1. Observing the Solar System
Chapter 14 Section 1

2. How does Earth move? Rotation Revolution
Earth turns on its own axis, rotating around the center.
This explains the stars we see in the photo below.
Revolution
Earth revolves around the Sun,
tracing out an elliptical path.

3. Geocentric The Greeks first studied the solar system:
Planets – “wanderers”
Geocentric – Earth is at the center with planets and star revolving around it
Ptolemy's Model

4. Heliocentric Later, other Greeks came up with new ideas:
Heliocentric – Earth and other plants revolve around the sun, which is at the center of the solar system.
Nicolaus Copernicus ( )
Arranged the planets and their motions around the sun
Initially, was rejected!
It took about 100 years for his ideas to be accepted.

5. Galileo Galilei Italian Scientist (1564-1642)
“I do not feel obliged to believe that the same God who has endowed us with sense, reason and intellect has intended us to forgo their use.”
Developed and used the telescope to study the solar system
Agreed with Copernicus’s heliocentric model
Where else have we talked about Galileo?
Private message a classmate.
What is he the “father” of?

6. Tycho Brahe
Danish nobleman who experimented with astronomy and alchemy.
( )
Fun Facts:
Tycho lost his nose in duel!
This fight was over a mathematic formula.
The rest of his life (nearly 50 years) he wore a silver or gold nose glued to his face.
Accepted Copernicus’s theory of a heliocentric solar system, but with different motion of the planets.
Studied the motion of the planets without using a telescope!
It wasn’t invented until after he died.
His assistant, was the great Johannes Kepler.

7. Johannes Kepler German mathematician and astronomer (1571-1630)
Lived and studied at the same time as Galileo, but often disagreed!
Believed and pioneered astrology
Best known for his planetary laws:
The motion of each planet is an ellipse (oval, flattened circle).
Planets move faster when they are closer to the sun.
Planets closer to the sun, orbit faster. Planets further from the sun, orbit slower.

8. The Modern Solar System
What is a moon?
A natural satellite. . . But what is a satellite?
Astronomical Unit, AU
The Earth’s average distance from the sun.
We can compare other planets to the Earth this way. . .
A planet that is less than 1 AU from the sun is closer / further away
A planet that is greater than 1 AU from the sun is closer / farther away
Example: Ceres is the largest group of asteroids, orbiting the sun at an average distance of 2.77 AU. Where would it be?

9. Exploring the Planets. . . Planet Sun Mercury Venus Earth Mars Jupiter
Diameter
Dist. from Sun
Rotation
Revolution
Moons
Sun
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto

10. Questions
Page 544 in your textbook.
Use the links for clues!