How did the Solar System form?

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					How did the Solar System form?

3. What are the broad general characteristics or
   physical features of our Solar System and
   how do they illuminate Solar System
   formation?
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QuickTime™ and a TIFF (Uncompressed ) d ecompressor are needed to see this picture.
QuickTime™ and a TIFF (Unco mpressed) d ecompressor are needed to see th is picture.
How did the Solar System form?

4. How did the terrestrial planets form and why
    is the Solar System differentiated?
How did the Solar System form: Differentiation?




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How did the Solar System form: Differentiation?

•    The Solar System is differentiated. This means that
     it is broken up into different parts, these parts are
     two types of planets (and ice-rocky bodies). We need
     a theory to account for this fact.

1.   Terrestrial-like or Inner Planets
2.   Jovian-like or Gas Giants
3.   Pluto-like bodies.

•    What Solar System feature separates these objects?
How did the Solar System form: Asteroids?

                                                                                                             • Asteroid = a rocky body
                                                                                                               that likely originated
                                                                                                               from the asteroid belt
                                                                                                               and is < 1000 km
                                                                                                               (although most are ~1
                                                                                                               km) in diameter. They
                                                                                                               are minor planets.
                                                                                                             • They are the remains of
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                                                                                                               the formation of Earth-
                                                                                                               like planets.
How did the Solar System form: Asteroids?

                        • On January 1st 1801,
                          Giuseppe Piazzi
                          discovered an object
                          which he thought was a
                          new comet.
                        • Its orbit, however, was
                          more like a small planet.
                        • He named the object
                          Ceres, after the Sicilian
                          goddess of grain.
                           – Thus the first asteroid was
                             discovered.
How did the Solar System form: Asteroid Location?
How did the Solar System form: Asteroid Location?


• The asteroid belt is located between Mars
  and Jupiter.
• It is approximately 2-3 AU from our star,
  known as the Sun.
How did the Solar System form: Meteorites?


• Meteorites are pieces of
  asteroids that travel
  through our solar system
  and land on Earth.
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• Before they land they are
  termed meteors.

• They are rocks from
  space!
How did …: Differentiated Meteorites?


• Iron meteorites -
   – These are the cores of
     minor planets.            Qui ckTi me™ and a TIFF (Uncompressed) decompressor are needed to see thi s picture.


   – They are mainly
     composed of Fe and Ni.
   – They comprise 7% of all
     the meteorites found on
     Earth.

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How did …: Differentiated Meteorites?


• Stony-iron meteorites.
   – These are the core-mantle
     boundaries of minor
     planets.
   – Such rocks are composed
     of Fe-Ni metal and
     silicates, usually the      QuickTime™ an d a TIFF (Uncomp ressed) decompre ssor are need ed to see this p icture .




     minerals olivine or
     pyroxene.

   – They compose 1% of all
     the meteorites found on
     this planet.
How did …: Differentiated Meteorites?


• Achondrites (a type of Stony
  meteorite).
   – Such rocks are similar to
     magma and lava on Earth.
     They may have come from
     mantle and crust areas of
     minor planets.
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   – They may also be from other
     planets such as Mars or from
     the Moon.

   – They compose 8% of all the
     meteorites found on this
     planet.
How did …: Differentiated Bodies?


•   This is the process of becoming
    different. A differentiated body
    (planet, moon, asteroid, etc.) is
    one that was heated internally
    and melted. Upon heating
    material then separates due to
    differences in the density.

•   The Earth, Venus, Mars,
    Mercury, Vesta, and the Moon
    are examples of differentiated
    bodies.

•   Thus, differentiated meteorites
    have been through a planetary-
    type melting process.
How did the Solar System Form: Undifferentiated Meteorites?


• Chondrites (another type of
  Stony meteorite).
    – No rocks on Earth are in any
      way like these rocks.
    – They have not been through
      a differentiation process.
      They are undifferentiated.     QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

    – They compose 84% of all the
      meteorites found on this
      planet.
• They are fossils or the
  physical remains of the
  formation of Terrestrial
  planets.
How did… : What are the components of chondrites?
How did… : What are the components of chondrites?


                                                                                       • Chondrules
                                                                                       • Calcium-rich,
                                                                                         aluminum-rich
                                                                                         inclusions
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                                                                                       • Circumstellar grains
                                                                                       • Matrix
How did…: Why should you care about chondrites?


