Origin of the Solar System

1
Origin of the Solar System
2
Early Hypotheses

• Catastrophic
• Passing star hypothesis
• Passing star pulled material off of our star to
  form solar system

3
Early Hypotheses

• Evolutionary
• Nebular hypothesis
• Rotating cloud of matter contracts under its own
  gravity and flattens into a disk
• Solar nebula hypothesis
• Planets form at the same time from the same cloud
  as the star.

4
Forming a Theory

• Hypothesis, theory or model?
• Once data is collected from observable planetary
  systems, a theory can be developed from the
  hypothesis and data collected.

5
Solar Nebular Theory

• Dust cloud
• Disruption supernova
• Contracts and forms spinning disk
• Spins faster leaving blob in center
• Planetesimals formed by two processes.
• Condensation
• Accretion
• Temperature influences type of planet formation

6
Solar Nebular Theory

• Nuclear reactions in core of star caused by
  radiation pressure cause star to heat up and
  become more luminous -expels gas and dust cocoon.
• Planetesimals collide and grow gas giants
  already formed
• After 100 millions years, planets in solar system
  are formed.

7
Solar Nebular evidence

• Predicts many stars have planetary systems
• Observations of extrasolar planets
• Wobble of star produces shift in spectrum
• Changes in brightness of star
• Many stars appear to have disk of gas and dust.

8
Properties of Solar System

• Disk shape
• Common rotation and revolution.
• Two types of planets
• Terrestrial
• Jovian
• Ring systems for all Jovian planets.
• Space debris such as asteroids, comets and
  meteoroids
• Age of solar system from Moon, Mars, and
  asteroids.
• Age of solar system from Sun.

9
Our Solar System
10
Our Solar System

• How do we compare planets?
• Density mass/volume
• Density of water 1000 kg/m3
• Density of rock 2000-4000 kg/m3
• Atmosphere and chemical composition
• Magnetic field strength
• Number of moons
• Mass
• Size
• Orbits
• Rotation and Revolution periods

11
Our Solar System

• Two categories of planets
• Terrestrial
• Mercury
• Venus
• Earth
• Mars

12
Our Solar System

• Two categories of planets
• Jovian
• Jupiter
• Saturn
• Uranus
• Neptune

13
Terrestrial Jovian

• Closely spaced orbits Largely spaced orbits
• High density Low density
• Few moons Many moons
• Rocky Gaseous
• Weak magnetic fields Strong magnetic fields
• Small mass Large mass
• Small radius Large radius
• Long rotation period Short rotation period