Outline

1. Brahe, Kepler, Galileo, and Newton: The Birth of Modern Science

1. Brahe, Kepler, Galileo, and Newton: The Birth of Modern Science

Tycho Brahe (Danish, 1546-1601)

• made very careful measurements of star and planet positions
  
• rejected the Copernican model because he could detect no parallax among the fixed stars (why couldn't he?), and rejected the Ptolemeic model because of its poor ability to predict planet locations.
  
• proposed a new, complex model with the Sun and Moon revolving around the Earth, and the other planets revolving around the Sun

Johannes Kepler (German, 1571-1630 -- Tycho's successor)

• Studied the data Tycho had carefully collected on planetary motions
• Realized that the planets move on ellipses, not perfect circles
• Supported a heliocentric (Copernican), not geocentric, view.
• Showed that the planets change speed during their orbit (faster when close to the Sun, slower when far from the Sun)

Galileo Galilei (Italian, 1564-1642) (99 years after Copernicus' death!)

• was first person to turn a telescope on the sky
• was first to see moons of Jupiter; sunspots; mountains on the Moon; phases of Venus; stars in the Milky Way; rings ("ears", "handles") around Saturn.
• proved that Earth could not possibly be the center of the Universe, thus supporting Copernican system

Isaac Newton (English, 1642-1727) (born the same year Galileo died!)

• studied the work of Galileo, Kepler, and apple trees
• figured out the laws of optics, gravity, and calculus
• came up with the physics to explain Kepler's Laws
• realized that mass and distance were both important in the Law of Gravity, and derived that fact mathematically