Download Orgins and Formation of the Solar System

Origins and Formation of the
Solar System
312-1
Describe theories on the formation of the solar system
Smash, crash and bang
The solar system is big, and big things have big
origins
A history of ideas
• The solar system wasn’t always seen in the
way we think of it today.
• In order to develop a theory on how the Solar
System formed, we needed to accept the idea
of HELIOCENTRISM
Heliocentrism – the SUN is the CENTER of the
solar system and all planets and objects orbit
around it.
vs. GEOCENTRISM – the former belief that the
EARTH was the center of the solar system, even
the Universe. This view was held as truth by
popular culture and religious authority for over
100 years.
Now enter the movers and the changers:
Copernicus
Kepler
Galilei
Challenging the popular model:
The combined observations and written arguments
of these three men eventually changed the world
view that the SUN is the center of the solar system
and not the Earth.
This was difficult to do at that time. Because the
Church held that the geocentric model was true,
many would not speak against the church in fear of
consequences against them.
We have only really accepted the Heliocentric
model for about 500 years!
Youtube - Galileo's Sun Centered System
FAST FOWARD:
Today our understanding of the origin of the
Solar System is called the:
NEBULAR HYPOTHESIS or SOLAR NEBULAR DISK
MODEL
• In a nut shell: 4.5 to 6 billion years ago
1. Giant cloud of gas (a NEBULA or GIANT
MOLECULAR CLOUD) collapses due to the
UNSTABLE gravity of particles at its center.
2. Gases (Hydrogen, Helium) at the center of this
collapse formed the SUN.
3. Other materials formed a spinning
PROTOPLANETARY DISC around the new born
sun.
4. From this DISC, the planets formed by the
smashing of materials into one another (a
process called ACCRETION)
NEBULA
Protoplanetary disc
Accretion of mater in
the protoplanetary disc
• Accretion continued:
The larger the ball of material grows , the more
gravity it exerts on stuff around it, the more stuff
will be attracted to it, making it even bigger!
Protoplanetary
disc with the
accretion of
materials
occuring
Formation of the planets….
-First to form were PLANETESIMALS, smaller
round bodies of material.
Planetesimals then became PROTOPLANETS.
These bodies then eventually settled into stable
orbits around the Sun and
developed their
atmospheres.
UnivColorado animation
of accretion
Gas giants, the snow line and Iron
The planets of the solar system are
grouped into the inner – TERRESTRIAL –
planets and the outer - JOVIAN and ICYplanets or GAS GIANTS.
Inner -Terrestrial
Mercury
Venus
Earth
Mars
Outer - Jovian and Icy
Jupiter
Saturn
Uranus
Neptune
These are composed
mostly of rock and
metals
These are composed
of mostly ice and
frozen gases.
Why are planets close to the sun made
of rock and those far away made of ice
and frozen gases?
• Its all about
1. temperature and
2. wind…
• 1) TEMPERATURE : Closer
to the new sun it was too
hot for gas and water to
condense into solids, only
metals like iron and rock
could be solid at such
high temperatures.
• 2) Solar WINDS – the
ignition of the Sun
created a blast that
pushed the lighter gases
outwards to the edges,
where it was cool enough
for them to condense
and form solids.
• SNOW LINE
This is at a certain distance from the Sun, where
temperatures are cold enough for water and other
gases to freeze and condense to form the icy
planets.
Astronomers believe snow lines in other solar
systems are VITAL to planet formation because
frozen water and help dust particles stick together
and so help ACCRETION.
Snow lines have been observed in other solar
systems. This direct observation helps support the
current theory on how the solar system formed.
Click here!
Youtube – Stephen Hawking and awesome graphics
Differing theories
• The Solar Nebula Hypothesis is not the only
one that tries to explain the formation of the
Universe but has currently been accepted as
the best.
There are many others that include ideas about
where the original dust particles came from and
why they began to stick together.