1. The basic structural unit of the universe appears to be the galaxy.
A Galaxy is a collection of billions of stars an various amounts of gas and dust held together by gravity.

3. 3 TYPES OF GALAXIES SPIRAL ELLIPTICAL IRREGULAR
THERE ARE 100,000,000,000 GALAXIES
THERE ARE 100,000,000,000 STARS IN EACH GALAXY
3 TYPES OF GALAXIES
THAT’S 10,000,000,000,000,000,000,000 STARS IN THE WHOLE UNIVERSE
The sun is one.

4. Spiral Galaxy (The Andromeda)

5. Blue color indicates very HOT stars
Spiral
Spiral
Blue color indicates very HOT stars

6. Edge-on view of the Milk Way Galaxy

7. Barred Spiral

8. Elliptical M87 Much more massive than Milky Way.
Mostly cool stars - gives it a yellowish color
Elliptical

9. Elliptical
NGC 5078
The smaller galaxy has been distorted into an 'S' shape by the interaction (gravity).
Encounters between galaxies such as this are common, can lead to them merging into a single entity.
80 million light years away
Elliptical
The dust lane is warped and broadened, probably by interaction with the faint companion galaxy IC 879, which is itself distorted into an 'S' shape by the interaction.
80 million light years away

10. Irregular NGC 1313 Scattered patches of star formation –no real shape.
15 million light years away
Irregular
15 million light years away

11. Colliding Galaxies
Colliding Galaxies

12. Cartwheel Galaxy 500 million light years away.
The Cartwheel itself was a galaxy about as big as the Milky Way probably with much the same spiral structure. However, one of the small companion galaxies has recently passed through its center.
Cartwheel Galaxy
500 million light years away.
The Cartwheel itself was a galaxy about as big as the Milky Way probably with much the same spiral structure. However, one of the small companion galaxies has recently passed through its center.

13. Galaxy cluster 3 Billion Light years away! 3 Billion Light years away!

14. MORE GALAXIES
MORE GALAXIES

15. Approximately 100,000 light years across
Milky Way
Milky Way galaxy
Approximately 100,000 light years across