1. Astronomy the Original Science
Chapter 1 Section 1

2. Astronomy
Astronomy: The study of the universe, is one of the oldest sciences
Imagine: years ago.
There are no clocks—no modern calendars.
How could you tell what time it was?
How could you know what day it was?
One way to tell the time is to study the movement of the stars, planets, and the moon.

3. Our Modern Calendar
Our Modern calendar is based upon observations of bodies in our solar system.
What is a year?
The time required for
Earth to orbit around the sun.
What is a month?
The time required for the
moon to orbit once around the Earth
What is a day?
The time required for the Earth
to rotate once on its axis

4. Who’s Who in Early Astronomy
Ptolemy
140 CE, Ptolemy, a Greek Astronomer, combined all the ancient knowledge on astronomy he could find.
His ideas became known as the
Ptolemaic Theory
Ptolemy believed the Earth
was the center of the Universe.
Sun revolves around the Earth
Geocentric Model

5. Ptolemy
Ptolemaic Theory
was supported for over 1,500 years in Europe

6. Copernicus
1543, a Polish Astronomer named Copernicus revolutionized Astronomy
Made several assumptions:
a. The Earth is NOT at the center of the universe
b. Sun is at the center, everything else revolves around it (Heliocentric)
c. The stars are very far away

7. Copernicus Historical Consequences Began the Copernican Revolution
Had to wait 150 years for general acceptance
Put on the forbidden book list because it challenged the prevailing view of the Church
Importance was that it challenged the prevailing world picture
Led to further observations to try to disprove.

8. Contributions
Galileo
Brahe
Newton
Kepler
Hubble

9. Read Pages 4-7
Complete the following questions on pg 7:
1,3,6,7 and 8

10. Tycho Brahe’s Model Made many detailed observations
Earth was in the center
Sun revolved around the Earth
Other planets revolved around Sun

11. Johannes Kepler Three Laws of Planetary Motion
Planets traveled in ellipses around the sun (ovals)
Planets move faster in their orbit when closer to the sun
The time required a planet to orbit depends on its distance to the sun

12. Galileo Edwin Hubble Improved the telescope
Made great observations about our solar system
Edwin Hubble
Determined that there were other galaxies
Determined that Universe was expanding

13. Isaac Newton Developed the Universal Law of Gravity:
Every object in the Universe attracts every other object in the Universe with a force that depends on:
objects’ masses
distance between them