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® Br ca ti anni LEARNING L I B R A R Y Exploring Space Journey through the solar system and beyond CHICAGO LONDON NEW DELHI PARIS SEOUL SYDNEY TAIPEI TOKYO PROJECT TEAM Judith West, Editorial Project Manager Christopher Eaton, Editor and Educational Consultant Kathryn Harper, U.K. Editorial Consultant Marilyn L. Barton, Senior Production Coordinator Editors Theodore Pappas Anthony L. Green Mary Rose McCudden Andrea R. Field Michael J. Anderson Colin Murphy Locke Petersheim Indu Ramchandani (Encyclopædia Britannica India) Bhavana Nair (India) Rashi Jain (India) Design and Media Specialists Nancy Donohue Canfield, Design Megan Newton-Abrams, Design Karen Koblik, Photos Joseph Taylor, Illustrations Amy Ning, Illustrations Jerry A. Kraus, Illustrations Michael Nutter, Maps Copy Editors Barbara Whitney Laura R. Gabler Dennis Skord Lisa Braucher, Data Editor Paul Cranmer, Indexer ENCYCLOPÆDIA BRITANNICA PROJECT SUPPORT TEAM EDITORIAL Linda Berris Robert Curley Brian Duignan Kathleen Kuiper Kenneth Pletcher Jeffrey Wallenfeldt Anita Wolff Charles Cegielski Mark Domke Michael Frassetto James Hennelly Sherman Hollar Michael R. Hynes Sandra Langeneckert Gene O. Larson Michael I. Levy Robert Lewis Tom Michael Janet Moredock DESIGN Steven N. Kapusta Carol A. Gaines Cate Nichols ART Kathy Nakamura Kristine A. Strom Nadia C. Venegas ILLUSTRATION David Alexovich Christine McCabe Thomas Spanos MEDIA ASSET MANAGEMENT Jeannine Deubel Kimberly L. Cleary Kurt Heintz Quanah Humphreys COPY Sylvia Wallace Jennifer F. Gierat Glenn Jenne Mary Kasprzak Thad King Larry Kowalski Joan Lackowski Dawn McHugh Julian Ronning Chrystal Schmit Sarah Waterman INFORMATION MANAGEMENT/ INDEXING Carmen-Maria Hetrea Edward Paul Moragne Marco Sampaolo Sheila Vasich Mansur G. Abdullah Keith DeWeese Catherine Keich Stephen Seddon EDITORIAL TECHNOLOGIES Steven Bosco Gavin Chiu Bruce Walters Mark Wiechec COMPOSITION TECHNOLOGY Mel Stagner MANUFACTURING Dennis Flaherty Kim Gerber INTERNATIONAL BUSINESS Leah Mansoor Isabella Saccà ENCYCLOPÆDIA BRITANNICA, INC. Jacob E. Safra, Chairman of the Board Jorge Aguilar-Cauz, President Michael Ross, Senior Vice President, Corporate Development Dale H. Hoiberg, Senior Vice President and Editor Marsha Mackenzie, Managing Editor and Director of Production © 2008 BY ENCYCLOPÆDIA BRITANNICA, INC. Cover photo (front and back): NASA; cover insert photo: © Myron Jay Dorf/Corbis International Standard Book Number: 978-1-59339-502-5 No part of this work may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher. BRITANNICA LEARNING LIBRARY: EXPLORING SPACE 2008 Britannica.com may be accessed on the Internet at http://www.britannica.com. (Trademark Reg. U.S. Pat. Off.) Printed in U.S.A. Exploring Space I N T R O D U C T I O N What do stars really look like? Could you live on Venus? Are aliens waiting for us in outer space? What did astronomers study hundreds of years ago? Exploring Space, you’ll discover In To help you on your journey, we’ve provided the following guideposts in Exploring Space : ■ Subject Tabs—The colored box in the upper corner of each right-hand answers to these questions page will quickly tell you the article subject. and many more. Through ■ Search Lights—Try these mini-quizzes before and after you read the pictures, articles, and fun article and see how much—and how quickly—you can learn. You can even facts, you’ll travel across time, visit outer space, meet fascinating people, and make this a game with a reading partner. (Answers are upside down at the bottom of one of the pages.) ■ Did You Know?—Check out these fun facts about the article subject. With these surprising “factoids,” you can entertain your friends, impress investigate strange and your teachers, and amaze your parents. wonderful things. ■ Picture Captions—Read the captions that go with the photos. They provide useful information about the article subject. ■ Vocabulary—New or difficult words are in bold type. You’ll find them explained in the Glossary at the end of the book. ■ Learn More!—Follow these pointers to related articles in the book. These articles are listed in the Table of Contents and appear on the Subject Tabs. Br ® ca itanni LEARNING L I B R A R Y Have a great trip! © 2008 Encyclopædia Britannica, Inc. © NASA/JPL/Caltech © 2008 Encyclopædia Britannica, Inc. Exploring Space TABLE OF CONTENTS INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 ASTRONOMY: Studying the Stars . . . . . . . . 6 UNIVERSE: Infinite Space . . . . . . . . . . . . . . 8 BIOGRAPHIES Nicolaus Copernicus: Student of the Sky . . . . . . . . . 44 Gravity: The Invisible Magnet . . . . . . . . . . . . . . . . . 10 Johannes Kepler: Stargazer . . . . . . . . . . . . . . . . . . . 46 Galaxies: Star Clusters . . . . . . . . . . . . . . . . . . . . . . 12 Sir Isaac Newton: An Apple, an Idea . . . . . . . . . . . . 48 Stars: Distant Fire. . . . . . . . . . . . . . . . . . . . . . . . . . 14 Albert Einstein: A Brilliant Wonderer . . . . . . . . . . . . 50 Planets: Wanderers in the Sky . . . . . . . . . . . . . . . . . 