space and technology earth in space

by Donna Latham
Scott Foresman Science 5.17
Genre Comprehension Skill Text Features Science Content
Nonfi ction Make Inferences • Captions
• Charts
• Diagrams
• Glossary
The Solar System
ISBN-13:
ISBN-10:
978-0-328-34246-4
0-328-34246-7
9 780328 342464
90000
Space and Technology
34246_CVR_FSD Page Cover1 1/23/07 4:40:10 PM christ34246_CVR_FSD Page Cover1 1/23/07 4:40:10 PM christ /Volumes/403/sf00207_SciLR_copyright%0/sf00207_G5/sf00207_G5a_Below/34246/Volumes/403/sf00207_SciLR_copyright%0/sf00207_G5/sf00207_G5a_Below/34246
by Donna Latham
Scott Foresman Science 5.17
Genre Comprehension Skill Text Features Science Content
Nonfi ction Make Inferences • Captions
• Charts
• Diagrams
• Glossary
The Solar System
ISBN-13:
ISBN-10:
978-0-328-34246-4
0-328-34246-7
9 780328 342464
90000
Space and Technology

34246_CVR_FSD Page Cover1 1/23/07 4:40:10 PM christ34246_CVR_FSD Page Cover1 1/23/07 4:40:10 PM christ /Volumes/403/sf00207_SciLR_copyright%0/sf00207_G5/sf00207_G5a_Below/34246/Volumes/403/sf00207_SciLR_copyright%0/sf00207_G5/sf00207_G5a_Below/34246
Illustration: 1, 4, 6, 7, 21 Bob Kayganich
Photographs: Every effort has been made to secure permission and provide appropriate credit for
photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its
attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott
Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom
(B), Left (L), Right (R) Background (Bkgd)
Opener: (B) NASA Image Exchange, (TC) Getty Images; 2 NASA; 3 ©Lowell Georgia/Corbis; 4 ©Dave
Robertson/Masterfile Corporation; 8 (CL, CC, CR) Getty Images, (CL) JPL/NASA, (CC) Corbis, (CR)
©Comstock, Inc.; 9 (CC) JPL/NASA, (CL) ©NASA/Roger Ressmeyer/Corbis; 10 (CC) Corbis, (Bkgd)
©Handout/Reuters/Corbis; 12 ©Phil Degginger/Color-Pic, Inc.; 13 ©GSFC/NASA; 14 ©NASA/DK
Images; 15 (BR) ©JPL/TSADO/Tom Stack & Associates, Inc., (CC) ©TSADO/NASA/Tom Stack &
Associates, Inc.; 16 ©Charles & Josette Lenars/Corbis; 18 (TR, BR) NASA Image Exchange; 19 Getty
Images; 20 Getty Images; 21 ©Eckhard Slawik/Photo Researchers, Inc.; 22 (CL, B) Jeff Newbery; 23 (TR)
NASA, (CL) Getty Images, (TC) ©Eckhard Slawik/Photo Researchers, Inc.
ISBN 13: 978-0-328-34246-4; ISBN 10: 0-328-34246-7
Copyright © Pearson Education, Inc.
All Rights Reserved. Printed in the United States of America. This publication is
protected by Copyright and permission should be obtained from the publisher prior
to any prohibited reproduction, storage in a retrieval system, or transmission in any
form by any means, electronic, mechanical, photocopying, recording, or likewise. For
information regarding permissions, write to: Permissions Department, Scott Foresman,
1900 East Lake Avenue, Glenview, Illinois 60025.
1 2 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07
Vocabulary
asteroid
axis
comet
Moon phase
revolution