1. They are 4.556 billion years old.
2. They are the oldest rocks in our collection.
3. Tell the story of the earliest time of our solar
   system’s formation. They should not exist by
   accepted astrophysical models for solar
   system formation.
4. Are what the Earth-like planets were made
   from.
5. Contain mineral grains from other stars.
How did… : Chondrules


• Chondrules are the most abundant component
  of chondrites.
• Chondros,  = grain or seed (Rose,
  1864)
• Chondrules are mm to cm-size spherical
  igneous rocks composed mainly of olivine,
  pyroxene, and glass. They are igneous rocks,
  rocks that have been melted in our nebula.

• They are the building blocks of Earth-like
  planets.
How did… : Chondrules and Their Formation.


• Because chondrules are igneous, they were melted.
• Because they are not predicted to exist, it is critical to
  determine what formed these objects.
• Because most meteorites are chondrites and thus most
  asteroids are likely chondrites, processing was
  extensive.

  Thus some mechanism operated that processed rock-
  forming materials by melting BEFORE the formation
  of the terrestrial-like planets.
How did… : Chondrules and Their Formation.


• What mechanisms are hypothesized to produce
  chondrules within our protoplanetary disk?

• Two general classes of hypotheses:
   – I. Observed or known to have occurred
      • 1. Link their formation to our YSO.
      • 2. Collisions
   – II. Hypothesized to have occurred
      • 1. Nebular Shock Waves
      • Some other process
How did the Solar System Form: Terrestrial Planets.


• The theory, as discussed by astronomy and
  astrophysics, states that planets within the
  inner solar system formed in three major
  stages.
• Stage I
   – 1. Dust grains acted as nuclei formation of matter,
     or meter-sized rocks.
   – 2. These meter-sized rocks accreted and collided to
     form kilometer-sized rocks (asteroids).
   – 3. These objects then formed planetesimals, small
     moon-sized objects.
How did the Solar System Form: Terrestrial Planets.


• The theory, as discussed by geologists, states that
  planets also formed in three major stages, but that
  Stage I has four parts:
   – 1. Dust grains acted as nuclei formation of millimeter-sized
     dust-balls that were melted and produced chondrules and CAI.
   – 2. Chondrules and CAIs then accreted to form meter-sized
     objects.
   – 3. Meter-sized objects then formed kilometer-sized objects.
   – 4. Kilometer-sized objects then formed planetesimals.
          – Melting and differentiation occurs here
How did the Solar System Form: Terrestrial Planets.


• Stage II:
   – Planetesimals then collide and merge due to
     gravitational forces between them. The total
     number of these types of bodies decrease and
     larger bodies known as protoplanets are
     produced.
How did the Solar System Form: Terrestrial Planets.


• Stage III: The process of accretion of
  planetesimals also leads to fragmentation
  of bodies and heavy bombardment
  occurs.
• The fragments are swept up by
  protoplanets.
• These objects then become planets.
How did the Solar System Form: Terrestrial Planets.


• After accretion we are left with a solar
  system. The condensation theory helps
  account for the differentiation of the
  solar system into terrestrial-like and
  Jovian-like planets.

• A major issue if not the major issue -
  Temperature!
How did the Solar System Form: Jovian Planets.


• Formation of the Jovian or gas-giant planets is a little
  less clear with a weaker consensus among scientists as
  to a party-line theory.

   – 1. These planets simply grew large or massive enough that
     their gravitational fields pulled large masses of gas to their
     “cores”.

   – 2. They formed from instabilities in the cool outer regions of
     the solar nebula, mimicking small scale nebular models.
   – As of July 2003, this last hypothesis is given more weight.
How did the Solar System Form: No more gas and dust.


• Where did all the gas go?
   – The major hypothesis states that gas, which
     did not fall into the sun or form into planets,
     was both blown off and reacted away by
     solar winds and solar radiation during the
     highly active stage of our star known as the
     T Tauri phase.
How did the Solar System Form: No more gas and dust.


• Where did all the dust go?
   – Simple, into the Sun or planets! Effective
     processing.
An Important Point of Interpretation

•   Standard textbooks form Terrestrial planets
    like this:
    –   Dust to m-sized objects to km-sized objects to
        Moon-sized objects to Planets!


•   But that’s wrong. Why? No chondrules!
    –   Dust to mm-sized objects then zap then m-sized
        objects, etc.
        •   REMEMBER THIS POINT

				
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posted:2/18/2012
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