1. Galaxies, Stars, and our Sun

2. Outline
Galaxies
Stars
The Sun

3. Galaxies
Galaxies are huge collection of gas, dust, and hundreds of billions of stars.
There are billions of galaxies

4. Galaxies Milky Way Galaxy Our Galaxy.
There are about 400 billion stars

5. Galaxies
Spiral Galaxy - a galaxy with a spiral structure

6. Barred Galaxy - spiral galaxy with a central bar-shape

7. Elliptical Galaxy
galaxy shaped like an oval and lacks spiral arms

8. Irregular Galaxy - galaxy that have no spirals and is not elliptical

9. What are Stars? Stars are large balls of hot gas.
They look small because they are a long way away,
many are bigger than the Sun.
The heat of the star is made by nuclear fusion reactions.

10. Star Life Cycle The life of stars are billions of years.
All stars start as Nebulas –clouds of dust and gases (H and He)

11. Star Life Cycle 2. Turns into a hot, dense clump that produces energy.
3. Once the energy is used up the star “dies”.

12. On-line Lessons: The Birth and Death of Stars
White Dwarf and Planetary Nebula
Collapsing cloud
Sun-like stars
A new star
Supernova Remnant and Neutron Star
Red Giant
Massive stars
Birth and Death of Stars - Summary

13. Star Classification Stars can be classified according to:
1. Colour: red (coldest)  orange  yellow  white  blue (hottest)
2. Size: dwarf (smallest)  giant star  supergiant star

14. Our Star – The Sun
The sun is the center of the solar system and everything revolves around it.
The diameter is km.
The Sun is 149,597,887.5 km away from Earth.

15. The Sun
The Sun is currently approximately 75% hydrogen and 25% helium.
It has been producing energy for 5 billion years.
It has enough fuel for another 5 billion years of “life”.

17. Constellations
Constellations are groups of stars in a galaxy that seem to form shapes or patterns.
Most constellations can only be seen certain times of the year.
Circumpolar Constellations - 3 constellations that we can see in the Canadian sky year round.

18. Big Dipper
The Big Dipper is also called Ursa Major or the Great/Big Bear.

19. Little Dipper Also called Ursa Minor or the Little Bear.
Polaris (the North Star) is located at the tip of the handle.
If you are in the northern hemisphere and are facing Polaris you are facing the North Pole.
Useful in navigating.

22. Cassiopeia
Shaped like a spread out W or M.

24. Classwork
Constellation Map
Seasonal Star Map