rotation
satellite
solar system
space probe
What Did You Learn?
1. What is one cycle that is caused by Earth’s movement in
space?
2. What caused the Moon’s craters?
3. Most of the asteroids in our solar system are located in a belt
between Mars and Jupiter. Why is this?
4.
The motion of objects in space
causes cycles to take place. One cycle, for example, is the
year that passes as Earth makes its way around the Sun. On
your own paper, write about another cycle that takes place.
Include examples and details from the book to support your
answer.
5.
Make Inferences Look back at the diagram on
page 7. Study the facts about each season in the Northern
Hemisphere. When would each season begin in the Southern
Hemisphere? Why do you think this is so?
34246_CVR_FSD Page Sec1:2 1/23/07 4:40:14 PM christ34246_CVR_FSD Page Sec1:2 1/23/07 4:40:14 PM christ /Volumes/403/sf00207_SciLR_copyright%0/sf00207_G5/sf00207_G5a_Below/34246/Volumes/403/sf00207_SciLR_copyright%0/sf00207_G5/sf00207_G5a_Below/34246
Earth in Space
by Donna Latham
34246_01-24_FSD 134246_01-24_FSD 1 1/17/07 11:38:24 AM1/17/07 11:38:24 AM
In what ways does
Earth move?
Earth’s Orbit
The solar system is made up of the Sun, its eight planets,

many moons, asteroids, and comets. Earth is a small, blue,
ball-shaped planet in the solar system. It has one moon. Each
of the planets follows its own path around the Sun. This path,
called an orbit, is not exactly round. It is elliptical, or shaped
like a flattened circle.
2
34246_01-24_FSD 234246_01-24_FSD 2 1/17/07 11:38:29 AM1/17/07 11:38:29 AM
3
A revolution is one orbit. It takes Earth just a little more
than 365 days to make its revolution around the Sun. Does
365 sound like a familiar number to you? It should! It’s a year.
The Moon’s revolution around Earth doesn’t take nearly that
long. It takes about 28 days, or about a month.
What keeps the planets in their orbits around the Sun? It’s
gravity. Gravity is the force that keeps you on the Earth. The
pull of gravity is very strong. Gravity also keeps the Moon
orbiting around the Earth.
34246_01-24_FSD 334246_01-24_FSD 3 1/17/07 11:38:34 AM1/17/07 11:38:34 AM
4
Day and Night
Planets spin. This causes any part of the planet to face the
Sun for a while. Then that part turns away from the Sun. When
our part of Earth faces the Sun, we have day. When it turns
away from the Sun, we have
night. The spinning of Earth
causes the changes of day
and night.
Look at the picture of the
spinning top. You can see
that it tilts, or leans as it

moves. A top spins around an
imaginary line called an axis.
Earth spins, or rotates, on an
axis too.
This diagram shows Earth’s
tilt. It also shows its spin. The
North Pole is at the top of the
axis. The South Pole is at the
bottom.
Earth’s axis is an imaginary line.
It is not really there. But if you
picture it in your mind, you can
see how Earth spins.
34246_01-24_FSD 434246_01-24_FSD 4 1/17/07 11:38:36 AM1/17/07 11:38:36 AM
5
A rotation is one spin of an object
on its axis. Earth completes a rotation
in 24 hours. That’s one day. Earth’s
tilt causes some parts of the planet
to receive more daylight than others.
Depending on where people live, the
length of day and night changes all
year. The change is greater in some
places than others. On one day in
spring and one day in fall, day
and night are the same length.
Earth’s Comfortable
Temperature
Because of the speed of
Earth’s rotation, day follows

night quickly. So, the Earth
does not get too hot or too
cold. Earth also has an
atmosphere, or layer of gases,
to help control temperature. It
reflects some of the Sun’s rays
to keep us cool, but also traps
some to keep us warm. Some
planets and our Moon have little
or no atmosphere. Their temperature
changes are too extreme for living
things to survive.
34246_01-24_FSD 534246_01-24_FSD 5 1/17/07 11:38:38 AM1/17/07 11:38:38 AM
6
The Pattern of Seasons
The pattern of changes which we call the seasons is caused
by Earth’s tilt. Earth always tilts the same way during its orbit.
So at different times of year, different parts of Earth tilt toward
the Sun. Those parts receive more daylight hours. They are also
warmer, because sunlight hits them at a more direct angle.
Daylight lasts longer in the summer. It is shorter in the winter.
Look at the diagram below. It shows Earth’s revolution
around the Sun. Do you see how the Sun is not exactly in the
middle of Earth’s orbit? The distance between Earth and the Sun
changes throughout the year. But this distance does not affect
our seasons.
January
147,500,000 km
152,600,000 km
Earth

