Born 1951 in Ashford/Kent (UK). Study of mathematics, MSc in astronomy Toronto Univ., doctorate in astronomy Cambridge Univ./UK (1977), senior research fellow Univ. of California/Berkeley (1981-1984), Associate Professor (1984-1987) and Professor Steward Observatory of the Univ. of Arizona (1987-1991), Sheepshanks Reader in Astronomy Univ. Cambridge/UK (1991-1994), Research Professor Steward Observatory of the Univ. of Arizona (1992), Director and Scientific Member at the Max Planck Institute for Astrophysics (since 1994), Honorary Professor Munich Univ. (1994), Honorary Professor, Shanghai Obs. (2000), Beijing Obs. (2002). Emeritus since 2019.