1. Observing the Solar System Chap 16, Sec 1

2. Chap 16 Sec 1 Essential Questions 1. What are the geocentric and heliocentric systems? 2. How did Copernicus, Galileo, and Kepler contribute to our knowledge of the solar system? 3. What objects make up the solar system? video

3. Stars Ancient Greeks noticed the stars are grouped together in patterns we call constellations. The stars in a constellation stay the same night after night, and year after year. Ancient Greeks noticed the stars are grouped together in patterns we call constellations. The stars in a constellation stay the same night after night, and year after year. There are 88 constellations There are 88 constellationsconstellations The Greeks also noticed several “stars” that seemed to wander slowly among the stars The Greeks also noticed several “stars” that seemed to wander slowly among the stars The Greeks named these lights planets (which is a Greek word for wanderers) The Greeks named these lights planets (which is a Greek word for wanderers) The Romans later named the planets they could see: Mercury, Venus, Mars, Jupiter, and Saturn The Romans later named the planets they could see: Mercury, Venus, Mars, Jupiter, and Saturn Look on page 554 at the time lapse photo. This was made while viewing the circumpolar constellations that circle around the north star. Look on page 554 at the time lapse photo. This was made while viewing the circumpolar constellations that circle around the north star.

4. Geocentric System Ancient Greeks believed Earth (Greek: geo) is at the center of the revolving planets and stars Ancient Greeks believed Earth (Greek: geo) is at the center of the revolving planets and stars This is known as the Geocentric system This is known as the Geocentric system Ptolemy further developed the geocentric model to show planets moving on small circles that move on bigger circles Ptolemy further developed the geocentric model to show planets moving on small circles that move on bigger circles His model was incorrect, but did explain the motions observed in the sky fairly accurately His model was incorrect, but did explain the motions observed in the sky fairly accurately This model was widely accepted for nearly 1500 years after Ptolemy introduced it This model was widely accepted for nearly 1500 years after Ptolemy introduced it

5. The Geocentric Model

6. Heliocentric System Another ancient Greek explanation for the motion of the planets said the sun is at the center and Earth and the other planets revolve around it Another ancient Greek explanation for the motion of the planets said the sun is at the center and Earth and the other planets revolve around it This is known as the heliocentric system (helios is Greek for sun) This is known as the heliocentric system (helios is Greek for sun) This explanation wasn’t widely accepted because so many believed the Earth had to be at the center This explanation wasn’t widely accepted because so many believed the Earth had to be at the center

7. The Heliocentric Model Heliocentric

8. Nicolaus Copernicus

9. In 1543 (almost 1500 years after Ptolemy’s geocentric work) Copernicus was able to work out the arrangement of the known planets and how they move around the sun. In 1543 (almost 1500 years after Ptolemy’s geocentric work) Copernicus was able to work out the arrangement of the known planets and how they move around the sun. Most people couldn’t accept this new idea – they would need proof first Most people couldn’t accept this new idea – they would need proof first By the way, Copernicus was Polish By the way, Copernicus was Polish

10. Galileo Galilei

11. Galileo made two important discoveries using the newly invented telescope that supported the heliocentric model Galileo made two important discoveries using the newly invented telescope that supported the heliocentric model In 1610 he discovered four moons revolving around Jupiter In 1610 he discovered four moons revolving around Jupiter This proves not everything in space revolves around Earth This proves not everything in space revolves around Earth He discovered Venus goes through a series of phases similar to our Moon. He discovered Venus goes through a series of phases similar to our Moon. Venus would not have a full set of phases if it encircled Earth Venus would not have a full set of phases if it encircled Earth Just so you know, Galileo was Italian Just so you know, Galileo was Italian

12. Tycho Brahe

13. In the late 1500s Tycho Brahe and his assistants observed and recorded the positions of the planets (this would be important later in changing the model developed by Copernicus) In the late 1500s Tycho Brahe and his assistants observed and recorded the positions of the planets (this would be important later in changing the model developed by Copernicus) They did this without telescopes because they hadn’t been invented yet They did this without telescopes because they hadn’t been invented yet Brahe was Danish Brahe was Danish

14. Johannes Kepler

15. Kepler was an assistant to Tycho Brahe who died in 1601. Kepler was an assistant to Tycho Brahe who died in 1601. Kepler carefully analyzed all the observations collected under Brahe and eventually found that the orbit of each planet is an ellipse (a flattened oval) Kepler carefully analyzed all the observations collected under Brahe and eventually found that the orbit of each planet is an ellipse (a flattened oval) This disproved the belief that all planets move in perfect circles This disproved the belief that all planets move in perfect circles He was German He was German

16. Modern Discoveries Today we know the solar system consists of the sun, the planets and their moons, and several kinds of smaller objects that revolve around the sun (such as comets and asteroids) Today we know the solar system consists of the sun, the planets and their moons, and several kinds of smaller objects that revolve around the sun (such as comets and asteroids) A moon is a natural satellite that revolves around a planet A moon is a natural satellite that revolves around a planet We have telescopes on Earth and orbiting in space We have telescopes on Earth and orbiting in space We have sent astronauts to the moon and launched many space probes to explore our solar system We have sent astronauts to the moon and launched many space probes to explore our solar system Our understanding of the solar system continues to grow every day. Our understanding of the solar system continues to grow every day. I wonder what will be discovered during your lifetime! I wonder what will be discovered during your lifetime!

17. Essential Questions Answered 1. What are the geocentric and heliocentric systems? The geocentric system said Earth is at the center of the revolving planets and stars (including the sun and moon). The heliocentric system says the sun is at the center of our solar system and is surrounded by planets and their moons. 2. How did Copernicus, Galileo, and Kepler contribute to our knowledge of the solar system? Copernicus – further developed the heliocentric system by calculating the arrangement of the planets and how they move around the sun Galielo – used the newly invented telescope to make discoveries that supported the heliocentric model Kepler – discovered the orbit of each planet is an ellipse

18. 3.What objects make up the solar system? The sun, the planets and their moons, and several kinds of smaller objects that revolve around the sun.