How to Use This Presentation

Copyright © by Holt, Rinehart and Winston. All rights reserved.

ResourcesChapter menu

How to Use This Presentation

• To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.”

• To advance through the presentation, click the right-arrow key or the space bar.

• From the resources slide, click on any resource to see a presentation for that resource.

• From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation.

• You may exit the slide show at any time by pressing the Esc key.



Chapter Presentation

Transparencies

Image and Math Focus Bank

Bellringers

Standardized Test Prep

CNN Videos

Visual Concepts

Resources



Formation of the Solar System

Section 1 A Solar System Is Born

Section 2 The Sun: Our Very Own Star

Section 3 The Earth Takes Shape

Section 4 A Solar System is Born

Chapter 20

Table of Contents



Chapter 20

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.




Chapter 20

• Explain the relationship between gravity and pressure in a nebula.

• Describe how the solar system formed.

Objectives




Chapter 20

Solar System• The solar system includes:• The sun and 8 planets• Satellites orbiting the planets• Thousands of asteroids: small rocky bodies that orbit

the sun, most are between Mars and Jupiter• Comets: small bodies of ice, rock, and cosmic dust

loosely packed, heats the ice giving off gas and dust in the form of a long tail




Chapter 20

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




Chapter 20

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.




Chapter 20

The Solar Nebula, continued• In science, temperature is a measure of kinetic energy,

which is energy in motion

• An increase in temperature causes particles to speed up, increasing collisions, which causes the particles to push away from each other, which causes pressure

• In a nebula, pressure pushes outward while gravitational attraction pushes inward. If these forces are in equilibrium, the nebula will not collapse; if it is upset, the nebula will not collapse




Chapter 20

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.



Chapter 20

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.




Chapter 20

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.



Chapter 20

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.




Chapter 20

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.




Chapter 20

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 nebula—the cloud of gas and dust that formed our solar system—may have formed in this way.




Chapter 20

How the Solar System Formed• After the solar nebula began to collapse, it took about

10 million years for the solar system to form.

• Balance of gravity & pressure became unbalanced and the solar nebula collapsed inward

• The solar nebula became denser & and the gravitational attraction between gas and dust increased. The center of the cloud became very dense and hot.




Chapter 20

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. They collided to form planetesimals (which are small planets)




Chapter 20

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.




Chapter 20

How the Solar System Formed, continued

• The central mass of the nebula became the sun, the planetesimals grew and eventually formed the planets




Chapter 20

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.




Chapter 20

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.




Chapter 20

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.




Chapter 20

How the Solar System Formed, continued

• Smaller clumps of matter around the planetesimals became moons, asteroids, and comets

• Moons are satellites, which are bodies that revolve around larger bodies




Chapter 20

Solar System Formation


Click below to watch the Visual Concept.

You may stop the video at any time by pressing the Esc key.

Visual Concept



Section 2 The Sun: Our Very Own StarChapter 20

Bellringer

Henry David Thoreau once said, “The sun is but a morning star.”

What do you think this quotation means?



Chapter 20

• 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.

Objectives




Chapter 20

The Structure of the Sun• The sun is basically a large ball of gas made mostly of

hydrogen and helium held together by gravity.• 150 million km from Earth• Medium sized & middle aged, yellow star• Largest mass in our solar system• Average star in terms of size, temp., and mass• Supplies the energy for life on Earth• Less dense than Earth because it is made of gases,

while Earth is made of solids and liquids




Chapter 20

The Structure of the Sun

• 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.




Chapter 20Structure of the Sun

• Core – center of sun, H fuses to He and releases heat and light

• Radiative zone – 300,000 km thick

• Convective zone – gases circulate, 200,000 km thick

• Photosphere – innermost, surface of the sun

• Chromosphere – middle layer, thicker & hotter than photosphere

• Corona – Outermost layer, hotter than chromo & photo but not as hot as the core




Chapter 20 Section 2 The Sun: Our Very Own Star



Chapter 20

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, but realized there was not enough energy to power sun

• 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.




