1. Chapter 15 – Stars, Galaxies and the Universe

2. Chapter 15 – Stars, Galaxies and the Universe
Section 5 – History of the Universe
Standards
2.g – Students know the role of gravity in forming and maintaining the shapes of planets, stars and the solar system
4.a – Students know galaxies are clusters of billions of stars and may have different shapes

3. Big Bang Theory
Big Bang Theory – initial explosion that resulted in the formation and expansion of the universe
Theory explained
Big Bang Theory states that the universe formed in an explosion about 10 to 15 billion years ago – Universe has been growing ever since the big bang

4. Moving Galaxies
Scientists can tell if galaxies are moving toward or away from earth based on a light spectrum of that galaxy
Hubble’s Law – states that the farther away a galaxy is, the faster it is moving away from us

5. Expanding Universe – Balloon Example
Each little piece on the balloon is like a galaxy and as the balloon grows (universe expands) the galaxies move apart

7. Speeding Galaxies
Use the graph to answer the questions about moving clusters of galaxies.

8. Speeding Galaxies Reading Graphs:
How far away is the Bootes cluster? How fast is it moving?
About 2.5 billion light-years
About 39,000 km/sec

9. Speeding Galaxies Drawing Conclusions:
How are the distance and speed of a galaxy related?
The greater the distance from Earth, the greater the speed of the galaxy.

10. Speeding Galaxies Predicting:
Predict the speed of a galaxy that is 5 billion light-years from Earth
Its speed would be about 80,000 km/s

11. Formation of the Solar System
About 5 billion years ago, a giant cloud of gas and dust, or nebula, collapsed to form the solar system

12. Formation of the Solar System
The nebula shrank to form a spinning disk and as gravity pulled some of the gas into the center of the disk, the gas became hot and dense enough for nuclear fusion to begin and created the sun

13. Solar Nebula
video
Solar Nebula – a large cloud of gas and dust that formed our solar system
Gravity pulled the nebula together, it shrank and spun faster
Elsewhere in the disk, gas and dust formed solid spheres smaller than the sun and the planets were created

14. The Future of the Universe
New observations lead many astronomers to conclude that the universe will likely expand forever.
Expanding Universe – Infinite Universe
(The crunch – alternative theory)
(The big rip – alternative theory)

15. Mysterious Stuff
Dark Matter (video) – matter that does not give off electromagnetic radiation (possibly 90% of all matter in the universe)
Dark Energy (video) – mysterious force that appears to be causing the expansion of the universe to accelerate