The full story of how our relationship with light shapes our health, productivity and mood.

'A sparkling and illuminating study, one of those rare books that could genuinely improve your life' Sunday Times

Since the dawn of time, humans have worshipped the sun. And with good reason. Our biology is set up to work in partnership with it. From our sleep cycles to our immune systems and our mental health, access to sunlight is crucial for living a happy and fulfilling life. New research suggests that our sun exposure over a lifetime - even before we were born - may shape our risk of developing a range of different illnesses, from depression to diabetes.

Bursting with cutting-edge science and eye-opening advice, Chasing the Sun explores the extraordinary significance of sunlight, from ancient solstice celebrations to modern sleep labs, and from the unexpected health benefits of sun exposure to what the Amish know about sleep that the rest of us don't.

As more of us move into light-polluted cities, spending our days in dim offices and our evenings watching brightly lit screens, we are in danger of losing something vital: our connection to the star that gave us life. It's a loss that could have far-reaching consequences that we're only just beginning to grasp.

J 2 J. MICHAEL SHl: LL, HARLEY A. THRO: \SOX, JR., A: '>D S. ALAN STER: \3 I University of Colorado, Dept. of Astrophysical. Planetary, &. Atmospheric Sciences 2 University of Wyoming and KASA Headquarters, Code SR 3 Southwest Research Institute, Boulder Office On May 15-17. 1995, three Rocky Motultain research institutions hosted a confererJce to dis cuss the scientific basis, teclmological options, and programmatic implications of a large-scale effort to find and study Earth-like planets outside the Solar System. Our workshop attracted scientists, erJgineers, space agency administrators, and the public media to discuss and debate the most promising teclmological options and opportunities. Major programs and proposals to search for and study exo-planets were preserJted and discussed. In addition, our meeting - incided .with NASA's "roadmap" study for the Exploration of Neighboring Planetary Systems ( "'\PS). Our meeting was the first international confererJce on this subject, affording an op portunity for several members of this study to participate in the debates over new technologies. Our meeting proyed to be timely. Shortly thereafter, in late 199.5 and early 1996, two groups of astronomers annotulced the first discoveries of planetary companions to nearby stars. using high-precision radial velocity measuremerJts to detect the gravitational reflex motion of the star. The first three detections include a Jupiter-mass companion to the solar-like star. 51 Pegasi, and two remarkable objects of mass at least 2. 3 and 6."

Rotation is ubiquitous at each step of stellar evolution, from star formation to the final stages, and it affects the course of evolution, the timescales and nucleosynthesis. Stellar rotation is also an essential prerequisite for the occurrence of Gamma-Ray Bursts.

In this book the author thoroughly examines the basic mechanical and thermal effects of rotation, their influence on mass loss by stellar winds, the effects of differential rotation and its associated instabilities, the relation with magnetic fields and the evolution of the internal and surface rotation. Further, he discusses the numerous observational signatures of rotational effects obtained from spectroscopy and interferometric observations, as well as from chemical abundance determinations, helioseismology and asteroseismology, etc.

On an introductory level, this book presents in a didactical way the basic concepts of stellar structure and evolution in "track 1" chapters. The other more specialized chapters form an advanced course on the graduate level and will further serve as a valuable reference work for professional astrophysicists.

This symposium was devoted to a new celestial mechanics whose aim has become the study of such objects' as the planetary system, planetary rings, the asteroidal belt, meteor swarms, satellite systems, comet families, the zodiacal cloud, the preplanetary nebula, etc. When the three-body problem is considered instead of individual orbits we are, now, looking for the topology of extended regions of its phase space. This Symposium was one step in the effort to close the ties between two scientific families: the observationally-oriented scientists and the theoretically-oriented scientists.

