The Universe, Solar System, and Planets II

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The Universe, Solar System, and Planets II
Review Hubbles Red Shift Review Penzias and Wi
lsons background radiation Formation of sola
r system, rocky planets, Jovian planets
Have a nice weekend!
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Using the Doppler Effect to Measure Velocity
Sound waves (shown here) are like light waves.
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Using the Doppler Effect to Measure Velocity
T1
T2
T3
T4
Redshift
Blueshift
See http//www.kettering.edu/drussell/Demos/dopp
ler/doppler.html
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Galaxy Spectroscopy

• Spectra of a nearby star and a distant galaxy
• Star is nearby, approximately at rest
• Galaxy is distant, traveling away from us at
  12,000 km/s

Stellar Spectrum
Sodium
Magnesium
The larger the redshift the greater the distance
from us
Galaxy Spectrum
Calcium
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Changing Composition of the Universe

• 100-200 million years after Big Bang, stars and
  galaxies began forming from leftover matter -
  hydrogen and helium
  
• nuclear fusion in stars has reduced the original
  composition of 100 H and He to 98
  
• when a dying star explodes, the heavier elements
  created by fusion are blown into space to be
  recycled by newly forming stars
  
• the overall composition of the galaxies is
  gradually changing to the heavier elements

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The Solar System - Its Origin and Early
Development
Sun and eddy
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General Characteristics of the Solar System

• Planetary orbits and rotation
• planet and satellite orbits are in a common
  plane
  
• nearly all planet and satellite orbital and spin
  motions are in the same direction
  
• rotation axes of nearly all planets and
  satellites are roughly perpendicular to the plane
  of the ecliptic

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General Characteristics of the Solar System

• Chemical and physical properties of the planets
• the terrestrial planets are small, have a high
  density, and are composed of rock and metallic
  elements
  
• the Jovian planets are large, have a low density,
  and are composed of gases and frozen compounds

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The Solar System the Relative Sizes of the
Planets
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Planets and Moons

• Earth-based and space probe research has returned
  a tremendous amount of information on size, mass,
  density, composition, magnetic field, and
  atmospheric conditions

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The Terrestrial Planets

• Terrestrial planets seem to have experienced a
  similar early history, with extensive volcanism,
  cratering, and internal differentiation
  
• Each has a metallic core and a silicate mantle
  crust, and shows evidence of continuing lava
  flows and meteorite impact
  
• Outgassing produced an atmosphere as light gases
  from the interior rose to the surface during
  volcanism

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The Terrestrial Planets

• Mercury
• heavily cratered
• large metallic core
• little tectonic activity
• no atmosphere

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The Terrestrial Planets

• Venus
• similar in size and mass to Earth
• extremely hot surface
• 96 CO2 atmosphere
• sulfuric acid cloud layers
• lava flows and folded mountain ranges have been
  observed

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The Terrestrial Planets

• Mars
• thin atmosphere of mostly CO2
• polar ice caps
• evidence of extensive volcanism, cratering, and
  water movement
  
• largest crater, volcano, and canyon in the solar
  system

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The Jovian Planets

• Jupiter
• largest of the Jovian planets, most complex of
  all
  
• dense, hot atmosphere of H, He, and other gases
• 16 moons

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The Jovian Planets

• Saturn
• smaller than Jupiter, but similar internal
  structure and atmosphere
  
• ring system consisting of thousands of spiraling
  bands of countless particles
  
• 18 known moons

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The Jovian Planets

• Uranus
• much smaller than Jupiter, but densities are
  about the same
  
• lies on its side - rotational axis is nearly
  parallel to the ecliptic
  
• faint rings and 18 small moons
• Neptune
• similar atmosphere as other Jovians, with zonal
  winds and storm systems
  
• three faint rings, 8 moons

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The Jovian Planets

• Pluto
• smallest planet, appears to be more composed of
  rock and methane gas and ice
  
• polar ice cap
• one moon
• highly elliptical orbit which is steeply inclined
  to the ecliptic

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Earth - Its Origin and Differentiation

• Differentiation into concentric layers of
  different composition and densities occurred
  early and was the most significant event in Earth
  history
• Led to formation of a crust, continents,
  out-gassing of light elements, and formation of
  the oceans and atmosphere

• internal heat that caused differentiation was
  generated by meteorite impact, gravitational
  compression, and radioactive decay

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The Earth-Moon System - How Did it Originate?

• The Moon
• 1/4 the size of Earth
• orbits Earth and rotates on its axis at the same
  rate - we always see the same side
  
• ice discovered in 1995
• surface dominated by igneous rocks, breccias, and
  dust
  
• impact with a large planetesimal early in Earths
  history seems to explain most of the Moons
  features best