Famous for his metal prosthetic nose, and for being associated with 'unlucky' days in Scandinavian folklore, Tycho Brahe (1546-1601) made the most accurate naked-eye astronomical measurements of his day. Cataloguing more than 1,000 new stars, his stellar and planetary observations helped lay the foundations of early modern astronomy. John Louis Emil Dreyer (1852-1926) was a fellow Dane, but he spent much of his working life in Ireland. When he was...