The Solar System: Chapter 29

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The Solar System Chapter 29
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Models of the Solar System(29.1)

• Aristotle (384-322 B.C.) promoted the geocentric
  model of the solar system
• the sun, the stars, and the planets revolve
  around the Earth
• Copernicuss Model (1500s) promoted the
  heliocentric model of the solar system
• the earth and other planets revolve around the
  Sun
• Also proposed that the planets orbit in the same
  direction but that each moves at a different
  speed and distance from the sun
• Confirmation came in 1600s when Galileo
  collected evidence with newly invented telescope

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Keplers Law

• Kepler developed three laws that explained most
  aspects of planetary motion.
• 1. Law of Ellipses
• 2. Law of Equal Areas
• 3. Law of Periods

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Law of Ellipses

• Each planet orbits the sun in a path called an
  ellipse. (Ellipse-and oval)
• Because the orbits of the planets are ellipses a
  planet is not always the same distance from the
  sun
• Perihelion-point where it is closest to the sun
• Aphelion-point where it is farthest from the sun

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Law of Equal Areas

• Describes the speed at which planets travel at
  different points in their orbits
• The earth moves fastest when it is closest to the
  sun

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Law of Periods

• Describes the relationship between the average
  distance of a planet from the sun and the orbit
  period of the planet. (Orbit period-amount of
  time required for the planet to make one
  revolution around the sun)
• The farther the planet is from the sun the longer
  the orbit period.

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Newtons Application of Keplers Laws

• Hypothesized that a moving body will change its
  motion only if an outside force causes it to do
  so.
• Inertia-tendency of a moving body to move in a
  straight line at a constant speed until an
  outside force acts on it.
• Gravity-the attractive force that exists between
  all objects in the universe
• This is the outside force that keeps the planets
  in orbit around the sun

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Check Point!

• What is the major difference between Aristotles
  and Copernicuss models of the universe?
• According to Kepler, what is the shape of
  planetary orbit?

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The Inner Planets (29.2)

• The four planets closest to the sun (a.k.a
  terrestrial planets because they are similar to
  earth)
• Mercury, Venus, Earth, and Mars
• Mostly made up of solid rock with a metal core
• No rings
• Moon varies from 0-2
• Impact Craters-bowl shaped depressions on their
  surfaces due to collisions

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Mercury

• Closest to sun
• Shortest orbit (88 days)
• Rotates very slowly on its axis (once every 59
  days)
• No moons
• Weak magnetic field
• Core of molten iron
• Surface is heavily cratered
• Inferring Mercury has changed little since the
  formation of the solar system
• Lava filled craters inferring Mercury being
  volcanic

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Mercurys Atmosphere

• Thin Atmosphere
• Due to its closeness to the sun
• Solar heat causes gas molecules near the surface
  to move rapidly
• Due to its size
• Gravitational pull is weak because its small
  radius and molecules can not be held within the
  atmosphere

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Mercurys Temperature

• Absence of a dense atmosphere and its slow
  rotation cause huge daily temperature ranges
• Daytime 427 degrees Celsius
• Nighttime -173 degrees Celsius

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Venus

• Second planet from the sun
• Orbit is 225 days long, rotation is slow like
  Mercury 243 days long
• Has no moons
• Clouds are droplets of sulfuric acid
• No water droplets on Venus (Too Hot!)
• Rotation is opposite of other planets
• Sun rises in west and sets in east

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Venus v. Earth

• Venus
• 100 times the atmospheric pressure
• Very hot due to its proximity to the sun and
  dense atmosphere
• Average temp. 453 degrees Celsius
• Venus as Earths twin
• Same size
• Same mass
• Same density

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Earth

• Third Planet from the Sun
• Orbit length is 365.24 days, and the planet
  completes one rotation in 23 hours and 56 minutes
• Weathering and erosion have changed and continue
  to change the surface of the earth

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Life on Earth

• Possible due to distance from sun
• Temperature is warm enough for water to exist as
  liquid
• Moderate temperatures to support life
• 14 degrees Celsius

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Mars

• Forth Planet from Sun
• Orbit is 687 days long and its rate of rotation
  is 24 hours and 37 minutes
• Seasons like on earth due to tilt of Mars
• Has two moons
• Largest volcanoes in solar system found here
• Three times higher than Mount Everest
• Base the size of Nebraska

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Mars Continued

• Temperature at equator 20 degrees Celsius during
  summer at poles during winter as low as -130
  degrees Celsius
• Atmospheric pressure and temperature too low
  presently to support liquid water
• Signs of water erosion are present giving
  evidence that Mars was once warmer and wetter

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Life on Mars?

• Martian meteorites indicate that primitive life
  may have existed on Mars.

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Check Point!

• What is unusual about the rotation of Venus?
• Describe two ways the earth and Mars are similar?
  
• What aspect of the earth makes it favorable for
  life?
• What evidence suggest that Mercury has changed
  little since it was formed?

