1. NEBULAR THEORY

2. Age of the solar system
Based on the age of the oldest meteorites and radiometric dating the age of the solar system is calculated to about 4.56 billion years

3. Two important features
FIRST: all the planets orbit in nearly the same flat, disk-like region
SECOND: all the planets orbit in the same direction around the Sun
These two features are important clues to how the solar system formed.

4. A Giant Nebula Big cloud of gas and dust
Made mostly of hydrogen and helium
Contained heavier elements as well
Gravity caused the nebula to contract
May have come from material leftover from the big bang or from previous supernovas

5. In the Nebular Hypothesis, a cloud of gas and dust collapsed by gravity begins to spin faster because of angular momentum conservation

6. The competing forces associated with gravity, gas pressure, and rotation, the contracting nebula begins to flatten into a spinning pancake shape with a bulge at the center.

7. As the nebula collapses further, instabilities in the collapsing, rotating cloud cause local regions to begin to contract gravitationally. These local regions of condensation will become the Sun and the planets, as well as their moons and other debris in the Solar System.

8. Formation of the Sun Sun first object to form in the solar system
Gravity pulled matter together to the center of the disk
Density and pressure increased
Nuclear fusion reactions began

9. Formation of the planets
The outer parts of the disk were cooling off
Small pieces of dust started clumping together
Clumps collided and combined with other clumps
Larger clumps attracted smaller clumps with their gravity
Eventually, all these pieces grew into the planets and moons that we find in our solar system today

10. The outer planets Jupiter Saturn Uranus Neptune
Condensed from lighter materials such as
Hydrogen
Helium
Water
Ammonia
Methane
It is so cold by Jupiter and beyond that these materials can form solid particles

11. The inner planets Mercury Venus Earth Mars Formed from denser elements
Iron
Silicon
Magnesium
Sulfur
Aluminum
Calcium
Nickel
These elements are solid even when close to the Sun

12. http://Formation of the solar system