Download What is the solar system?

What is the solar system?
The solar system can be defined as matter
that is gravitationally bound to our Sun
1.  Sun
2.  Planets & their Moons
3.  Asteroids, Kuiper belt objects,
& Oort cloud
4.  Comets & Meteors
5.  Dust
How would we go about describing the
solar system?
1.  What does it look like?
2.  What are the bulk characteristics of solar system
materials?
3.  What are the masses of the solar system and its individual
constituents?
4.  What is the elemental composition of the solar system?
5.  What are the angular momenta of the solar system and its
individual constituents?
6.  What are the energy sources in the solar system?
How would we go about describing the
solar system?
1.  How can we describe the motions of the bodies of the solar system?
• 
What accounts for the motions?
2.  What is the mass distribution of the solar system?
• 
Why is most of the mass in the center of the solar system?
3.  What is the chemical composition of the solar system and its
constituents?
• 
Do each of the constituents of the solar system have the same mix of elements?
• 
What controls what compounds are formed?
4.  What processes are likely responsible for the formation and
subsequent evolution of the solar system?
Planetary motion - orbital direction
Planetary motions - orbital inclinations
Orbits of the asteroid belt
Orbits of the Kuiper belt objects
Orbits of the Oort cloud objects
Evolution
of dust in
the solar
system
A simple conceptual model – or at least
questions
•  Based on these observations what could we say
about the formation of the solar system?
•  How old is the solar system?
•  From what did it form?
•  Was the starting material uniform in
composition?
•  What are the energy sources in the solar
system?
•  Why did the sun form?
•  How did planets form?
What are the bulk characteristics of
solar system materials?
Similarities in bulk characteristics may imply similar
physical processes.
The Sun
• 
The bulk of the mass is concentrated in the Sun, it
controls the dynamical evolution of the solar system
• 
The Sun is the only body in the solar system that
generates energy by fusion
• 
The Sun generates magnetic fields
• 
The Sun can accelerate particles
Bulk characteristics of solar system
materials – inner planets
  The terrestrial planets are denser and are
located in the inner solar system ( Mercury,
Venus, Earth,and Mars)
Bulk characteristics of solar system
materials – outer planets
 
The gas-rich giant planets, Jupiter, Saturn,
Uranus, and Neptune, are located further
away from the Sun
Bulk characteristics of solar system
materials - satellites
 
Some moons are comprised of silicates
 
Other moons have icy compositions
Bulk characteristics of solar system
materials – asteroids?
• 
Located between the
orbits of Mars & Jupiter
(2.2 to 3.8 AU) are
thousands of asteroids
Bulk characteristics of solar system
materials – outermost planet?
 
Pluto seems somewhat out of place
Bulk characteristics of solar system
materials – Kuiper belt?
• 
Kuiper belt asteroids
are located outside the
orbit of Neptune
– 
Pluto is considered to be
the largest member of
this group
What are the bulk characteristics of
solar system materials – small objects?
• 
Far outside (up to 105 AU) of even the Kuiper belt
is a 3-dimensional cloud of objects, hunks of “dirty
ice”
What are the bulk characteristics of
solar system materials – small objects?
• 
Cosmic Dust
A simple conceptual model based on bulk
characteristics
•  With only the information we have in hand can
we form a model of how the solar system formed
that explains the motions and mass distributions
of planets, small bodies, and dust?
•  What are some questions we could ask?
–  Was the starting material uniform in composition and
why is it not now evenly distributed?
–  What are the energy sources in the solar system?
–  What controls the motions of the planets?
How do we describe the solar system elemental abundance?
• 
The solar system is 90% H,, ~9% He
• 
The terrestrial planets are depleted in these elements
• 
What does this say about the homogeneity of the
starting composition?
• 
What could account for the depletion of volatiles in the
terrestrial planets?
Our model could be that the starting gas was
homogeneous in composition, to first order, and
something occurred to the terrestrial planets that
caused them to lose their volatiles
How do we describe the solar system –
angular momentum?
• 
All the planets have the same orbital direction
• 
Most solar system material is on a plane
• 
Jupiter contains most of the angular momentum of the
solar system
• 
Angular momentum is conserved so the angular
momentum now present in the solar system was
probably there even before it exited in its current state
A simple model for the formation of the solar
system
•  The solar system formed out of a rotating cloudlike structure, dominated by H and He
•  Something triggered the fragmentation of this
cloud and it became gravitationally unstable,
allowing its collapse
•  In the center temperatures were hot enough to
trigger fusion
•  Moving radially outward from the sun
temperatures decreased in the nebula
A simple model for the formation of the solar
system
•  At any given distance from the Sun there was a
~ unique temperature
•  The temperature controlled the nature of
materials condensing
•  As material condensed out of a gas they were
swept up to form larger and larger bodies,
eventually forming planets
•  In the region of the terrestrial planets all volatiles
were lost
What is the mass of the solar system and
its constituents?
• 
The sun accounts for 99.87% of the total mass of the
solar system
• 
The mass of the sun is 1.99 x 1030kg
• 
Jupiter’s mass is 1.899 x 1027kg
• 
An accounting by mass essentially ignores all the rest
Solar system processes?
Solar processes
– 
Nuclear fusion
– 
Hydrostatic equilibrium
– 
Radiation transport
– 
Generation of magnetic fields and particle acceleration
Solar system processes?
Planetary Processes
– 
Volcanic activities
– 
Radio-active decay
– 
Plate tectonics
– 
Atmospheric processes
– 
Impact processes
– 
Dynamical evolution of orbital parameters
– 
Core formation and planetary scale differentiation processes
Solar system processes?
Cometary and asteroidal Processes
– 
Evolution of orbital parameters
– 
Creation of dust in the inner solar system
– 
Surface heating
Processes affecting multiple solar system bodies
– 
Solar insolation
– 
Gravitation