1. The Universe

2. The Big Bang Theory
Scientists believe that our universe began with a big explosion of gas and dust in space. This explosion is called the Big Bang.
All of this matter and energy in space was concentrated at one point before the Big Bang.
They believe this explosion occurred about 15 billion years ago.
Since that time, the universe has been expanding (getting bigger and more spread out).

3. animation of the formation of the universe:

4. our solar system
Our solar system consists of the sun, planets, dwarf planets (or plutoids), moons, an asteroid belt, comets, meteors, and other objects.
The sun is the center of our solar system; the planets, over 61 moons, the asteroids, comets, meteoroids and other rocks and gas all orbit the Sun.

5. This is the compostion of our solar system: Sun: 99. 85% Planets: 0
This is the compostion of our solar system: Sun: 99.85% Planets: 0.135% Comets: 0.01% ? Satellites: % Minor Planets: % ? Meteoroids: % ? Interplanetary Medium: % ?

6. animation of our solar system.

7. galaxy Definition: A cluster of hundreds of billions of stars.
Our galaxy is the Milky Way.
The Milky Way is a spiral galaxy.
Our solar system is on a spiral arm of the Milky Way.

8. The Milky Way Galaxy

9. Types of Galaxies: Elliptical galaxies
Huge; contain stars, gas, and dust
Held together by gravity
Round-to-oval shape
Mainly old stars are
present

10. Types of Galaxies: Spiral galaxies
Huge; contain stars,
gas, and dust
Held together by
gravity
Pinwheel shape
Young and old stars
are present

11. Types of Galaxies: Irregular galaxies
No regular shape
May show signs of a
disk and/or a bulge;
halo is present
Usually rich in gas and
dust
Young and old stars
are present

12. formation of our solar system