Galaxies & the Big Bang Theory
Types of Galaxies
- • Galaxies are made up of nebula, stars and black holes
- • Three types of galaxies:
**Spiral
**elliptical--disk shaped
**irregular--due to 2 galaxies colliding?
Anatomy of a Galaxy
- • There are 100 billion to a trillion stars in a galaxy
- • Gravitational pull binds the galaxy together as stars revolved around the black hole in the center
- • 100-200 billion galaxies in our known universe
Milky Way Galaxy...Our Galaxy
Milky Way Galaxy
- • Barred spiral galaxy
- • 100,000 light years in diameter
• Andromeda Galaxy is our sister galaxy
• Part of the Local Group: ~20 galaxies in our local group
Milky Way Galaxy
- • All stars in the night sky are part of the Milky Way Galaxy
- • The Milky Band in the night sky looks into the spiral arm
- • The sun is about 2/3 the way out of the spiral arm
Big Bang Theory
- • The theory of how the universe started 15-17 billion years ago from a large explosion
- • H, He and Li formed during the Big Bang-- other elements due to nuclear fusion of stars
Supporting Evidence:
- • Quasars: Very old galaxies that give off x-rays from their centers
- • The Universe is still expanding: Doppler Effect: Galaxies are moving away from each other
Space Travel
- • We will NEVER be able to travel across our galaxy.
- • We can NEVER go the speed of light
- • Why? We have mass!
- • Anything with mass cannot go the speed of light due to special relativity!