Mount Erebus was discovered on January 27, 1841 (and observed to be in eruption), by polar explorer Sir James Clark Ross on his Antarctic expedition, who named it and its companion, Mount Terror, after his ships, HMS Erebus and HMS Terror (which were later used by Sir John Franklin on his disastrous Arctic expedition). Present with Ross on HMS Erebus was the young Joseph Hooker, future president of the Royal Society and close friend of Charles Darwin. Erebus is a dark region in Hades in Greek mythology, personified as the Ancient Greek primordial deity of darkness, the son of Chaos.