Planetary science

The SOHO and Cluster missions form a single ESA cornerstone. Yet they observe verydifferentregionsinoursolarsystem:thesolaratmosphereononehandandthe Earth’s magnetosphere on the other. At the same time the Ulysses mission provides observations in the third dimension of the heliosphere, and many others add to the picture from the Lagrangian point L1 to the edge of the heliosphere. It was our aim to tie these observations together in addressing the topic of Solar Dynamics and its Effects on the Heliosphere and Earth with a workshop at the International Space Science Institute (ISSI), under the auspices of the International Living With a Star (ILWS) program. It started out with an assessment and description of the reasons for solar dynamics and how it couples into the heliosphere. The three subsequent sections were each devoted to following one chain of events from the Sun all the way to the Earth’s magnetosphere and ionosphere: The normal solar wind chain, the chain associated with coronal mass ejections, and the solar energetic particles chain. The ?nal section was devoted to common physical processes occurring both at the Sun and in the magnetosphere such as reconnection, shock acceleration, dipolarisation of magnetic ?eld, and others. This volume is the result of an ISSI Workshop held in April 2005. An international group of about forty experimenters, ground-based observers, and theoreticians was invited to present and debate their data, models, and theories in an informal setting.
Starting in 1995 numerical modeling of the Earth’s dynamo has ourished with remarkable success. Direct numerical simulation of convection-driven MHD- ow in a rotating spherical shell show magnetic elds that resemble the geomagnetic eld in many respects: they are dominated by the axial dipole of approximately the right strength, they show spatial power spectra similar to that of Earth, and the magnetic eld morphology and the temporal var- tion of the eld resembles that of the geomagnetic eld (Christensen and Wicht 2007). Some models show stochastic dipole reversals whose details agree with what has been inferred from paleomagnetic data (Glatzmaier and Roberts 1995; Kutzner and Christensen 2002; Wicht 2005). While these models represent direct numerical simulations of the fundamental MHD equations without parameterized induction effects, they do not match actual pla- tary conditions in a number of respects. Speci cally, they rotate too slowly, are much less turbulent, and use a viscosity and thermal diffusivity that is far too large in comparison to magnetic diffusivity. Because of these discrepancies, the success of geodynamo models may seem surprising. In order to better understand the extent to which the models are applicable to planetary dynamos, scaling laws that relate basic properties of the dynamo to the fundamental control parameters play an important role. In recent years rst attempts have been made to derive such scaling laws from a set of numerical simulations that span the accessible parameter space (Christensen and Tilgner 2004; Christensen and Aubert 2006).
This book is one of two volumes meant to capture, to the extent practical, the scienti?c legacy of the Cassini-Huygens prime mission, a landmark in the history of planetary exploration. As the most ambitious and interdisciplinary planetary exploration mission ?own to date, it has extended our knowledge of the Saturn system to levels of detail at least an order of magnitude beyond that gained from all previous missions to Saturn. Nestled in the brilliant light of the new and deep understanding of the Saturn planetary system is the shiny nugget that is the spectacularly successful collaboration of individuals, - ganizations and governments in the achievement of Cassini-Huygens. In some ways the pa- nershipsformedandlessonslearnedmaybethemost enduringlegacyofCassini-Huygens.The broad, international coalition that is Cassini-Huygens is now conducting the Cassini Equinox Mission and planning the Cassini Solstice Mission, and in a major expansion of those fruitful efforts, has extended the collaboration to the study of new ?agship missions to both Jupiter and Saturn. Such ventures have and will continue to enrich us all, and evoke a very optimistic vision of the future of international collaboration in planetary exploration. The two volumes in the series Saturn from Cassini-Huygens and Titan from Cassini- Huygens are the direct products of the efforts of over 200 authors and co-authors. Though each book has a different set of three editors, the group of six editors for the two volumes has worked together through every step of the process to ensure that these two volumes are a set.
‘Incoming Asteroid!’ is based on a project within ASTRA (the Association in Scotland to Research into Astronautics) to provide scientific answers to the question – what would we do if we knew there was going to be an asteroid impact in ten years’ time or less?
Clearly there are many things humanity can do nothing about, for example an unseen object traveling towards us so fast that we have no time to prepare, or an object so large it may be unstoppable. A realistic hazard model was decided upon, and the scenario developed from that: an incoming object about 1 kilometer in diameter, in an orbit ranging from the outer rim of the Asteroid Belt to within that of Earth’s.
Three basic possibilities are considered in this book. The first is the deflection of the asteroid, using remote probes along with a number of possible technologies to change the asteroid’s course. Second is the attempt of a manned mission, in order to plant a propulsion system on the asteroid to push it into a different orbit. Third is the nuclear option, a last-ditch attempt to break up and then disperse the asteroid using nuclear weapons. (A rather impractical combination of these second and third options were used as the plot of the popular 1998 Bruce Willis feature film, Armageddon.)
Although the cost of developing the technology needed to protect the Earth would be substantial, there would certainly be spin-off benefits. These could eventually result in practical small-scale atomic energy sources, new propulsion systems that could make extraterrestrial mining within the solar system a possibility, and other as-yet unforeseen benefits.