Chapter 20

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 sun’s gravitational energy were released, the sun would last only 45 million years, and there are fossils that are older than that




Chapter 20

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.




Chapter 20

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.




Chapter 20

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.




Chapter 20

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.







Chapter 20

Energy Production in the Sun, continued• Energy produced in the center, or core, of the sun

takes millions of years to reach the sun’s 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.




Chapter 20

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.




Chapter 20

Solar Activity, continued• Sunspots The sun’s 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. Change in cycles every 11 years. Believe sunspot activity causes lower temperatures on Earth




Chapter 20

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.”




Chapter 20

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 sun’s 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.




Chapter 20

Solar Activity• The churning of hot gases in the sun, combined

with the sun’s 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 Earth’s magnetic field. This type of solar storm can disrupt TV signals and damage satellites.




BellringerThe 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.

Chapter 20 Section 3 The Earth Takes Shape



Chapter 20

• Describe the formation of the solid Earth.

• Describe the structure of the Earth.

• Explain the development of Earth’s atmosphere and the influence of early life on the atmosphere.

• Describe how the Earth’s oceans and continents formed.

Objectives




Chapter 20

• 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.

Formation of the Solid Earth




Chapter 20

• 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.

Formation of the Solid Earth, continued




Chapter 20

• 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.





Chapter 20

• 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.





Chapter 20

• 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.





Chapter 20

• As the Earth’s 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.

How the Earth’s Layers Formed




Chapter 20 Section 3 The Earth Takes Shape



Chapter 20

• 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.

How the Earth’s Layers Formed, continued




Chapter 20

• The mantle is the layer of rock between the Earth’s 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.





Chapter 20

• 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 Earth—almost 6,400 km below the surface.





Chapter 20

• Earth’s Early Atmosphere Scientists think that the Earth’s early atmosphere was a mixture of gases that were released as the Earth cooled.

• During the final stages of the Earth’s formation, its surface was very hot—even molten in places. The molten rock released large amounts of carbon dioxide and water vapor.

Formation of the Earth’s Atmosphere




Chapter 20

• Earth’s 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 Earth’s first oceans.

Formation of Earth’s Atmosphere, continued




Chapter 20

• Comets, which are planetesimals made of ice, may have contributed to this change of Earth’s 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.

Formation of Earth’s Atmosphere, continued




Chapter 20

• 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.

• Earth’s early atmosphere probably did not have the protection of the ozone layer that now shields our planet from most of the sun’s UV rays. So many of the molecules in the air and at the surface were broken apart by UV radiation.

The Role of Life




Chapter 20

• Over time, broken down molecular material collected in the Earth’s 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.

The Role of Life, continued




Chapter 20

• 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 oxygen—a gas that was not abundant in the atmosphere at the time.





Chapter 20

• Photosynthetic organisms played a major role in changing Earth’s 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.





Chapter 20

• 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.





Chapter 20

• Scientists think that the oceans probably formed during Earth’s 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.

Formation of Oceans and Continents




Chapter 20

Ocean Formation


Click below to watch the Visual Concept.

You may stop the video at any time by pressing the Esc key.

Visual Concept



Chapter 20

• 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.

Oceans and Continents, continued




Chapter 20

• 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.

Oceans and Continents, continued




Section 4 Planetary MotionChapter 20

BellringerA 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.



Chapter 20

• Explain the difference between rotation and revolution.

• Describe three laws of planetary motion.

• Describe how distance and mass affect gravitational attraction.

Objectives

Section 4 Planetary Motion



Chapter 20

• 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.

A Revolution in Astronomy




Chapter 20 Section 4 Planetary Motion

Earth’s Rotation and Revolution



Chapter 20

• Johannes Kepler made careful observations of the planets that led to important discoveries about planetary motion.

• Kepler’s First Law of Motion Kepler discovered that the planets move around the sun in elliptical orbits.

A Revolution in Astronomy, continued





Ellipse



Chapter 20

• Kepler’s 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.





Chapter 20

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





Chapter 20

• Kepler did not understand what causes the plans farther from the sun to move slower than the closer planets.