The 34th Saas-Fee advanced course of the Swiss Society of Astronomy and Astrophysics (SSAA) took place from March 15 to 20, 2004, in Davos, on the subject of The Sun, Solar Analogs and the Climate. PresentlytheSwissmountainresortofDavosisprobablymostwellknown for hosting an event on globalization. However, it is because Davos also happens to be the seat of the Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center, that this course on a "global" subject was hosted here. Exceptionally, the topic of this course was not purely astrophysical, but themembersoftheSSAAdecidedtosupportitallthesameduetothetimely topic of global warming and its possible link to solar variations. In these times of concern about global warming, it is important to und- stand solar variability and its interaction with the atmosphere. Only in this way can we distinguish between the solar and anthropogenic contributions to the rising temperatures. Therefore, this course addressed the observed va- ability of the Sun and the present understanding of the variability's origin and its impact on the Earth's climate. Comparing the solar variability with that of solar analog stars leads to a better understanding of the solar activity cycle and magnetic activity in general, and helps us to estimate how large the solar variations could be on longer time scales. Inspiteofthefantasticweatherandsnowconditionswhichreignedduring this week, the participants assiduously took part in the lectures. This is proof ofthehighqualityofthelecturesthatthethreespeakers,JoannaHaigh,Mike Lockwood and David Soderblom, delivered. We deeply thank them for their contributions and e?orts and hope that the readers will enjoy the book as much as we enjoyed their lectures.

The principal elements of the theory of polarized light transfer in planetary atmospheres are expounded in a systematic but concise way. Basic concepts and practical methods are emphasized, both for single and multiple scattering of electromagnetic radiation by molecules and particles in the atmospheres of planets in the Solar System, including the Earth, and beyond. A large part of the book is also useful for studies of light scattering by particles in comets, the interplanetary and interstellar medium, circumstellar disks, reflection nebulae, water bodies like oceans and suspensions of particles in a gas or liquid in the laboratory.

Throughout the book symmetry principles, such as the reciprocity principle and the mirror symmetry principle, are employed. In this way the theory is made more transparent and easier to understand than in most papers on the subject. In addition, significant computational reductions, resulting from symmetry principles, are presented. Hundreds of references to relevant literature are given at the end of the book. Appendices contain supplementary information such as a general exposition on properties of matrices transforming Stokes parameters of light beams. Each chapter concludes with a number of problems with answers or hints for solution.

The readers should have some basic knowledge of physics and mathematics. The book is suitable as a textbook for advanced undergraduates and graduate students. It will also be of interest to science professionals in one of the many disciplines in which electromagnetic scattering plays an important role, like astrophysics, atmospheric optics, remote sensing, marine optics, biophysics and biomedicine.

"He is beautiful and radiant with great splendor ... " St. Francis, from Cantico del sole Two decades have elapsed since the publication of Solar Prominences, 20 years that have seen a nearly phenomenal increase in the interest, as well as the infor mation, concerning these fascinating and beautiful manifestations of solar ac tivity. During this period many meetings have been held, and several books and proceedings have been published, all dealing with specific aspects of solar prominences. However, no unifying and comprehensive accord has appeared. Recently some of my colleagues suggested that the time was ripe for a new addition of Solar Prominences, and Kluwer Academic Publishers wanted to pub lish such a book. I, therefore, venture to present this monograph in the hope of kindling the interest of some graduate students in the study of this-probably the most spectacular and often the most beautiful of solar activity manifestation. However, since it is the physical processes behind these events that will particu larly interest us, I also hope the book may be of help to some of my colleagues. In a rapidly developing field of science it is difficult, if not impossible, to present an overview that is up to date in every respect. I have made nearly every effort to include the latest contributions in the broad area of prominence research, but I am sure I have overlooked some important investigations. For these oversights, I apologize."

