History of the Solar System

1. History of the Solar System William Allen

2. Nebular Theory • The most popular theory of the formation of the solar system is the nebular theory. • The theory is that the solar system formed when an interstellar nebula collapsed, and the sun and a disk of rock, metal, gas, and ice formed. These objects formed the planets, asteroids and other objects that orbit the sun, and the spinning of this disk is what started the orbits of everything in the solar system that are still happening today.

3. Collapse of the Nebula There was once a nebula floating in space. One day, the nebula began to collapse and rotate because of gravity. It got smaller and smaller, and spun faster and faster, and got hotter and hotter and then it became a protostar. A protostar is to a star as an embryo is to a baby.

4. Protoplanetary Disk • While the protostar was forming, a disk around it also came into existence. As the nebula spun, gases that didn’t become part of the protostar were forced outward into a disk shape.

5. The Sun • When the protostar condensed and heated up enough, our sun was born. The protoplanetary disk continued to spin…

6. Planets, Asteroids, and Pluto • …and the metal, ice, rock, and gas in the disk separated into small groups. These groups became the planets, moons, asteroids, comets, planetary rings, and Pluto.

7. The Solar System • When the protoplanetary disk became the planets and other astronomical objects, they continued to spin around the sun. Today, 4.6 billion years later, these objects still orbit the sun in an arrangement known as….