Space and TechnologySpace and Technology by Ann J. Jacobsby Ann J. Jacobs GenreGenre Comprehension SkillComprehension Skill Text FeaturesText Features Science ContentScience Content Nonfi ctionNonfi ction SequenceSequence • Captions• Captions Day and NightDay and Night • Labels• Labels SkySky • Diagrams• Diagrams • Glossary• Glossary Scott Foresman Science 3.15Scott Foresman Science 3.15 ì<(sk$m)=bdifaa<ì<(sk$m)=bdifaa<ISBNISBN 0-328-13850-90-328-13850-9 +^-Ä-U-Ä-U+^-Ä-U-Ä-U
Vocabulary What did you learn?Patterns in the Sky axis 1. Why does the Sun look larger than the rest of the stars in the sky?by Ann J. Jacobs constellation lunar eclipse 2. When are shadows shortest during the day? Explain your answer. phase 3. What is the phase of the Moon called when it revolution looks like a big circle? rotation 4. In this book you have read star about the four seasons. Write to explain why the seasons change. Use details from the book. telescope 5. Sequence Explain the phases of the Moon in order. Illustration: 16 Paul Oglesby 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: (Bkgd) ©NASA/Corbis; Title Page: STScI/NASA; 2 ©Beverly Joubert/NGS Image Collection; 4 ©Paul A. Souders/Corbis, ©Medford Taylor/NGS Image Collection; 6 ©Gallo Images/Corbis; 13 NASA Image Exchange; 14 NASA Image Exchange; 16 ©John Sanford/Photo Researchers, Inc.; 18 ©Roger Ressmeyer/Corbis; 19 STScI/NASA; 20 ©Roger Ressmeyer/Corbis; 21 ©Roger Ressmeyer/Corbis; 22 ©David Nunuk/Photo Researchers, Inc.; 23 ©Frank Zullo/Photo Researchers, Inc. ISBN: 0-328-13850-9 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. 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05
What are some patterns that Day and Night repeat every day? Earth is moving all the time. It spins around an imaginary line called an axis. One end of this line passes through the North Pole. The other end passes The Sun through the South Pole. Earth spins on its axis in The Sun is always in the sky. You can see it on a counterclockwise direction. This is the opposite sunny days. It is there on cloudy days too. The Sun is direction of the way hands on a clock move. a star. A star is a big ball of hot, glowing gases. Light and heat on Earth’s surface come from the Sun. Earth is small compared to the Sun. But they are Axis both shaped like a ball. Earth does not make its own light. The side of Earth facing the Sun is lit by sunlight. The side of Earth facing away from the Sun is dark. 2 3
The Sun is at its highest point in the sky at around noon. The Sun appears to move lower in the western sky as Earth rotates. Daytime begins when Earth’s rotation causes the Sun to appear over the eastern horizon. Earth makes one full spin on its axis every 24 hours. The Sun may trick you. It appears to rise in the east. This is called a rotation. During this time, half of Then the Sun seems to move across the sky and set Earth faces the Sun. It is daytime there. The other half in the west. But the Sun is not moving at all! It only of Earth has night. appears to move. It is really Earth that is moving. Earth always rotates at the same speed. During the year, some days have more sunlight than others. The number of hours of sunlight and darkness changes. But the total hours of sunlight and darkness in a day always add up to 24 hours. 4 5
Shadows The length and direction Have you ever stood in the shade of a tree? If so, of shadows change. Find the you were really standing in a shadow. A shadow shadow in the top picture. The forms when an object blocks the light that hits it. The Sun appeared in the east. The shadow is cast onto a surface. It is shaped like the shadow is long. It stretches in object that blocks the light. the opposite direction from the Sun. Morning shadows stretch toward the west. Find the shadow in the middle picture. At noon, the Sun is high in the sky. Shadows are short. Later in the day, shadows become longer again. Afternoon shadows stretch toward the east. You can see this in the bottom picture. Once the Sun disappears, there is no light to make shadows. How do the length and direction of the shadow cast by this basketball hoop change during the day? 6 7
What patterns repeat Sometimes the northern half of Earth tilts toward the Sun. At other times the southern half tilts toward every year? it. The part tilted toward the Sun gets the most direct sunlight. This part gets the most heat. It also gets more Earth Moves Around the Sun hours of daylight than darkness in a day. Earth turns on its axis. Earth’s axis is not straight up and down. It is tilted. Earth also moves, or revolves, around the Sun. In one year, Earth moves all the way March around the Sun. This trip is called a revolution. The northern and southern halves of As Earth moves, its axis always points in the same Earth get equal amounts of sunlight. The northern half is warming up. direction. The southern half is cooling down. The part of Earth tilted toward the Sun gets the most light. December The northern half of Earth tilts away from the Sun. This half gets less sunlight June than the southern half. It The northern half of is winter in the northern Earth tilts toward the half. In the southern half, Sun. This half gets it is summer. more sunlight than the southern half. It is summer in the northern half. It is winter in the southern half. September The northern and southern halves get the same amount of sunlight. The northern half of Earth is cooling down. The southern half is warming up. 8 9
Seasons In different seasons, the Sun’s place in the sky The four seasons are spring, summer, fall, and changes. This is due to Earth’s tilted axis. The Sun is winter. Which one do you like best? higher in the sky in summer. The Sun is lower in the The amount of sunlight changes from season to sky in winter. season. So do temperatures. These changes happen In spring and fall, Earth’s axis is not pointed toward in patterns. Temperatures are often hot in the summer. the Sun or away from it. Temperatures are not as cold In winter, temperatures are usually cold. as winter. But they are not as hot as summer. The Think about December. The northern half of Earth hours of daylight and darkness are about the same is tilted away from the Sun. This means it gets less each day. sun. Temperatures are cold. There are fewer hours of daylight. Earth’s tilted axis causes When the Sun is higher the Sun’s position in the in the sky, there are sky to change. more hours of daylight. June East West December This picture shows how the Sun’s position changes on the northern half of Earth. 10 11