16 Subrahmanyan Chandrasekhar: Aryabhata: Ancient Mathematician-Astronomer. . . . 42 Asteroids: Minor Planets . . . . . . . . . . . . . . . . . . . . . 18 Discovering How Stars Grow. . . . . . . . . . . . . . . . . 52 Comets: Rocketing Masses with Fuzzy Tails . . . . . . 20 Sally Ride: First American Woman in Space . . . . . . 54 SOLAR SYSTEM: Family of the Sun . . . . 22 Mercury: The Planet Nearest to the Sun. . . . . . . . . . 24 SPACECRAFT: Exploring the New Frontier . . . . . . . . . . . . 56 Venus: A Morning and Evening Star. . . . . . . . . . . . . 26 Astronauts: Going Up in Space. . . . . . . . . . . . . . . . . 58 Moon: A Trip to the Moon. . . . . . . . . . . . . . . . . . . . . 28 Extraterrestrial Life: Life Beyond the Earth . . . . . . . 60 Mars: The Red Planet . . . . . . . . . . . . . . . . . . . . . . . 30 GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Jupiter: King of the Planets . . . . . . . . . . . . . . . . . . . 32 Saturn: The Ringed Planet . . . . . . . . . . . . . . . . . . . 34 Uranus: King George’s Star . . . . . . . . . . . . . . . . . . . 36 Neptune: The Eighth Planet . . . . . . . . . . . . . . . . . . . 38 Pluto: The Dwarf Planet. . . . . . . . . . . . . . . . . . . . . . 40 Br ® ca itanni LEARNING L I B R A R Y © 2008 Encyclopædia Britannica, Inc. SE A
T GH RCH LI Which of these things do astronomers study? - stars - planets - moons - astronauts - comets g n i St udy 6 © 2008 Encyclopædia Britannica, Inc. a r t s S e th ASTRONOMY KNOW? to DID YOkUes about eight minutethse Sunlight ta million miles from 93 travel the Earth. e th Sun to L ook at the sky. What do you see? If it’s day you’ll see the Sun. If it’s night you’ll see the Moon. And if the sky is clear you’ll see stars. In big cities you may see only a few hundred stars. But out in the country or on the ocean you’ll see many thousands. You may even see planets and, if you’re lucky, a comet. There are people who look at the sky for hours and hours, night after night. They study the stars, the planets, and other objects in the sky. These people are called “astronomers.” The word “astronomy” comes from the Greek for “star” and “arrangement.” Astronomers study the universe in many different ways. Some watch faraway objects. Others work in laboratories, where they look at samples of meteorites, rocks from the Moon, and space debris from other planets. Some try to make models of different objects people have studied. Not all astronomers get paid for the work they do. Some do it for a hobby. Such people are called “amateur astronomers.” How do astronomers study objects that are millions, even billions, of miles away? They use powerful telescopes that make things look large enough to be seen in detail. Some telescopes are small enough to be held in the hand. Others are as big as a school bus! Answer: They study all of these except for astronauts. © 2008 Encyclopædia Britannica, Inc. ★ LEARN MORE! READ THESE ARTICLES… COPERNICUS • SOLAR SYSTEM • UNIVERSE 7 Infinite Space T he universe is a vast expanse of space that contains all matter and energy, from the smallest particle to the biggest galaxy. It contains all the planets, the Sun, stars, asteroids, our Milky Way Galaxy, and all the other galaxies too. No one knows how big the universe is. Astronomers believe that it is still growing outward in every direction. How did it all begin? No one knows that for sure either. Most scientists believe that at first everything was one incredibly solid, heavy ball of matter. This ball exploded billions of years ago—and the universe was born. The moment of this explosion is called the “big bang.” It is from this moment that time began. After the explosion the early universe was small and extremely hot. As it cooled, it expanded and pieces spread out. Small pieces formed the basic SE A
T GH RCH LI If the universe is still growing, is it moving toward or away from the Earth? 8 © 2008 Encyclopædia Britannica, Inc. UNIVERSE elements hydrogen and helium. Other pieces began to join together, and objects began to form. Over billions of years the objects became galaxies, stars, and planets. This is still only a theory, an idea. But different parts of it have proved true over the years. Astronomers try to investigate the theory all the time. One way they do this is to use a “spectroscope.” A spectroscope measures the color of light coming from an object. Changes in the color indicate whether an object is moving away from or toward the Earth. Because of spectroscope readings scientists believe that the universe is still growing outward in every direction. LEARN MORE! READ THESE ARTICLES… GALAXIES • SOLAR SYSTEM • STARS KNOW? the DID YObUelieve that much of th ing Answer: Everything in the universe is moving away from everything else. You can see how this works if you put black dots on a balloon, blow it up, and watch the dots spread apart. © 2008 Encyclopædia Britannica, Inc. ★ f some Scientists e made o b y a m e is hidden univers atter.” Th m uman rk a d “ nce that h called ta s b u s a be mass may efore e never b v a h beings red. encounte 9