A. Balogh

M.J. Thompson

J.L. Culhane

Å. Nordlund

S.K. Solanki

J.-P. Zahn

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).

The Origin and Dynamics of Solar Magnetism

Louis J. Lanzerotti

Steve T. Suess

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 Heliosphere through the Solar Activity Cycle

Leonid Ksanfomality

Rudolf von Steiger

This fascinating book reviews the progress made in Mercury studies since the flybys by Mariner 10 in 1974-75. Thus far, it is the only book on Mercury which balances a wide range of Earth-based observations, made under difficult conditions, with the only available space-based data. The text is based on continued research using the Mariner 10 archive, on observations from Earth, and on increasingly realistic models of this mysterious planet’s interior evolution.

Mercury

A. Balogh

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