Why does the Moon’s The closest natural object to Earth is 384,000 kilometers (239,000 miles) away. It is the Moon. At shape change? night, the Moon is very bright. But the Moon does not make its own light. Light from the Sun shines on the The Moon and Earth Moon and bounces off. The Moon rotates and revolves like Earth. The Moon You can see the Moon sometimes during the day. rotates on its axis. It revolves around Earth. The This is because daytime light in the air is less bright. Moon takes about 27 days to make one rotation. We always see the same side of the Moon from The Moon makes one revolution in almost the same Earth. No one saw the other side until a spacecraft amount of time. took pictures of it in 1959! The Moon rotates on its axis and revolves around Earth in about the same amount of time. 12 13
The Moon and the Sun Lunar Eclipse Sometimes the Moon looks like a circle. At other A lunar eclipse is caused by the Moon moving times you cannot see the Moon at all. Between these behind Earth. When it does, Earth blocks sunlight from times you can only see part of the Moon. This pattern reflecting off the Moon. During a lunar eclipse, Earth’s of changes is the same. It starts over about every four shadow covers the whole Moon. weeks or 291 days. 2 Each different way that the Moon looks is called a phase. You see more of the Moon each night until the phase called a full Moon. Then you start to see less of the Moon. Soon you cannot see the Moon at all. This phase is called a new Moon. Half of the Moon is always lighted. We cannot always see this half. We see different amounts of the lighted half as the Moon and Earth move. The Moon Earth’s The Sun shadow Earth makes a shadow on the Moon during a lunar eclipse. 14 15
First Quarter Phases of the Moon This phase is a week after Crescent the new Moon. The Moon This phase is right after the looks like a half circle. new Moon. Now we see The inner ring only a small piece of the Full Moon shows how the lighted part of the Moon. This phase is a week Moon looks after the First Quarter. from space. We can see all of the lighted half of the Moon. It looks like a circle. Earth Light The outer photos New Moon show how the Moon The dark half of the looks from Earth. Moon faces toward Earth. We cannot Third Quarter see the Moon at all. 16 17
Star Patterns There are different kinds of telescopes. Some use tubes, mirrors that reflect light, and lenses that bend Stars and the Telescope light. These parts let lots of light into the telescope. Suppose you are looking at the night sky. Do you This makes objects in the sky easy to see. see stars? Stars may look small. But they are far There are even telescopes that do not collect light away. Some stars are bigger than the Sun! Others are waves. They collect different waves instead. Some smaller. The stars that are very far away can be hard collect radio waves! to see. There are tools to help you see these stars. A telescope magnifies faraway objects as binoculars do. Both tools make objects look bigger. Then the objects are easier to see. 18 19
Patterns of Stars Long ago, people saw many shapes in star patterns. They saw objects, animals, and people. They made Some stars seem to be in groups. These groups make up stories about what they saw. They gave these patterns. A group of stars that make a pattern is called constellations names that we still use today. a constellation. The stars in a constellation look close together. But See how the lines connect stars together in two they are very far apart. What if you looked at the same groups below? One looks like a big cup. It is part of a stars from faraway in deep outer space? You would see larger constellation. The other looks like a little cup. different patterns. Its stars make up a second constellation. North Star This photograph shows the same constellations in the winter sky. Little Dipper Big Dipper Big Dipper Little Dipper This photograph shows the Big Dipper and the Little Dipper in the summer sky. North Star 20 21
Like the Sun, stars seem to move across the sky. But Look at the sky tonight. You might see the Moon. the stars really do not move. It just looks that way. What phase is it in? Can you see any stars? What This is because Earth is rotating on its axis. about constellations? The sky has many patterns. It is Star patterns change with the seasons. As Earth fun to learn about the patterns and watch them. moves around the Sun, constellations are in different places in the sky. 22 23
VocabularyGlossary What did you learn? axisaxis the imaginary line around which 1. Why does the Sun look larger than the rest of the Earth spins stars in the sky? constellation constellationlunar eclipse a group of stars that make a pattern 2. When are shadows shortest during the day? lunar eclipse Earth’s shadow covering the Moon Explain your answer. phase phase each different way the Moon looks 3. What is the phase of the Moon called when it revolution looks like a big circle? revolution one complete trip around the Sun rotation 4. In this book you have read rotation one complete spin on Earth’s axis about the four seasons. Write to explain why the star star a big ball of hot, glowing gases seasons change. Use details from the book. telescope telescope a tool that magnifies faraway objects 5. Sequence Explain the phases of the Moon in order. Illustration: 16 Paul Oglesby 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: (Bkgd) ©NASA/Corbis; Title Page: STScI/NASA; 2 ©Beverly Joubert/NGS Image Collection; 4 ©Paul A. Souders/Corbis, ©Medford Taylor/NGS Image Collection; 6 ©Gallo Images/Corbis; 13 NASA Image Exchange; 14 NASA Image Exchange; 16 ©John Sanford/Photo Researchers, Inc.; 18 ©Roger Ressmeyer/Corbis; 19 STScI/NASA; 20 ©Roger Ressmeyer/Corbis; 21 ©Roger Ressmeyer/Corbis; 22 ©David Nunuk/Photo Researchers, Inc.; 23 ©Frank Zullo/Photo Researchers, Inc. ISBN: 0-328-13850-9 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. 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05 24
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