And finally, Incoming Asteroid! considers the political implications - how governments across the world should best react to the threat with a view to minimizing loss of life, and in the weeks running up to the possible impact, preventing panic in the population.

Ever since the Montgolfier's hot air balloon carried a chicken, a goat, and a duck into the Parisian skies, scientists have dreamed of contraptions to explore the atmosphere. With the advent of the space age, new airborne inventions were needed. From the Soviet Venus balloons to advanced studies of blimps and airplanes for use in Mars' and Titan's atmospheres, Drifting on Alien Winds surveys the many creative and often wacky ideas astronautical engineers and space scientists have had for exploring alien skies. Through historical photographs and stunning original paintings by the author, readers also explore the weather on various planets and moons, from the simmering acid-laden winds of Venus to the liquid methane-soaked skies of Titan.

Louis Friedman of the Planetary Society and Jacques Blamont of CNES (both involved in Mars and Venus balloon projects) are both interviewed, along with Victor Kerzhanovich of NASA's Jet Propulsion Laboratory (planetary balloon systems), Julian Nott (balloonist adventurer and Titan balloon enthusiast), Ralph Lorenz (John Hopkins University's Applied Physics Lab, team member of the proposed Montgolfier balloon on NASA's flagship mission to Titan), Lockheed Martin's Ben Clark (early atmospheric probe designer), Joe Palaia (UAV tests to Devon Island, Canadian Arctic), Joel Levine, Langley Research Center's principal investigator for the Mars ARES (Aerial Regional Environmental Survey), and Andrew Ingersoll, planetary atmospheres expert at California Institute of Technology, among others.

Information collected by satellites recently sent by the USA, the European Space Agency, Japan, Germany, the United Kingdom, and Russia to monitor the Sun has changed our knowledge and understanding of the Sun, particularly its effect on Earth. This book presents these findings in a way that will be welcomed by amateur astronomers, students, educators and anyone interested in the Sun. Enhanced by many colour photographs, the book combines newly acquired scientific understanding with detailed descriptions of features visible on the Sun’s surface and in its atmosphere.

In the past, observing the Sun has been left to academics with specialised instruments, since solar observation has been unsafe because of the risk of eye damage. This book explains how amateur astronomers can safely observe the various solar phenomena using special hydrogen-alpha telescopes that are not too expensive. Amateurs can now make a positive contribution to science by monitoring the Sun as professionals do.

Amateurs can also access the solar images taken by satellites via the internet. This book helps readers interpret and understand what these images are showing about the Sun, including the latest 3D images. Solar observers will enjoy comparing their own solar telescope observations with those produced by space probes such as SDO, SOHO, Hinode and STEREO, and further enjoy learning about transits, eclipses, and space weather and how the Sun compares to other stars in the universe.

