The conference is timely in view of many new opportunities in the fields of helio- and asteroseismology. These include the NASA space mission Solar Dynamics Observatory, the CNES missions COROT and Picard, all of which will become operational in the next few years, and the fast pace of development and data acquisition of ground-based asteroseismology investigations as well as the continuing success stories of ground- and space-based helioseismology.
The title of the conference Beyond the Spherical Sun: a new era in helio-and asteroseismology reflects two particularly important themes. "Beyond the Spherical Sun" refers on the one part to "beyond the spherical", the exciting developments in local helioseismology in particular which have enabled us to image the full three-dimensional nature of the solar interior and to begin to understand its workings beyond the traditional spherically symmetric picture of the inside of a star. For the second part, the title brings out the theme "beyond the Sun", as new developments of asteroseismology take us beyond our nearest star to probe the interiors of other stars using seismic techniques and hence to test and improve our understanding of the physics of stars of different masses, ages and chemical composition across the Hertzsprung-Russell diagram.
One of the pioneers of helioseismology was Professor George Isaak, who died on 5 June 2005. George Isaak was an imaginative and insightful physicist and a prime mover in helioseismology not only in the UK, where he was professor at the University of Birmingham, but internationally. Our conference is dedicated to his memory.
There is a tradition for GONG meetings every two years: the last three were in in Santa Cruz, Tenerife (2000), Big Bear, California (2002) and Yale, New Haven (2004). We are happy to host the GONG 2006 meeting in Sheffield. All of the aforementioned meetings have been co-sponsored as SOHO meetings, and we are pleased that the present meeting also follows in that tradition as SOHO 18. Finally we are also pleased to be the first international conference of the Helioseismology and Asteroseismology Network (HelAs).