1. Formation of the Universe
Earth and Environmental Science
Unit 7

2. Galaxies- groups of stars, dust, and gases held together by gravity
The universe has hundreds of billions of galaxies
Galaxies are grouped in galactic clusters
Our galactic cluster is called the Local Group and contains at least 28 galaxies

3. Our Galaxy
Milky Way - our spiral galaxy consisting of over 400 billion stars, plus gas and dust arranged into three general components
1. halo - a roughly spherical distribution which contains the oldest stars in the Galaxy
2. nuclear bulge and Galactic Center
3. disk, which contains the majority of the stars, including the sun, and virtually all of the gas and dust

5. Our Solar System

6. Our Sun Did you know- 1.3 million earths can fit inside
870,000 miles wide
93 million miles away from earth
8 ½ mins for light to reach earth
Guess how hot?
10,000 million degrees

7. The power of the Sun…
The Sun gives us heat, light, our food, and the air that we breathe. It powers the atmosphere to give us the winds and rain. Even the coal and oil that generate electricity for light and power come from plants and animals that lived hundreds of millions of years ago and depended on the Sun for life.

8. We Aren’t as Big as We Think.

14. But how did this all get here? The Beginning:
The Big Bang Theory-
Initially, the entire universe was confined to a dense, hot, super-massive ball
About 13.7 billion years ago, a violent explosion may have occurred, hurling this material in all directions
Expansion and cooling continues today
**This marks the beginning of the universe**
First stars and galaxies formed 200 million years after big bang
Solar system formed 4.6 billion years ago from a huge cloud of dust and gases, according to the nebular theory

15. Big Bang Expansion

16. Background for Big Bang
Most information about the universe comes from the study of light
Electromagnetic radiation- different types of energy including gamma rays, X-rays, ultraviolet light, visible light, infrared radiation, microwaves, and radio waves
The narrow band of electromagnetic radiation we can see is visible light

17. Electromagnetic Spectrum

18. Visible Light Violet has shortest wavelength
Red has longest wavelength

19. Red light has the longest wavelength which means that the object is moving away from the observer
Violet/blue light has the shortest wavelength which means that the object is moving towards the observer
Violet light has the most energy (gamma rays) and red light has the least energy (radio waves)

21. The Big Bang Theory Evidence
Cosmic Background Radiation moves in front of our universe and is one piece of evidence supporting this theory
When viewing the sky with a radio telescope, the sky is not black, but has a faint glow (this is CBR)

22. Cosmic Background Radiation
The color differences are variations
in temperature.

23. Evidence for the Big Bang Theory
Doppler Effect- change in wavelength of a wave that is emitted from a source moving away or toward an object
Occurs for both sound and light waves
Astronomers are only concerned with the changes of light wavelengths, not sound.
It tells us whether an object is moving towards or away from Earth
Large Doppler shifts indicate high speeds

25. Evidence for the Big Bang Theory
If the source moves away, the wave becomes stretched (longer wavelength)
If the source moves toward you, the waves get closer (shorter wavelength)
The light from sources moving away appears red
The light from sources moving closer appears blue
So…when an object moves towards Earth, the wavelength will be shortened and the color will be violet/blue and when it moves away, the wavelength will get longer and the color will be red
                                     

26. Red Shift
“Red Shift” means that an object in space in moving away from Earth
The Red Shift of distant galaxies tell us that the universe is expanding
Greater red shifts in the color spectrum
of distant galaxies indicate faster speeds

27. Edwin Hubble- 1920s astronomer
observed the light from distant galaxies and he noticed something amazing.
He saw that the light from these galaxy clusters was red-shifted, which meant that they were all moving away from us.
The galaxy clusters that were farther away from us were moving at a faster rate, the farther they were away.
The universe seemed to be expanding!

28. Hubble’s Law
According to this law, galaxies are moving away at a speed that is proportional to their distance.

29. Hubble Expansion

30. Raisin Bread Dough Model
                                                                                                                  
Raisin Bread Dough Model
Let's assume that this ball of dough is our universe, and each raisin represents a galaxy cluster. The raisins are distributed fairly uniformly throughout the dough, just like the galaxy clusters in our universe.

31.                                                                                                                   
But what happens if we let the raisin bread dough sit out to rise for awhile? The dough rises and expands, and the raisins start to move away from each other. The raisins closer to the edges of the dough move away from the center faster than the one that are closer to the center. Now imagine our galaxy cluster as one of the raisins near the center of the dough. The farther the other raisins are from us, the faster they are moving away from us.