Chapter 1 Section 1

Imagine: 5000 years ago. Imagine: 5000 years ago. There are no clocks—no modern calendars. There are no clocks—no modern calendars. How could you tell what time it was? How could you tell what time it was? How could you know what day 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. Astronomy: The study of the universe, is one of the oldest sciences

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

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

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

1543, a Polish Astronomer named Copernicus revolutionized Astronomy 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

Historical Consequences 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.

Brahe Kepler Galileo Newton Hubble

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

Made many detailed observations Made many detailed observations Earth was in the center Earth was in the center Sun revolved around the Earth Sun revolved around the Earth Other planets revolved around Sun Other planets revolved around Sun

Three Laws of Planetary Motion 1.Planets traveled in ellipses around the sun (ovals) 2.Planets move faster in their orbit when closer to the sun 3.The time required a planet to orbit depends on its distance to the sun

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

Developed the Universal Law of Gravity: 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 objects’ masses distance between them distance between them