Download Solar System Origins

Our Solar System
and Its Origin
What does the solar system look
like?
Recall scale of solar system
Planets are very tiny
compared to
distances between
them.
6.2 Clues to the Formation
of Our Solar Sytem
Our Goals for Learning
• What features of our solar system provide
clues to how it formed?
• What theory best explains the features of
our solar system?
What features of our solar system
provide clues to how it formed?
The Sun, planets, and large moons
orbit and rotate in an organized way
Counterclockwise
seen from above
the north pole)
Terrestrial planets are small, rocky, and close to the Sun.
Jovian planets are large, gas-rich, and far from the Sun.
(What about Pluto?)
What theory best explains the
features of our solar system?
According to the
nebular theory
our solar system
formed from a
giant cloud of
interstellar gas
(nebula = cloud)
What have we learned?
• What features of our solar
system provide clues to how
it formed?
• Four major features
provide clues: (1) The
Sun, planets, and large
moons generally rotate
and orbit in a very
organized way. (2) With
the exception of Pluto,
the planets divide clearly
into two groups:
terrestrial and jovian. (3)
The solar system
contains huge numbers of
asteroids and comets. (4)
There are some notable
• What theory best
explains the features
of our solar system?
• The nebular theory,
which holds that
the solar system
formed from the
gravitational
collapse of a great
cloud of gas.
Where did the solar system come
from?
The cloud of gas that gave birth to our solar system
resulted from the recycling of gas through many
generations of stars within our galaxy.
What caused the orderly patterns of
motion in our solar system?
Solar System
Formation:
1- gravity forced the
cloud to become
smaller, it began to spin
faster and faster
2- Collisions flatten the
cloud into a disk.
6.4 The Formation of Planets
Our Goals for Learning
• Why are there two types of planets?
• Where did asteroids and comets come
from?
• How do we explain the existence of our
Moon and other “exceptions to the
rules”?
• When did the planets form?
Four Unexplained Features
of our Solar System
√ Why do large bodies in our solar system have
orderly motions?
--> 2) Why are there two types of planets?
3) Where did the comets and asteroids come
from?
4) How can we explain the exceptions the the ‘rules’
above?
Why are there two types of planet, when all
planets formed from the same nebula?
Fig 9.5
Inside the frost line: too hot for hydrogen compounds to
form ices.
Outside the frost line: cold enough for ices to form.
Tiny solid
particles stick
to form
planetesimals.
Gravity draws
planetesimals
together to
form planets
This process
of assembly
is called
accretion
Why are there two types of
planets?
1. Jovian planets form from because cooler
temperatures allow H, He, and ice to
condense forming a gas giant.
2. Terrestrial Planets form because the
warmer temperatures only allowing metal
and rock to condense
Review of
nebular theory
Fig 6.27
When did the planets form?
We cannot find the age of a planet, but we can
find the ages of the rocks that make it up
We can determine the age of a rock through
careful analysis of the proportions of
various atoms and isotopes within it
The decay of radioactive elements into
other elements is a key tool in finding
the ages of rocks
Age dating of meteorites
that are unchanged
since they condensed
and accreted tell us
that the solar system
is about 4.6 billion
years old.