The main purpose of this book is to present some of the fascinating solar phenomena in their full splendor to readers through a variety of illustrations, photographs and easy to understand text.p/p

When in 1981 Louis and Walter Alvarez, the father and son team, unearthed a tell-tale Iridium-rich sedimentary horizon at the 65 million years-old Cretaceous-Tertiary boundary at Gubbio, Italy, their find heralded a paradigm shift in the study of terrestrial evolution. Since the 1980s the discovery and study of asteroid impact ejecta in the oldest well-preserved terrains of Western Australia and South Africa, by Don Lowe, Gary Byerly, Bruce Simonson, Scott Hassler, the author and others, and the documentation of new exposed and buried impact structures in several continents, have led to a resurgence of the idea of the catastrophism theory of Cuvier, previously largely supplanted by the uniformitarian theory of Hutton and Lyell. Several mass extinction of species events are known to have occurred in temporal proximity to large asteroid impacts, global volcanic eruptions and continental splitting. Likely links are observed between asteroid clusters and the 580 Ma acritarch radiation, end-Devonian extinction, end-Triassic extinction and end-Jurassic extinction. New discoveries of ~3.5 – 3.2 Ga-old impact fallout units in South Africa have led Don Lowe and Gary Byerly to propose a protracted prolongation of the Late Heavy Bombardment (~3.95-3.85 Ga) in the Earth-Moon system. Given the difficulty in identifying asteroid impact ejecta units and buried impact structures, it is likely new discoveries of impact signatures are in store, which would further profoundly alter models of terrestrial evolution..
Martian Outpost provides a detailed insight into the various technologies, mission architectures, medical requirements, and training needed to send humans to Mars. It focuses on mission objectives and benefits, and the risks and complexities that are compounded when linked to an overall planet exploration program involving several expeditions and setting up a permanent presence on the surface.

The first section provides the background to sending a human mission to Mars. Analogies are made with early polar exploration and the expeditions of Shackleton, Amundsen, and Mawson. The interplanetary plans of the European Space Agency, NASA, and Russia are examined, including the possibility of one or more nations joining forces to send humans to Mars. Current mission architectures, such as NASA’s Constellation, ESA’s Aurora, and Ross Tierney’s DIRECT, are described and evaluated.

The next section looks at how humans will get to the Red Planet, beginning with the preparation of the crew. The author examines the various analogues to understand the problems Mars-bound astronauts will face. Additional chapters describe the transportation hardware necessary to launch 4-6 astronauts on an interplanetary trajectory to Mars, including the cutting edge engineering and design of life support systems required to protect crews for more than a year from the lethal radiation encountered in deep space. NASA’s current plan is to use standard chemical propulsion technology, but eventually Mars crews will take advantage of advanced propulsion concepts, such as the Variable Specific Impulse Magnetoplasma Rocket, ion drives and nuclear propulsion.

The interplanetary options for reaching Mars, as well as the major propulsive maneuvers required and the trajectories and energy requirements for manned and unmanned payloads, are reviewed . Another chapter addresses the daunting medical problems and available countermeasures for humans embarking on a mission to Mars: the insidious effects of radiation on the human body and the deleterious consequences of bone and muscle deconditioning. Crew selection will be considered, bearing in mind the strong possibility that they may not be able to return to Earth. Still another chapter describes the guidance, navigation, and control system architecture, as well as the lander design requirements and crew tasks and responsibilities required to touch down on the Red Planet.

Section 3 looks at the surface mission architectures. Seedhouse describes such problems as radiation, extreme temperatures, and construction challenges that will be encountered by colonists. He examines proposed concepts for transporting cargo and astronauts long distances across the Martian surface using magnetic levitation systems, permanent rail systems, and flying vehicles. In the penultimate chapter of the book, the author explains an adaptable and mobile exploration architecture that will enable long-term human exploration of Mars, perhaps making it the next space-based tourist location.

This volume gives an integrated summary of the science related to the four giant planets in our solar system. It is the result of an ISSI workshop on "A comparative study of the outer planets before the exploration of Saturn by Cassini-Huygens" which was held at ISSI in Bern on January 12-16, 2004. Representatives of several scientific communities, such as planetary scientists, astronomers, space physicists, chemists and astrobiologists have met with the aim to review the knowledge on four major themes: (1) the study of the formation and evolution processes of the outer planets and their satellites, beginning with the formation of compounds and planetesimals in the solar nebula, and the subsequent evolution of the interiors of the outer planets, (2) a comparative study of the atmospheres of the outer planets and Titan, (3) the study of the planetary magnetospheres and their interactions with the solar wind, and (4) the formation and properties of satellites and rings, including their interiors, surfaces, and their interaction with the solar wind and the magnetospheres of the outer planets. Beyond these topics, the implications for the prebiotic chemical evolution on Europa and Titan are reviewed.

