The Universe

planets moons stars solar systems galaxies nebulae empty space more?

What’s in it?

What’s wrong with this model of the universe?

It is not to scale.

Interstellar cloud of dust and gassesBirthplace of stars

Nebulae

Galaxiescollection of stars, gas & dust held

together by gravity

millions of galaxies are known to existgalaxies can contain from hundreds of

thousands to one trillion stars3 major types

● Spiral galaxies ● spiral arms made of stars ● barred spiral - has two or more long

arms extending away from the central “bar” cluster of stars

● Elliptical galaxies ● no spiral arms and no flattened disk

(think football)● Irregular galaxies

● have no regular shape

Galaxies: The Three Types

Milky Way ● Spiral galaxy (Barred-Spiral)● 100,000 light-years in diameter. ● contains about 200 billion stars● Home to Our Sun● the Sun and Earth are located 2/3 away from

center in one of the outer spiral arms● Sun orbits central Milky Way at about 235

km/s around the center of the galaxy

You are here!

Andromeda Galaxynearest galaxy neighbor

about 2.5 million light years away120,000 light years wide

A spiral galaxyThe largest galaxy in our local

group of galaxies

So Where Did It All Come From?

Scientifically believed origins:1. Big Bang2. Oscillating Universe3. Geocentric Model4. Heliocentric Model

Big BangThe universe was created from

one, instantaneous, large explosion outwardmost widely scientific accepted

theory of the origin of the universe

Oscillating Universestates that the universe grows

outward until gravity pulls it back to the center and then expands outward over and over again

Geocentric Modelstates all celestial bodies orbit the

Earth

Heliocentric Modelstates all objects in our solar system circle

the Sun.