Formation of the Solar System

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Formation of the Solar System
Preview
Section 1 A Solar System Is Born Section 2 The
Sun Our Very Own Star Section 3 The Earth
Takes Shape Section 4 Planetary Motion
Concept Mapping
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Section 1 A Solar System Is Born
Bellringer
Could astronauts land on a star in the same way
that they landed on the moon? Explain why or why
not. Write your answer in your science journal.
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Section 1 A Solar System Is Born
Objectives

• Explain the relationship between gravity and
  pressure in a nebula.
• Describe how the solar system formed.

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Section 1 A Solar System Is Born
The Solar Nebula

• All of the ingredients for building planets,
  moons, and stars are found in the vast, seemingly
  empty regions of space between the stars. Clouds
  called nebulas are found in these regions.
• A nebula is a large cloud of gas and dust in
  interstellar space

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Section 1 A Solar System Is Born
The Solar Nebula, continued

• Nebulas contain gases -- mainly hydrogen and
  helium -- and dust made of elements such as
  carbon and iron.
• These gases and elements interact with gravity
  and pressure to form stars and planets.

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Section 1 A Solar System Is Born
The Solar Nebula, continued

• Gravity Pulls Matter Together The gas and dust
  that make up nebulas are made of matter, which is
  held together by the force of gravity.

• Gravity causes the particles in a nebula to be
  attracted to each other.

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Section 1 A Solar System Is Born
The Solar Nebula, continued

• Pressure Pushes Matter Apart The relationship
  between temperature and pressure keeps nebulas
  from collapsing. Temperature is a measure of the
  average kinetic energy, or energy of motion, of
  the particles in an object.
• If the particles in a nebula have little kinetic
  energy, they move slowly and the temperature of
  the cloud is very low. If the particles move
  fast, the temperature is high.

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Section 1 A Solar System Is Born
The Solar Nebula, continued

• As the particles in a nebula move around, they
  sometimes crash into each other.

• When the particles move closer together,
  collisions cause the pressure to increase and
  particles are pushed apart.

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Section 1 A Solar System Is Born
The Solar Nebula, continued

• In a nebula, outward pressure balances the
  inward gravitation pull and keeps the cloud from
  collapsing. With pressure and gravity balanced,
  the nebula become stable.

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Section 1 A Solar System Is Born
Upsetting the Balance

• The balance between gravity and pressure in a
  nebula can be upset if two nebulas collide or if
  a nearby star explodes.
• These events compress, or push together, small
  regions of a nebula called globules, or gas
  clouds.

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Section 1 A Solar System Is Born
Upsetting the Balance, continued

• Globules can become so dense that they contract
  under their own gravity.
• As the matter in a globule collapses inward, the
  temperature increases and the stage is set for
  stars to form.
• The solar nebulathe cloud of gas and dust that
  formed our solar systemmay have formed in this
  way.

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Section 1 A Solar System Is Born
How the Solar System Formed

• After the solar nebula began to collapse, it
  took about 10 million years for the solar system
  to form.
• As the nebula collapsed, it became denser and
  the attraction between the gas and dust particles
  increased. The center of the cloud became very
  dense and hot.

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Section 1 A Solar System Is Born
How the Solar System Formed, continued

• Much of the gas and dust in the nebula began to
  rotate slowly around the center of the cloud.
  While the pressure at the center of the nebula
  was not enough to keep the cloud from
  collapsing, this rotation helped balance the pull
  of gravity.
• Over time, the solar nebula flattened into a
  rotating disk. All of the planets still follow
  this rotation.

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Section 1 A Solar System Is Born
How the Solar System Formed, continued

• From Planetesimals to Planets As bits of dust
  circled the center of the solar nebula, some
  collided and stuck together to form golf
  ball-sized bodies.
• These bodies eventually drifted into the solar
  nebula, where further collisions caused them to
  grow. As more collisions happened, the bodies
  continued to grow.
• The largest of these bodies are called
  planetesimals, or small planets. Some of these
  planetesimals are part of the cores of current
  planets.

