1. Who’s Who of Early Astronomy

3. Ptolemy 100-170AD Observed motion of planets
Timeline 1
Ptolemy AD
Observed motion of planets
Developed the geocentric model of solar system
Accepted for 1,500 years.

6. Geocentric = Earth is center of solar system/universe

8. Draw a diagram of the geocentric solar system and label it
Geocentric=Earth is at the center of revolving planets and stars
Draw a diagram of the geocentric solar system and label it

9. Copernicus 1473-1543 Proposed heliocentric model of the solar system
Not everyone accepted this theory

11. Heliocentric = Sun is center of solar system

12. Heliocentric=Earth and other planets revolve around the sun
Diagram heliocentric solar system and label it.

13. Tycho Brahe
Tracked planetary motion through careful observation for 20 years.
Careful experiment vs. philosophical arguments.

14. Kepler
Used Brahe’s data to develop three laws of planetary motion.

15. Galileo
Used newly developed telescope to gather evidence that supported the heliocentric model.

16. Newton 1642-1727 Explained the force that keeps planets in orbit
They are the same forces that work here on Earth!
A universal force!

20. Hubble
He was the first astronomer to find observable evidence that the universe is expanding
His discovery helped establish the “Big Bang Theory.”
Use detailed observations to prove that other galaxies existed beyond the edge of our galaxy the Milky Way.
His data confirmed that the universe is much larger than our own galaxy, the Milky Way.

21. Lemaître 1894-1966 Created Big Bang Theory
He figured that if you traced the idea of the universe back in time, all the way to the very beginning, everything had to converge into a single point.
Lemaître called that point a superatom.
He suggested that the expansion of the universe had resulted from the explosion of this superatom that hurled materials in all directions, and set the universe as we know it in motion.

23. Bondi
Created Steady State Theory