1. Chapter 18 Studying Space
Chap 18, Sect 1 (Astronomy: The Original Science) Objectives:
Describe two early ideas of the structure of the universe.
Describe the contributions of Brahe, Kepler, Galileo, Newton, and Hubble to modern astronomy.

2. The guys with their eyes on the skies
History of Astronomy
The guys with their eyes on the skies

3. Claudius Ptolemy
AD 140
like the Greeks (Aristotle) he thought Earth was at the center of the system of planets Geocentric Model
accepted for over 1,500 years (“what the church says, goes!”)

4. Geocentric versus Heliocentric
Ptolemy's Geocentric Universe Copernicus's Heliocentric Universe
Geocentric versus Heliocentric

5. Nicolaus Copernicus 1500's (died in 1543)
Put Sun in the center of our universe Heliocentric Model
Insisted Earth rotated...stars chasing across sky was an illusion caused by rotation
Afraid of Church revenge he published his theory on his death bed

6. Tycho Brahe
late 1500's
Favored geocentric theory (sun & moon revolve around earth) BUT thought other planets revolve around sun
His team observed and recorded data, data, data for more than 20 years
His data was the basis for later discoveries

7. Johannes Kepler 1600's One of Brahe’s assistants
proved that orbits were NOT perfect circles: they are ellipses

8. Galileo Galilei Early 1600's Changed lenses in telescope to mirrors
Using the telescope he proved the heliocentric model with the following discoveries:
4 moons revolving around Jupiter
phases of Venus
craters on the Moon
Sunspots on Sun
Proved these were not wandering stars but physical bodies like Earth

9. Summary of the Universe in Galileo’s Eyes

10. Heliocentric Theory Prevails
Since Galileo’s theory clashed with the religious views of the time, he underwent many trials and tribulations, eventually being sentenced to house arrest for his remaining years.
But his view has withstood the test of time.
Today we talk about our solar system, not our Earth system

11. Sir Isaac Newton
1665
explained why the planets stay moving around the sun: inertia and gravity
1st law: inertia -a body will continue in a straight line unless acted on by a force.
Gravity keeps the moving planets in orbit around Sun

12. Newton Brainpop