Our Place in the UniverseDrew Smith

Important Principles

•The Cosmological Principle▫The universe is isotropic and

homogenous (it “looks” the same in all directions.)

•The Copernican Principle▫Humans are not special observers of

the universe. No place was the “starting point” of the universe.

What is the Universe?•The observable universe contains

nearly a septillion stars (1 X 1024). ▫This is more than the number of

grains of sand on earth.•These stars are located in at least 80

billion galaxies.▫These galaxies are then clustered,

and superclustered.

Where do we fit? Solar System

Where do we fit? Interstellar Neighborhood

Where do we fit? Milky Way Galaxy

Where do we fit? Local Group

Where do we fit? Supercluster

Where do we fit? Local Clusters

Where do we fit? Observable Universe

The Universe is EXPANDING• Each object increased in

distance by double, which means the rate of expansion is constant across the universe. However, the object that began 10 cm away travelled 10 cm in the same time that the closer object travelled 5 cm. It was twice as far away, so its recession velocity was twice as great.

Any Questions?•Assignment:

▫Write a story about the origin of earth, the solar system, the galaxy, the universe, or all of the above.