It is with great sadness that that we record the news that Professor Michael Thompson passed away unexpectedly on October 15, while on a research visit to Japan. Michael was well known to many in the UK Solar Physics community, latterly from when he was Head of the School of Mathematics & Statistics at the University of Sheffield. He subsequently moved to the US, where first he was Director of the High Altitude Observatory (HAO) in Boulder, and had most recently held the role of Deputy Director and Chief Operating Officer of the US National Center for Atmospheric Research (NCAR).

Michael was one of the pioneers and leaders of the international helioseismology community. He did his PhD with Douglas Gough in Cambridge, after which he spent a year working closely with fellow postdoc Joergen-Christensen Dalsgaard at Aarhus University in Denmark. Michael then moved to HAO in Boulder, before coming back to the UK to take a PPARC fellowship and then a faculty position at Queen Mary University of London, joining Ian Roxburgh. Following a subsequent move to Imperial College London, Michael was appointed Head of School in Sheffield.

Michael was in the forefront of applying and developing so-called “inverse” analysis techniques for application to helioseismic data, to allow the Sun’s internal structure and rotation to be inferred in great detail. That work included studies of sub-surface flows, which carry important signatures of the solar cycle. His interests also encompassed solar and stellar physics more generally, including asteroseismology.

Over the past decade, Michael held big administrative leadership roles, but very recently he had been in the process of becoming research active once more and was leading an international project to provide timely updates on the Sun’s internal rotation (work that will be completed to honor his legacy to the field).

Michael will be much missed by all who knew him.