California science grade 5 (11)

Students know the Sun, an average star, is the central and largest body in the solar system and is composed primarily of hydrogen and helium... The planets and the other objects in the s

POEM

ELA R 5.3.7

Evaluate the author’s use of various techniques (e.g.,

appeal of characters in

a picture book, logic and

credibility of plots and

settings, use of figurative

language) to influence

readers’ perspectives.

ELA W 5.2.1 Write

narratives:

a Establish a plot, point

of view, setting, and

conflict.

b Show, rather than tell,

the events of the story.

SCIENCE VERSE

It s in our solar system though

I’m thinking that it might be Mars,Because it has that reddish glow

But you know it could be Venus

And if that’s true, then just between us,

It might be wise to leave beforeAny locals might have seen us

Could be Pluto Might be Neptune

Don’t they both have more than one moon?

I’m running out of oxygen

I’d better figure this out soon

Yes space is lovely, dark and deep

For one mistake I now do weep:

In science class I was asleep

In science class I was asleep

Write About ItResponse to Literature The space traveler in this poem cannot tell where he or she is Write a fictional narrative as if you were the space traveler in this poem and were landing on this planet

- Journal Write about it online

@www.macmillanmh.com

295

Lesson 1

The Sun

On January 20, 2005, satellites that carried

cell phone and cable signals suddenly shut

down They had been struck by a burst of

energy Where did this energy come from?

5 ES 5.a Students know the Sun, an average star, is the central and largest body

in the solar system and is composed primarily of hydrogen and helium.

296

ENGAGE

How does the Moon’s diameter compare with that of Earth? Do research to answer this question and make a model to represent the difference in their sizes.

Use Numbers What would the diameter of the Sun be if the diameter of Earth was 0.5 cm?

Make a Model Use appropriate tools to design

a model of earth and the Sun to this scale.

How many Earths would it take to cover the length

of the model Sun’s diameter?

Draw Conclusions Communicate Explain why this model does,

or does not, show an accurate comparison between the diameters of the Sun and Earth.

297

EXPLORE

▶Main Idea 5 ES 5.a

The Sun is a star made

of hydrogen and helium

The Sun is located at the

center of the solar system

and is also its largest

What is the Sun?

The Sun is a star A star is an object that produces its own energy,

including heat and light The planets

and the other objects in the solar

system are not stars because they do

not produce their own light

The stars that produce the most energy make about ten million times

more energy than the Sun The

least-productive stars make only

one-hundreth as much energy as

the Sun

The Sun is an average-sized star and the largest object in the solar system

The Sun’s diameter is about 1,390,000

kilometers (863,706 miles) If the Sun

were a hollow ball, more than a million

Earths could fit inside it The Sun

looks larger than the other stars that

can be seen in the night sky because it

is much closer to Earth

The mean, or average, distance between the Sun and Earth is

149,591,000 kilometers (92,960,000

miles) This number is known as one

astronomical (as•truh•NAH•mi•kulh)

unit (AU) The closest stars to the solar

system are found in the Alpha Centauri

star system They are about 271,931

AUs away

Finding the Sun’s Mass

It is impossible to measure the weight of the Sun After all, the Sun cannot be put on a scale

However, you can measure the mass

of the Sun, or the amount of matter

in it The mass of the Sun can be calculated if you know two facts The first fact is the length of time it takes for a planet to make one trip around the Sun (for Earth, that is 365.24 days) The second is the distance between the planet and the Sun (for Earth, that is 149,591,000 kilometers)

Using this information, scientists have calculated the Sun’s mass to be

2 million trillion trillion kilograms

That’s 2,000,000,000,000,000,000,000,000,000,000 kilograms! This is

745 times greater than the mass of all the other objects in the solar system put together As a matter of fact, the mass of the Sun makes up 99.8% of all the mass in the solar system

299

EXPLAIN

What are the parts

of the Sun?