In this book, the author draws on his broad experience to describe both the theory and the applications of wave propagations. The contents are presented in four parts and the sequence of these parts reflect the development of ionospheric and propagational research in areas such as space research geophysics and communications. The first part of the book presents an outline of the theory of electromagnetic waves propagating in a cold electron plasma. For reference, vector analysis, dyadics and eigenvalues introduced in this part are presented in the appendices. Practical aspects of radio wave propagation are the subject of the second part. The typical conditions in different frequency ranges are discussed and the irregular features of the ionospheric structure such as sound and gravity waves are also considered. Warm plasma and the effects of ions are considered in the third part, which includes a discussion of sound-like waves in electron and ion plasmas. Nonlinear effects and instabilities are described in the fourth part.

If our eyes were radio rather than optical wide-band detectors it is well known that for us the brightest object in the sky would still be the Sun; that planets, stars and the Milky Way would still shine feebly (and that we would still occasionally be blinded by man-made sources). What is less well known is that quite a different earthbound overcast would hover about us, with its climatic zones, its seasonal changes, its unpredictable storms and scintillating transparence. To be sure, we can get a sort of glimpse of this peculiar type of weather when we tune our receiver to radio broad casting from some remote spot, or photograph the Earth from space at certain specific wavelengths. Nevertheless no one has ever looked at the ionized shroud of the Earth without the help of sophisticated apparatus, and this is one of the reasons why in this domain the phenomena are not easily abstracted from the use of specific techniques. For generations, the study of the ionosphere has been deeply interwoven with the practice of radio communication and detection. Today however, ionospheric physics is best thought of as a branch of space physics; that part of physics which deals with processes at work in the solar system and methods developed for its exploration."

The reader will find in this volume the Proceedings of the NATO Advanced Study Institute held in Maratea-Acquafredda, Italy, between June 29 and July 12, 1997, entitledTHE DYNAMICS OF SMALL BODIES IN THE SOLAR SYSTEM: A MAJOR KEY TO SOLAR SYSTEM STUDIES . This Advanced Study Institute was the latest in the 'Cortina' series of NATO ASI's begun in the early 1970's firstly under the directorship of Professor Victor Szebehely and subsequently under Professor Archie Roy. All, except the latest, were held at the Antonelli Institute, Cortina d'Ampezzo, Italy. Many of those now active in the field made their first international contacts at these Institutes. The Institutes bring together many of the brightest of our young people working in dynamical astronomy, celestial mechanics and space science, enabling them to obtain an up-to-date synoptic view of their subjects delivered by lecturers of high international reputation. The proceedings from these institutes have been well-received in the internationalcommunity of research workers in the disciplines studied. The present institute included 15 series of lectures given by invited speakers and some 45 presentations made by the other participants. The majority of these contributions are includedinthese proceedings.

Physics of Planetary Rings describes striking structures of the planetary rings of Saturn, Uranus, Jupiter, and Neptune: Narrow ringlets, spiral waves, and a chain of clumps. The author has contributed essential ideas to the full understanding of planetary rings via the stability analysis of dynamical systems. The combination of a high-quality description, the set of interesting illustrations, as well as the fascinating and natural presentation will make this book of considerable interest to astronomers, physicists, and mathematicians as well as students. There is no competing text for this book so far.

Both the high level of activity in worldwide space exploration programmes and the discovery of extra-solar planets have spurred renewed interest in the physics and evolution dynamics of solar systems. The present book has grown out of a set of lectures by leading experts in the field within the framework of the well-known EADN summer schools. It addresses primarily graduate students and young researchers but will be equally useful for scientists in search of a comprehensive tutorial account that goes beyond the material found in standard textbooks.

An up-to-date progress report on the current status of solar-terrestrial relation studies with an emphasis on observations by the Russian Interball spacecraft and the Czech Magion subsatellites. Papers in the volume describe the various spacecraft in the International Solar-Terrestrial Program and the research questions that they are being used to address. The emphasis is on correlative studies employing multiple instruments and multiple spacecraft. The book begins with a description of each spacecraft active in 1998 and describes the roles they can play in correlative studies. This is followed by an up-to-date status report concerning ongoing studies of the solar wind, foreshock, bow shock, magnetopause, magnetotail, and ionosphere, with an emphasis on the observations made by the four Interball spacecraft. Readership Researchers and graduate students of space physics and astrophysics.

