Formation of the Solar System

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Formation of the Solar System
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So, what is the solar system?

• The solar system includes the sun and the bodies
  revolving around the sun.

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The debate

• Scientists have long debated the origins of the
  solar system.
• In the 1600s and 1700s, scientists that the sun
  formed first and threw off the materials that
  later formed the planets.

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What are planets?

• Before August 2006, there was not a
  scientifically approved definition of a planet.
  One definition said that planets were the nine
  major bodies orbiting the sun.

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New Definition

• The IAU adopted the following definition of a
  planet on August 24, 2006
• "a celestial body that (a) is in orbit around the
  Sun, (b) has sufficient mass for its self-gravity
  to overcome rigid body forces so that it assumes
  a hydrostatic equilibrium (nearly round) shape
  and (c) has cleared the neighborhood around its
  orbit."

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New Solar System
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Marquis Pierre Simon de Laplace

• Who was he?
• A French mathematician
• Why was he important?
• He advanced the hypothesis that became the
  nebular theory.
• The what?

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What is the nebular theory?

• De Laplaces hypothesis stated that the sun and
  planets condensed out of the same spinning nebula.

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What is a nebula?

• A nebula is a cloud of gas and dust.

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The rest of the hypothesis

• He went on to tell us that the entire solar
  system formed at approximately the same time.
• This hypothesis developed into what we now know
  as the Nebular theory.

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• The big bang spread matter throughout the
  expanding universe.
• Some of this matter gathered into clouds of dust
  and gas.

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• The clouds of gas and dust that became our solar
  system was the solar nebula.
• The solar nebula was larger than our solar system
  is now.

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• 4 to 5 billion years ago, shock waves from a
  nearby supernova or some other force caused a
  cloud of dust and gas to contract, forming the
  solar nebula.
• The sun began to form in the center of the solar
  nebula.

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• About 99 percent of the matter in the solar
  nebula became part of the sun.

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The planets

• As the sun was forming, planets were forming in
  the outer regions of the solar nebula.
• The formation of the planets occurred in stages.

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What are moons, anyway?

• We often hear them called satellites.
• The book defines them as the smaller bodies that
  orbit the planets.

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• http//www.cnn.com/TECH/space/9804/21/nasa.planets
  /planet.formation.38.4.3.mov

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Formation of planets

• The distance between a protoplanet and the
  developing sun influenced the composition of the
  planet that formed from the protoplanet.

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• The 4 protoplanets closest to the sun became
  Mercury, Venus, Earth and Mars.
• They contained large amounts of the heavier
  elements, such as iron.

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• The next four protoplanets became Jupiter,
  Saturn, Uranus, and Neptune.
• They formed in the cold regions of the solar
  nebula.

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• The material of these outer protoplanets was
  helium, hydrogen, and frozen gases such as water,
  methane, and ammonia.

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• They formed into huge planets due to their
  distance from the sun.
• We now refer to them as gas giants.

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Pluto

• At the time that our book was written, Pluto was
  the farthest planet from the sun.
• It was also the smallest of the known planets.
• Pluto is best described as an ice ball of frozen
  gases and rock.

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Dwarf Planets

• Pluto is now a dwarf planet.
• According to NASA, a dwarf planet
• (a) is in orbit around the Sun, (b) has
  sufficient mass for its self-gravity to overcome
  rigid body forces so that it assumes a
  hydrostatic equilibrium (nearly round) shape, (c)
  has not cleared the neighborhood around its
  orbit, and (d) is not a satellite.