1. How was the universe created?
Big Bang Theory
An explosion occurred billion years ago in space causing the universe to expand in all directions

2. Edwin Hubble American astronomer
Discovered that other galaxies in the universe were moving away from us…which would mean at one time they were all together at one point
The Hubble Telescope was named in his honor

3. What is the Milky Way? A cluster of stars called a galaxy
Contains hundreds of billions of stars
Traveling at the speed of light-it would take about 2 million years to reach another galaxy…the Andromeda Galaxy
It’s where our solar system is located

4. The Milky Way
Often called “Our Galaxy”

5. Types of Galaxies
Spiral Elliptical Irregular

6. Spiral Galaxies Resembles a pinwheel
Our solar system is located about 2/3 of the way out on one of the spiral arms
It’s difficult to see the spiral shape of our galaxy because we’re on the inside

7. Elliptical Galaxies Resemble a flattened ball
Contain billions of stars & little to no dust between them
Stars are really close together-may even appear to be 1 giant star
Consist of old stars

8. Irregular Galaxies Irregular shape
Large Magellanic Cloud is about 160,000 light years away from us

9. Stop HERE!

10. What about the stars?
Stars begin as a large cloud of dust & gas called a nebula

13. Protostar
The nebula contracts & becomes so hot that nuclear fusion begins…causing a protostar to be born

14. Red Giant/Supergiant
A star becomes a red giant or a supergiant when it begins to run out of fuel

15. What happens to a dying star?
When a star begins to “die” it becomes a white dwarf, a neutron star, or a black hole

16. White Dwarf Blue-white hot core of a star left behind from a red giant
About the size of Earth
Have no fuel-just burn from leftover energy
Becomes a black dwarf when it stops glowing

17. Neutron Star Smaller & denser than white dwarfs
May contain 3 times the mass of our Sun but be 20km in diameter

18. What is a supernova?
A dying giant or supergiant star can suddenly explode causing a huge bang
Some of the material from the star expands into space which becomes part of nebula again
“Recycled Star”

19. Black Holes Most massive stars 40 times the mass of the Sun
After the star becomes a supernova, the gravity is so strong that the gas is pulled inward packing it into a smaller space
Gravity is so strong that nothing can escape...

20. Black Holes
…not even light!

21. Black Holes Astronomers cannot detect black holes directly
They find gas near a black hole rotating faster & faster

22. How are stars classified?
Size
Temperature
Brightness

23. Star Sizes All stars appear to be the same size
Our Sun is a medium-sized star which most stars are
Giant Stars or Supergiants are very large
White dwarf stars are about the size of Earth
Neutron stars are even smaller

24. Star Temperatures
A star’s color reveals its temperature

25. Red/Orange
Giants
3,000-5,000 °C
Betelegeuse

26. Yellow
Supergiants
6,000°C
“Polaris”
Sun

27. Blue/White
Main Sequence/White Dwarfs
10,000-50,000°C
“Rigel”

28. What is the H-R diagram?
Graph used to show the relationship between temperature & brightness

29. Main Sequence Diagonal band on the H-R Diagram
90% of all stars are main sequence
Our Sun

30. What is a light-year?
Is the distance that light travels in 1 year or about 9.5 million million km

31. What is a constellation?
Pattern of stars in the sky

32. Big Dipper

33. Hercules

34. Orion

35. Cancer

36. Pegasus