• Sir Isaac Newton’s description of gravity provides an answer.

Newton to the Rescue!




Chapter 20

• The Law of Universal Gravitation Newton’s 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.

Newton to the Rescue! continued




Chapter 20

• Orbits Falling Down and Around Inertia is an object’s 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.

Newton to the Rescue! continued





Gravity and the Motion of the Moon



Formation of the Solar System

Concept MapUse the terms below to complete the concept map on the next slide.

Chapter 20

cometsplanetssunssolar nebulas

orbitsolar systemsnuclear fusionplanetesimals



Formation of the Solar SystemChapter 20



Formation of the Solar SystemChapter 20



End of Chapter 20 Show



Standardized Test Preparation

Reading

Read each of the passages. Then, answer the questions that follow each passage.

Chapter 20




Passage 1 You know that you should not look at the sun, right? But how can we learn anything about the sun if we can’t look at it? We can use a solar telescope! About 70 km southwest of Tucson, Arizona, is Kitt Peak National Observatory, where you will find three solar telescopes. In 1958, Kitt Peak was chosen from more than 150 mountain sites to be the site for a national observatory.

Continued on the next slide

Chapter 20




Passage 1, continued Located in the Sonoran Desert, Kitt Peak is on land belonging to the Tohono O’odham Indian nation. On this site, the McMath-Pierce Facility houses the three largest solar telescopes in the world. Astronomers come from around the globe to use these telescopes. The largest of the three, the McMath-Pierce solar telescope, produces an image of the sun that is almost 1 m wide!

Chapter 20




1. Which of the following is the largest telescope in the world?

A Kitt Peak

B Tohono O’odham

C McMath-Pierce

D Tucson

Chapter 20




1. Which of the following is the largest telescope in the world?

A Kitt Peak

B Tohono O’odham

C McMath-Pierce

D Tucson

Chapter 20




2. According to the passage, how can you learn about the sun?

F You can look at it.

G You can study it by using a solar telescope.

H You can go to Kitt Peak National Observatory.

I You can study to be an astronomer.

Chapter 20




2. According to the passage, how can you learn about the sun?

F You can look at it.

G You can study it by using a solar telescope.

H You can go to Kitt Peak National Observatory.

I You can study to be an astronomer.

Chapter 20




3. Which of the following is a fact in the passage?

A One hundred fifty mountain sites contain solar telescopes.

B Kitt Peak is the location of the smallest solar telescope in the world.

C In 1958, Tucson, Arizona, was chosen for a national observatory.

D Kitt Peak is the location of the largest solar telescope in the world.

Chapter 20




3. Which of the following is a fact in the passage?

A One hundred fifty mountain sites contain solar telescopes.

B Kitt Peak is the location of the smallest solar telescope in the world.

C In 1958, Tucson, Arizona, was chosen for a national observatory.

D Kitt Peak is the location of the largest solar telescope in the world.

Chapter 20




Passage 2 Sunlight that has been focused can produce a great amount of thermal energy—enough to start a fire. Now, imagine focusing the sun’s rays by using a magnifying glass that is 1.6 m in diameter. The resulting heat could melt metal. If a conventional telescope were pointed directly at the sun, it would melt. To avoid a meltdown, the McMath-Pierce solar telescope uses a mirror that produces a large image of the sun.

Continued on the next slide

Chapter 20




Passage 2, continued This mirror directs the sun’s rays down a diagonal shaft to another mirror, which is 50 m underground. This mirror is adjustable to focus the sunlight. The sunlight is then directed to a third mirror, which directs the light to an observing room and instrument shaft.

Chapter 20




1. In this passage, what does the word conventional mean?

A special

B solar

C unusual

D ordinary

Chapter 20




1. In this passage, what does the word conventional mean?

A special

B solar

C unusual

D ordinary

Chapter 20




2. What can you infer from reading the passage?

F Focused sunlight can avoid a meltdown.

G Unfocused sunlight produces little energy.

H A magnifying glass can focus sunlight to produce a great amount of thermal energy.

I Mirrors increase the intensity of sunlight.