Much of the excitement in modern Solar Physics has come from the realisation that the Sun is a plasma and that this plasma is interacting with the magnetic field in a wide variety of subtle ways. As well as being of great interest in their own right the observed plasma phenomena on the Sun are of much wider importance, since they reveal to us details of basic phenomena that are expected to be occurring throughout the universe. It was with this in mind that 173 solar physicists from 17 countries gathered together in Bangalore with an air of anticipation. We were not disappointed as we received the warmest of welcomes from our graceful and charming host, Vinod Krishan. She and her colleagues worked tirelessly to make our stay a most memorable one and to ensure that the meeting ran with calm and efficiency. In addition to being stimulated by an excellent series of talks on the up-to-the minute advances in our subject, it was a pleasure to make new friendships from so many countries and to learn, in particular, of the Solar Physics being done in India which has a great tradition and is of a high standard. Furthermore, we enjoyed hearing about Indian culture and appreciating its beauty, especially on our day's tour into the countryside to visit some Hindu and Jain temples."

Planetary nebulae are the classic subject of astrophysics. The physical pro cesses occurring in this highly ionized gaseous medium, the formation of emis sion lines in clearly specified conditions, the continuous emission extending from the far ultraviolet up to infrared and radio frequencies, the generation of exotic forms of radiation predicted by atomic physics, along with methods for deciphering the observed spectra and detecting physical and kinematic parameters of the radiating medium, etc. - all these problems form the solid foundations of the physical theory of gaseous nebulae. They are an essential part of the arsenal of powerful tools and concepts without which one cannot imagine understanding and interpreting the enormous diversity of processes taking place in the Universe - in gaseous envelopes surrounding the stars of various classes, from cool dwarfs and flare stars up to hot supergiants, as well as in stellar chromospheres and coronae, in atmospheres of unstable and anomalous stars, in circumstellar clouds and gaseous shells born in nova and supernova explosions, in diffuse nebulae and the interstellar medium, in interacting binary systems, in galaxies with emission lines, in quasars, etc. The last thirty years have seen a turning-point in our knowledge concern ing the very nature of planetary nebulae (PNs). The radio emission of PNs was discovered after it was predicted theoretically. On the other hand, the powerful infrared emission discovered both in the continuum and in emission lines was never expected."

Meteorites are natural objects that have fallen from space to the Earth's surface. Once considered bad omens, they are now recognised as a unique window onto the processes that forged the formation of the solar system 4,570 million years ago. They reveal how impacts have shaped and modified planets, asteroids and moons; and they even contain evidence of astrophysical phenomena that occurred long before our solar system was born. In Meteorites, leading experts from the Natural History Museum, London provide a compelling and cutting edge introduction to the evolving science of meteoritics. They reveal what meteorites are, where they are most likely to be found, and the type of celestial bodies that they hail from. The book contains all the latest information on key meteorite falls and considers some of the big questions that still remain - such as whether our solar system is unusual in creating a planet that supports life, and if it is likely we will find complex life elsewhere. With a mix of photographs, diagrams and maps, Meteorites is essential reading for all those with an interest in the nature of our solar system.

Recent space missions to the outer solar system, Galileo (1996 2003) and Cassini-Huygens (2004 today), together with ground observations, have revealed that the moons of the outer solar system are enigmatic objects, introducing extraordinary challenges for geologists, astrobiologists, organic chemists, and planetologists. Chemical exchange exists through the different layers that form their interiors, and also from the interior to the surface. The most convincing evidence is certainly the discovery of water vapour and ice particles emerging from Enceladus s active south polar region. Evidence for exchange with a subsurface liquid ocean has also been provided by the inference of hydrated salts on the surfaces of Jupiter s moons, Europa and Ganymede, as well as the detection of sodium salts in particles originating in Enceladus s plumes. Aqueous exchange with the rocky core may also be possible, considering that 40Ar has been observed in the plumes of Enceladus during one flyby of Cassini and in the atmosphere of Titan. The ongoing CH4 replenishment in Titan s atmosphere is additional striking evidence of exchange processes within the moons."

