Man must rise above Earth, to the top of the atmosphere and beyond; for only then will he fully understand the world in which he lives. Socrates

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Man must rise above Earth, to the top of the
atmosphere and beyond for only then will he
fully understand the world in which he lives.
Socrates
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The Earth and Other Planets

• Science 2201
• Chapter 16

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morning stars wanderers
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Geocentric Solar System
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Heliocentric Model
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Solar System
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Figure 16-1 Most of the mass in the solar system
is in the Sun, and most of the rest is in the
Jovian planets. (Distances in this figure are not
to scale.)
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The Sun and its Planets

• Planets and moons tend to orbit about the sun in
  a counterclockwise direction
• Orbits of planets and their moons are in the same
  general plane
• Planets and moons tend to rotate on their axis in
  counterclockwise direction

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Solar System
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The Nebular Hypothesis

• theory for origin of solar system
• rotating nebula had formed gaseous rings which
  condensed into the planets and moons, with the
  nebulas nucleus forming the sun p. 323

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Figure 16-2 As the nebula that formed the solar
system collapsed, it began to rotate and flatten
into a disk. The stages in solar system formation
include (a) a slowly rotating nebula, (b) a
flattened disk with massive center, (c) planets
in the process of birth represented as mass
concentrations in the nebula, and (d) the solar
system.
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The Planets
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Mercury (.39 au)
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Small, rocky, airless world withan extreme
climate!

• Mariner 10, did 3 flybys 1974-75
• Years Days fastest planet
• Orbital period 88 Earth days
• Rotation period 59 Earth days
• Planet of Extremes
• Day temps exceed 800oF
• Night temps drop to 280oF
• Surface
• Almost doubles as the moon. Mercury contains
  impact craters ranging from ½ mile to one over
  800 miles wide. Ridges and basins filled with
  cooled lava fill the picture.

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Venus (.72 au)
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A forbidding yet fascinating worldof scorching
temps, rocky plains, huge volcanoes.

• Data from 17 landing probes 18 flyby
• Spacecraft (Pioneer of 78 Magellan of 93)
• An Out-of-Control Greenhouse Effect
• 30-mile thick atmosphere of CO2 generates surface
  pressure 100X Earths and traps heat, sustaining
  temps gt 800oF.
• Slow and Backward Planet
• Venus rotates very slowly, once every 243 Earth
  days
• Venus orbits the sun every 225 Earth days, so on
  Venus, a day is longer than a year!
• Spins not from west to east, like the other
  planets, but from east to west. Perhaps an
  asteroid collision set Venus on a backward
  rotation.

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Earth (1 au)
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The very special third rock.

• Hospitable Home Planet
• Vast oceans of liquid water and protective
  atmosphere rich in oxygen.
• Orbits in stable, nearly circular path, so never
  too far or too close to the Sun
• One Moonlarge by solar system standardsacts to
  stabilize Earth, preventing tilt from shifting
  wildly.
• Oceans of water absorb and transfer heat,
  regulating global temperatures.
• Precious envelope of air serves as a breathable,
  protective blanket.

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Mars (1.52 au)
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The red planet, our nearest neighbor.

• Observed by Mariner 9, 71, Viking 77,
• And Pathfinder spacecraft of 1997
• An Unearthly World
• Thin atmosphere (like Earths at 140,000 ft) of
  95 CO2
• Elliptical orbit accentuates seasonal
  differencestemp range from 190oF to 62oF
• Dry, desolate surface, but tilted axis gives it
  polar ice caps
• 2 small moons Deimos Phobosmay be captured
  asteroids
• Olympus Mons 13 mile high volcanoe the size of
  Arizona!
• Valles Marineris system of canyons up to 4
  miles deep forms an immense gash 2500 miles
  across.

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Asteroids
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Tens of thousands of small rocky bodies orbit the
sun in a large area between Mars and Jupiter.
(asteroids, or better, planetoids)

• Thought to be material that failed to become a
  planet during formation of solar system.

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Asteroids
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(No Transcript)
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Rocks in space through which the Earth passes as
it travels around the Sun.

• Meteors may be tiny grains of sand or may be very
  large.
• Billions enter Earths atmosphere each year,
  encounter friction some 50 miles overhead and
  burn white hot.
• If lands meteorite.

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Meteors
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The Planets kidzone link