In every scientific discipline there are milestones - periods of significant accom plishment when it is appropriate to pause and summarize the state of the field. Such is the case for the study of the behavior of cosmic rays in the heliosphere. We are just passing through solar minimum conditions, when the heliosphere has a well-ordered and relatively simple configuration. We have been fortunate to have an array of spacecraft - unprecedented in the history of space exploration and unlikely to be repeated for generations - to provide comprehensive measurements of cosmic rays throughout the heliosphere. Ulysses has completed its historic first exploration of the heliosphere at high heliographic latitudes. Pioneer and Voyager have been exploring the outer heliosphere. The durable IMP-8 and now the WIND spacecraft have provided detailed baseline measurements at Earth. Concurrently, there has been a steady improvement in theoretical understanding of cosmic ray behavior through the use of ever more sophisticated numerical models. This milestone in cosmic ray studies was celebrated with a Workshop on Cos mic Rays in the Heliosphere which was convened by L. A. Fisk, J. R. Jokipii.

Our knowledge of the heliosphere in three dimensions near solar minimum has advanced significantly in the last 10 years, largely as a result of the on-going ESAINASA Ulysses mission. Similar advances in our understanding of the global heliosphere near solar maximum are to be expected with the return of Ulysses to high solar latitudes in 2000/200 I. With this in mind, the 34th ESLAB Symposium, held at ESTEC in Noordwijk, The Netherlands, on 3-6 October, 2000, was devoted to 'The 3-D Heliosphere at Solar Maximum'. This was the third ESLAB Sympo sium focusing on the three-dimensional heliosphere (previous symposia being in 1985 and 1994), and the timing was particularly appropriate, marking as it did the 10th anniversary of the launch of the Ulysses spacecraft. Furthermore, Ulysses had just started its third high-latitude pass, the second over the Sun's south polar regions. The symposium addressed a wide range of topics related to the solar-maximum heliosphere, with presentations on many of the latest findings from Ulysses and other space-based missions. Ground-based studies and theoretical modeling were also well represented. Specific questions to which answers were sought included the following.

Chapter 1 briefly describes the main properties of space plasmas and primary CR. Chapter 2 considers the problem of CR propagation in space plasmas described by the kinetic equation and different types of diffusion approximations. Chapter 3 is devoted to CR non-linear effects in space plasmas caused by CR pressure and CR kinetic stream instabilities with the generation of Alfvèn turbulence. In Chapter 4 different processes of CR acceleration in space plasmas are considered. The book ends with a list providing more than 1,300 full references, a discussion on future developments and unsolved problems, as well as Object and Author indexes.

In the first part, the book gives an up-to-date summary of the observational data. In the second part, it deals with the kinetic description of cosmic ray plasma. The underlying diffusion-convection transport equation, which governs the coupling between cosmic rays and the background plasma, is derived and analyzed in detail. In the third part, several applications of the solutions of the transport equation are presented and how key observations in cosmic ray physics can be accounted for is demonstrated.

Contributors examine the physics of wind origin and physical phenomena in winds, including heliospheric shocks, magnetohydrodynamic turbulence, and kinetic phenomena--and their interactions with surrounding media. Contributions range from studies of the interstellar cloud surrounding the solar system to solar wind interaction with comets.

The year 1998 marked the 50th anniversary of the invention of the neutron monitor, a key research tool in the field of space physics and solar-terrestrial relations. In honor of this occasion a workshop entitled 'Cosmic Rays and Earth' was organized to review the detection of cosmic rays at the surface and in the lower atmosphere of Earth, including the effect that this radiation has on the terrestrial environment. A special focus was the role of neutron monitors in the investigation of this radiation, on the science enabled by the unique dataset of the worldwide network of neutron monitors, and on continuing opportunities to use these data to solve outstanding problems. This book is the principal product of that workshop, integrating the contribu tions of all participants. Following a general summary of the workshop prepared by the editors, the volume leads off with a keynote article by Professor John Simpson describing his invention of the neutron monitor in 1948 and the early scientific discoveries made with this instrument.

This is the first volume in the new COSPAR Colloquia series which will provide a forum for an in-depth discussion on selective topics of importance to the international community. The International Heliospheric Study (IHS) was initially approved by COSPAR in 1982 when it was anticipated that the study would centre on the ESA/NASA Ulysses spacecraft. This mission was delayed until October 1990, but it was decided to commence the study in 1986 in order to exploit the existence of the Pioneer 10 and 11 and the Voyager 1 and 2 spacecraft in the outer heliosphere. The primary purpose of Physics of the Outer Heliosphere is to study the three-dimensional structure of the solar wind and interplanetary magnetic field carried by it, the propagation of energetic solar particles throughout the heliosphere and the modulation of galactic cosmic rays by the heliosphere. This volume provides information for scientists interested in spectroscopic studies of the local interstellar medium, galactic and solar cosmic ray populations in the outer heliosphere and also plasma and magnetic field aspects of the distant solar wind.