Europa The Ocean Moon tells the story of the Galileo spacecraft probe to Jupiter's moon, Europa. It provides a detailed description of the physical processes, including the dominating tidal forces that operate on Europa, and includes a comprehensive tour of Europa using images taken by Galileo's camera. The book reviews and evaluates the interpretative work carried out to date, providing a philosophical discussion of the scientific process of analyzing results and the pitfalls that accompany it. It also examines the astrobiological constraints on this possible biosphere, and implications for future research, exploration and planetary biological protection. Europa The Ocean Moon provides a unique understanding of the Galileo images of Europa, discusses the theory of tidal processes that govern its icy ridged and disrupted surface, and examines in detail the physical setting that might sustain extra-terrestrial life in Europa's ocean and icy crust. "

Solar Physics publishes up to two Topical Issues per year that focus on areas of especially vigorous and active research. The present Topical Issue contains papers of recent results on the solar corona, as well as on the transition region and low solar wind. The majority of these papers, which were all refereed in accordance with the standards of Solar Physics, were presented in August 1999 at a workshop held in Monterey, California. The authors were offered the opportunity to present relevant parts of their contributions on an accompanying CD ROM of this Topical Issue. The Sun's magnetic field is responsible for the spectacularly dynamic and intri cate phenomenon that we call the corona. The past decade has seen an enormous increase in our understanding of this part of the solar outer atmosphere, both as a result of observations and because of rapid advances in numerical studies. The Yohkoh satellite has observed the Sun now for over eight years, producing spectac ular sequences of images that convey the complexity of the corona. The imaging and spectroscopic instruments on SOHO have added information on the cooler part of the corona. And since April of 1998 TRACE has given us very high resolution images of the 1-2 MK corona, at cadences that allow detailed observations of field oscillations, loop evolution, mass ejecta, etc.

It was about fourteen years ago that some of us became intrigued with the idea of searching the sky for X-ray and gamma-ray sources other than the Sun, the only celestial emitter of high-energy photons known at that time. It was, of course, clear that an effort in this direction would not have been successful unless there occurred, somewhere in space, processes capable of producing high-energy photons much more efficiently than the processes responsible for the radiative emission of the Sun or of ordinary stars. The possible existence of such processes became the subject of much study and discussion. As an important part of this activity, I wish to recall a one-day conference on X-ray astronomy held at the Smithsonian Astrophysical Observatory in 1960. The theoretical predictions did not provide much encouragement. While several 'unusual' celestial objects were pin-pointed as possible, or even likely, sources of X-rays, it did not look as if any of them would be strong enough to be observable with instru mentation not too far beyond the state of the art. Fortunately, we did not allow our selves to be dissuaded. As far as I am personally concerned, I must admit that my main motivation for pressing forward was a deep-seated faith in the boundless re sourcefulness of nature, which so often leaves the most daring imagination of man far behind."

The progress of science during the past centuries has been in some measure energized by the development of new technologies. People are no more intelligent now than they were five centuries ago, or indeed five millenia ago. The differences are in the pool of past experience and the availability of means for manipulating the physical and mental environment. Until fairly recently, the development of new technologies in astronomy and geodesy has served primarily either to broaden the scope of phenomena that could be studied or to improve the precision with which one could examine already-studied phenomena. There seemed to be no likelihood that a situation could arise similar to that in particle physics, where the uncertainty principle indicates that the observation of the state of an object alters that state, affecting the observation. Indeed, we have not yet reached that point, but certain of the new techniques have introduced a degree of complication and inter dependence perhaps not previously encountered in the macro sciences. When observational capability is so fine that the data can be corrupted by the tidal motions of the instruments, for example, then there are a myriad of physical effects that must be considered in analyzing the data; the happy aspect of this is that the data can be used to study exactly these same effects. The complication does not, however, extend only to predictive computations against which the data are compared."

