Joseph Ivor Silk FRS (born 3 December 1942) is the Savilian Chair of Astronomy at the University of Oxford. He was educated at Tottenham County School (1954-1960) and went on to study Mathematics at the University of Cambridge (1960-1963). He gained his PhD in Astronomy from Harvard in 1968. Silk took up his first post at Berkeley in 1970, and the Chair in Astronomy in 1978. Following a career of nearly 30 years there, Silk returned to the UK in 1999 to take up the Savilian Chair.
He is an Emeritus Fellow of New College, Oxford and a Fellow of the Royal Society (elected May 1999). He was awarded the 2011 Balzan Prize for his works on the early Universe. Silk has given more than two hundred invited conference lectures, primarily on galaxy formation and cosmology.