大开眼界__Space

Open your eyes to a world of discovery Eye Wonder Eye Wonder First American Edition, 2001 01 02 03 04 05 10 9 8 7 6 5 4 3 2 1 Published in the United States by DK Publishing, Inc. 95 Madison Avenue New York, New York 10016 Copyright © 2001 Dorling Kindersley Limited All rights reserved under International and Pan-American Copyright Conventions. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyright owner. Published in Great Britain by Dorling Kindersley Limited. Library of Congress Cataloging-in-Publication Data Holland, Simon, 1955– Space / by Simon Holland.— 1st American ed. p. cm. -- (Eye Wonder) Includes index. ISBN 0-7894-7854-4 -- ISBN 0-7894-8182-0 (lib. bdg.) 1. Astronomy--Juvenile literature. [1. Outer Space. 2. Astronomy.] I. Title. II. Series. QB46 .H73 2001 520--dc21 2001017277 ISBN 0-7894-7854-4 Color reproduction by Colourscan, Singapore Printed and bound in Italy by L.E.G.O. See our complete catalog at www.dk.com Written and edited by Simon Holland Designed by Tanya Tween, Claire Penny, and Tory Gordon-Harris Publishing manager Mary Ling Managing art editor Rachael Foster US editors Gary Werner and Margaret Parrish Jacket design Chris Drew Picture researcher Jo Haddon Production Kate Oliver DTP designer Almudena Díaz Space consultant Carole Stott 4-5 Staring into space 6-7 Our place in space 8-9 A closer look 10-11 Journey to the Moon 12-13 Earth’s moon 14-15 The Sun 16-17 Family of the Sun 18-19 Mercury and friends 20-21 Sister Venus 22-23 The Red Planet 24-25 A rocky racetrack 26-27 King of the planets LONDON, NEW YORK, SYDNEY, DELHI, PARIS, MUNICH, and JOHANNESBURG Contents 28-29 Planet of the rings 30-31 Distant twins 32-33 Pluto and the comets 34-35 Secrets of the stars 36-37 The Milky Way 38-39 About the universe 40-41 Liftoff 42-43 Life in space 44-45 Our future in space 46-47 Space glossary 48 Index and acknowledgments IT’S QUIET UP THERE... When something makes a sound, the noise spreads out into the air around our ears. Our world is full of air, which is why we can hear lots of sounds – but there is no air in space. Even if we could take an entire orchestra into space and sit next to it, we would not hear any of the music – not even the drums! 4 Our nearest neighbor After the Sun has gone down, the Moon is the brightest thing in the sky. The Moon is the closest object to us in space, much closer to us than the Sun. Although it looks quite big in our sky, it is many times smaller than the Sun. What is space? Beyond our world there are many other objects. Some are colorful and massive, others distant and mysterious, but all of them are moving. In between, there are enormous, empty gaps that we call space. We also use the word “space” to refer to everything that lies outside our own world. Staring into space is something people do all the time. On a clear night, we are able to see bright objects in the sky. These objects are in space. Things in space look like tiny dots to us, because they are so far away, but most are actually extremely large. Staring into space 5 Why is it so dark in space? Light is something that travels through space. Day and night, all the light we receive comes from the stars. We can only see light when it hits an object and bounces off it. Our planet (Earth) is nice and bright because light can bounce off tiny specks, called “particles,” in the atmosphere around it (see page 7). Space is empty, so there are no particles for the light to hit. Gazing at stars We live on a planet, and most of the bright dots in our night sky are stars. The nearest star to us is the big, yellow-orange ball we can see during the day – the Sun. It is much bigger than a planet like ours. The Sun looks enormous in our sky because it is so much closer to us than other stars. Up in space there are gigantic areas of nothingness. This satellite is an object in space that is lit up by light from the Sun. 6 Nearly three quarters of the Earth’s surface is covered in water. Why is the sky blue? Sunlight is made up of different colors. When the light reaches Earth its different colors bounce off tiny particles of dust and water vapor in the atmosphere. Because of this, the colors get scattered all around in the sky. The blue parts of the light are scattered more than the others, which is why our sky looks blue during the day. Planet Earth turns and travels in space, but here on the ground we cannot feel it moving. There is a giant ball of solid metal at the center of our planet. This is the Earth’s “core.” Earth spins around as it travels. It takes just under 23 hours and 56 minutes for it to make one full turn. 7 Our place in space AN INVISIBLE FORCE If somebody dropped an object, it would fall down toward their feet. This is because everything on Earth is held in place by a special, invisible force called gravity. Earth’s