The Solar System

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The Solar System

• What is our little corner of the Milky Way Galaxy
  like?

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Composition of the Solar System

• The Sun contains 99.85 of all the matter in the
  Solar System. The planets, which condensed out of
  the same disk of material that formed the Sun,
  contain only 0.135 of the mass of the solar
  system. Jupiter contains more than twice the
  matter of all the other planets combined.
  Satellites of the planets, comets, asteroids,
  meteoroids, and the interplanetary medium
  constitute the remaining 0.015.

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Percentages

• Sun 99.85
• Planets 0.135
• Comets 0.01 ?
• Moons 0.00005
• Minor Planets 0.0000002
• Meteoroids 0.0000001
• Interplanetary Medium 0.0000001

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Solar System Structure

• The planets revolve around the Sun in orbits that
  lie close to a common plane. (Mercury 7o Pluto
  17.2o)
• All planets orbit the sun in a counter-clockwise
  fashion as seen from above the north pole of the
  sun. Orbits are contained within a very narrow
  disk or plane.
• Most orbits are very nearly circular with the
  exception of Mercury and Pluto.

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General Structure

• The spin axes of most planets and moons are
  perpendicular to the orbital plane (Venus and
  Uranus are notable counter examples).
• Thus solar system is basically disk shaped with
  the Sun near the center.

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Small Rocky Worlds

• Terrestrial Planets are small, dense, rocky
  worlds with less atmosphere than the other type
  of planet. Craters, no rings, very few moons,
  very small. (Densities between 3.3-5.5 g/cm3)
• Mercury
• Venus
• Earth
• Mars

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Terrestrial Planets
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Big Gaseous Worlds

• Jovian Planets are large, gaseous, low density
  worlds. Thick gaseous mostly hydrogen
  atmospheres, rings, lots of moons, and very large
  in comparison to terrestrial planets. (Densities
  are 1.75 g/cm3 or lower!)
• Jupiter
• Saturn
• Neptune
• Uranus

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Jovian Planets
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Pluto

• Pluto doesnt fit either category. Pluto is a
  small icy world clearly different from either the
  Jovian and Terrestrial worlds. Since its
  discovery by Clyde Tombaugh in 1930, it has been
  a unique mystery mostly because of its great
  distance from the Earth and is peculiar orbit.

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Space Debris

• Asteroids ? (minor planets) are small rocky
  worlds. Most (not all) orbit between Mars and
  Jupiter. Most are irregular in shape, cratered,
  and dense.

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Comets

• Comets ? An impressive glowing object that is
  illuminated by the Sun as it sweeps through the
  inner solar system. Dirty snowball theory. (Water
  and CO2 ices) Vapor tail, particle tail, which
  can extent to 1 A.U. on bright comets.

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• Meteor ? falling shooting star bits of rock
  and metal falling into the Earths atmosphere and
  bursting into vibrant light as they drastically
  heat because of the friction created between them
  and the Earths atmosphere. These bits are, on
  average, tiny specks of dust, sand grain size,
  small pebbles NOT large.
• Meteoroid ? in space before its fiery collision
  with the Earths atmosphere.
• Meteorite ? fallen piece that survived the fall.
  Most shooting stars are less than 1 gram of
  material.

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Age of the Solar System

• Oldest Rocks dated on Earth 3.9 billion years,
  however the Earths own volcanism and
  plate-techtonics erase most of the evidence!!
• Lunar Rocks are dated to 4.48 billion years.
• Meteorites 4.6 billion years
• Sun estimate based on all the circumstantial
  evidence 5 billion years.

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Solar Nebula Theory
A large massive slowly rotating cloud of
interstellar material begins to collapse under
the influence of gravity. A star forming nebula
begins to grow warm and grow denser.
The warming center is becoming a protostar of
mostly hot hydrogen gas. Further out in the
nebula other clumps of dust and debris are
gathering into asteroid sized objects and
planetesimals.
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Solar Nebula Theory
When nuclear fusion begins we have a new star!
The star will vaporize the inner regions of the
cloud and begin to drive off the gaseous and
dusty material
As the star continues to shine and produce energy
the nebula is driven off revealing the surviving
material planets, comets, and asteroids.
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