The Sun is a huge sphere made

up mostly of two very light gases,

hydrogen and helium About 71% of

the Sun’s mass is made up of hydrogen

Another 27% is made up of helium

Other materials, such as oxygen and

carbon, make up the remaining 2%

of the Sun’s mass

Most of the energy that the Sun

produces is formed in its core At its

core, the Sun has a temperature of 10

million to 20 million degrees Celsius

The pressure is more than 1 billion

times greater than the air pressure at

sea level on Earth

The radiation layer, which is next to

the core, moves the energy produced in

the core in every direction It can take

millions of years for energy to move

out of this layer

In the convection layer, gases with different energies move in circles in

a way similar to air with different densities Energy moves out of this layer in about a week

The photosphere is the visible surface

of the Sun It is not a solid surface, but rather a layer of gases The photosphere

is cooler than the core Its temperature

is about 5,730°C (10,346°F)

The next layer of the Sun is the chromosphere, or the inner layer of the Sun’s atmosphere When it can be seen, it looks like a red circle around the Sun

The corona is the outermost layer

of the Sun’s atmosphere The corona takes on different shapes around the Sun depending on changes in the temperature of the photosphere

Solar Flares

Solar flares are bursts of heat and energy that stretch out from

the corona and chromosphere into

space Sometimes this energy disrupts

satellites, interfering with TV, radio,

and cell phone communication systems

Energy from solar flares also causes displays of different-colored lights in

the upper atmosphere These lights are

called the aurora borealis (uh•RAW•uh

bawr•ee•AL•is), or northern lights The

northern lights are most often seen

in Alaska, Canada, and the northern

United States They are only seen in

the southern United States when the

Sun releases large amounts of energy

Solar flares are also sometimes associated with sunspots Sunspots,

or dark spots on the Sun, are regions

of the photosphere that have a lower

temperature than the surrounding

regions

The Parts of the Sun

Make a Model Use modeling clay

to make a model of the Sun that includes all of the layers.

Be careful Using a plastic

knife, cut away a quarter of your Sun so you can see into it.

Add sunspots and solar flares

to the surface of your Sun.

Communicate Write a description

of your Sun Include a color key

to identify the layers.

Quick Check

Draw Conclusions Why does it take millions of years for energy that moves in every direction to leave the radiation layer?

Critical Thinking Which three layers of the Sun can be seen?

What is the layer of the Sun between the core and the convection layer called?

Clue: Find the labels on the diagram for the core and for the convection layer, and look for the name of the layer between them.

How does the Sun

produce energy?

More than 100 years ago, Albert

Einstein discovered a relationship

between energy and mass He expressed

the discovery in what has become one

of the most famous equations in science:

The E stands for energy The m

stands for mass The c represents

the speed of light The little 2 over

the c means that the speed of light is

squared, or multiplied by itself This

equation tells us that a little bit of mass

can be changed into a lot of energy

As you learned earlier in this

lesson, the Sun is mostly made up of

hydrogen Hydrogen has very little

mass However, inside of the Sun hydrogen particles smash together

to make helium This smashing together of particles is called fusion

(fyew•zhuhn) A little bit of mass is lost when hydrogen particles combine to make helium According to Einstein’s equation, that little bit of mass is changed into energy We see this energy

as light and heat, as well as other kinds

of energy that cannot be seen

What happens to hydrogen particles

in the Sun during fusion?

Clue: Starting on the left, follow what happens to the hydrogen particles.

Reading Diagrams

Fusion

1 Particles of hydrogen move

throughout the Sun.

2 Two particles of hydrogen collide.

3 One particle of helium is formed and

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Think, Talk, and Write

Main Idea What is the largest object

in the solar system?

Vocabulary An object in the solar system that produces heat and light is

Test Practice All of the following are part of the solar system EXCEPT

Make a two-tab book

(see p 479) Use the

titles shown On the

inside of each tab,

draw conclusions

about the title.

Descriptive Writing

Using what you have learned in this

lesson, write about the Sun Discuss

the layers of the Sun, fusion, and the

Sun’s size and mass.

Earth’s Mass

The Sun’s mass is roughly 330,000 times Earth’s mass If you made a model of the Sun with a mass that was 1,000 kilograms, what would be the mass of Earth in grams?

The Sun is a star and

the largest object

in the solar system

(pp 298–299)

The Sun produces energy when hydrogen

combines to form helium and energy.