gravity pulls everything down toward the ground – so without this force we would all float up into the sky, and our oceans would spill into space! Earth is not the only place in space where this force is at work – gravity exists everywhere in the universe. Lively planet Earth is the only planet we know of where living things can survive. Many different kinds of plants and animals live on this planet – so many, in fact, that nobody has counted them all. Plants and animals need water and a gas called oxygen to live. There is plenty of both on planet Earth. Our home in space is called Earth. It is a planet, a huge world that moves around in space. Planet Earth is largely made of rock, but most of the surface is covered in water – our seas and oceans. Special blanket Our planet is covered in a thick layer of gases called the atmosphere. We cannot feel this layer, but it contains the air that we breathe and the clouds that give us rain. It is important because it lets in all the light and heat we need from the Sun, but keeps out all the harmful things in the Sun’s rays. The outer part of our atmosphere is where Earth ends and space begins… Luckily, the conditions on Earth are just right for living things. It is easy for us to see familiar objects in the night sky, such as the stars – but space is a big place, so there is always more to discover. People practice astronomy to get a closer, clearer look at things in space, or simply to try to see as far away as possible. Exciting new finds are being made all the time. A closer look The Great Bear The Centaur The biggest and most powerful telescopes are kept in large buildings called observatories. The astronomer’s tool There is a special instrument, called a telescope, which helps astronomers to see distant objects in space. It works like a very strong magnifying glass, making objects look much bigger and clearer to the eye. Telescopes come in different strengths and sizes. Eyes in the sky Earth has a thick atmosphere, which gets in the way when astronomers are trying to see objects more clearly. To get a better view of things, some large telescopes are based high up on mountains – where the atmosphere is thinner and clearer – or even in space (on board specially made satellites). Space patterns The first astronomers made patterns out of the stars in our sky – like connect-the-dot pictures – to help them tell the stars apart. These patterns are called constellations. Each one has its own name. The Hubble Space Telescope (HST) WOODEN WONDERS The first telescopes were made around 400 years ago. They were not as powerful and accurate as today’s equipment, but helped astronomers to make important discoveries. In 1781, an English astronomer called William Herschel discovered the planet Uranus using a wooden telescope. Today, astronomers do not even have to look into the sky themselves, because their telescopes have special computers that can collect the information for them. Antenna Dish Radio telescopes Some telescopes work by tuning in to radio waves from space. The large dish picks up the radio waves and focuses them onto the antenna, which then turns them into electrical signals. A computer uses these signals to build up pictures of objects in space. Journey to the Moon Apart from planet Earth, the Moon is the only place in space where human beings have walked. There have been six successful missions to put people on the Moon, all between 1969 and 1972. A total of 12 astronauts have explored the surface. Rocket ride In 1969, three American astronauts set off from Earth in a space capsule called Apollo 11. The capsule was launched into space by Saturn V, a powerful rocket. In space, the Apollo craft separated from the rocket and made its way toward the Moon. When it reached the Moon, a special lunar landing module, called the Eagle, dropped down onto the surface with two astronauts inside. 10 A view seen by few The crew of the Apollo 8 spacecraft were the first people to see an “Earthrise” – Earth rising above the lunar landscape (above) – when they flew around the Moon in 1968. Earth’s daytime side is lit up by the Sun, while its nighttime side is lost in darkness. A rocket journey to the Moon and back takes about six days. This is what our planet looks like from the Moon. Launch of the Saturn V rocket, July 1969. With no wind to remove them, an astronaut’s footprints could stay in the Moon’s soil for millions of years. Moon walking The Moon’s gravity is much weaker than Earth’s. This means that objects on the Moon are not pulled down toward the ground as strongly. This makes walking difficult. In fact, the easiest way to get about is by hopping like a kangaroo! A Moon astronaut could jump almost six times as high as a person on Earth. Back with a splash The Apollo 11 command module, Columbia, made a safe return to Earth by falling into the Pacific Ocean. This is called a splashdown. After the module had come back into Earth’s atmosphere, three parachutes opened out to slow it down on its way toward the ocean. Moon machine The first men to walk on the Moon were Neil Armstrong and Edwin “Buzz” Aldrin. This is the Eagle craft which took them down onto the surface – and later, back to Apollo. Astronauts on the Moon can only talk to each other by using the special radios inside their helmets. 