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Section 1 A Solar System Is Born
How the Solar System Formed, continued

• Gas Giant or Rocky Planet? The largest
  planet-esimals formed near the outside of the
  rotating solar disk, where hydrogen and helium
  were located.
• These planetesimals were far enough from the
  solar disk that their gravity could attract the
  nebula gases.
• These outer planets grew to huge sizes and
  became the gas giants Jupiter, Saturn, Uranus,
  and Neptune.

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Section 1 A Solar System Is Born
How the Solar System Formed, continued

• Closer to the center of the nebula, where
  Mercury, Venus, Earth, and Mars formed,
  temperatures were too hot for gases to remain.
• Therefore, the inner planets in our solar system
  are made of mostly rocky material.

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Section 1 A Solar System Is Born
How the Solar System Formed, continued

• The Birth of a Star As the planets were
  forming, other matter in the solar nebula was
  traveling toward the center. The center became so
  dense and hot that hydrogen atoms began to fuse,
  or join, to form helium
• Fusion released huge amounts of energy and
  created enough outward pressure to balance the
  inward pull of gravity. When the gas stopped
  collapsing, our sun was born.

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Section 1 A Solar System Is Born
How the Solar System Formed, continued

• The structure of a nebula and the process that
  led to the birth of the solar system are reviewed
  in the following Visual Concepts presentation.

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Section 1 A Solar System Is Born
Solar System Formation
Click below to watch the Visual Concept.
Visual Concept
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Section 2 The Sun Our Very Own Star
Bellringer
Henry David Thoreau once said, The sun is but a
morning star. In your science journal, explain
what you think this quotation means.
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Section 2 The Sun Our Very Own Star
Objectives

• Describe the basic structure and composition of
  the sun.
• Explain how the sun generates energy.
• Describe the surface activity of the sun, and
  identify how this activity affects Earth.

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Section 2 The Sun Our Very Own Star
The Structure of the Sun

• The sun is basically a large ball of gas made
  mostly of hydrogen and helium held together by
  gravity.
• Although the sun may appear to have a solid
  surface, it does not. The visible surface of the
  sun starts at the point where the gas becomes so
  thick that you cannot see through it.
• The sun is made of several layers, as shown on
  the next slide.

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Chapter 15
Section 2 The Sun Our Very Own Star
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Section 2 The Sun Our Very Own Star
Energy Production in the Sun

• The sun has been shining on the Earth for about
  4.6 billion years. Many scientists once thought
  that the sun burned fuel to generate its energy.
• The amount of energy that is released by
  burning would not be enough to power the sun. If
  the sun were simply burning, it would last for
  only 10,000 years.

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Section 2 The Sun Our Very Own Star
Energy Production in the Sun, continued

• Burning of Shrinking? Scientists later began
  thinking that gravity was causing the sun to
  slowly shrink and that gravity would release
  enough energy to heat the sun.
• While the release of gravitational energy is
  more powerful than burning, it is not enough to
  power the sun. If all of the suns gravitational
  energy were released, the sun would last only 45
  million years.

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Section 2 The Sun Our Very Own Star
Energy Production in the Sun, continued

• Nuclear Fusion Albert Einstein showed that
  matter and energy are interchangeable. Matter can
  change into energy according to his famous
  formula
• E ? mc2
• (E is energy, m is mass, and c is the speed of
  light.)
• Because c is such a large number, tiny amounts
  of matter can produce a huge amount of energy.

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Section 2 The Sun Our Very Own Star
Energy Production in the Sun, continued

• The process by which two or more low-mass nuclei
  join together, or fuse, to form another nucleus
  is called nuclear fusion.
• In this way, four hydrogen nuclei can fuse to
  form a single nucleus of helium. During the
  process, energy is produced.
• Scientists now know that the sun gets its energy
  from nuclear fusion.

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Section 2 The Sun Our Very Own Star
Energy Production in the Sun, continued

• Fusion in the Sun During fusion, under normal
  conditions, the nuclei of hydrogen atoms never
  get close enough to combine.
• The reason is that the nuclei are positively
  charged, and like charges repel each other, just
  as similar poles on a pair of magnets do.

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Section 2 The Sun Our Very Own Star
Energy Production in the Sun, continued

• In the center of the sun, however, temperature
  and pressure are very high.
• As a result, hydrogen nuclei have enough energy
  to overcome the repulsive force, and hydrogen
  fuses into helium, as shown on the next slide.

