1. The
Universe
Chapter 25.3

2. The Expanding Universe

3. DOPPLER EFFECT
The Change in wavelength of a wave that is emitted from a source that is moving away or toward an object.
SOUND
Doppler Demo:
Siren Sound:
Moving Ambulance:

4. LIGHT
In Astronomy, the Doppler effect is used to determine whether a star is moving away from or toward Earth
Movement is determined by the length and color of the wave

5. Moving toward  appears more blue because wavelength is shorter…
Moving toward  appears more blue because wavelength is shorter….BLUE SHIFT
Moving away  appears more red because wavelength is longer…….RED SHIFT

6. HUBBLE’S LAW
Galaxies are moving away from Earth at a speed that is proportional to their distance.
Hubble observed that galaxies that were farthest from Earth were moving at the fastest speeds
These galaxies had a greater red shift
Video

7. THE BIG BANG
Theory states that at one time, the entire universe was confined to a dense, hot, supermassive ball.
Then about 13.7 billion years ago, a violent explosion occurred, hurling this material in all directions.

8. galaxies: large scale groups of stars, dust, & gas held together by gravity
there are 50 billion-1 trillion galaxies
we are in the Milky Way galaxy
Andromeda is the next nearest galaxy (over 2 light years away)

11. The Milky Way Galaxy
There may be more than 100 billion stars in the Milky Way!
It is about 100,000 light years wide and about 10,000 light-years thick at the nucleus!
It has at least three distinct spiral arms.
Our solar system is about 30,000 light years from the center!
Our solar system orbits the nucleus about every 200 million years!

14. spiral: bright center of stars with arms spiraling out
Types of Galaxies
spiral: bright center of stars with arms spiraling out
Milky Way is a spiral

15. Andromeda Galaxy

16. barred spiral: have a group of stars making a bar through the center

17. elliptical: shape ranges from spherical to oblong
no arms
60% of all galaxies are elliptial

18. irregular: small, faint stars spread out unevenly with no pattern

19. Large Magellanic Cloud
Small Magellanic Cloud