1. Bell Work: What is the center of the Universe?
Unit 8 Earth in Space
Bell Work:
What is the center of the Universe?

2. The Origins of the Universe: David Christian – “The History of our world in 18’”

3. Timeline of the Universe
Phase 1:
Began ~14 billion years ago
Lasted > 300 million years
Major events:
Big Bang and Universe expands
Elements, stars & galaxies form

4. Began ~5 billion years ago Ended ~1000 years ago Major events:
Phase 2:
Began ~5 billion years ago
Ended ~1000 years ago
Major events:
Our solar system forms inside Milky Way Galaxy
Plants, animals, humans appear
Origins of our solar system

5. Phase 3:
Began ~1000 AD
Continues today
Major events:
Discovery of gravity, relativity, telescopes, and the expanding universe

6. Phase 4:
Scientists have projected ~100 trillion years into the future
Possible Events:
If universe keeps expanding it will eventually whither away and eventually only black holes will remain

7. Earth’s Relationship with other systems in space
Our Solar System
Earth
Is part of
Is part of
The Milky Way Galaxy
The Universe
Is part of

8. How big is the Universe?

9. The Planets in our Solar System:

10. Many solar systems in our galaxy

11. There are ~100 billion galaxies in the Universe

12. Bell Work
How much time elapsed between the “Big Bang”, when the Universe formed, and the formation of our solar system?
What events occurred during this time?

13. Earth’s Motion in Space
Nicholas Copernicus (1543):
Heliocentric model of the solar system (sun at the center)
Earth and other objects revolved around Sun in a circle
Earth rotated on its axis
Earth was tilted on its axis

14. Kepler’s 1st Law Johannes Kepler (1610):
Three laws of planetary revolution
Kepler’s 1st Law
The orbit of a planet about a star is an ellipse with the star at one focus.

15. Kepler’s 2nd Law
A line joining a planet and the Sun sweeps out equal areas in equal time.

16. Kepler’s 3rd Law
The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit:
P2 proportional to R3

17. Revolution Movement of one object around another object
Earth’s revolution around the sun: ~365 days

18. Rotation (R)
Earth’s movement on its axis
24 hrs per rotation

19. Precession (P) Conical sweep of Earth’s rotation on its axis
Caused by Gravitational pull of sun & moons
Cycles every 26,000 years

20. Nutation (N) A wobble in Earth’s rotation
Caused by gravity from Sun & Moon
Cycles every 41,000 years

21. Barycenter
The center of mass between 2 bodies orbiting in space. The center depends on the mass of the 2 objects.

22. Oblate Spheroid
A sphere that is squashed at its poles and swollen at the equator.
Earth has an oblate spheroid shape.