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Section 2 The Sun Our Very Own Star
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Section 2 The Sun Our Very Own Star
Energy Production in the Sun, continued

• Energy produced in the center, or core, of the
  sun takes millions of years to reach the suns
  surface.
• Energy passes from the core through a very dense
  region called the radiative zone. The matter in
  the radiative zone is so crowded that light and
  energy are blocked and sent in different
  directions.

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Section 2 The Sun Our Very Own Star
Energy Production in the Sun, continued

• Eventually, energy reaches the convective zone.
  Gases circulate in the convective zone, which is
  about 200,000 km thick.
• Hot gases in the convective zone carry the
  energy up to the photosphere, the visible surface
  of the sun.
• From the photosphere, energy leaves the sun as
  light, which takes only 8.3 minutes to reach
  Earth.

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Section 2 The Sun Our Very Own Star
Solar Activity

• The churning of hot gases in the sun, combined
  with the suns rotation, creates magnetic fields
  that reach far out into space.
• The constant flow of magnetic fields from the
  sun is called the solar wind.
• Sometimes, solar wind interferes with the
  Earths magnetic field. This type of solar storm
  can disrupt TV signals and damage satellites.

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Section 2 The Sun Our Very Own Star
Solar Activity, continued

• Sunspots The suns magnetic fields tend to slow
  down activity in the convective zone. When
  activity slows down, areas of the photosphere
  become cooler than the surrounding area.
• These cooler areas show up as sunspots. Sunspots
  are cooler, dark spots of the photosphere of the
  sun. Some sunspots can be as large as 50,000
  miles in diameter.

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Section 2 The Sun Our Very Own Star
Sunspots
Click below to watch the Visual Concept.
Visual Concept
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Section 2 The Sun Our Very Own Star
Solar Activity, continued

• Climate Confusion Sunspot activity can affect
  the Earth. Some scientists have linked the period
  of low sunspot activity, 1645-1715, with a period
  of very low temperatures that Europe experienced
  during that time, known as he Little Ice Age.

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Section 2 The Sun Our Very Own Star
Solar Activity, continued

• Solar Flares The magnetic fields responsible
  for sunspots also cause solar flares. Solar
  flares are regions of extremely high temperatures
  and bright-ness that develop on the suns
  surface.
• When a solar flare erupts, it sends huge streams
  of electrically charged particles into the solar
  system. Solar flares can interrupt radio
  communications on the Earth and in orbit.

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Section 3 The Earth Takes Shape
Bellringer
The Earth is approximately 4.6 billion years old.
The first fossil evidence of life on Earth has
been dated between 3.7 billion and 3.4 billion
year ago. Write a paragraph in your science
journal describing what Earth might have been
like during the first billion years of its
existence.
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Section 3 The Earth Takes Shape
Objectives

• Describe the formation of the solid Earth.
• Describe the structure of the Earth.
• Explain the development of Earths atmosphere
  and the influence of early life on the
  atmosphere.
• Describe how the Earths oceans and continents
  formed.

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Section 3 The Earth Takes Shape
Formation of the Solid Earth

• The Earth is mostly made of rock. Nearly
  three-fourths of its surface is covered with
  water.
• Our planet is surrounded by a protective
  atmosphere of mostly nitrogen and oxygen, and
  smaller amounts of other gases.

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Section 3 The Earth Takes Shape
Formation of the Solid Earth, continued

• The Earth formed as planetesimals in the solar
  system collided and combined.
• From what scientists can tell, the Earth formed
  within the first 10 million years of the collapse
  of the solar nebula.

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Section 3 The Earth Takes Shape
Formation of the Solid Earth, continued

• The Effects of Gravity When a young planet is
  still small, it can have an irregular shape. As
  the planet gains more matter, the force of
  gravity increases.
• When a rocky planet, such as Earth, reaches a
  diameter of about 350 km, the force of gravity
  becomes greater than the strength of the rock.
• As the Earth grew to this size, the rock at its
  center was crushed by gravity and the planet
  started to become round.

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Section 3 The Earth Takes Shape
Formation of the Solid Earth, continued

• The Effects of Heat As the Earth was changing
  shape, it was also heating up. As planetesimals
  continued to collide with the Earth, the energy
  of their motion heated the planet.
• Radioactive material, which was present in the
  Earth as it formed, also heated the young planet.