The volume is intended to provide active researchers in the fields of planetary and solar system science, space plasma physics, and astrobiology with an up-to-date status report on the topic, and also to serve graduate students with introductory material into the field. At the time of publication of this book, the study of the outer planets is particularly motivated by the fact that the Saturn system is being investigated by the Cassini-Huygens mission.

Given the fundamental importance of and universal interest in whether extraterrestrial life has developed or could eventually develop in our solar system and beyond, it is vital that an examination of planetary habitability go beyond simple assumptions such as, "Where there is water, there is life". This book has resulted from a workshop at the International Space Science Institute (ISSI) in Bern, Switzerland which brought together planetary geologists, geophysicists, atmospheric scientists and biologists to discuss the multi-faceted problem of how the habitability of a planet co-evolves with the geology of the surface and interior, the atmosphere, and the magnetosphere.

Each of the six chapters have been written by authors with a range of expertise so that each chapter is itself multi-disciplinary, comprehensive, and accessible to scientists in all disciplines. These chapters delve into what life needs to exist and ultimately to thrive, the early environments of the young terrestrial planets, the role of volatiles in habitability, currently habitable (but possibly not inhabited) geologic environments, the connection between a planet’s inner workings and the habitability of its surface, and the effects on planetary atmospheres of solar evolution and the presence or absence of a magnetosphere.

This book serves as an ideal reference for those planning missions that will hunt for biomarkers (especially on Mars), for biologists and geoscientists seeking the other side of the story, and for researchers and upper level students interested in an in-depth review of the geologic evolution of terrestrial planets, from their cores to their magnetospheres, and how that evolution shapes the habitability of the planetary surface.

With current technology, a voyage to Mars and back will take three

years. That’s a lot of time for things to go wrong. But sooner or later

a commercial enterprise will commit itself to sending humans to Mars.

How will the astronauts survive? Some things to consider are:

ith current technology, a voyage to Mars and back will take three

years. That’s a lot of time for things to go wrong. But sooner or later

a commercial enterprise will commit itself to sending humans to Mars.

How will the astronauts survive? Some things to consider are:

• Who decides what medical resources are used for whom?

Who decides what medical resources are used for whom?

• What is the relative weight of mission success and the health of the

crew?

What is the relative weight of mission success and the health of the

crew?

• Do we allow crewmembers to sacrifi ce their lives for the good of the

mission?

Do we allow crewmembers to sacrifi ce their lives for the good of the

mission?

• And what if a crewmember does perish? Do we store the body for

return to Earth or give the member a burial in space?

Questions like these, and hundreds of others, have been explored by

science fi ction, but scant attention has been paid by those designing

missions. Fortunately, the experience gained in polar exploration more

than 100 years ago provides crews and mission planners with a framework

to deal with contingencies and it is this that forms the core of this book.

Why the parallels between polar and space exploration? Because polar

exploration offers a better analogy for a Mars mission today than those

invoked by the space community. Although astronauts are routinely

compared to Lewis and Clark, Mars-bound astronauts will be closer in their

roles to polar explorers. And, as much as space has been described as a

New Frontier, Mars bears greater similarity to the polar regions, which is

why so much can be learned from those who ventured there.

And what if a crewmember does perish? Do we store the body forreturn to Earth or give the member a burial in space?

Questions like these, and hundreds of others, have been explored by

science fi ction, but scant attention has been paid by those designing

missions. Fortunately, the experience gained in polar exploration more

than 100 years ago provides crews and mission planners with a framework

to deal with contingencies and it is this that forms the core of this book.

Why the parallels between polar and space exploration? Because polar

exploration offers a better analogy for a Mars mission today than those

invoked by the space community. Although astronauts are routinely

compared to Lewis and Clark, Mars-bound astronauts will be closer in their

roles to polar explorers. And, as much as space has been described as a

New Frontier, Mars bears greater similarity to the polar regions, which is

why so much can be learned from those who ventured there.