Sun
July
34246_01-24_FSD 634246_01-24_FSD 6 1/17/07 11:38:40 AM1/17/07 11:38:40 AM
7
Around June 21,
Summer: The North
Pole tilts toward the
Sun. The Sun’s most
direct rays fall on the
Northern Hemisphere.
So it has the most
daylight hours and
becomes warmer.
Around September 21,
Fall: The hours of daylight
and night are equal.
Around December 21,
Winter: The North
Pole has its greatest
slant away from
the Sun. Daylight is
shorter than on any
other day of the year.
Around March 21, Spring:
The hours of daylight and night
are equal.
Earth’s Seasons
This diagram shows the seasons for the Northern Hemisphere, where the
United States is located. The seasons change as the Earth orbits the Sun.
But the tilt of Earth’s axis never changes.

7
34246_01-24_FSD 734246_01-24_FSD 7 1/17/07 11:38:41 AM1/17/07 11:38:41 AM
Our solar system is made up of the Sun and its eight planets.
This diagram shows the position of the planets in the solar
system. The diagram is not to scale, because if it were, it would
not fit on the page. The planets are too far apart. Planets close
to the Sun move quickly and have small orbits. Planets far from
the Sun move slowly and have large orbits. Their revolutions
take many Earth years.
What are the parts
of the solar system?
Mercury
Venus
Earth
asteroid belt
Mars
Jupiter
Saturn
8
34246_01-24_FSD 834246_01-24_FSD 8 1/17/07 11:38:45 AM1/17/07 11:38:45 AM
Because the planets
are so far away from
one another, and space
is so huge, the units
of measure we use on
Earth don’t work very
well. They are much
too small. Scientists use
AUs, or astronomical
units, instead of miles

or kilometers. One
AU is the average
distance between Earth
and the Sun.
Uranus
Neptune
9
Planet
Diameter
(Compared to Earth)
Mercury 0.4
Venus 0.9
Mars 0.5
Jupiter 11.0
Saturn 10.0
Uranus 4.0
Neptune 4.0
Planet Diameters
34246_01-24_FSD 934246_01-24_FSD 9 1/17/07 11:38:55 AM1/17/07 11:38:55 AM
Visiting the Planets
Space probes have been used to explore the planets for years.
Space probes are spacecraft that can gather data without
any people aboard to run them. But they do carr
y special
instruments. With them, space probes find out about planet
surfaces and what they are made of.
Mariner 10, a space probe,
has given us pictures of
Mercury’s surface.
In 2004, the Mars rovers

Spirit and Opportunity were
landed on Mars. They sent
color pictures back to Earth.
10
34246_01-24_FSD 1034246_01-24_FSD 10 1/17/07 11:38:57 AM1/17/07 11:38:57 AM
11
Mercury
Scientists think Mercury’s core is mostly
made of iron. Mercury has almost no
atmosphere. Mercury’s surface temperature
can go from –170°C to 430°C .
Venus
Venus is the closest planet to Earth. Venus
is just as hot during the night as it is during
the day. That’s because the Sun’s heat gets
trapped in the planet’s thick clouds. Venus’s
atmosphere is made up of poisonous gases.
Mars
Mars has a very thin atmosphere. It looks
red because of the reddish-brown iron in its
soil. Mars has giant volcanoes. It also has ice
caps at its poles.
The Gas Giants
Past Mars are four “gas giant” planets.
They are Jupiter, Saturn, Uranus, and
Neptune. These huge planets are gigantic
balls of gas. These planets all have many
moons and rings.
Pluto
Pluto is a dwarf planet. Scientists think