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Section 3 The Earth Takes Shape
Formation of the Solid Earth, continued

• After Earth reached a certain size, the
  temperature rose faster than the interior could
  cool, and the rocky material inside began to
  melt.
• Today, the Earth is still cooling from the
  energy that was generated when it formed.
• Volcanoes, earthquakes, and hot springs are
  effects of this energy trapped inside the Earth.

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Section 3 The Earth Takes Shape
How the Earths Layers Formed

• As the Earths layers formed, denser materials,
  such as nickel and iron, sank to the center of
  the Earth and formed the core.
• Less dense materials floated to the surface and
  became the crust. This process is shown on the
  next slide.

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Section 3 The Earth Takes Shape
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Section 3 The Earth Takes Shape
How the Earths Layers Formed, continued

• The crust is the thin and solid outermost layer
  of the Earth above the mantle. It is 5 to 100 km
  thick.
• Crustal rock is made of materials that have low
  densities, such as oxygen, silicon, and aluminum.
  

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Section 3 The Earth Takes Shape
How the Earths Layers Formed, continued

• The mantle is the layer of rock between the
  Earths crust and core. It extends 2,900 km below
  the surface.
• Mantel rock is made of materials such as
  magnesium and iron. It is denser than crustal
  rock.

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Section 3 The Earth Takes Shape
How the Earths Layers Formed, continued

• The core is the central part of the Earth below
  the mantle. It contains the densest materials,
  including nickel and iron.
• The core extends to the center of the
  Earthalmost 6,400 km below the surface.

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Section 3 The Earth Takes Shape
Formation of the Earths Atmosphere

• Earths Early Atmosphere Scientists think that
  the Earths early atmosphere was a mixture of
  gases that were released as the Earth cooled.
• During the final stages of the Earths
  formation, its surface was very hoteven molten
  in places. The molten rock released large amounts
  of carbon dioxide and water vapor.

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Section 3 The Earth Takes Shape
Formation of Earths Atmosphere, continued

• Earths Changing Atmosphere As the Earth cooled
  and its layers formed, the atmosphere changed
  again. This atmosphere probably formed from
  volcanic gases.
• Volcanoes released chlorine, nitrogen, and
  sulfur, in addition to large amounts of carbon
  dioxide and water vapor. Some of this water vapor
  may have condensed to form the Earths first
  oceans.

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Section 3 The Earth Takes Shape
Formation of Earths Atmosphere, continued

• Comets, which are planetesimals made of ice, may
  have contributed to this change of Earths
  atmosphere.
• As they crashed into the Earth, comets brought
  in a range of elements, such as carbon, hydrogen,
  oxygen, and nitrogen.
• Comets also may have brought some of the water
  that helped form the oceans.

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Section 3 The Earth Takes Shape
The Role of Life

• Ultraviolet Radiation Scientists think that
  ultraviolet (UV) radiation helped produce the
  conditions necessary for life. UV light has a lot
  of energy and can break apart molecules.
• Earths early atmosphere probably did not have
  the protection of the ozone layer that now
  shields our planet from most of the suns UV
  rays. So many of the molecules in the air and at
  the surface were broken apart by UV radiation.

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Section 3 The Earth Takes Shape
The Role of Life, continued

• Over time, broken down molecular material
  collected in the Earths waters, which offered
  protection from UV radiation.
• In these sheltered pools of water, chemicals may
  have combined to form the complex molecules that
  made life possible.
• The first life-forms were very simple and did
  not need oxygen to live.

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Section 3 The Earth Takes Shape
The Role of Life, continued

• The Source of Oxygen Sometime before 3.4
  billion years ago, organisms that produced food
  by photo-synthesis appeared. Photosynthesis is
  the process of absorbing energy from the sun and
  carbon dioxide from the atmosphere to make food.
• During the process of making food, these
  organisms released oxygena gas that was not
  abundant in the atmosphere at the time.

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Section 3 The Earth Takes Shape
The Role of Life, continued

• Photosynthetic organisms played a major role in
  changing Earths atmosphere to become the mixture
  of gases it is today.
• Over the next hundreds of millions of years,
  more oxygen was added to the atmosphere while
  carbon dioxide was removed.

