Chapter 29

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Chapter 29 Our Solar System

• "The earth is the cradle of humankind, but one
  cannot live in the cradle forever."
• -- Konstantin Tsiolkovsky, 1895

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29.1 Overview of our solar system
OBJECTIVES Describe early models of our solar
system. Examine the modern heliocentric model of
our solar system. Relate gravity to the motions
of celestial bodies.
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Early Ideas
Geocentric ,meaning Earth Centered
In the early 1500s, Nicholas Copernicus
formulated the heliocentric model of the solar
system.
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Copernicus

• Nicolaus Copernicus found that in a heliocentric
  model of the solar system,
• the inner planets move faster in their orbits
  than the outer planets,
• giving the appearance from Earth that some
  planets move in a retrograde motion.

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Retrograde Motion
Retrograde motion is the movement of a planet in
an opposing direction across the sky.
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Galileo
Galileos discovery of Jupiters moons proved
that not all celestial bodies orbit Earth
therefore, Earth is not necessarily the center of
the solar system.
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Keplers First Law
Keplers first law demonstrates that each planet
has an elliptical orbit of unique size and shape
with the Sun at one focus.
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AU
Earths average distance from the Sun 1.496 x
108 km or 1 astronomical unit.
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Planets Orbits
All of the planets ( former planets) and their
satellites orbit the Sun in the same direction,
and all their orbits, except Pluto's lie near the
same plane.
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Eccentricity
When a planet is closest to the sun in its orbit,
it is at ____________ and when it is farthest
from the sun, it is at _________.
perihelion
aphelion
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Ellipses
Terms to be familiar with.

• Major axis
• Foci
• Semi-major axis
• Perihelion
• Sun
• Aphelion

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Eccentricity
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Keplers Second Law
Closer ? Faster Farther ? slower
Keplers second law is an imaginary line between
the Sun and a planet that sweeps out equal
amounts of area in equal amounts of time.
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Center of Mass
Isaac Newton determined that each planet does not
orbit the Sun but instead orbits a center of mass
between it and the Sun.
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29.1 Overview of our Solar System Quiz
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29.2 The Terrestrial Planets
OBJECTIVES Describe the properties of the
terrestrial planets. Compare Earth with the other
terrestrial planets.
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Precession
The wobble of the Earths rotational axis is
called precession. The Moons gravitational
force on Earth causes the sideways push that is
responsible for precession.
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Mercury

• has the largest day-night temperature difference
  of all the planets in the solar system.

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Venus

• is the planet most similar to Earth in physical
  properties, such as diameter, mass, and density.

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Venus (more)

• The high concentration of carbon dioxide (CO2) in
  the atmosphere of Venus inhibits infrared
  radiation from escaping and keeps the surface
  extremely hot.

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Earth

• is the only known planet in our solar system
  where H2O is present in three states, solid,
  liquid gas.

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Terrestrial

• planets are close to
  the size of Earth and have solid and rocky
  surfaces, while the gas giant planets are larger,
  more gaseous, and lack solid surface.

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29.2 The Terrestrial Planets
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Atmospheric conditions of the four terrestrial
planets

• Mercury

• Venus

Earth
Mars

• thick clouds
• primarily of carbon dioxide and nitrogen
• Include sulfuric acid

• almost non-existent
• mostly oxygen and sodium

• thin and there is consistent wind.
• composition is similar to Venuss

• moderately dense
• composed of 78 nitrogen and 21 oxygen

Venus
Mars
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29.3 The Gas Giant Planets
OBJECTIVES Describe the properties of the gas
giant planet. Identify the unique nature of the
object formerly-known-as-the-Planet-Pluto.
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29.3 The Gas Giant Planets
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29.3 the object formerly-known-as-the-Planet-Plut
o.
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Composition

• The gas giants are composed primarily of
  lightweight elements, such as hydrogen, helium
  methane.

Saturn
Uranus
Jupiter
Neptune
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Rapid Rotation

• The rapid rotation of the largest gas giant
  Jupiter, causes its clouds to flow in alternating
  cloud types called belts and zones.

Jupiter
Belts are low, warm, dark-colored clouds that
sink. Zones are high, cool , light-colored clouds
that rise.
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Blue Color

• Neptune and Uranus , the two gas giants appear
  blue because of the methane in their atmosphere.

Uranus
Neptune
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Neptune

• Neptune has clouds and atmospheric belts and
  zones similar to those of Saturn and Jupiter.

Neptune
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Plutos Eccentricity

• Plutos orbit is so eccentric that while at
  perihelion, Pluto is closer to the Sun than
  Neptune is.

Pluto's orbit seen from the plane of the
ecliptic, showing its high inclination compared
to the other planets
The eccentric orbit of Pluto is 50 AU from the
Sun at aphelion and almost 30 AU from the Sun at
perihelion.
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Terrestrial and the Gas giant planets
Both are categories of the planets of our solar
system

• Gas giant planets

• Terrestrial planets

• four planets close to the Sun
• Mercury, Venus, Earth, and Mars
• solid, rocky surfaces
• smaller

• farther from the Sun
• Jupiter, Saturn, Uranus, and Neptune
• more gaseous
• lack a solid surface
• larger

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29.2 29.3 Quiz (8pts)Riddle me this .
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29.4 Formation of Our Solar System
OBJECTIVES Describe how the planets formed from
a disk surrounding the young sun. Explore
remnants of solar system formation.
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Interstellar Cloud
Interstellar cloud, a cloud of gas and dust from
which stars and planets are formed.
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Solar Nebula Theory
Interstellar cloud can condense and become
concentrated enough to form a star and possibly
planets. The dense concentration of gas at
the center of the solar nebula eventually became
the Sun.
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Planetismals
Planetismals are tiny grains of condensed
material that accumulate and merge together to
form these large bodies possibly growing until
they reach hundreds of kilometers in diameter.
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Asteroids
Bodies of interplanetary debris that orbit the
Sun with most in the area between Mars and
Jupiter are called asteroids.
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Comets
Comets are small, icy body made of ice and rock
that has a highly eccentric orbit around the
Sun. The Oort cloud and the Kuiper belt are
two cluster of comets.
Haley 's comet seen here in 1986. It will appear
again in 2062.
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Meteor
The result when Earth intersects a cometary orbit
is a meteor shower.
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Meteor
Meteor is interplanetary material that burns up
and becomes a bright, glowing streak of light in
Earths atmosphere. Two examples are the
Perseids (August) Leonid (November).
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Meteorite
Is interplanetary material that enters Earths
atmosphere and collides with the ground rather
than burning up.
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29.4 Quiz