Chapter 20




2. What can you infer from reading the passage?

F Focused sunlight can avoid a meltdown.

G Unfocused sunlight produces little energy.

H A magnifying glass can focus sunlight to produce a great amount of thermal energy.

I Mirrors increase the intensity of sunlight.

Chapter 20




3. According to the passage, which of the following statements about solar telescopes is true?

A Solar telescopes make it safe for scientists to observe the sun.

B Solar telescopes don’t need to use mirrors.

C Solar telescopes are built 50 m underground.

D Solar telescopes are 1.6 m in diameter.

Chapter 20




3. According to the passage, which of the following statements about solar telescopes is true?

A Solar telescopes make it safe for scientists to observe the sun.

B Solar telescopes don’t need to use mirrors.

C Solar telescopes are built 50 m underground.

D Solar telescopes are 1.6 m in diameter.

Chapter 20




Interpreting Graphics

The diagram below models the moon’s orbit around the Earth. Use the diagram below to answer the questions that follow.

Chapter 20




1. Which statement best describes the diagram?

Chapter 20

A Orbits are straight lines.

B The force of gravity does not affect orbits.

C Orbits result from a combination of gravitational attraction and inertia.

D The moon moves in three different directions depending on its speed.




1. Which statement best describes the diagram?

Chapter 20

A Orbits are straight lines.

B The force of gravity does not affect orbits.

C Orbits result from a combination of gravitational attraction and inertia.

D The moon moves in three different directions depending on its speed.




2. In which direction does gravity pull the moon?

Chapter 20

F toward the Earth

G around the Earth

H away from the Earth

I toward and away from the Earth




2. In which direction does gravity pull the moon?

Chapter 20

F toward the Earth

G around the Earth

H away from the Earth

I toward and away from the Earth




3. If the moon stopped moving, what would happen?

Chapter 20

A It would fly off into space.

B It would continue to orbit the Earth.

C It would stay where it is in space.

D It would move toward the Earth.




3. If the moon stopped moving, what would happen?

Chapter 20

A It would fly off into space.

B It would continue to orbit the Earth.

C It would stay where it is in space.

D It would move toward the Earth.




Math

Read each question, and choose the best answer.

Chapter 20




1. An astronomer found 3 planetary systems in the nebula that she was studying. One system had 6 planets, another had 2 planets, and the third had 7 planets. What is the average number of planets in all 3 systems?

A 3B 5C 8D 16

Chapter 20




1. An astronomer found 3 planetary systems in the nebula that she was studying. One system had 6 planets, another had 2 planets, and the third had 7 planets. What is the average number of planets in all 3 systems?

A 3B 5C 8D 16

Chapter 20




2. A newly discovered planet has a period of rotation of 270 Earth years. How many Earth days are in 270 Earth years?

F 3,240

G 8,100

H 9,855

I 98,550

Chapter 20




2. A newly discovered planet has a period of rotation of 270 Earth years. How many Earth days are in 270 Earth years?

F 3,240

G 8,100

H 9,855

I 98,550

Chapter 20




3. A planet has seven rings. The first ring is 20,000 km from the center of the planet. Each ring is 50,000 km wide and 500 km apart. What is the total radius of the ring system from the planet’s center?

A 353,000 km

B 373,000 km

C 373,500 km

D 370,000 km

Chapter 20




3. A planet has seven rings. The first ring is 20,000 km from the center of the planet. Each ring is 50,000 km wide and 500 km apart. What is the total radius of the ring system from the planet’s center?

A 353,000 km

B 373,000 km

C 373,500 km

D 370,000 km

Chapter 20




4. If you bought a telescope for $87.75 and received a $10 bill, two $1 bills, and a quarter as change, how much money did you give the clerk?

F $100

G $99

H $98

I $90

Chapter 20




4. If you bought a telescope for $87.75 and received a $10 bill, two $1 bills, and a quarter as change, how much money did you give the clerk?

F $100

G $99

H $98

I $90

Chapter 20



Chapter 20 Section 1 A Solar System Is Born















Standardized Test PreparationChapter 20

Documents

How to Use This Presentation