1. History of Astronomy

2. Ptolemy- the “P” is silent
Used the observations of ancient astronomers to come up with a ___________________ model of the universe.
His model became the accepted explanation of the universe for the next _______ centuries.
This model did not create any _________________ or _______________________issues and was widely accepted.

3. Ptolemy’s Model

4. Retrograde Motion and Epicycles
______________________ motion is the apparent “___________________” motion of a planet when viewed from Earth.
Early models of the universe, including Ptolemy’s, explained this by adding ________________, or _________________ circles of planetary motion within the large circle of its ________________around
the Earth.

5. Retrograde Motion of Mars

6. Nicolaus Copernicus
Believed that a simpler model of the universe would make more sense, and suggested that the sun was at the ______________,
and not the Earth.
___________ orbited in circles
around the ____________. Due to some minor irregularities, Copernicus did add some epicycles to explain the data.

7. Nicolaus Copernicus
Did not publish his ideas until he was on his ______________ because he feared criticism and ridicule from scientists and the _________________.
The church did not take his work seriously when it was first published and did not take much _______________ of it.

8. Copernicus’ Model

9. Retrograde Motion and Copernicus’ Model

10. Galileo Galilei
Galileo was the first astronomer to use a ___________________ to study, in detail, celestial objects.
His telescope showed that the sun and the moon were not “______________” heavenly bodies, as many people thought.
He observed ____________ on the
moon and ________________ on the
sun.
His observations also showed that the sun ______________ and was not stationary.

11. Galileo Galilei
Defended the ___________________ model of the universe and publicly __________________the earlier (and still widely believed) geocentric view of the solar system.
When Galileo started to provide strong observational evidence for ___________________, the church took noticed and eventually convicted him of _____________________(going against the proclaimed doctrine of the church).
Galileo spent the remainder of his life under house arrest for his “________________.”

12. Tycho Brahe
Collected vast amounts of _______________________ data without using a________________.
His model attempted to combine the ______________________ logic of Coperincus’ heliocentric model with Ptolemy’s more widely accepted ___________________________ model in order to avoid conflict with _______________________.

13. Tycho Brahe ____________________________
Was a keen accurate ______________ and note taker
Measured the position of _______stars without a _______________________
Measured the position of the ________, ________________, and planets daily for almost _______ years.

14. Tycho Brahe’s Model All planets except Earth orbit the ___________
Moon and the sun (with all other planets) orbit the _______________
Stars are in a fixed ______________
around the whole
system

15. “Tychonic” Model
Tycho Brahe’s model was used favorably for quite some time, since it did not go against religious teachings, explained all observational _________, and eliminated the need for confusing ______________________.

16. Johannes Kepler
A student of Tycho Brahe’s, _______________ used the extensive data to come up with his model.
Kepler determined that the orbits of the planets must be slightly ___________________, or similar to an _____________ shape.
An ellipse has two center points, called ______________. The __________is at one focus in Kepler’s model.

17. Kepler’s Model
Fit observational data perfectly
No need for epicycles

18. Acceptance of Model
Kepler’s model was not immediately accepted. Even Galileo thought __________________ orbits were improbable.
Many people objected, on philosophical grounds, to the use of _______________ to explain the _______________ of heavenly bodies.
Kepler’s model is the basis of our current understanding of ______________________ motion (with only minor changes).