1. Solar System Formation
Orion Nebula (NASA)

2. Nebular Theory
The leading hypothesis to explain how the solar system formed is called the condensation theory, which is based on a related explanation called the nebular theory.
A nebula is a large cloud of gas and dust that exists in the depths of interstellar space.

3. Nebular Theory
These clouds typically form during the death of a giant star when it goes supernova. This mighty explosion sends most of the star's mass outward into space as a massive wave of debris. The nebular cloud from which our solar system formed may have accumulated from one or more stars that went supernova billions of years ago.
Stars forming in small protrusions from the Eagle Nebula

4. Supernova Shock Wave
Shell of gases ejected from a supernova as a shock wave.

5. Over time, this nebular cloud began to collapse inward
* Over time, this nebular cloud began to collapse inward. The collapse may have been triggered by a supernova that sent shockwaves through the cloud causing it to compress. * The nebula continued to contract under the influence of gravity causing it to spin faster. The more the cloud contracted, the faster it rotated. * The rate of contraction was greatest near the center of the cloud where a dense central core began to form. As the rate of rotation of the nebula continued to increase, the spinning cloud flattened into a disk with a bulge at its center.

6. The middle of this spinning disk further condensed to eventually form the Sun at the center of the solar system.
The material spinning around this new star also condensed into several large chunks of material called planetoids.
As these planetoids collided, they created larger bodies to form the planets that exist today.

7. Because the Sun and planets all formed from the same nebular cloud, they all rotate in the same direction.
Not only do the planets all rotate counter-clockwise around the Sun, but the Sun and nearly all the planets rotate counter-clockwise about their axes.

8. The End Result – Planets to Size

9. Inner and Outer Planets to Size

10. Formation of Moons by Same Process

11. Internal Structure of Planets and Moons
Ganymede - differentiated
Callisto - undifferentiated

12. Our Earth

13. Core Comparison

14. Comets - Kuiper Belt Objects

15. KBOs – Edge View