1. GALACTIC UNIVERSE

2. What is a Galaxy?
It is a group of billions and billions of stars held together by gravity.

3. All existing matter; everything
Universe
All existing matter; everything

4. Spiral Galaxy Huge; contains stars, gas, and dust
Side View
Bulge
Disk
Top View
Huge; contains stars, gas, and dust
Held together by gravity
Pinwheel shape/looks like a hurricane
Bulge and thin disk
Halo (glow) is present
Rich in gas and dust
Young and old stars are present

5. The “Milky Way” galaxy is a spiral galaxy
The “Milky Way” galaxy is a spiral galaxy. The Sun is in a spiral arm half-way out from the center.

6. Map of Milky Way Our Sun(yellow dot) is in a spiral arm, ½-way out

7. Spiral Galaxy

8. Spiral Galaxy

9. Spiral Galaxy

10. Spiral Galaxy

11. Huge; contains stars, gas, and dust Held together by gravity
Elliptical Galaxy
Huge; contains stars, gas, and dust
Held together by gravity
Round to oval
Bulge but no disk
Halo is present
Little cool gas and dust
Mainly OLD STARS are present

12. Elliptical Galaxy

13. Elliptical Galaxy

14. Elliptical Galaxy

15. Elliptical Galaxy

16. Irregular Galaxy
Huge; contains stars, gas, and dust
Held together by gravity
No regular shape
May show signs of a disk and/or bulge
Halo is present
Usually rich in gas and dust
Young and old stars are present

17. Irregular Galaxy

18. Irregular Galaxy

19. Irregular Galaxy

20. Stellar Nebula (where stars are born)
Nebulae
Stellar Nebula (where stars are born)
Planetary Nebula
(death of a star)
Movie

21. Stellar Nebula

22. Stellar Nebula

23. Stellar Nebula

24. Stellar Nebula

25. Planetary Nebula

26. Planetary Nebula

27. Planetary Nebula

28. Planetary Nebula

29. Colliding Galaxies

34. Orion Constellation Betelgeuse Rigel
Betelgeuse is the brightest star in the Orion Constellation. Discuss Betelgeuse’s and Rigel’s apparent magnitude after comparing their size

35. Recently Betelgeuse showing bubbles and losing mass
Recently Betelgeuse showing bubbles and losing mass. Discuss the possibility that it has already become a supernova but it’s light has not reached us yet.

36. View of an expanding halo of light around V838-Mon at the outer edge of our Milky Way galaxy. The illumination of interstellar dust comes from the red supergiant star at the middle of the image, which gave off a flashbulb-like pulse of light in 2002, becoming 600,000 times more luminous than our Sun. It was thus one of the most luminous stars in the entire Milky Way. The dust and gas was probably ejected from the star after a previous explosion some tens of thousands of years ago.” It is thought that it is in the process of becoming a supernova.

37. Supernovae

38. Stellar Nebula Massive Star Neutron Star Red Supergiant Black Hole
White Dwarf
Planetary Nebula
Red Giant
Sun/main sequence star
Stellar Nebula
Protostar
Stars form in a nebula from collapsing clouds of interstellar gas and dust.
Massive Star
Neutron Star
Red Supergiant
Supernova
Black Hole