Understanding the Universe
128 Pages
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Understanding the Universe


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128 Pages


Accurate, detailed visual information is all defined in lay language to make it readily accessible to the non-expert. Definitions to scientific terms are given either in the explanation itself, or in the comprehensive glossary.



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Published 09 August 2012
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EAN13 9782764408919
Language English
Document size 60 MB

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Understanding The Universe
ISBN 2-7644-0017-9
9 782764 400173 QA INTERNATIONALUnderstanding
theUniversePublisher Jacques Fortin
Editorial Director François Fortin
Executive Editor Serge D’Amico
Art Director Marc Lalumière
Graphic Designer Anne Tremblay
Writers Nathalie Fredette
Claude Lafleur
Computer Graphic Artists Mamadou Togola
Alain Lemire
Hoang-Khanh Le
Ara Yazedjian
Mélanie Boivin
Jean-Yves Ahern
Michel Rouleau
Page Layout Lucie Mc Brearty
Véronique Boisvert
Geneviève Théroux Béliveau
Researchers Anne-Marie Villeneuve
Anne-Marie Brault
Astronomy Reviewer Louie Bernstein
Copy Editor Jane Broderick
Production Gaétan Forcillo
Guylaine Houle
Prepress Kien Tang
Karine Lévesque
Translation Käthe Roth
Canadian Cataloguing in Publication Data
Main entry under title:
The visual guide to Understanding the Universe
(The visual guides to knowledge)
Translation of: Comprendre l’Univers
Includes index
ISBN 2-7644-0891-9
1. Astronomy - Encyclopedias. 2. Cosmography - Encyclopedias. 3. Planets -
Encyclopedias. 4. Stars - Encyclopedias. 5. Outer space - Exploration -
Encyclopedias. 6. Astronomy - Observations - Encyclopedias. I. Series.
QB14.S4213 2007 520’.3 C99-941237-X
The Visual Guide to Understanding the Universe was created and produced by
QA International
e329, rue de la Commune Ouest, 3 étage
Montréal (Québec) H2Y 2E1 Canada
T 514.499.3000 F 514.499.3010
©2007 QA International. All rights reserved.
No part of this book may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying and recording, or by any
information storage and retrieval system, without written permission in writing from
the Publisher.
We acknowledge the financial support of the Government of Canada
through the Book Publishing Industry Development Program (BPIDP)
for our publishing activities.
Printed and bound in Canada.
10 9 8 7 6 5 4 3 2 1 04 03 02 01
46 Dwarf planets
45 Neptune
44 Uranus
43 Saturn
42 Jupiter
40 Comets
38 Meteorites
37 The asteroids
36 Mars
35 Lunar eclipses
34 Lunar phases
32 The Moon
30 The seasons
29 Astronomical coordinates
28 Geographic coordinates
26 Earth’s atmosphere 74 Active galaxies
24 The magnetosphere 73 Galactic clusters
22 The origin of Earth 72 The Local Group
21 Earth 70 The Milky Way
20 Venus 69 Classification of the galaxies
19 Mercury 68 The galaxies
6 | The solar system 17 | Planets and Satellites 47 | The Stars 66 | The Galaxies
8 The solar system 49 The origin of stars
10 Comparative table of the planets 50 Multiple stars
12 The Sun 51 Classification of stars
14 How the Sun evolved 52 Low-mass stars
16 Solar eclipses 54 Massive stars
56 Black holes
58 Star clusters
60 The constellations
62 The constellations of the Southern Hemisphere
64 The constellations of the Northern Hemisphere
119 Exploring small astral bodies
118 Ulysses
117 Cassini and Huygens
116 Galileo
115 Voyager
114 Pioneer 10 and 11
113 Magellan
83 Cosmic background radiation 110 Exploration of Mars
82 The Universe expands 108 Exploration of the Moon
80 The Big Bang 106 Space probes
78 The size of the Universe 104 Surrounding Earth
76 | Structure of the Universe 84 | Astronomical 102 | Space 120 | Glossary
observation Exploration 122 | Index
86 The electromagnetic spectrum
88 Telescopes
90 Astronomical observatories
92 A new generation of telescopes
94 The Hubble Space Telescope
96 Radio telescopes
98 Life elsewhere in the Universe
100 Extrasolar planets
5Although it seems incredibly big from our point of view, the solar system is infinitely small
on the scale of the universe. Nevertheless, studying it is invaluable for acquiring