it is made of ice and rock. Pluto’s moon,
Charon, is about half the size of the planet
itself! Some scientists call Pluto and Charon
a “double planet.”
34246_01-24_FSD 1134246_01-24_FSD 11 1/17/07 11:39:00 AM1/17/07 11:39:00 AM
What are comets
and asteroids?
Comets
Comets are icy, dusty masses orbiting the Sun. There
may also be rocky matter inside them. Much smaller than
planets, comets come from beyond Pluto. Their paths are
very stretched out.
Each year, a few comets enter our solar system and circle
the Sun. But only the very largest ones can be seen without
a telescope.
Nucleus
A comet’s nucleus has an uneven
shape. Scientists call it a “dirty
snowball.” Made of dust and
ice, the nucleus grows black
and solid over time. The nucleus
is very small, sometimes only a
few kilometers across.
12
34246_01-24_FSD 1234246_01-24_FSD 12 1/17/07 11:39:00 AM1/17/07 11:39:00 AM
A comet is made up of a solid core called a nucleus and a
cloud of dust and gas called a coma. Look at the diagram to
learn more about each part of a comet.
Coma
Around the nucleus is a giant cloud of dust and

gases. The coma can be even larger than the
planet Jupiter. The fine dust reflects sunlight
brightly. The gases take in energy and glow.
It’s the coma that gives a comet its fuzzy look.
The coma and tail form only when the comet
gets close to the Sun. There, sunlight melts part
of the nucleus.
Two Tails
Comets have two tails. They stream out in a
direction away from the Sun. The tails may be
up to 80 million kilometers long! The ion tail is
made of tiny, magnetic particles of gas. It is thin
and blue in color and sticks straight out from the
comet. The dust tail is wide and yellow. It is made
of dust that is released by the melting nucleus.
13
34246_01-24_FSD 1334246_01-24_FSD 13 1/17/07 11:39:03 AM1/17/07 11:39:03 AM
Asteroids
An asteroid is a rocky mass that revolves around the Sun
and is much smaller than a planet. Asteroids can be several
hundred kilometers wide, but some are as tiny as pebbles.
Many asteroids have odd, uneven shapes. And some even have
smaller asteroids that orbit them. Jupiter’
s gravity holds most
asteroids in a belt beyond Mars, but occasionally one will hit
Earth. Take a look at these images of asteroids.
By a nose
Here’s an asteroid with an odd shape!
Some people think it looks like a flying
nose. The largest asteroids, though, are

more ball-shaped, like the planets.
14
34246_01-24_FSD 1434246_01-24_FSD 14 1/17/07 11:39:06 AM1/17/07 11:39:06 AM
Asteroid Eros
Look at the surface of Eros. Can you
spot the craters, boulders, and rock
layers? More than 33 kilometers long
and 13 kilometers thick, Eros is the
first asteroid to be landed on
by a spacecraft.
Asteroid Ida
Ida is about 58 kilometers long
and 23 kilometers wide. It is in
the asteroid belt between Mars
and Jupiter.
15
34246_01-24_FSD 1534246_01-24_FSD 15 1/17/07 11:39:06 AM1/17/07 11:39:06 AM
Meteors, Meteoroids, and Meteorites
Small asteroids are called meteoroids. They are usually the
size of a grain of sand but can be as big as a boulder. When
meteoroids hit Earth’s atmosphere, they become meteors. They
heat up and make a glowing streak across the night sky. You
may have seen this happen but called it a shooting star. Very
bright meteors are called fireballs. When Earth passes through
the orbit of a comet, we see many meteors at once. This is called
a meteor shower.
Arizona’s Meteor Crater
16
34246_01-24_FSD 1634246_01-24_FSD 16 1/17/07 11:39:08 AM1/17/07 11:39:08 AM
Although most meteors burn up before they crash into

Earth, some do not. Then, pieces of them may fall to Earth.
A meteorite is a piece of rock or metal that lands on Earth.
Most are very small, but sometimes a large one lands, causing
great damage.
This crater was caused by a small meteorite.
It is about two hundred meters deep and
twelve hundred meters across.
17
34246_01-24_FSD 1734246_01-24_FSD 17 1/17/07 11:39:12 AM1/17/07 11:39:12 AM
18
What is known
about the Moon?
Traveling with Earth
At about 384,000 kilometers
(238,000 miles) away, the Moon
is Earth’s closest neighbor. You
might not think that sounds very
close. But compared to everything
else in our solar system, the Moon
is quite close.
The Moon is the only place,
other than Earth, where people
have stood. It is also Earth’s only
natural satellite. A satellite
is an object in orbit around
another object.
Looking at the Moon
As the Moon orbits Earth, we
can see only one side. Called the
near side, this half of the Moon

