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When geologists first wandered the spectacular ring of hills straddling the Vaal River north of Vredefort nearly 150 years ago, they immediately recognised that the unusually shattered and uptilted rocks bore witness to an exceptionally violent event in the distant past. However, it took more than a century of painstaking work before the accumulated evidence revealed the cause — the impact with Earth of a meteorite, the size of a mountain, about 2 020 million years ago. This book presents an opportunity to travel back in time to this remarkable event — arguably the single greatest geological catastrophe yet uncovered on our planet. It presents an easy to read account of the ten minutes that, quite literally, shook the world. Readers are taken both to the farthest reaches of our Solar System and back to its beginnings in a search for the source of meteorites. The book shows how the immense violence of the event and aeons of slow erosion have combined to provide us with a unique window onto the early history of planet Earth and into the deep levels of its interior. It goes on to show how the lessons learned from the rocks around Vredefort are being used throughout the world to teach a new generation of scientists of the reality, and danger, of similar events in the future. Finally, this book reviews more than 200 000 years of human habitation in this area of exceptional natural beauty and biodiversity. This history starts with the early San hunters, whose graceful art survives today on rocks formed during the impact event. The arrivals and settlements of Sotho, Tswana, Afrikaner and British settlers are discussed, including the landmark wars that affected the region over the last three centuries. This book documents the rich geological, archaeological, cultural and botanical heritage presented by the Vredefort region in an easily digestible manner, opening up the information to non- geoscientists. It concludes with a guide to key sites that highlight the heritage of this area, which was proclaimed a World Heritage Site in July 2005.

Solar system --- zonnestelsel --- planeten

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This book offers an overview of solar physics with a focus on solar activity, particularly the activity cycle. It is known that solar activity varies periodically, but there are also phases of intermittency, such as the Maunder minimum, during which solar activity is very low or high over several decades. The book provides a brief introduction to chaos theory and investigates solar activity in terms of its chaotic behavior. It also discusses how intermittent phases of solar activity have affected and can affect Earth’s climate and long-term space weather, and reviews the underlying theories relating to the solar dynamo mechanism. Furthermore, each chapter includes references to scientific literature (review articles and papers) so that readers can delve deeper into the subjects covered. This richly illustrated book will appeal to a wide readership, and is also useful as a textbook for courses in solar physics and astrophysics.

Solar system --- Geophysics --- zonnestelsel --- geofysica

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This thesis describes the studies on the solar interior where turbulent thermal convection plays an important role. The author solved, for the first time, one of the long-standing issues in solar physics, i.e., the maintenance mechanism of the solar differential rotation in the near-surface shear layer. The author attacked this problem with a newly developed approach, the reduced speed of sound technique, which enabled him to investigate the surface and deep solar layers in a self-consistent manner. This technique also made it possible to achieve an unprecedented performance in the solar convection simulations for the usage of the massively parallel supercomputers such as the RIKEN K system. It was found that the turbulence and the mean flows such as the differential rotation and the meridional circulation mutually interact with each other to maintain the flow structures in the Sun. Recent observations by helioseismology support the author's proposed theoretical mechanism. The book also addresses the generation of the magnetic field in such turbulent convective motions, which is an important step forward for solar cyclic dynamo research.

Space research --- Solar system --- zonnestelsel --- planeten --- ruimtevaart

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This book provides a systematic introduction to the observation and application of kinetic Alfven waves (KAWs) in various plasma environments, with a special focus on the solar-terrestrial coupling system. Alfven waves are low-frequency and long-wavelength fluctuations that pervade laboratory, space and cosmic plasmas. KAWs are dispersive Alfven waves with a short wavelength comparable to particle kinematic scales and hence can play important roles in the energization and transport of plasma particles, the formation of fine magneto-plasma structures, and the dissipation of turbulent Alfven waves. Since the 1990s, experimental studies on KAWs in laboratory and space plasmas have significantly advanced our understanding of KAWs, making them an increasingly interesting subject. Without a doubt, the solar–terrestrial coupling system provides us with a unique natural laboratory for the comprehensive study of KAWs. This book presents extensive observations of KAWs in solar and heliospheric plasmas, as well as numerous applications of KAWs in the solar-terrestrial coupling system, including solar atmosphere heating, solarwind turbulence, solar wind-magnetosphere interactions, and magnetosphere-ionosphere coupling. In addition, for the sake of consistency, the book includes the basic theories and physical properties of KAWs, as well as their experimental demonstrations in laboratory plasmas. In closing, it discusses possible applications of KAWs to other astrophysical plasmas. Accordingly, the book covers all the major aspects of KAWs in a coherent manner that will appeal to advanced graduate students and researchers whose work involves laboratory, space and astrophysical plasmas.

Solar system --- Plasma physics --- plasma --- zonnestelsel --- planeten

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This book presents pioneering work on a critical observational test of the planet formation theory based on the theoretical study of the water snowline, beyond which water takes the form of ice, in the protoplanetary disks – the place where planets are formed. Since the water snowline is thought to divide the regions of rocky and gas-giant planet formation, the location of the snowline is essential for the planet formation process. The book proposes a novel method to locate the snowlines using high-dispersion spectroscopic observations of water vapor lines, which is based on in sophisticated chemical modeling and line radiative transfer calculations. The author obtained the water vapor distribution in the disks using the chemical reaction network, which includes photoreactions and gas–grain interactions. The simulated transition lines of water vapor in the disks demonstrate that relatively weak transition lines with moderate excitation energies are the best tracers of water snowline. Furthermore, the author observed submillimeter lines of water vapor in a disk using ALMA (Atacama Large Millimeter/submillimeter Array) to obtain the upper limit of the line fluxes with the highest sensitivity to date. These unprecedented findings are important in locating the snowlines in the disks, and the method goes a long way toward achieving a comprehensive understanding of the planet formation processes as well as of the origin of water on rocky planets, including our Earth, based on future observations using ALMA and SPICA (Space Infrared Telescope for Cosmology and Astrophysics).

Solar system --- Astronomy --- zonnestelsel --- planeten --- astronomie