11 The backpack contains a supply of air. The lower part of the craft was left behind when the Eagle left the Moon. A special visor protects the astronaut’s eyes from the Sun’s bright rays. Armstrong and Aldrin spent nearly a whole day on the surface. Meanwhile, Michael Collins orbited the Moon inside the Apollo 11 command module. The Moon is the largest, brightest object in our night sky. But, unlike the Sun, it has no light of its own to give out. It looks so bright because its surface is lit up by the Sun. There is no air, weather, or life of any kind on the Moon. Earth’s moon This picture of the Moon was taken by the Apollo 11 spacecraft as it flew back to Earth. These dark patches are called “seas,” but they do not contain any water. Near side Moving around The Moon is always traveling in space – on a path around our planet. This journey is called an orbit. As it travels, it also turns like a spinning top. It spins exactly once during each orbit of the Earth. 12 Our moon is like a nighttime lantern in the sky. This is where the Eagle module landed. Data zone 13 Crescent First Quarter Full MoonGibbous Far side A secret side The same side of the Moon faces our planet all the time. This means that there is one side that we can never see from Earth. The far side (right) is very different from the near side (left). There are fewer dark “seas” but many more craters. When it faces the Sun, the Moon’s rocky surface can get too scorching hot to touch. These bowl-shaped hollows on the surface are called craters. Very old ice The Lunar Prospector space probe (above) discovered some frozen water near to the Moon’s north and south poles. This ice is probably left over from comets that crashed into the Moon’s surface a long time ago. Does the Moon change shape? As the Moon moves around the Earth, we see different amounts of its sunlit side. This is why the Moon seems to change shape. These changes are called the phases of the Moon. The first phase is the new moon, when it cannot be seen at all. Then we see the crescent, the first quarter, the gibbous, and finally the full moon. 13 New Moon • The Moon travels around the Earth in just over 27 days. • A Russian space probe called Luna 3 was the first spacecraft to take pictures of the far side of the Moon. 14 The Sun is the nearest star to Earth. Like all stars, it is an enormous ball of burning, scorching hot gas. It is a fiery monster, but the Sun is what makes all life on Earth possible. Sunset light show It is dangerous to look directly into the Sun because it is so bright. One way of enjoying our local star more safely is by watching the sky at sunset. As the Sun sets, we can see more of the colors in its light – and the beautiful patterns they form. The Sun This probe has been exploring the unknown regions of space above the Sun’s north and south poles. The Ulysses space probe Fantastic fireworks The Sun’s center, or “core,” is like an enormous furnace where gases burn. At the surface, gas leaps up in bright bursts called solar flares. Often, these blasts of really hot gas arch up high above the surface to form “solar prominences” – great big, fiery loops. A loop-shaped prominence leaping out. 15 An eclipse of the Sun A solar eclipse takes place when the Moon passes between the Sun and Earth. When this happens, the Moon stops some of the Sun’s light from reaching us and casts a shadow on parts of our planet. At these places on Earth, day turns to night for a short time. It takes eight minutes for the Sun’s light to reach planet Earth. ANCIENT ASTRONAUTS There is a Greek myth about an inventor called Daedalus who made wings for himself and his son, Icarus, out of feathers and beeswax. When Icarus used the wings he flew too close to the Sun. The wax melted and he fell into the sea. The center of the Sun is like a giant bomb that never stops exploding. Storms on the surface send “blastwaves” into space. These can damage satellites, and even cause power outages on Earth! 16 The Sun is at the center of a neighborhood of planets called the solar system. Earth is one of nine planets that each make a special journey, called an orbit, around the Sun. Family of the Sun Sun Mercury Venus Earth Mars Jupiter Asteroid Belt Sun and planets not to scale All the planets travel in the same direction around the Sun The “inner planets” ar e made of rock s and meta ls Each plane t spins on a tilt Jupiter takes nearly 12 Earth years to orbit the Sun. A planetary year A planet’s year is the time it takes to make one full journey (orbit) around the Sun. The further a planet is from the Sun, the longer its orbit will be. Planets with the biggest orbits have the longest years. 