GALACTIC UNIVERSE

It is a group of billions and billions

of stars held together by gravity.

What is a Galaxy?

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

Side View

Bulge

Disk

Spiral Galaxy

Spiral Galaxy

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

Elliptical Galaxy

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

Irregular Galaxy

Nebulae

Planetary Nebula

(death of a star)

Movie

Stellar Nebula (where stars are

born)

http://faculty.randolphcollege.edu/tmichalik/Movies/helix.mpeg

Stellar Nebula

Planetary Nebula

Colliding Galaxies

Betelgeuse

Rigel

Orion Constellation

Supernovae

GALACTIC UNIVERSE

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