faces Earth at all times. That’s
because the Moon spins and orbits
at about the same speed. It takes
the Moon about 27 days to orbit the
Earth. In the same amount of time,
it rotates once.
The Moon’s Surface
The Moon is covered with
mountains, craters, and
smooth plains. Craters were
caused by rocks or comets
crashing into the Moon.
The Moon has no air or
water, but it does have
some ice. At one time
lava flowed on the
Moon, creating
large areas of
smooth rock.
34246_01-24_FSD 1834246_01-24_FSD 18 1/17/07 11:39:12 AM1/17/07 11:39:12 AM
Visiting the Moon
On July 20, 1969, Neil Armstrong
became the first person to step
on the Moon. From 1969 to 1972,
twelve people walked on the Moon.
This is the near side of
the Moon. That’s the
half that faces Earth,
and the side we see.
A satellite took this

photo of the far
side of the Moon.
19
Neil Armstrong
34246_01-24_FSD 1934246_01-24_FSD 19 1/17/07 11:39:16 AM1/17/07 11:39:16 AM
20
Phases of the Moon
Have you noticed that the
Moon appears to change
shape at different times
of the month? These
different shapes are
called Moon phases.
Although the Moon
often looks very bright
in the sky, it doesn’t
really produce any light.
“Moonlight” is really
sunlight reflecting off the
Moon’s surface. Only one side
of the Moon is lit by the Sun.
At different times of the month,
different amounts of the lit
side face Earth. This is why the
Moon seems to change shape.
When we see the Moon from
Earth, we see its lit side. As the
Moon orbits Earth, different
amounts of this side can be seen.
Over a month, the Moon appears in

different shapes. We call them phases.
34246_01-24_FSD 2034246_01-24_FSD 20 1/17/07 11:39:20 AM1/17/07 11:39:20 AM
View from Earth
New Moon
You can hardly see a new Moon!
It passes between the Earth and
the Sun. The side in shadow faces
Earth. The sunlit side faces away.
Crescent Moon
For a few days after the new
Moon, you can see a crescent
Moon. It is a little slice of the
Moon’s sunlit side.
Full Moon
You can see the full Moon
about a week after the first
quarter. Earth is between the
Moon and the Sun.
First Quarter Moon
The first quarter Moon is seen
about a week after the new Moon.
Half of the Moon’s sunlit side
faces Earth.
21
34246_01-24_FSD 2134246_01-24_FSD 21 1/17/07 11:39:23 AM1/17/07 11:39:23 AM
High and Low Tides
If you’ve ever spent a day at an ocean beach, you know that
the ocean has high and low tides. The water level rises and then
goes back down. There are two high tides and two low tides
each day.

The Moon’s gravity causes the tides. It makes the ocean
bulge out toward the Moon. Tides are high in the areas that
bulge out, and low in the areas that don’t. As the Moon moves
around Earth, the bulge moves with it, causing the high tides to
travel around the world.
The Bay of Fundy is
famous for its tides. They
are the highest in the
world, reaching 15 meters
(50 feet). At low tide,
boats end up sitting
in the mud!
22
34246_01-24_FSD 2234246_01-24_FSD 22 1/17/07 11:39:27 AM1/17/07 11:39:27 AM
The Sun’s gravity affects the tides too. But it is a much
smaller effect than the Moon’s. During a full Moon or new
Moon, the Sun and Moon both pull on the Earth. At this time
the highest tides take place. At the first quarter or third quarter
Moon, things are different! The Sun pulls on Earth at one angle.
The Moon pulls at another. This causes the lowest tides.
In this short journey around the solar system, you’ve learned
many things. You have learned that it is made up of the Sun
and its planets —including Earth. You have also learned that
the Moon, meteors, comets, and asteroids are also part of the
solar system.
You have learned that Earth’s orbit causes many things to
happen. For example, day becomes night. Seasons change.
Tides rise and fall. And the phases of the Moon occur each
month. Our neighbors in the solar system may be far away,
but they have a big effect on our world!

