1. Galaxies

2. The Milky Way galaxy as seen
from Earth’s surface.

3. Galaxies are
collections of stars
(usually between 200 billion
and 400 billion)
that all rotate
(orbit) around
a massive
central point.

4. There are 3 types of galaxies…
Spiral
Elliptical
Irregular

5. 3 Types of Galaxies Elliptical
shaped like spheres or eggs; have almost no dust or gas between stars; contain old stars
Irregular
faint galaxies without a definite shape; smaller than the other types of galaxies; contain fewer stars
Spiral
have arms of stars, gas , and dust that curve away from the center of the galaxy in a spiral pattern
Ex. – Milky Way
The process of galaxies colliding to create a larger galaxy is known
as “galactic cannibalism.”
Images taken from:

6. Spiral Galaxies

7. 1. Spiral Arms The arms contain gas, dust and stars. The arms rotate
around the galactic core.

9. 2. The Galactic Plane Spiral galaxies form a flat rotating disk
of material.

10. Side View
Galactic Plane

12. 3. The Galactic Core The core of the galaxy is where most of the stars
are found. It is
very bright and
is an intense source
of x-rays and radio waves.

13. Our solar system orbits
around the galactic core.
It takes 250 million years
for us to make one complete
orbit.

14. Our Galaxy We are located about 2/3 of the way out from
the galactic core.

15. Barred Spiral Galaxies - They’re a type of spiral galaxy in which there are only two spiral arms. Can you see why how it got its name?

17. Elliptical Galaxies are . . .
you guessed it, they’re oval shaped.

18. Elliptical
galaxies
contain
almost
NO gas
or dust.
They only
have
stars in
them.