““How Did Our Solar How Did Our Solar System Form?”System Form?”

Ch. 29.4Ch. 29.4

Space is not really empty. There is gas Space is not really empty. There is gas and dust in between the stars.and dust in between the stars. This gas is mostly hydrogen, left over from the This gas is mostly hydrogen, left over from the

“big bang”“big bang” The dust is made of all the other elements. It The dust is made of all the other elements. It

is the remains of exploded stars.is the remains of exploded stars.

Gravity causes this gas and dust to form Gravity causes this gas and dust to form into clouds.into clouds.

This cloud, called a This cloud, called a nebulanebula, contracts due , contracts due to gravity.to gravity.

As the As the nebulanebula contracts, it begins to spin. contracts, it begins to spin.

The spinning causes it to take on a disc The spinning causes it to take on a disc shape.shape.

As the As the nebulanebula continues to contract the continues to contract the disc spins faster. This is what sets the disc spins faster. This is what sets the direction for the future planets.direction for the future planets.

In the center of the nebula, the density of In the center of the nebula, the density of material is the highest.material is the highest.

This means it has the most gravity, and is This means it has the most gravity, and is the hottest part of the nebula.the hottest part of the nebula.

Eventually, the center of the nebula gets Eventually, the center of the nebula gets so hot that fusion of hydrogen into helium so hot that fusion of hydrogen into helium begins. This is the birth of the Sun.begins. This is the birth of the Sun.

Meanwhile, gravity is pulling together Meanwhile, gravity is pulling together material in the discmaterial in the disc

Objects, from dust to rocks collide and Objects, from dust to rocks collide and merge. This forms the planets.merge. This forms the planets.

As the Sun begins releasing energy, the As the Sun begins releasing energy, the area near the Sun is too hot for the light area near the Sun is too hot for the light gasses to exist so they are blown outward.gasses to exist so they are blown outward.

In the outer part of the disc, the forming In the outer part of the disc, the forming planets collect this gas.planets collect this gas.

Since Jupiter was the first to form, it got Since Jupiter was the first to form, it got most of the gas.most of the gas.

This is why the inner planets are made of This is why the inner planets are made of dense materials and the outer planets are dense materials and the outer planets are mostly gas.mostly gas.

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

AssignmentAssignmentOn the left side of your notebook, make a 6 On the left side of your notebook, make a 6 panel, full-color diagram of the formation of panel, full-color diagram of the formation of the solar system. The panels should the solar system. The panels should contain these diagrams:contain these diagrams: 1 – The nebula1 – 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 center3 – The Sun begins forming in the center 4 – The terrestrial planets begin forming4 – The terrestrial planets begin forming 5 – The gas giant planets begin forming5 – The gas giant planets begin forming 6 – The solar system as it looks today6 – The solar system as it looks today