This book provides an up-to-date interdisciplinary geoscience-focused overview of solid solar system bodies and their evolution, based on the comparative description of processes acting on them.

Planetary research today is a strongly multidisciplinary endeavor with efforts coming from engineering and natural sciences. Key focal areas of study are the solid surfaces found in our Solar System. Some have a direct interaction with the interplanetary medium and others have dynamic atmospheres. In any of those cases, the geological records of those surfaces (and sub-surfaces) are key to understanding the Solar System as a whole: its evolution and the planetary perspective of our own planet.

This book has a modular structure and is divided into 4 sections comprising 15 chapters in total. Each section builds upon the previous one but is also self-standing. The sections are:

  • Methods and tools
  • Processes and Sources
  • Integration and Geological Syntheses
  • Frontiers

The latter covers the far-reaching broad topics of exobiology, early life, extreme environments and planetary resources, all areas where major advancements are expected in the forthcoming decades and both key to human exploration of the Solar System.

The target readership includes advanced undergraduate students in geoscience-related topics with no specific planetary science knowledge; undergraduates in other natural science domains (e.g. physics, astronomy, biology or chemistry); graduates in engineering and space systems design who want to complement their knowledge in planetary science.

The authors’ backgrounds span a broad range of topics and disciplines: rooted in Earth geoscience, their expertise covers remote sensing and cartography, field mapping, impact cratering, volcanology and tectonics, sedimentology and stratigraphy exobiology and life in extreme environments, planetary resources and mining. Several generations of planetary scientists are cooperating to provide a modern view on a discipline developed from Earth during and through Space exploration.


Continuum radio emission and fine structure (in particular millisecond spikes) have recently raised interest as diagnostic tools for the interpretation of energy release and particle acceleration in flares. In the circles of the European solar radio astronomers, loosely organized in CESRA, the idea of a workshop came up intended for active observers of the impulsive phase of flares in radio and associated emissions. The scientific organizing committee included A.D. Benz (chairman), A. Magun, M. Pick, G. Trottet, and P. Zlobec. The workshop was held on May 27-31, 1985 in the castle of Duino near Trieste, Italy. The meeting intended to find a common terminology, to compare radio observations with measurements in other emissions and to confront observations with theoretical concepts. We have achieved a representative summary on the current status of the field and a clear perspective for the next cycle. This volume contains the reviews and a selection of contributions and extended abstracts of papers presented at the workshop. I wish to thank the local organizers, in particular A. Abrami, M. Comari, F. Depolli, L. Fornasari, M. Messerotti (chairman), M. Nonino, and P. Zlobec. Financial support was graciously provided by the Italian Research Council (CNR). Most of all, however, I would like to express my thankfulness to our host, His Highness Prince Raimondo della Torre e Tasso, for his invaluable hospitality. We are deeply sorry to hear of his passing in the meantime. To his memory these proceedings are dedicated.
In the 25th Century, the effects of overpopulation and global warming on Earth have led to the formation of human colonies on the Moon, Mars and elsewhere in the Solar System, yet the limited number of viable places forces humanity to look to the stars. A crash program has been developed to send Protos 1, a giant multigenerational star ship, to a newly discovered Earth-like planet orbiting a nearby star. The plan is for awake crewmembers to run the ship and for people in suspended animation to be roused before planet fall to use their skills in exploration and colony formation. To fulfill the goals of the mission and ensure that the in-flight population does not deplete the limited resources, the Protos Mandate is set up to govern a tightly controlled social system for the duration of the journey, which will take several generations. But problems threaten to sabotage the mission during its launch and transit and what finally awaits the crewmembers shocks them in an unpredictable way. This novel chronicles the trials and tribulations of this epic first interstellar mission.The scientific appendix at the end of the book discusses the challenges of such an interstellar mission based on an extensive literature review and it links these challenges to specific episodes in the novel. Issues that are considered include interstellar propulsion systems, economic considerations of interstellar flight, psychological and sociological factors inherent in a multigenerational space mission, problems with suspended animation, current knowledge of exoplanets and issues related to colonizing a distant planet and the possible discovery of extraterrestrial life. A history of interstellar missions in science fiction is also reviewed.Nick Kanas is an Emeritus Professor of Psychiatry at the University of California, San Francisco, where he directed the group therapy training program. For over 20 years he conducted research on group therapy, and for nearly 20 years after that he was the Principal Investigator of NASA-funded research on astronauts and cosmonauts. He is the co-author of Space Psychology and Psychiatry, which won the 2004 International Academy of Astronautics Life Science Book Award, and the author of Humans in Space: The Psychological Hurdles, which won the 2016 International Academy of Astronautics Life Science Book Award.

