The Earth is the only planet in the Solar System where liquid water is present on the surface, a condition that seems necessary for the development of life. Its sisters Venus and Mars are extremely different. Why did these three planets, born under fairly comparable conditions, evolve to the conditions we observe today? Understanding the physical or chemical factors that are at the origin of such divergent evolutions is a first step in an approach to the problem of the origin of life on Earth.

Together with Virgo, the Coma Berenices cluster is one of the most well-studied clusters at all wavelengths and in all aspects, from the Sunyaev-Zeldovich effect to star formation in galaxies. In a way, it is the prototype of rich clusters. Recent observational results, linked to the improvement of techniques such as X-ray and UV observations, along with multi-object spectroscopy, have shown that they could change our vision of this cluster. It is thus time for observers and theoreticians to confront all these new ideas and observations on the Coma cluster.The topics in this volume include:...