Edmond (or Edmund) Halley (; 8 November [O.S. 29 October] 1656 – 25 January 1742 [O.S. 14 January 1741]) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720.
From an observatory he constructed on Saint Helena in 1676–77, Halley catalogued the southern celestial hemisphere and recorded a transit of Mercury across the Sun.