Dr. Kanas has presented talks on space psychology and on celestial mapping at several regional and Worldcon science fiction conventions. A Fellow of the Royal Astronomical Society (London), he has been an amateur astronomer for over 50 years and is an avid reader of science fiction. He is also the author of two non-fiction books (Star Maps: History, Artistry, and Cartography and Solar System Maps: From Antiquity to the Space Age) and two science fiction novels (The New Martians andThe Protos Mandate), all published by Springer.

Camille Flammarion (1842-1925) began his career at 16 as a human computer under the great mathematician U. J. J. Le Verrier at the Paris Observatory. He soon tired of the drudgery; he was drawn to more romantic vistas, and at 19 wrote a book on an idea that he was to make his own—the habitability of other worlds. There followed a career as France’s greatest popularizer of astronomy, with over 60 titles to his credit. An admirer granted him a chateau at Juvisy-sur-l’Orge, and he set up a first-rate observatory dedicated to the study of the planet Mars. Finally, in 1892, he published his masterpiece, La Planete Mars et ses conditions d’habitabilite, a comprehensive summary of three centuries’ worth of literature on Mars, much of it based on his own personal research into rare memoirs and archives. As a history of that era, it has never been surpassed, and remains one of a handful of indispensable books on the red planet.

Sir Patrick Moore (1923-2012) needs no introduction; his record of popularizing astronomy in Britain in the 20th century equaled Flammarion’s in France in the 19th century. Moore pounded out hundreds of books as well as served as presenter of the BBC’s TV program “Sky at Night” program for 55 years (a world record). Though Moore always insisted that the Moon was his chef-d’oeuvre, Mars came a close second, and in 1980 he produced a typescript of Flammarion’s classic. Unfortunately, even he found the project too daunting for his publishers and passed the torch of keeping the project alive to a friend, the amateur astronomer and author William Sheehan, in 1993. Widely regarded as a leading historian of the planet Mars, Sheehan has not only meticulously compared and corrected Moore’s manuscript against Flammarion’s original so as to produce an authoritative text, he has added an important introduction showing the book’s significance in the history of Mars studies. Here results a book that remains an invaluable resource and is also a literary tour-de-force, in which the inimitable style of Flammarion has been rendered in the equally unique style of Moore.

Two important factors have given rise to mankind’s successful evolution into space: the first is that the possibilities are bounded only by our imaginations – if we can conceive it, historically it has been proved that we can do it, and in a predetermined timescale. The second factor is recognition of the evolving civilizations on the Moon and Mars as separate entities from Earth.

Space, whether we or our children live in it or on the Moon or Mars, will be important to all of us, not only to aerospace engineers and cosmologists, because of the new opportunities for freedom and limitless growth it offers. Our continued prosperity and survival as a species will in part depend upon space exploration and the resources it provides for our industrial societies and for the markets it will create. The expansion of Earth’s success in science and culture to the Moon, then Mars, and eventually the Solar System, can only strengthen mankind’s core positive achievements: democracy, individual rights and equal opportunities for all. The significant topic of returning to the Moon, this time to stay, is a central part of space exploration.

Concepts for lunar base structures have been proposed since long before the dawn of the space age. Suggestions made during the last 25 years are likely to form the pool from which eventual lunar base designs will evolve. Studies have intensified, both within NASA and outside national governments in industry and academe, since the days of the Apollo program, when it appeared likely that the Moon would become a second home to humans. Since then, science on the Moon, the economics of lunar development, and human physiology in space and on planetary bodies, as well as related policy issues have been studied as they are all needed to plant Man on the Moon in a sustainable and viable way.

