Charnan Simon - Earth

Published in the United States of America by Cherry Lake Publishing Ann Arbor, Michigan www.cherrylakepublishing.com Content Adviser: Dr. Tobias Owen, University of Hawaii Institute for Astronomy Photo Credits: Cover and page 4, Orlando Florin Rosu/Dreamstime.com; cover and page 8, Reistlin Magere/Shutterstock, Inc.; cover and page 12, Tim Martin/ Dreamstime.com; cover and pages 14, 16, 18, 20, NASA; page 6, Sebastian Kaulitzki/Shutterstock, Inc.; page 10, maryo/Shutterstock, Inc. Copyright 2012 by Cherry Lake Publishing
All rights reserved. No part of this book may be reproduced or utilized in any
form or by any means without written permission from the publisher. LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA Simon, Charnan. p. cm.(21st junior library) Includes bibliographical references and index. cm.(21st junior library) Includes bibliographical references and index.

ISBN-13: 978-1-61080-081-5 (lib. bdg.) ISBN-10: 1-61080-081-8 (lib. bdg.) 1. EarthJuvenile literature. I. II. Series. Series.

QB631.4.S53 2011 525dc22 2010052190 _______________________________________________________ Cherry Lake Publishing would like to acknowledge the work of
The Partnership for 21st Century Skills.
Please visit www.21stcenturyskills.org for more information. Printed in the United States of America Corporate Graphics Inc. July 2011 CLFA09

Each planet in the solar system moves around the Sun. Earth is one of the eight planets in our solar system. It travels around the Sun, just like all the other planets. But Earth is special. Earth is the only planet in the solar system where people, animals, and plants can live.

Earth is our home! The Sun is too bright to look at without special cameras. Earth is the third planet from the sun. if earth were closer to the sun, it would be too hot for us to live. if earth were farther from the sun, it would be too cold. earth is not too hot or too cold. it is just right! Ask Questions! Earth is the fifth-largest planet.

Ask your parents or teacher which four planets are larger than Earth. Which three planets are smaller than Earth? Asking questions is a good way to learn! Earths orbit is part of how we measure time.

Like all the other planets, earth travels around the sun in a path called an orbit. Earth takes 365 days to go around the sun. Thats one year. Earth speeds through space at almost 19 miles (31 kilometers) per second.

Thats fast! We cant feel this movement because were moving right along with Earth. Earths axis is tilted just a little bit. Earth moves in another way, too. it spins on its axis. earths axis is an imaginary line that runs through the middle of the planet. earth takes 24 hours to spin all the way around on its axis. earth takes 24 hours to spin all the way around on its axis.

This makes one full day and night. Create! Roll some clay into a small ball. Poke a pencil all the way through the center. Imagine your clay ball is Earth and the pencil is its axis. Turn the pencil to make Earth spin on its axis! A cloud is a collection of water droplets or ice crystals floating in Earths atmosphere.

Every planet in the solar system has a layer of gases surrounding it.

This is called the atmosphere. Earths atmosphere is made up mostly of nitrogen and oxygen. This is the air we breathe. earth is the only planet that has the perfect mixture of air that people need to live. Oceans cover most of Earths surface. Earth is also the only planet with a lot of flowing water on its surface.

People need water to live. so do plants and animals. Earth has rivers and lakes and oceans. it has plains and mountains and canyons. earth has everything we need to live. Look! Water covers almost three-quarters of Earths surface.

From outer space, Earth looks blue because it has so much water. Sometimes Earth is called the big blue marble. Can you see why? You can see the Moon in the sky on most nights, but sometimes you can only see it after midnight.

Have you ever looked at the full Moon in the night sky? almost all the planets in the solar system have moons. These moons circle around their planets while the planets circle around the sun. earth has just one. Neil Armstrong and Buzz Aldrin were the first astronauts to walk on the Moon. Neil Armstrong and Buzz Aldrin were the first astronauts to walk on the Moon.

The Moon is our closest neighbor in space. it is also the only place in space that people have visited. Astronauts first landed on the Moon on July 20, 1969. Scientists are still studying the moon rocks and soil that the astronauts brought back. The Hubble Space Telescope helps scientists see far off into the universe. so far, they have not found any other place where people could live. so far, they have not found any other place where people could live.

Earth is just one small planet in a huge universe. but it is just right for us! Make a Guess! Earth is the only planet in our solar system where people can live. Do you think people might be able to live on other planets outside our solar system?

astronauts (ASS-truh-nawts) people who fly in spaceships atmosphere (AT-muhss-fihr) the gases or air surrounding a planet axis (AK-siss) an imaginary line that goes through an object and around which the object turns