Letter: 1 – Professor FW Dyson, Astronomer Royal, who was important in proving Einstein’s theory of relativity.

Letter: 2 – Prof Herbert Dingle, Astronomer and opponent of Einstein.

Letter: 3 – Prof EA Milne, astrophysicist at Oxford University who worked on implications of the theory of relativity.

Letter 4 in German – Prof Albert Einstein, Nobel Prize winner and originator of the theory of relativity.

Letter: 5 – Dr Otto Struve, Russian born astronomer who worked in America and was one of the most important astronomers of the 20th century.

Letter: 6 – Lt Col FJM Stratton, astronomer and Professor of Astrophysics at Cambridge University.

Letter: 7. Sir Arthur Eddington, astronomer and popular science writer who wrote explanations of Einstein’s theories for the general public

Letter: 8 – Prof HN Russell, American astronomer