17 Saturn Uranus Neptune PlutoPluto has the longest path around the Sun. ...but at different speeds. ...the “ outer plane ts” a re fa t, ga ssy gia nt s. ...but so me tilt more than other s. Saturn has at least 22 moons, and astronomers are always looking for more. Planets and moons A moon is a large, rocky object in space that orbits a planet. Moons come in a variety of sizes, but most look like small planets. Apart from Mercury and Venus, all the planets have one or more moons. Saturn and Uranus have more than 20 each! A Neptune year is the same as 165 Earth years. • The planets of the solar system are held in this arrangement by gravity. The Sun has the strongest gravity of all – so all the planets are forced to keep to their paths around it. Gravity is also what keeps a moon in orbit around its planet. • Mercury, Venus, Earth, and Mars make up a group called the “inner planets.” • Jupiter, Saturn, Uranus, Neptune, and Pluto are the “outer planets.” • The planets nearest to the Sun travel much faster than those that are farther away. Data zone SPINNING TOPS All the planets spin, or “rotate,” as they travel in their orbits around the Sun – but each one spins at a different speed. Even though it is the largest planet in the solar system, Jupiter turns the fastest. It makes one full rotation in less than 10 hours. Earth rotates once every 23.93 hours. This is Callisto, Jupiter’s second largest moon. It is the same size as planet Mercury. 18 If people moved to Mercury, they would be four times as many years old! Hot planet, cold planet... Mercury is scorching hot during the day, when temperatures are four or five times greater than the hottest places on Earth. But its thin atmosphere is not able to hold on to any heat from the Sun – so at night, Mercury quickly plunges into a deep freeze! 19 Too hot for humans Venus has a thick atmosphere that hides the surface from view. It works like an enormous winter blanket, trapping all the heat from the Sun. Because of this, Venus is the hottest planet in the solar system. SPACE RACER It takes just 88 Earth days for Mercury to complete its journey around the Sun – so it has the shortest year in the solar system. It is also the fastest-moving planet, which is how it got its name. In Roman mythology, “Mercury” was the name of the swift-footed messenger of the gods. Mercury and friends Th eE ar th ’s at m os ph er e i s t hic k enough to protect it from m ostasteroids. Today, the Mariner 10 space probe is still in orbit around the Sun. The days on Mars are almost the same length as those on Earth, but the seasons are twice as long. Rivers once flowed on the surface of Mars. Mercury, Venus, Earth, and Mars are known as the “inner planets” because they are the nearest to the Sun. These globes are made up of the same kind of materials – mainly rocks and metals – and have a solid outer surface called a crust. Lonely explorer The US Mariner 10 probe is the only spacecraft ever to have visited Mercury. It set off in 1973 to help make a map of the planet’s surface. Collision course Mariner 10 discovered that Mercury is covered in large dents and hollows called craters. These were caused by rocky objects in space, called asteroids, which crashed into the surface of Mercury. Venus is the closest planet to Earth. Some call it our “twin sister,” because it is almost the same size and is made up of the same kinds of rocks and metals as Earth. But it is not a good home for humans. This picture of the landscape on Venus was made by a computer, using information from the Magellan spacecraft. There are no rivers, seas, or oceans on the surface of Venus. • Planet Venus is named after the Roman goddess of love. • The sky is orange on this planet, and it is always cloudy. • The atmosphere on Venus is like a pressure cooker. Visitors would shrivel up in seconds and roast like potatoes! Data zone 20 Sister Venus Poisonous planet Venus has a cloudy, swirling atmosphere – like planet Earth has – but Venus’s is burning hot and poisonous. The yellow clouds in the sky are full of a harmful acid. If it rained, it would burn our skin. Stormy winds blow the clouds around the planet at high speeds. THE LONGEST DAYS IN SPACE? On Earth, there are 24 hours in a day and 365 days in a year. A Venus year is shorter than ours – 225 of our Earth days. But the really amazing thing about Venus is the length of its days, which last for 243 Earth days. This means that a Venus day is actually longer than a Venus year! 21