Economics and politics will play a heavy if not deciding role in space and lunar settlement. The issues of pollution and related environmental matters, the question of ownership, and how these affect the investor communities, including governments, will be considered. Human exploration and colonization of the Moon and the planets appears far off but it is important to discuss the safeguarding of the integrity of these planetary bodies in advance of the economic development that will be explosive once it begins. For purposes of discussion, it will be assumed that by the year 2050 there will be a well-developed human colony of many hundreds of people on the Moon, created by several democratic Earth governments in partnership with numerous industrial concerns. Its purpose will be to learn survival on a non-terrestrial body naturally hostile to human life and to explore and use the resources of the Moon, leading eventually to self-sufficient large lunar cities that will survive economically by exporting lunar minerals and finished products to Earth, and by servicing transportation, both commercial and military, between Earth and emerging settlements on Mars, its moons, as well as early mining activity on the asteroids and the moons of the gas giants of the outer solar system.

Given the fact that there are perhaps 400 billion stars in our Galaxy alone, and perhaps 400 billion galaxies in the Universe, it stands to reason that somewhere out there, in the 14-billion-year-old cosmos, there is or once was a civilization at least as advanced as our own. The sheer enormity of the numbers almost demands that we accept the truth of this hypothesis. Why, then, have we encountered no evidence, no messages, no artifacts of these extraterrestrials?

In this second, significantly revised and expanded edition of his widely popular book, Webb discusses in detail the (for now!) 75 most cogent and intriguing solutions to Fermi's famous paradox: If the numbers strongly point to the existence of extraterrestrial civilizations, why have we found no evidence of them?

Reviews from the first edition:

"Amidst the plethora of books that treat the possibility of extraterrestrial intelligence, this one by Webb ... is outstanding. ... Each solution is presented in a very logical, interesting, thorough manner with accompanying explanations and notes that the intelligent layperson can understand. Webb digs into the issues ... by considering a very broad set of in-depth solutions that he addresses through an interesting and challenging mode of presentation that stretches the mind. ... An excellent book for anyone who has ever asked ‘Are we alone?’." (W. E. Howard III, Choice, March, 2003)

"Fifty ideas are presented ... that reveal a clearly reasoned examination of what is known as ‘The Fermi Paradox’. ... For anyone who enjoys a good detective story, or using their thinking faculties and stretching the imagination to the limits ... ‘Where is everybody’ will be enormously informative and entertaining. ... Read this book, and whatever your views are about life elsewhere in the Universe, your appreciation for how special life is here on Earth will be enhanced! A worthy addition to any personal library." (Philip Bridle, BBC Radio, March, 2003)

Since gaining a BSc in physics from the University of Bristol and a PhD in theoretical physics from the University of Manchester, Stephen Webb has worked in a variety of universities in the UK. He is a regular contributor to the Yearbook of Astronomy series and has published an undergraduate textbook on distance determination in astronomy and cosmology as well as several popular science books. His interest in the Fermi paradox combines lifelong interests in both science and science fiction.

In recent years, there has been increased interest in our Solar System. This has been prompted by the launching of giant orbiting telescopes and space probes, the discovery of new planetary moons and heavenly bodies that orbit the Sun, and the demotion of Pluto as a planet. In one generation, our place in the heavens has been challenged, but this is not unusual. Throughout history, there have been a number of such world views. Initially, Earth was seen as the center of the universe and surrounded by orbiting planets and stars. Then the Sun became the center of the cosmos. Finally, there was no center, just a vast array of galaxies with individual stars, some with their own retinue of planets. This allowed our Solar System to be differentiated from deep-sky objects, but it didn’t lose its mystery as more and more remarkable bodies were discovered within its boundaries.

This book tells the exciting story of how we have conceptualized and mapped our Solar System from antiquity to modern times. In addition to the complete text, this story is made more vivid by:

• 162 Solar System and planetary maps, diagrams, and images (over a third in color);

• direct quotes and figures from antiquarian, contemporary, and Space Age documents and photographs that allow the reader to track how humans have viewed the Solar System from original sources;

• nine tables that compare the various world views, relative planetary positions, and components of the Solar System with each other.

Broad in scope and rich in imagery, this book will draw the reader into the story of our Solar System and how it has been mapped since the beginning of recorded time.

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