The 3 D Heliosphere At Solar Maximum

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.

Understanding how the Sun changes though its 11-year sunspot cycle and how these changes affect the vast space around the Sun – the heliosphere – has been one of the principal objectives of space research since the advent of the space age. This book presents the evolution of the heliosphere through an entire solar activity cycle. The last solar cycle (cycle 23) has been the best observed from both the Earth and from a fleet of spacecraft. Of these, the joint ESA-NASA Ulysses probe has provided continuous observations of the state of the heliosphere since 1990 from a unique vantage point, that of a nearly polar orbit around the Sun. Ulysses’ results affect our understanding of the heliosphere from the interior of the Sun to the interstellar medium - beyond the outer boundary of the heliosphere. Written by scientists closely associated with the Ulysses mission, the book describes and explains the many different aspects of changes in the heliosphere in response to solar activity. In particular, the authors describe the rise in solar activity from the last minimum in solar activity in 1996 to its maximum in 2000 and the subsequent decline in activity.

The 19th ESLAB Symposium on 'The Sun and the Heliosphere in Three Dimensions' was held in Les Diablerets (Switzerland) on 4-6 June 1985. Organised almost exactly ten years after the Goddard Space Fl i ght Center Sympos i um dea 1 i ng with the Sun and the i nterp 1 anetary medium in three dimensions, the aim of this Symposium was not only to review the progress made in understanding the three-dimensional structure and dynamics of the heliosphere, but also to look ahead to the scientific return to be expected from the Ulysses mission. Scheduled for launch in May 1986, the scientific instrumentation on board Ulysses will shed light on the conditions and processes occurring away from the ecliptic plane, thereby adding literally a new dimension to our understanding of the only stellar plasmasphere to which we have direct access. The scientific programme of the Symposium was built around a series of invited review papers dealing with aspects of the corona and its influence on the interplanetary medium via transient ejecta, the solar wind, energetic solar particles and galactic cosmic rays, interplanetary dust and neutral gas. These invited talks were supplemented by a number of contributed and poster papers. With the exception of three contributed talks and Wibberenz' review of coronal and acceleration of energetic particles, all papers propagation presented at the Symposium are included in this volume.

The editors present a state-of-the-art overview on the Physics of Space Weather and its effects on technological and biological systems on the ground and in space. It opens with a general introduction on the subject, followed by a historical review on the major developments in the field of solar terrestrial relationships leading to its development into the up-to-date field of space weather. Specific emphasis is placed on the technological effects that have impacted society in the past century at times of major solar activity. Chapter 2 summarizes key milestones, starting from the base of solar observations with classic telescopes up to recent space observations and new mission developments with EUV and X-ray telescopes (e.g., STEREO), yielding an unprecedented view of the sun-earth system. Chapter 3 provides a scientific summary of the present understanding of the physics of the sun-earth system based on the latest results from spacecraft designed to observe the Sun, the interplanetary medium and geospace. Chapter 4 describes how the plasma and magnetic field structure of the earth's magnetosphere is impacted by the variation of the solar and interplanetary conditions, providing the necessary science and technology background for missions in low and near earth's orbit. Chapter 5 elaborates the physics of the layer of the earth's upper atmosphere that is the cause of disruptions in radio-wave communications and GPS (Global Positioning System) errors, which is of crucial importance for projects like Galileo. In Chapters 6-10, the impacts of technology used up to now in space, on earth and on life are reviewed.

The First Edition of The Sun from Space, completed in 1999, focused on the early accomplishments of three solar spacecraft, SOHO, Ulysses, and Yohkoh, primarily during a minimum in the Sun’s 11-year cycle of magnetic activity. The comp- hensive Second Edition includes the main ndings of these three spacecraft over an entire activity cycle, including two minima and a maximum, and discusses the signi cant results of six more solar missions. Four of these, the Hinode, RHESSI, STEREO, and TRACE missions were launched after the First Edition was either nished or nearly so, and the other two, the ACE and Wind spacecraft, extend our investigations from the Sun to its varying input to the Earth. The Second Edition does not contain simple updates or cosmetic patch ups to the material in the First Edition. It instead contains the relevant discoveries of the past decade, integrated into chapters completely rewritten for the purpose. This provides a fresh perspective to the major topics of solar enquiry, written in an enjoyable, easily understood text accessible to all readers, from the interested layperson to the student or professional.