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Section 3 The Earth Takes Shape
The Role of Life, continued

• As oxygen levels increased, some of the oxygen
  formed a layer of ozone in the upper atmosphere.
• The ozone blocked most of the UV radiation and
  made it possible for life, in the form of simple
  plants, to move onto land about 2.2 billion years
  ago.

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Section 3 The Earth Takes Shape
Formation of Oceans and Continents

• Scientists think that the oceans probably formed
  during Earths second atmosphere, when the Earth
  was cool enough for rain to fall and remain on
  the surface.
• After millions of years of rainfall, water began
  to cover the Earth. By 4 billion years ago, a
  global ocean covered the planet.

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Section 3 The Earth Takes Shape
Ocean Formation
Click below to watch the Visual Concept.
Visual Concept
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Section 3 The Earth Takes Shape
Oceans and Continents, continued

• The Growth of Continents After a while, some of
  the rocks were light enough to pile up on the
  surface. These rocks were the beginning of the
  earliest continents.
• The continents gradually thickened and slowly
  rose above the surface of the ocean. These
  continents did not stay in the same place, as the
  slow transfer of thermal energy in the mantle
  pushed them around.

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Section 3 The Earth Takes Shape
Oceans and Continents, continued

• About 2.5 billion years ago, continents really
  started to grow. By 1.5 billion years ago, the
  upper mantle had cooled and had become denser and
  heavier.
• At this time, it was easier for the cooler parts
  of the mantle to sink. These conditions made it
  easier for the continents to move in the same way
  they do today.

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Section 4 Planetary Motion
Bellringer
A mnemonic device is a phrase, rhyme, or anything
that helps you remember a fact. Create a
mnemonic device that will help you differentiate
between planetary rotation and revolution.
Record your mnemonic device in your science
journal.
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Section 4 Planetary Motion
Objectives

• Explain the difference between rotation and
  revolution.
• Describe three laws of planetary motion.
• Describe how distance and mass affect
  gravitational attraction.

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Section 4 Planetary Motion
A Revolution in Astronomy

• Each planet spins on its axis. The spinning of
  a body, such a planet, on its axis is called
  rotation.
• The orbit is the path that a body follows as it
  travels around another body in space.
• A revolution is one complete trip along an
  orbit.

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Section 4 Planetary Motion
Earths Rotation and Revolution
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Section 4 Planetary Motion
A Revolution in Astronomy, continued

• Johannes Kepler made careful observations of the
  planets that led to important discoveries about
  planetary motion.
• Keplers First Law of Motion Kepler discovered
  that the planets move around the sun in
  elliptical orbits.

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Section 4 Planetary Motion
Ellipse
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Section 4 Planetary Motion
A Revolution in Astronomy, continued

• Keplers Second Law of Motion Kepler noted that
  the planets seemed to move faster when they are
  close to the sun and slower when they are farther
  away.

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Section 4 Planetary Motion
A Revolution in Astronomy, continued

• Keplers Third Law of Motion Kepler observed
  that planets more distant from the sun, such as
  Saturn, take longer to orbit the sun.

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Section 4 Planetary Motion
Newton to the Rescue!

• Kepler did not understand what causes the plans
  farther from the sun to move slower than the
  closer planets.
• Sir Isaac Newtons description of gravity
  provides an answer.

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Section 4 Planetary Motion
Newton to the Rescue! continued

• The Law of Universal Gravitation Newtons law
  of universal gravitation states that the force of
  gravity depends on the product of the masses of
  the objects divided by the square of the distance
  between the objects.
• According to this law, if two objects are moved
  farther apart, there will be less gravitational
  attraction between them.

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Section 4 Planetary Motion
Newton to the Rescue! continued

• Orbits Falling Down and Around Inertia is an
  objects resistance to change in speed or
  direction until an outside force acts on the
  object.
• Gravitational attraction keeps the planets in
  their orbits. Inertia keeps the planets moving
  along their orbits.

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Section 4 Planetary Motion
Gravity and the Motion of the Moon
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Formation of the Solar System
Concept Mapping
Use the terms below to complete the concept map
on the next slide. comets orbit planets solar
systems suns nuclear fusion solar
nebulas planetesimals
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Formation of the Solar System
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Formation of the Solar System