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 publication is a result of three meetings, each 5 days long, held at the Goddard Space Flight Center on January 24-28, 1983, June 8-14, 1983, and February 13-17, 1984. The meetings were held in the interim between the full operations of the Solar Maximum Mission (SMM) in 1980, and the renewed operations after its repair in orbit in April 1984. Their general objectives were as follows: o Synthesize flare studies after three years of SMM data analysis. Many analyses of individual flares and individual phenomena, often jointly across many data sources had been published, but a need existed for a broader synthesis and updating of our understanding of solar flares since the Skylab Flare Workshops held several years earlier. o Encourage a broader participation in the SMM data anlysis and combine this more fully with theory and other data sources--data obtained with other spacecraft such as the HINOTORI, P78-1, and ISEE-3 spacecrafts, and with the Very Large Array (VLA) and many other ground-based instruments. Many coordinated data sets, unprecedented in their breadth of coverage and multiplicity of sources, had been obtained within the structure of the Solar Maximum Year (SMY). o Stimulate joint studies, and publication in the general scientific literature. The intended primary benefit was for informal collaborations to be started or broadened at the Workshops with subsequent publications. o Provide a special publication resulting from this Workshop. o Provide a starting point of understanding for planning renewed full observations with the repaired SMM.

The 10th ESLAB Symposium was held at Grossenzersdorf near Vienna on 10-13 June 1975 under the title 'The Scientific Satellite Programme During the Inter national Magnetospheric Study'. The Symposium was attended by an invited audience of 60 scientists from the ESA Member States, the United States, Japan, Canada and Austria. Following a report by the joint COSPAR-IUCSTP Special Working Group, the International Magnetospheric Study (lMS) is proposed as an international co operative enterprise of limited duration, having as its principal objective the achie vement of a comprehensive, quantitative understanding of the dynamical processes operating in the Earth's plasma and field environment. In order to accomplish this objective, it is thought to be necessary to carry out simultaneous measurements with nearly identical instrumentation at various points in space. These measurements will need to be made in combination with appropriate observations at or near the Earth's surface. Besides near-Earth observations by ground-based, rocket- and balloon-borne instrumentation, satellite investigations are expected to make an important contri bution to the IMS. A number of satellites assigned to magnetospheric research have recently been launched, or will be launched shortly, to be operational during the IMS. The European Space Agency has devoted two of its forthcoming scientific satellites - GEOS and ISEE-B - to magnetospheric and interplanetary research.

Even before the present Administrator of NASA, Daniel Goldin, made the phrase 'better, faster, cheaper' the slogan of at least the Office of Space Science, that same office under the Associate Administrator of Lennard Fisk and its Division of Solar System Exploration under the direction of Wes Huntress had begun a series of planetary spacecraft whose developmental cost, phase CID in the parlance of the trade, was to be held to under $150M. In order to get the program underway rapidly they chose two missions without the open solicitation now the hallmark of the program. One of these two missions, JPL' s Mars Pathfinder, was to be a technology demonstration mission with little immediate science return that would enable later high priority science missions to Mars. Many of the science investigations that were included had significant foreign contributions to keep NASA's cost of the mission within the Discovery budget. The second of these missions and the first to be launched was the Near Earth Asteroid Rendezvous mission, or NEAR, awarded to Johns Hopkins University's Applied Physics Laboratory. This mission was quite different than Mars Pathfinder, being taken from the list of high priority objectives of the science community and emphasizing the science return and not the technology development of the mission. This mission was also to prove to be well under the $150M phase CID cap.