knowledge of the cosmos as a whole. After all, our Sun, the fiery ball around which the planets orbit, is a star just
like any of the “astronomical” number of stars in the universe!The solar system
8 The solar system
Our little corner of the universe
10 Comparative table of the planets
Tour of the solar system
12 The Sun
A very ordinary star
14 How the Sun evolved
Our Sun: its birth and its fate
16 Solar eclipses
A spectacular disappearing actThe solar system
Nine planets circling the Sun
The solar system includes one star (the Sun), nine planets, about 60 natural
satellites orbiting the planets, thousands of asteroids (small rocky objects),
millions of comets (lumps of dust and frozen gas), billions of meteoroids, and
interplanetary dust and gas.
Our solar system is on the edge of the Milky Way, our galaxy. The Milky Way stretches over some 12 billion
billion (or 12 million million million) km. If we think of the Milky Way as a beach, our solar system is just a
grain of sand.
The giant planets farthest away from the Sun are gaseous globes (made mainly of hydrogen and helium),
which all have rings and a number of satellites.
Sun Jupiter Saturn
Pluto is the most distant planet from the
The Kuiper Belt, located beyondSun. It is also the smallest and coldest planet Neptune
Neptune’s orbit, is formed of objectsin the solar system, and is in a class by itself.
made of ice; it is similar to Pluto in
composition.THE ECLIPTIC
All planets revolve around the Sun on approximately the same plane of orbit, Pluto (17.2˚)
the ecliptic, which is defined as the plane of Earth’s orbit. The chart
below shows the inclination of the planets’ orbits; Pluto’s
orbit inclines the most sharply.
Earth (0˚) Jupiter (1.3˚) Mars (1.9˚) Venus (3.4˚)
Uranus (0.8˚) Neptune (1.8˚) Saturn (2.5˚) Mercury (7˚)
The solar systemE0
In general, a star (such as the Sun) is a heavenly body
that emits a great quantity of energy (light and heat).
A planet Q is a body that orbits a star and reflects
part of that energy; a natural satellite W (or moon)
revolves around a planet. All nine planets orbit
Sunaround the Sun in a counter-clockwise direction E.
Except for Venus and Uranus, they also rotate
counter-clockwise on their axis R.
Planets travel around the Sun in an elliptical
orbit – in other words, their path is slightly W0
oval. Only Mercury and Pluto have orbits that
are visibly oval.
elliptical orbit
In spite of the many objects of all sorts in the solar
system, it is almost empty. Most illustrations show
the planets close together, but there are in fact vast
empty spaces between them. The distances between
the outer planets are even greater.
The Oort Cloud, made up of trillions of comets,
orbits the solar system at a distance of about
4,500 billion kilometers.
The planets closest to the Sun are smaller and
very dense; they are telluric, or rocky.
The asteroid belt, which forms the border between
the inner and outer planets, is the region of the Venus
solar system where the most asteroids are found.
The solar systemComparative table
of the planets
Tour of the solar system
Mercury Venus Earth Mars
Diameter (km) 4,878 12,100 12,756 6,787
Average distance from the Sun
0.39 AU 0.72 AU 1 AU 1.52 AU(1 AU = 149,600,000 km)
Rotation period 58.6 days 243 days 23.9 h 24.6 h
Revolution period 87.9 days 224.7 days 365.2 days 686.9 days
Orbital inclination 7.0˚ 3.4˚ 0.0˚ 1.9˚
(relative to the ecliptic)
24Mass (relative to Earth) 0.056 0.82 1 (5.9 x 10 kg) 0.11
Number of known moons0 012
trace of hydrogen 96% CO ,3% nitrogen, 78% nitrogen, 21% 95% CO , 1.6% argon, 2 2Composition of atmosphere and helium 0.1% water oxygen, 1% argon 3% nitrogen
Moon Phobos
Mercury MarsEarth
The solar systemTHE OUTER PLANETS
Jupiter Saturn Uranus Neptune Pluto
142,984 120,536 51,108 49,538 2,350
5.2 AU 9.54 AU 19.19 AU 30.06 AU 39.44 AU
9.8 h 10.6 h 17.2 h 16 h 6.3 days
11.8 years 29.4 years 84 years 164.8 years 248.5 years
1.3˚ 2.5˚ 0.8˚ 1.8˚ 17.2˚
318 95 15 17 0.002
63 60 27 13 1
90% hydrogen, 10% 96% hydrogen, 3% 84% hydrogen, 14% 74% hydrogen, 25% methane and nitrogen
helium, traces of methane helium, 0.5% methane helium, 2% methane helium, 1% methane
Dione Neptune
The solar system