(pp 300–302)

- Review Summaries and quizzes online @www.macmillanmh.com

303

EVALUATE

Draw Conclusions

Scientists began recording

data about sunspots in 1749

After they collected years of

data, scientists concluded

that the number of sunspots

increases and decreases

during an 11-year cycle From

the beginning of the cycle,

the number of sunspots tends

to increase over a period of

about five years to a maximum

number Over the next six

years, the number of sunspots

decreases to a minimum

number A new cycle begins

when the number of sunspots

increases.

Learn It

When you draw conclusions, you look at

all the facts and decide what can be based

on those facts Be careful not to “jump to

conclusions,” or to draw conclusions that are

not supported by the data

Look at the chart It lists the number of

sunspots recorded each year beginning in 1750

When scientists looked at the first two years

of data, they could have concluded that the

number of sunspots always decreased However,

in 1752, the number of sunspots increased

This means that their conclusion was no longer

supported by the data They needed to collect

more data and draw a new conclusion.

When you gather data, it is important to

record it Having a record of your data gives

you the information that you need to be able to

5 IE 6.h Draw conclusions from scientific evidence and indicate whether further information is needed to support a specific conclusion.

304

EXTEND

▶ In which year do you conclude that an

11-year cycle began? How do you know?

▶ What can you conclude about the

frequency of sunspots between 1993 and

2004 compared to between 1750 and 1761?

▶ What can you conclude about the expected

sunspot activity in 2005 and 2006?

▶ Scientists recently began recording data

about the number of solar flares that occur every year Their hypothesis was that solar flares increase and decrease on the same cycle as sunspots Would you conclude that the recorded data supports this hypothesis?

Why?

▶ What could you do to provide additional

support for your conclusion that solar flares increase and decrease on the same cycle

as sunspots?

Try It

Use the chart of sunspots from 1750 to 1761 to draw conclusions

as you answer the following questions

▶ In which year would you conclude that this cycle began? Why?

▶ If you were a scientist studying sunspots, in which years did you

observe changes in the number of sunspots that might make you question the existence of a cycle? Why?

▶ If you only had ten years of data, but you hypothesized that the

sunspot cycle was longer than ten years, what would you have

to do before you could draw a conclusion?

305

EXTEND

As the Sun sets over Paranal Observatory in

Chile, you can see stars and planets in the sky

The three brighter objects are Venus (center),

Mercury (below), and Saturn (left) How can

you tell how far away these planets are?

5 ES 5.b Students know the solar system includes the planet Earth, the Moon, the Sun, eight other planets and their satellites, and smaller objects, such as asteroids and comets.

306

ENGAGE

Make a Model Mark the location of the Sun and each planet on the paper towels.

Draw Conclusions

Analyze Data Compare the distances between Mercury and Mars, Mars and Jupiter, and Jupiter and Neptune Which are farthest apart?

Infer What can you conclude about the distances between the planets in the solar system?

5 IE 6.c Plan and conduct a simple investigation based on

a student-developed question and write instructions others can follow to carry out the procedure.

307

EXPLORE

P5_CAUBC06_L2_284379_F.indd 307 2/15/07 1:22:14 PM

▶ Main Idea 5 ES 5.b

The solar system is made

up of the Sun, the planets

and their moons, comets,

asteroids, and meteoroids.

What is the solar system?

The Sun is at the center of the solar system The

word solar means “of the Sun.” The solar system

is a system of objects of, or around, the Sun

Besides the Sun, the objects in the solar system include the eight planets and their moons From nearest to farthest from the Sun, the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune

In 1610 Galileo Galilei used a telescope to observe the planets and saw moons revolving around Jupiter A telescope uses lenses to see distant objects Before Galileo’s discovery, people thought that everything in the solar system

revolved around Earth

Telescopes take pictures of and collect data about objects in the solar system Scientists have launched some telescopes into space so they can gather data without interference from Earth’s atmosphere Other telescopes are built on mountains to decrease atmospheric interference

The solar system also contains several dwarf planets These include Pluto, once considered the

ninth planet, and the larger, more distant 2003 UB313 (named Eris) Ceres, the largest object in

the asteroid belt (located between the orbits of

Mars and Jupiter), is also a dwarf planet

Space probes have examined all eight planets

Only Earth’s Moon has been explored by

astronauts—people who travel in space

◀ Galileo discovered Jupiter’s moons using this telescope.