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The Outer Planets

• Five planets furthest from the Sun
• A.K.A Outer Planets
• Jupiter, Saturn, Uranus, Neptune, and Pluto
• First four are called Giant Planets
• Largest planets in solar system
• A.K.A Jovian Planets-because they are similar to
  Jupiter
• Far less dense then inner planets
• Thick atmosphere made up mostly of hydrogen and
  helium
• Each probably has a core of rock, metals, and
  water

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Jupiter

• Fifth planet from the sun
• At least 16 moons and one ring
• Orbit is 12 years
• Rotates faster then any other planet
• 9 hours and 50 minutes
• Largest planet in the solar system
• Mass is twice that of all the other eight planets
  combined

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Jupiter Continued

• Liquid metallic core surrounded by lighter
  elements
• Large mass causes temperatures and pressure in
  its interior to be great
• Temperature in interior rises as high as 30,000
  degrees Celsius
• Enormous magnetic field due to liquid metallic
  hydrogen core

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Jupiter Continued

• Light and Dark colored could bands on surface
• Fast rotation of earth causes chemicals to form
  bands
• Chemicals Methane, Ammonia, Water Vapor
• Mostly made up of gases (Like the Sun)
• 92 hydrogen and helium
• Surface is not solid but a mixture of hot gases
  and liquids
• Never became a star because not enough mass to
  start nuclear fusion

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Jupiter Continued

• Has thunderstorms and lightening just like Earth
  does
• Lightning Ammonia Methane Water Vapor
  Life
• No evidence for life on Jupiter
• Distinctive feature is the Great Red Spot
• Giant rotating storm somewhat like a hurricane on
  earth that has been raging for several hundred
  years or more

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Saturn

• Sixth planet from the Sun
• Second largest planet in solar system
• Average Temperatures of -176 degrees Celsius
• At least 20 moons and several rings
• Rotates every 10 hours and 40 minutes
• Rapid rotation causes bulge at equator and
  flatten at pole

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Saturn Jupiter Similarities

• Saturn also has bands of colored clouds that run
  parallel to its equator
• Small, rocky core, interior of liquid metallic
  hydrogen, and dense atmosphere of hydrogen and
  helium gas

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Saturn and Jupiter Differences

• Much more complex system of rings
• Orbit of Saturn is nearly 20 years longer than
  that of Jupiter
• 29.5 years Saturn v. 12 years Jupiter
• Saturn is much less dense then Jupiter
• Saturn is least dense planet in solar system
• Half the density of water
• What would Saturn do if placed in water?

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Uranus

• Seventh planet from the sun
• Third largest planet in the solar system
• Discovered in 1781
• First planet discovered since ancient times
• At least 11 small rings
• At least 15 moons
• Orbit is 84 years

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Uranus

• Uranuss Unusual Rotation
• Rotates like a rolling ball
• Axis of Uranus is almost horizontal to the plane
  of its orbit
• Rotates every 17 hours
• Greenish color indicates atmosphere contains
  methane
• Atmosphere is mainly hydrogen and helium

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Neptune

• Eighth planet from the Sun
• Similar to Uranus in size and mass
• Orbit is 165 years, rotates every 16 hours
• Eight moons, and four rings
• Named after Roman god of the sea
• Atmosphere is mainly Hydrogen, Helium and methane
• White clouds in upper atmosphere composed of
  frozen methane
• Active weather systems
• Winds exceed 1,000 km/hour
• Great Dark Spot-Earth sized storm
• Average temperature is -225 degrees Celsius

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Pluto

• Ninth Planet from the Sun
• Discovered in 1930
• Smallest planet in the solar system
• Rotates every 6 days and orbits every 250 years
• Elongated ellipse orbit around sun
• Sometimes inside the orbit of Neptune

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Pluto

• Has one moon
• Made of frozen methane, rock, and ice.
• Average temperature of -208 degrees Celsius
• Small size, unusual orbit, and comparatively
  large moon of Pluto lead some astronomers to
  believe that the planet was once a moon of
  Neptune and the gravity of a passing object
  pulled Pluto away from Neptune and into its own
  orbit

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Check Point!

• In what way is the axis of Uranus unusual?
• How dense is Saturn compared to the other
  planets?
• What makes Jupiter similar to the sun?
• List the names of the five outer planets

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Asteroids, Comets, and Meteoroids

• Asteroids-Largest of the smaller bodies in the
  solar system
• Minor Planets
• Orbits are elliptical
• Asteroid Belt-region between Mars and Jupiter
  where most asteroids exist
• Earth Grazers have elongated elliptical orbits
  that sometimes come very close to sun and earth
• Do collide with earth on occasion

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Comets

• Comets-body of rock, dust, methane, and ice
• Core, or nucleus made up of rock, metal, and ice
• Spherical cloud of gas and dust (coma) surrounds
  nucleus
• Bright appearance of comets due to sunlight
  reflected by the coma
• Tail is the gas and dust that streams out of the
  head

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Meteoroids

• Meteoroids-smaller bits of rock or metal
  throughout solar system
• Meteorites-a meteor that is left after it hits
  the earth

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Meteors

• Meteor-meteoroid that enters earths atmosphere
• Burn up through earths surface due to friction
• Shooting star
• Vaporize quickly in a flash of light
• Fireball
• Meteor Shower-large number of small meteoroids
  entering earths atmosphere in a short period of
  time

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Check Point!

• Between the orbits of what planets are the
  asteroid belts located?
• How is a meteor different from a meteorite?

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Cheat Sheet TableYou will be able to use this on
your quiz!

• Make a data chart comparing the planets
• Distance from sun
• Length of rotation
• Length of revolution
• Atmospheric conditions
• Weather
• Temperature
• Distinguishing Features (Moons, Rings, Volcanoes,
  Cracks, Etc)