter’s moons was used by Astronomers and mariners as a clock

Galileo PaysGalileo wrote a book:

“The Starry Messenger” which contradicted authorities (Aristotle & Ptolemy)

that the Catholic Church had established.Galileo, forced to recant, and put on house arrest for

the rest of his life.His works were ordered destroyed in Catholic

Countriesbut

they already had reached protestant lands such as England where they would inspire

Isaac Newton

Isaac Newton (1642-1727)Inspired by Galileo and Kepler, before he was 23 Isaac

Newton laid the foundation of modern physics.Galileo inspired him to create His three laws of

motionKepler inspired his Universal Law of GravityNewton would go on to:• make discoveries in Optics • and to lead efforts to find an astronomical solution

to the problem of longitude by using Jupiter’s moons

The first Physics, was Astrophysics.