Geo Unit 4

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Geo Unit 4

• Chapters 23, 24, and 25

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The Solar System

• Terrestrial Planets
• Mercury, Venus, Earth, Mars
• Smaller
• Inner (near Sun)
• More dense

• Jovian Planets
• Jupiter, Saturn, Uranus, Neptune
• Larger
• Outer planets
• Less dense

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Planets are made of

• Hydrogen and helium
• Silicates, iron, and gases
• Bigger planets can hold more gases in due to
  their gravity, so they have a more structured
  atmosphere

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Formation of the Solar System

• The Nebular Theory
• Everything was a cloud of dust and gas
• Rotation caused disk formation with the sun at
  the center
• Continued rotation and collisions formed larger
  bodies of more dense material called planetesimals

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Mercury

• Closest to the sun
• No atmosphere
• Small
• Craters and cracks
• Greatest temp extremes

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Venus

• Earths twin
• Clouds and carbon dioxide
• Mountains, plateaus, tectonic activity
• Very hot

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Mars

• Thin atmosphere
• Water as ice, frozen carbon dioxide
• Cold
• Craters and canyons

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Jupiter

• Largest planet
• Bands of different colored clouds
• Liquid hydrogen
• 63 moons

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Saturn

• Rings of ice and rock
• Strong winds
• 11 moons

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Uranus

• Rotates up and down (not left to right)
• One ring

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Pluto???

• Pluto is a dwarf planet
• It has a moon
• It is no longer considered a legit planet because
  other planets interrupt its orbital path

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Other stuff in space

• Asteroids- located mostly within the asteroid
  belt between Mars and Jupiter
• Have irregular shapes
• Are broken off pieces of something larger

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• Comets- rocks and metals stuck together by frozen
  water and other gases and liquids
• Comet vaporize as they get closer to the sun and
  then becomes a coma
• Halleys Comet has a 76 year orbital period

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• Asteroid
• Not moving

• Meteoroid
• Small and solid
• Travels through space
• Radiometric dating is used
• They are the oldest part of the solar system
• 4.57 billion years old

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Radiation

• The electromagnetic spectrum

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• Light travels as waves
• Contains photons (particles)
• The shorter the wavelength, the more energy it
  contains

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3 types of spectra

• 1. Continuous- all the colors of visible light
• 2. Absorption- shows all the colors except where
  the gases are present you see a black line

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• 3. Emission- all dark except where the gases are
  present you see the colored bands
• Remember, the lines represent the elements
  present in the source (ex star)

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Doppler Effect

• Change in the wavelength due to motion
• Longer wavelengths- moving away
• Red
• Shorter wavelength- moving towards
• Blue
• Helps us understand star movement

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Telescopes

• Refracting
• Lens used to bend light
• Objective lens bends light to the focus
• Problem chromatic aberration produces a halo
  around the image

• Reflecting
• Uses concave mirror to focus light
• Advantage better quality image

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• Radio telescopes
• Uses an antenna and a dish
• Detect radio waves
• Less affected by weather disturbances

• Space telescope
• Orbit above the atmosphere
• Clearer images
• Ex Hubble Telescope

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3 Main Properties of Telescopes

• 1. light gathering
• 2. resolution
• 3. magnification

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The Sun

• Corona- outermost (gives off solar wind)
• Chromosphere- gives off the color we see
• Photosphere- gives off the light we see

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• Solar flare- flows out from the surface
• Solar prominence- flows out and arcs back
• Sunspots are cool patches of gas
• Go in a 11 year cycle

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• Energy of the sun comes from hydrogen fusion
• H H ? He

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Stars

• Constellations are groups of stars humans see as
  patterns

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Color

• Color is related to temperature
• Hotter stars emit shorter wavelengths
• Cooler stars emit longer wavelengths

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Mass

• Stars orbiting each other are binary
• They help us calculate mass by finding the center
  of mass

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Distance

• Measuring the distance to stars is done by
  parallax
• Farther away the star, the smaller the angle
  because there is less apparent motion
• Distance is measured in light years
• 1 light year 9.5 x 1012 km

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Brightness

• Apparent
• How it appears from Earth
• Depends on how big, hot, or far away it is
• Larger the the dimmer the star

• Absolute
• How bright the star actually is
• From 32.6 light years
• Lower the , the brighter the star

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HR Diagram

• Absolute magnitude verses temperature

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• Cepheid variables fluctuate their brightness
• The light period is the time between two
  consecutive brightest moments

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• Nova
• Explosion and death of a star

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Life cycle of a star

• 1. Nebula- cloud of gas and dust
• 2. Protostar- rotation flattens into disk shape
• 3. Main Sequence- once 10 million K reached,
  hydrogen fusion begins
• This is the longest stage
• 4. Red giant- all the hydrogen has been used up,
  He fuses into Carbon now at 100 million K, there
  is less gravity than mass so the star swells

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• 5. Now there is more gravity than energy because
  the star has run out of fuel. The star condenses
  into a dwarf. This happens in medium sized
  stars.
• Large stars can have a super nova explosion and
  become a black hole.

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• New elements can be acquired from dying stars by
  nucleosynthesis
• The more massive a star is, the heavier the
  elements it can produce.

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The Universe

• We live in the Milky Way galaxy. It is a spiral
  galaxy.

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3 types of galaxies

• 1. spiral
• Contains a nucleus and spiral arms
• The younger stars are in the arms
• 2. elliptical
• Round to oval shaped
• Smallest

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• 3. irregular
• No set shape
• Large and Small Magellinic Cloud
• Galaxies group together in clusters.
• Quasars emit low level radiation.

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Expanding Universe

• Red shift
• Galaxies emit red shift because they are moving
  away from each other (except those within the
  same cluster)
• Hubbles Law
• More distant galaxies have a greater red shift
  which means they are moving away at a faster rate

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The Big Bang Theory

• The universe was compressed into a dense, hot
  point
• So much pressure was built up that it caused an
  explosion 13.7 billion years ago
• Sent all matter flying outward

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Evidence

• 1. Red shift of galaxies
• 2. Cosmic background radiation
• 3. Quasars