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The Solar System

308

EXPLAIN

The Solar System

Planet Name

Radius at the Equator (km)

Mean Surface Temperature (°C)

Surface Materials Rings Mercury 2,440 179 Rock No

Venus 6,052 482 Rock No

Earth 6,378 15 Rock No

Jupiter 71,492 -121 Gas Yes

Saturn 60,268 -125 Gas Yes

Uranus 25,559 -193 Gas Yes

Neptune 24,746 -193 to -153 Gas Yes

Planetary Data from NASA

Which planets have gas as their only surface material?

Clue: Find Surface Materials column of the chart.

Reading Charts

Uranus Saturn

Jupiter

Venus

Mars Mercury

What is a moon?

A moon is an object that circles

around a planet Different planets have

different numbers and sizes of moons

Mercury and Venus do not have moons

Earth has one moon, Mars has two,

and Jupiter has at least 63 moons

Saturn has 49 moons Astronomers

have discovered at least 27 moons

around Uranus and 13 moons orbiting

Neptune The dwarf planet Pluto has

at least three moons

The sizes of the moons vary Some

of the moons are very small Seven

of the moons in the solar system are

actually bigger than Pluto! These

include Jupiter’s Ganymede, which is

the largest moon, and Earth’s Moon

Moons are also called satellites

(SAT•uh•lights) A satellite is an object

in space that circles around another object The moons of the planets are natural satellites Man-made satellites circle around Earth These provide weather information and are part of communication systems

▶ Earth’s Moon is the only moon that can be seen without using a telescope

How large are these moons?

Clue: Look at the scales.

Reading Photos

Hyperion (Saturn)

Ganymede

(Jupiter)

Moon (Earth)

Mimas (Saturn)

1 cm 1,000 km

Various Moons of the Solar System

1 cm

100 km

310

EXPLAIN

Forming Craters

When objects in space collide, the impact forms a crater, or a hole The

surface of Earth’s Moon has millions

of these craters The craters are easy

to see because the impact knocks the

surface material away so the darker

rock underneath shows through

Most objects that fall toward Earth burn up in Earth’s atmosphere Since

the Moon has no atmosphere, the

objects that fall toward it do not burn

up As a result, the Moon has more

craters than Earth

Quick Check

Summarize Describe Earth’s Moon

Critical Thinking What is the difference between a moon and

Then sprinkle whole wheat flour

on top to represent topsoil.

Measure the diameter of three different-sized marbles.

Drop the largest marble from about 3 inches straight above the pan Remove it carefully, then measure the diameter and depth

of the crater.

Drop the other marble over different spots from the same height Measure each crater and record the data.

Are the craters bigger or smaller than the diameter of the marbles?

What do you see at the crater sites? Why did this happen?

How is your model similar to what happens when an object hits the surface of the Moon?

Phobos (Mars)

1 cm

10 km

Deimos (Mars)

311

EXPLAIN

What are the smaller

objects in the solar

system?

Anasteroid (AS•tuh•roid) is a rock

that revolves around the Sun Most

of the thousands of asteroids in the

solar system are located between

Mars and Jupiter in the asteroid belt

Many asteroids have irregular shapes,

somewhat like a potato Some asteroids

are less than 1 mile wide, while others

can be up to 500 miles wide!

A comet is a mixture of frozen

gases, ice, dust, and rock that moves

in an irregular circle around the Sun

When a comet is far from the Sun, it is

usually no more than a few kilometers

in diameter However, as it gets closer,

energy from the Sun warms the surface

of the comet This makes the ice melt

Then a glowing ball of gases and dust,

which is called a coma, forms around

the comet Once the comet forms, the

Sun’s energy shapes it into shimmering tails of dust and of gases that maystretch out millions of kilometers into space from the head of the comet

Because the tails are produced by energy from the Sun, they always blow away from the Sun Therefore, as a comet moves around the Sun, the comethead always stays closest to the Sun and the tails trail out behind it

The solar system is full of other small objects In space, these objects are

called meteoroids(MEE•tee•uh•roids) The objects that cross paths with Earthand enter Earth’s atmosphere are called

Comets have tails of dust and gases.

312

EXPLAIN