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NOTE: In 2006, scientists from the International Astronomical Union classified Pluto as a “dwarf planet.” However, not all scientists agree with the decision. Use the Internet or current newspaper and magazine articles to find the latest information about the planets. Copyright © by Harcourt, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be addressed to School Permissions and Copyrights, Harcourt, Inc., 6277 Sea Harbor Drive, Orlando, Florida 32887-6777. Fax: 407-345-2418. HARCOURT and the Harcourt Logo are trademarks of Harcourt, Inc., registered in the United States of America and/or other jurisdictions. Printed in the United States of America ISBN-13: 978-0-15-349167-2 ISBN-10: 0-15-349167-1 1 2 3 4 5 6 7 8 9 10 179 15 14 13 12 11 10 09 08 07 06 If you have received these materials as examination copies free of charge, Harcourt School Publishers retains title to the materials and they may not be resold. Resale of examination copies is strictly prohibited and is illegal. Possession of this publication in print format does not entitle users to convert this publication, or any portion of it, into electronic format.
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Patterns in the Sky Lessons 1–2 Lesson 1 What Planets Orbit the Sun? . . . . . . . . . . 2 Lesson 2 What Patterns Do Earth and the Sun Follow? . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Visit The Learning Site! www.harcourtschool.com
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11 WhatWhat VOCABULARY PlanetsPlanets planet orbittelescope Orbit theOrbit the moon solar system Sun?Sun? A planet is a large To travel around an object in space that object is to orbit. This travels around a star. planet is orbiting the This is the planet sun. Saturn. 2
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A telescope is a tool that scientists use to The solar system is see objects that are far the sun and everything away. Objects seem that orbits it. The solar closer and larger when system includes nine you look at them planets and the planets’ through a telescope. moons. A moon is a large object that orbits a planet. The Earth has one moon that orbits it. 3
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READING FOCUS SKILL COMPARE AND CONTRAST You compare things by looking for ways they are alike. You contrast things by looking for ways they are different. Compare and contrast the planets. Find details that show how the planets are alike and different. Planets and Moons We live on Earth. Earth is a planet. A planet is a large body of rock or gas in space. Planets are moving. Earth is moving right now, but you cannot feel it. Planets orbit, or travel around, a star. Earth is one of nine planets that orbit the sun. It takes Earth one year to orbit the sun one time. 4
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The moon is smaller than Earth. A moon is a large body that orbits a planet. Earth has one moon that orbits it. The moon takes about one month to orbit Earth once. You can see the moon in the sky at night. 5
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The Solar System The solar system is the sun and the things that orbit it. The sun is the center of the solar system. The word solar means “sun.” There are nine planets in the solar system. The moons that orbit the planets are part of the solar system, too. How do the planets move in the solar system? Nine planets orbit the sun. Jupiter Earth Mercury Venus Mars 6
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Looking at the Sky A telescope is a tool that helps you see things that are far away. Telescopes make things look closer and larger. A telescope helps you see details. You need a telescope to see the planets that are far away. How is looking through a telescope different from using your eyes alone? These two people are using a telescope. C Saturn Neptune Pluto Uranus 7
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The Inner Planets There are nine planets in the solar system. The four planets that are closest to the sun are called the inner planets. The inner planets are Mercury, Venus, Earth, and Mars. MERCURY FUN FACT: The surface is hot enough to melt lead. MOONS: none VENUS FUN FACT: It once had an ocean that has dried up. MOONS: none 8
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EARTH FUN FACT: Earth is the only planet with water. MOONS: 1 All the inner planets have rocky surfaces. They are also warmer than some of the other planets because they are closer to the sun. How is Earth different from other inner planets? MARS FUN FACT: Mars has the largest volcano in the solar system. MOONS: 2 9
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The Outer Planets The five planets that are farthest from the sun are called the outer planets. They are Jupiter, Saturn, Uranus, Neptune, and Pluto. Most of them are larger than the inner planets. Other than Pluto, the outer planets are made mostly of gases. What is one way the outer planets are different from the inner planets? JUPITER FUN FACT: It has the Great Red Spot, which is a storm. MOONS: more than 60 SATURN FUN FACT: Saturn has many rings around it. MOONS: more than 55 URANUS FUN FACT: Uranus spins on its side. MOONS: more than 25 10
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NEPTUNE FUN FACT: When Pluto crosses Neptune’s orbit, it will be the planet farthest from the sun. MOONS: more than 10 PLUTO FUN FACT: Pluto is made of ice. MOONS: 1 ReviewReview Complete these sentences to compare the planets. 1. Nine planets ______ the sun. 2. All ______ are large bodies of rock or gas that travel around the sun. Complete these sentences that contrast the planets. 3. The ______ planets are closer to the sun than the ______ planets. 4. Some planets have one or more ______ orbiting them. 11
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22 WhatWhat VOCABULARY Patterns DoPatterns Do rotation axisNorthern Earth andEarth and Hemisphere the Sunthe Sun Follow?Follow? The Earth is always spinning. The spinning is called rotation. One rotation of Earth takes 24 hours. 12
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Earth has an imaginary line that runs through it. The line runs from the North Pole to the South Pole. We call this the Earth’s axis. Earth spins around its axis. The Northern Hemisphere is the northern half of Earth. 13
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READING FOCUS SKILL CAUSE AND EFFECT A cause is something that makes another thing happen. An effect is the thing that happens. Look for the effects of the movements of Earth. Day and Night Earth moves in two ways. Rotation is the spinning of Earth. It takes Earth 24 hours, or one day, to make one rotation. Earth also orbits the sun. It takes Earth 365 days to orbit the sun. Earth is rotating, or spinning. 14
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The sun is lighting only the side of Earth that is facing it. This is why we have day and night. The part of Earth that is lit by the sun is always changing because of Earth’s rotation. When it is daytime for one half of Earth, it is night for the other half. What causes day and night? D The sun is shining on California. At the same time, it is night on the other half of the Earth. C 15
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Shadows Change Every day, the sun comes up in the east. Later, the sun sets in the west. Notice how the sun’s position changes in the pictures on the next page. Shadows change because the sun’s position changes. What causes shadows to get longer and shorter? The sun is rising. Think about how the sun will move across the sky. 16
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The Sun’s Positions Earth has an imaginary line that runs through it. The line is called its axis. Earth’s axis is not straight up and down. It is tilted toward or away from the sun. The part of Earth that is tilted toward the sun has summer. The part that is tilted away from the sun has winter. California is in the Northern Hemisphere, the half of Earth that is closer to the North Pole. In summer, the sun is higher in the sky, so the days are longer. In winter, the sun is lower in the sky and the days are shorter. In summer, the sun is higher in the sky. B A In winter, the sun is lower in the sky. 18
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