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Galileo Galilei (1564-1642). Galileo tried something new ? doing experiments!Dropping balls to measure gravityRolling balls to examine inertiaObserving the sky through a telescope!Newton: ?If I have seen a little further it is by standing on the shoulders of Giants.". What Galileo Saw. An imperfect Sun (sunspots).
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2. Galileo Galilei (1564-1642) Galileo tried something new doing experiments!
Dropping balls to measure gravity
Rolling balls to examine inertia
Observing the sky through a telescope!
Newton: If I have seen a little further it is by standing on the shoulders of Giants.
3. What Galileo Saw An imperfect Sun (sunspots)
4. What Galileo Saw An imperfect Sun (sunspots)
A Moon with mountains and craters
5. What Galileo Saw An imperfect Sun (sunspots)
A Moon with mountains and craters
The ears of Saturn
6. What Galileo Saw An imperfect Sun (sunspots)
A Moon with mountains and craters
The ears of Saturn
Four moons orbiting Jupiter
7. What Galileo Saw An imperfect Sun (sunspots)
A Moon with mountains and craters
The ears of Saturn
Four moons orbiting Jupiter
The phases of Venus
8. Tycho Brahe (15461601) Tycho Brahe (without a telescope) made extremely accurate measurements of the positions of the stars and planets over the course of 20 years.
9. Tycho Brahes Model Earth at the center of the Universe (because parallax is not seen)
The Sun travels about the Earth in a perfect circle
The planets move around the Sun in perfect circles
10. Keplers Analysis By working for Tycho Brahe (and stealing his data), Johannes Kepler (15711630) had access to the most precise data on planetary positions in history.
He fit the data in every way imaginable by hand with pen and paper.
He failed in every conceivable way until he tried elliptical orbits (for the second time)
11. Keplers Laws Keplers Laws
Planets move in ellipses with the Sun at one focus
12. Keplers Laws Keplers Laws
Planets move in ellipses with the Sun at one focus
Planets in their orbits sweep out equal areas in equal times
13. Keplers Laws Keplers Laws
Planets move in ellipses with the Sun at one focus
Planets in their orbits sweep out equal areas in equal times
14. Keplers Laws
15. Keplers Third Law
16. Keplers Laws
Planet A is more massive than Planet B. Which of the 2 planets will move around the star in the shortest time? Why?
If A and B switch positions, would you change your answer to #1? Explain why or why not.
Would the orbital period of A increase, decrease, or stay the same if it moved away from the star? Why?
If As orbit currently lasts one year, and it is moved to a new orbit at twice its current distance from the star, how long would its new orbit take?
17. Summary Galileo: Father of experimental science
Tests of inertia and acceleration
Observed the sky with telescope: Heavens not perfect
Fought for acceptance of heliocentric Solar System
Tycho Brahe
Recorded precise naked-eye positions of planets
Hired Kepler to fit data with his quasi-geocentric model
Kepler
Discovered three mathematical laws describing the motions of the planets to very high precision first improvement in planetary prediction since Ptolemy
Could not explain or justify his laws on physical grounds