文档介绍：LEARN & EXPLORE
New Views of the
Solar System
®
Compton’s by Britannica
CHICAGO LONDON NEW DELHI PARIS SEOUL SYDNEY TAIPEI TOKYO
Learn & Explore series
New Views of the Solar System
Compton’s by Britannica
Copyright© 2009 by Encyclopædia Britannica, Inc.
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No part of this work may be reproduced or utilized in any form or by any means, electronic or
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Library of Congress Control Number: 2007908762
International Standard Book Number: 978-1-61535-327-9
Britannica may be accessed at the .
Front cover (top): Magellan spacecraft, NASA/JPL
Front and back cover (center): illustration of the eight s, NASA/Lunar and ary Laboratory
Front cover (bottom): the sun, SOHO/ESA/NASA
Back cover (top): NASA
Back cover and title page (left to right): Saturn, NASA/The Hubble Heritage Team; solar prominence, TRACE/NASA;
Saturn’s moon Rhea, NASA; artist’s concept of the Mars Exploration Rover, NASA/JPL/California
Institute of Technology
iii
EDITOR’S PREFACE “The eight chief s, in the order of their distance from the sun, are
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.” That
quote is taken from the 1929 edition pton’s Encyclopedia, prior to the
discovery of Pluto. . astronomer Percival Lowell had predicted the
existence of a beyond the orbit of Neptune. This initiated the search
that ended in Pluto’s discovery by Clyde Tombaugh at Lowell Observatory at
Flagstaff, Ariz., on Feb. 18, 1930. For the next 76 years Pluto was considered
our solar system’s ninth .
There is a popular saying that goes, “everything old is new again.” In August
2006 the International Astronomical Union, aniz