1. The Big Stuff Galaxies The Universe and The Big Bang

2. Galaxies… Millions or billions of stars, made of gas and dust The Universe…Everything

3. Three Types of Galaxies Spiral -shaped like pinwheels; have huge spiral arms Ex:Milky Way Elliptical - Vary in shape from nearly spherical to flat discs; contain very little gas & dust Irregular - does not have an orderly or definite shape; much less common

4. What kind of galaxy? Andromeda galaxy and The Milky Way

5. What kind of galaxy? No spiral arms -

6. What kind of galaxy? Large Magellanic Cloud – within our galactic neighborhood

7. The Milky Way… …Our Galaxy A huge pinwheel-shaped disc with a bulge in the middle. 200 Billion+ Stars. Most older stars found near the nucleus. Stars here are crowded together 1000’s of times more densely than in spiral arms. 200 million years to rotate once. 100,000 light years in diameter Sun is 26,000 light years from center

10. Andromeda Galaxy The closest galaxy to the Milky Way (2.5 Million Light Years!!!) The other spots of light in the picture are other galaxies, not other stars!

11. Active Galaxies Huge Black Hole in Center?

12. NEBULA A large cloud of dust and gas in interstellar space – a region in space where stars are born or where stars explode at the end of their lives. NEW STARS can form in regions of nebulas SPIRAL GALAXIES usually contain nebulas, but ELLIPTICAL GALAXIES contain very few

13. GLOBULAR CLUSTER A tight group of stars that looks like a ball and contains up to 1 million stars They are located in a spherical HALO that surrounds spiral galaxies such as the Milky Way.

14. OPEN CLUSTERS Groups of closely grouped stars that are usually located along the spiral disk of a galaxy

15. nebula, globular clusters and open clusters

16. Quasars – discovered in the 1960’s QUASi-StellAR Radio Source Looked like stars, but strong radio emitters Brightest objects in Universe Highly Energetic Galaxies? Most Distant Objects in Universe (12 Billion Light years) Black Hole at center? May be caused by BLACK HOLES

17. SO, WHERE DID WE ALL COME FROM?

18. COSMOLOGY – The study of the origin, structure, and future of the universe. Measurements have shown that galaxies are moving apart Raisin bread model

19. The Big Bang Scientists’ theory about what they think happened starting less than a second after universe formed. About 10-20 (14?) Billion Years ago Everything started in a small hot dense object: The Singularity Singularity exploded and everything have been moving apart since.

20. Evidence for The Big Bang Cosmic Background Radiation- The “echo” of the Bang, static in space, comes from all directions. Red Shift of All galaxies Galaxies (Quasars) that are further away are more red shifted

21. How to calculate the age of the universe Measure distance from Earth to various galaxies – can estimate the age of the universe and predict its rate of expansion Calculate the ages of old, nearby stars. Universe must be as old as the oldest stars it contains.

22. What’s next? Open Universe - Everything will continue to expand and will eventually cool off. Closed Universe - Gravity will overcome expansion and, expansion will stop, the universe will start to contract, leading to a “Big Crunch”