“How Did Our Solar System Form?” Ch. 29.4

Space is not really empty. There is gas and dust in between the stars. This gas is mostly hydrogen, left over from the “big bang” This gas is mostly hydrogen, left over from the “big bang” The dust is made of all the other elements. It is the remains of exploded stars. The dust is made of all the other elements. It is the remains of exploded stars. Gravity causes this gas and dust to form into clouds.

This cloud, called a nebula, contracts due to gravity. As the nebula contracts, it begins to spin. The spinning causes it to take on a disc shape. As the nebula continues to contract the disc spins faster. This is what sets the direction for the future planets.

In the center of the nebula, the density of material is the highest. This means it has the most gravity, and is the hottest part of the nebula. Eventually, the center of the nebula gets so hot that fusion of hydrogen into helium begins. This is the birth of the Sun.

Meanwhile, gravity is pulling together material in the disc Objects, from dust to rocks collide and merge. This forms the planets. As the Sun begins releasing energy, the area near the Sun is too hot for the light gasses to exist so they are blown outward.

In the outer part of the disc, the forming planets collect this gas. Since Jupiter was the first to form, it got most of the gas. This is why the inner planets are made of dense materials and the outer planets are mostly gas.

Some left-over planetesimals were unable to form into a planet due to Jupiter’s gravitational influence. These are the asteroids. They made of material very similar to the terrestrial planets. Comets are the left-over materials from the outer solar system, rich in methane and other ices. They have highly eccentric (very oval- shaped) orbits bringing them closer to the Sun.

Assignment On the left side of your notebook, make a 6 panel, full-color diagram of the formation of the solar system. The panels should contain these diagrams: 1 – The nebula 1 – The nebula 2 – Nebula contracts, spins, and forms a disc 2 – Nebula contracts, spins, and forms a disc 3 – The Sun begins forming in the center 3 – The Sun begins forming in the center 4 – The terrestrial planets begin forming 4 – The terrestrial planets begin forming 5 – The gas giant planets begin forming 5 – The gas giant planets begin forming 6 – The solar system as it looks today 6 – The solar system as it looks today