Our Solar System

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Chapter 23 "Our Solar System"
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Facts about our Solar System

• 99.85 of all the mass in our solar system is
  contained in the sun, which means all of the
  planets only add up to .15 of the mass within
  our solar system!!!
• All planets move in the same direction around the
  sun counterclockwise.
• My Very Educated Mother Just
• Sold Us Nine Pizzas
• Order of the planets Mercury, Venus, Earth,
  Mars, Jupiter, Saturn, Uranus, Neptune, Pluto

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Planets Overview

• Terrestrial Planets
• Small and rocky, made from solid material
• Mercury, Venus, Earth, and Mars
• Jovian Planets
• Huge gas GIANTS, made from dense gaseous material
• Jupiter, Saturn, Uranus, and Neptune

• Pluto doesnt quite fit into either
  category?!?
• Why? It is terrestrial, but also composed of
  gaseous solid material (ice) due to its extreme
  distance from the sun.

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Terrestrial vs. jovian

• Size the most obvious difference between the
  two types
• Terrestrial small compared with Jovian planets
• Jovian giants
• Density
• Terrestrial densities 5 times the density of
  water
• Jovian densities only 1.5 times that of water
• According to its density,
• Saturn would float on water!
• Chemical makeup, and rate of rotation are two
  other ways in which the two types of planets
  differ.

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Planetary data table
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Interiors of the Planets

• The substances that make up the planets are
  divided into three groups
• 1. Gases hydrogen and helium
• 2. Rocks silicate minerals and metallic iron
• 3. Ices ammonia, methane, carbon dioxide, and
  water
• Terrestrial planets are dense so they contain
  more of the rocky and metallic substances
• Jovian planets are less dense so they contain
  large amounts of gases and ice.
• They do have substantial amounts of rocky and
  metallic materials in their core however.

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The Atmosphere of the Planets

• A planets ability to keep an atmosphere is
  dependent on its mass and temperature.
• The more mass a planet has, the great ability it
  has to retain an atmosphere (due to gravity!)
• The hotter a planet is, the less ability it has
  to retain an atmosphere because the heat burns up
  the gases!
• Jovian planets have thick atmospheres of
  hydrogen, helium, methane, and ammonia.
• Terrestrial planets, including Earth, have
  very thin atmospheres in comparison to the Jovian
  planets.

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The Formation of the Solar System

• The Nebular Theory
• The sun and planets formed from a rotating disk
  composed of dust and gases.
• Nebula - cloud of gas and/or dust in space
• Planetesimals - small, irregularly shaped bodies
  formed by colliding matter
• Three Steps to the Nebular Theory
• Step 1 The nebula cloud began rotating.
• Step 2 Particles within the cloud condensed and
  formed into planetesimals
• Step 3 Planetesimals continued to condense and
  formed into planets and moons.

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The nebular theory
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Evidence to Support the Nebular Theory

• Orbits of the planets lie nearly in the same
  plane with the sun at the center
• The planets all revolve in the same direction

Pluto is the only planet that does not orbit the
sun in the same plane, this is another idea that
supports that Pluto was once a moon of Neptune.
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The Big Bang Theory

• The most widely accepted theory explaining the
  formation of the universe.
• Why? Because it is the only scientifically
  supported theory that we currently have

• Step 1 All matter and energy in the universe was
  once located in a single dense point called a
  singularity.
• Step 2 A HUGE explosion occurred!
• Step 3 Matter and energy were propelled outward
  in all directions as the universe began to expand.

Step 4 Matter began to condense - forming
galaxies and these galaxies continue to move
outward today.
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How The Big Bang Theory came to be

• In 1927 Belgian priest Georges Lemaître proposed
  that the universe began with the explosion of an
  early atom.
• His proposal came after observing the red shift
  (objects moving away from us) in distant nebulas.

• Years later, Edwin Hubble found experimental
  evidence to help justify Lemaître's theory.
• He found that distant galaxies in every direction
  are going away from us with speeds proportional
  to their distance.
• NASA named the Hubble Space Telescope after Edwin
  Hubble due to his great contributions to
  astronomy!

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Evidence for the Big Bang Theory

• The Big Bang Theory explains why distant galaxies
  are traveling away from us at great speeds.
• This theory also predicts the existence of cosmic
  background radiation the energy glow left over
  from the explosion.

• The Big Bang Theory received its strongest
  confirmation when this radiation was discovered
  in 1964 by Arno Penzias and Robert Wilson, who
  later won the Nobel Prize for this discovery.

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Evidence for the Big Bang Theory

• What continues to support this theory today?
• The universe is currently expanding as observed
  by the movement of cosmic background radiation.
• Most of the most distant stars observed to be in
  red-shift (they are moving away from Earth)