1. Astronomy

2. Big Bang theory – Origin of the Universe
Big Bang marks the beginning of the universe
Occurred about 15 billion years ago
All matter and space was created
Not a huge explosion that hurled matter in all directions. Technically, there was no “bang”
Technically, matter is not moving outward in all directions. Reality: space expands

3. Raisin bread analogy of an expanding universe

4. Origin of the Universe

5. The structure of the Universe
A galaxy is a collection of billions of stars held together by gravity
The universe contains billions of galaxies and each galaxy contains billions of stars.
Our galaxy is a spiral galaxy called the Milky Way

6. NO! What makes objects in space keep moving?
Gravity -- a force of attraction between objects
Greater mass = greater gravity
Greater distance = less gravity
Weight is a measure of the pull of gravity
Is weight the same as mass?
NO!
Weight changes due to gravity; mass stays the same
2. Inertia -- an object in motion stays in motion and an object at rest stays at rest, unless acted on by a different force

7. What would life be like without gravity?

8. Rotation vs. Revolution
Rotation: an object spinning on its axis
Revolution: an object orbiting around another object or point in space

9. Two forces keep objects moving in space: 1
Two forces keep objects moving in space: 1. gravity – the force of attraction between objects with mass 2. inertia – an object will continue doing what it’s doing unless acted on by a different force

10. Gravity pulls gases and dust in space together to form planets, moons, and stars

11. Where do stars come from?
Stars form in nebulae where gases condense and nuclear fusion reactions generate tons of energy

12. Orion Nebula

13. Rosette Nebula
Rosette Nebula. Stars forming in the center of this nebula have taken in the gas as part of their formation. This leaves the holes in the cloud (where the gas was used up.) This nebula would give a bright line spectrum because it is a hot, low pressure gas.
Stars as they form clear all the nebula away from the vicinity because they eject material away from their surface (solar wind)

14. Betelgeuse
Orion Nebula
Rigel

15. Not all stars in a constellations are actually near each other All stars are not alike in size, color, or brightness

17. Stars are very different from each other, depending on their mass and place in their life cycle
HIGH MASS STARS
LOW MASS STARS

18. Stars form in gas nebulas
Our Sun is actually a very average star in the middle of it’s life cycle....medium brightness , temperature, and size
Stars form in gas nebulas
They enter the main sequence at various points depending on how much mass they collect
The Sun (and our solar system) is about 5 billion years old.

19. Stars get their energy from nuclear fusion