Stephen Hawking is turning 75 on 8 January. In 1959, he began studying physics at University College, Oxford, aged 17.Hawking was diagnosed with ALS at the age of 21. He was married to Jane Hawking for 25 years, before splitting in 1995. After the divorce, he married his nurse, Elaine Mason, until they divorced in 2006.Hawking has 12 honorary degrees. His 1998 book A Brief History of Time has sold 10 million copies.