(Until William Herschel’s advances in telescopes, stars seemed to have “rays” or “tails.”)

At a dinner given by Mr Aubert in the year 1786, William Herschel was seated next to Mr Cavendish, who was reputed to be the most taciturn of men. Some time passed without his uttering a word, then he suddenly turned to his neighbour and said: ‘I am told that you see the stars round, Dr Herschel’. ‘Round as a button’, was the reply. A long silence ensued till, towards the end of the dinner, Cavendish again opened his lips to say in a doubtful voice: ‘Round as a button?’ ‘Exactly, round as a button’, repeated Herschel, and so the conversation ended.

— Constange A. Lubbock, The Herschel Chronicle, 1933