Formation of the Solar System

Formation of the Solar System

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  • Created by: Jelena
  • Created on: 23-03-13 15:06

Formation of Our Sun

  • Estimated to be formed about 4.6 billion years ago
  • Solar Nebula Theory: Sun formed by collapse of giant molecular cloud (nebula)
  • Gravity pulled mass of nebula towards centre = the Sun!
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Formation of the Planets

  • Accretion = most accepted theory
  • Planetary systems form from a protoplanetary disk
  • Disk formed by materials left over from creation of central star
  • Central star = mixture of gas and dust
  • Materials pushed into disk shape by conservation of angular momentum
  • Gas and dust in disk collide and stick to each other
  • Clumps form planetesimals
  • Planetesimals = objects of at least 1 km
  • Planetesimals with large mass attracts smaller mass clumps b/c of gravity
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Formation of the Inner Planets

  • Region of solar system inside 4 AU too warm for volatile molecules to condense 
  • Planetismals that formed there could only form from compounds with high melting points
  • So, metals like tungsten, iron, nickel, aluminium and rocky silicates
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Formation of the Gas Giant Planets

  • Beyond 4 AU (frost line) temperatures were cold
  • So, volatile compounds (like water and methane) could remain solid = ice
  • Accretion drew ice together
  • Ice that formed outer planets more abundant than metals and silicates of inner planets
  • Gas giant planets grew big enough to capture hydrogen and helium
  • B/c hydrogen and helium were so abundant, gas giants grew massive
  • Gas giants = 99% of all mass orbiting the Sun
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The Remaining Debris

  • Amount of interplanetary debris thinned out b/c it crashed into planets or was diverted out of solar system
  • Most debris was ejected out of solar system
  • Planetismals b/w Jupiter + Mars (AKA the Asteroid Belt) remained there b/c of Jupiter's gravitational force
  • It prevented them from merging to form a planet
  • Asteroids range from a few km to 1000 km in diameter
  • Asteroids have a pitted, irregular surface
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