Transcript Document

“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”
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 ovalshaped) 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
2 – Nebula contracts, spins, and forms a disc
3 – The Sun begins forming in the center
4 – The terrestrial planets begin forming
5 – The gas giant planets begin forming
6 – The solar system as it looks today