xviii Preface to the Second Edition
from the roversSpiritandOpportunityand new orbital ex-
ploration of the red planet. Galileo’s remarkable discovery
of evidence for subsurface oceans on the icy Galilean satel-
lites is treated fully in new chapters devoted to Europa and
to Ganymede and Callisto. New information from theDeep
Impactmission and theStardustsample return is included
as well. We continue to find out more and more about the
denizens of the most distant reaches of the solar system, and
have expanded the discussion of the Kuiper belt with a new
chapter on physical properties. The area of observational
techniques and instrumentation has been expanded to in-
clude chapters covering the X-ray portion of the spectrum,
new generation telescopes, and remote chemical analysis.
Finally, nothing exemplifies the dynamic character of
our knowledge than the area of extra-solar planets, which
completes the volume. In the first edition the chapter on
extra-solar planets contained a section entitled, “What is
a Planet?” which concluded with this: “The reader is cau-
tioned that these definitions are not uniformly accepted.”
The chapter included a table of nineteen objects cautiously
labeled “Discovered Substellar Companions.” As this work
goes to press, more than 200 extra-solar planets are known,
many in multi-planet systems, with more being discovered
every day. And at the 2006 General Assembly of the Inter-
national Astronomical Union, the question of the definition
of “planet” was still being hotly debated. The current IAU
definition is discussed in the introductory chapter by one
of us (PRW) and other views concerning the status of Pluto
may be found in the chapter on that body.
In addition to the energy and hard work of all of our au-
thors, this edition of the Encyclopedia is greatly enhanced
by the vision and talents of our friends at Academic Press.
Specifically, we wish to thank Jennifer Hel ́e, our Publishing
Editor, who oversaw the project and learned the hard truth
that herding scientists and herding cats are one and the
same thing. Jennifer was the task master who made us real-
ize that we could not just keep adding exciting new results
to the volume, but one day had to stop and actually publish
it. Francine Ribeau was our very able Marketing Manager
and Deena Burgess, our Publishing Services Manager in the
U.K., handled all of the last minute loose ends and made
certain that the book was published without a hitch yet on a
very tight schedule. Frank Cynar was our Publishing Editor
for the first edition and for the beginning of the second, as-
sisted by Gail Rice who was the Developmental Editor early
on for the second edition. At Techbooks, Frank Scott was
the Project Manager who oversaw all the final chapter and
figure submissions and proof checking. Finally, also at Tech-
books, was Carol Field, our Developmental Editor, simply
known as Fabulous Carol, who seemed to work 30-hour
days for more than a year to see the volume through to
fruition, while still finding time to get married in the midst
of it all. This Encyclopedia would not exist without the tire-
less efforts of all of these extremely talented and dedicated
individuals. To all of them we offer our eternal thanks.
Extensive use of color and new graphic designs have
made the Encyclopedia even more beautiful and enhanced
its readability while at the same time allowing the authors
to display their information more effectively. The Encyclo-
pedia you have before you is the result of all these efforts
and we sincerely hope you will enjoy reading it as much as
we enjoyed the process of compiling it.
Which brings us back to the quotation at the start of
the Preface. We sincerely hope that this edition of the
Encyclopedia will indeed also be out of date by the time
you read it. TheNew Horizonsspacecraft is on its way to
the Pluto/Charon system,MESSENGERis on its way to
Mercury,Rosettais en route to a rendezvous with periodic
comet Churyumov-Gerasimenko, new spacecraft are prob-
ing Venus and Mars, many nations are refocusing on explo-
ration of the Moon, plans are being laid to study the deep
interior of Jupiter and return to Europa, while the results
from the Saturn system, Titan and Enceladus, have sparked
a multitude of ideas for future exploration. We hope this
Encyclopedia will help you, the reader, appreciate and en-
joy this on-going process of discovery and change as much
as we do.Lucy-Ann McFadden
Paul R. Weissman
Torrence V. Johnson
November 1, 2006