23
34246_01-24_FSD 2334246_01-24_FSD 23 1/17/07 11:39:34 AM1/17/07 11:39:34 AM
24
Glossary
asteroid a rocky mass orbiting the Sun that can be
several hundred kilometers wide
axis the imaginary line around which Earth
rotates, or spins
comet a frozen mass of ice and dust that orbits
the Sun
Moon phase the changes in shape the Moon goes through
in a month as seen from Earth
revolution one full orbit of an object around another
object
rotation one whole spin of an object on its axis.
satellite an object that orbits another
solar system the Sun and all the bodies that orbit it
space probe a spacecraft that gathers data without a crew
34246_01-24_FSD 2434246_01-24_FSD 24 1/17/07 11:39:41 AM1/17/07 11:39:41 AM
Illustration: 1, 4, 6, 7, 21 Bob Kayganich
Photographs: Every effort has been made to secure permission and provide appropriate credit for
photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its
attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott
Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom
(B), Left (L), Right (R) Background (Bkgd)
Opener: (B) NASA Image Exchange, (TC) Getty Images; 2 NASA; 3 ©Lowell Georgia/Corbis; 4 ©Dave
Robertson/Masterfile Corporation; 8 (CL, CC, CR) Getty Images, (CL) JPL/NASA, (CC) Corbis, (CR)
©Comstock, Inc.; 9 (CC) JPL/NASA, (CL) ©NASA/Roger Ressmeyer/Corbis; 10 (CC) Corbis, (Bkgd)
©Handout/Reuters/Corbis; 12 ©Phil Degginger/Color-Pic, Inc.; 13 ©GSFC/NASA; 14 ©NASA/DK
Images; 15 (BR) ©JPL/TSADO/Tom Stack & Associates, Inc., (CC) ©TSADO/NASA/Tom Stack &

Associates, Inc.; 16 ©Charles & Josette Lenars/Corbis; 18 (TR, BR) NASA Image Exchange; 19 Getty
Images; 20 Getty Images; 21 ©Eckhard Slawik/Photo Researchers, Inc.; 22 (CL, B) Jeff Newbery; 23 (TR)
NASA, (CL) Getty Images, (TC) ©Eckhard Slawik/Photo Researchers, Inc.
ISBN 13: 978-0-328-34246-4; ISBN 10: 0-328-34246-7
Copyright © Pearson Education, Inc.
All Rights Reserved. Printed in the United States of America. This publication is
protected by Copyright and permission should be obtained from the publisher prior
to any prohibited reproduction, storage in a retrieval system, or transmission in any
form by any means, electronic, mechanical, photocopying, recording, or likewise. For
information regarding permissions, write to: Permissions Department, Scott Foresman,
1900 East Lake Avenue, Glenview, Illinois 60025.
1 2 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07
Vocabulary
asteroid
axis
comet
Moon phase
revolution
rotation
satellite
solar system
space probe
What Did You Learn?
1. What is one cycle that is caused by Earth’s movement in
space?
2. What caused the Moon’s craters?
3. Most of the asteroids in our solar system are located in a belt
between Mars and Jupiter. Why is this?
4.
The motion of objects in space

causes cycles to take place. One cycle, for example, is the
year that passes as Earth makes its way around the Sun. On
your own paper, write about another cycle that takes place.
Include examples and details from the book to support your
answer.
5.
Make Inferences Look back at the diagram on
page 7. Study the facts about each season in the Northern
Hemisphere. When would each season begin in the Southern
Hemisphere? Why do you think this is so?
34246_CVR_FSD Page Sec1:2 1/23/07 4:40:14 PM christ34246_CVR_FSD Page Sec1:2 1/23/07 4:40:14 PM christ /Volumes/403/sf00207_SciLR_copyright%0/sf00207_G5/sf00207_G5a_Below/34246/Volumes/403/sf00207_SciLR_copyright%0/sf00207_G5/sf00207_G5a_Below/34246