Palmer, Nathaniel Brown (1799–1877), a United States sea captain who may have been the first to sight the mainland of Antarctica. Palmer was born in Stonington, Connecticut. He went to sea at 14. While searching for seal breeding grounds in 1820, he sighted what came to be called Palmer Peninsula (now known as the Antarctic Peninsula). In 1821 Palmer and George Powell, an Englishman, discovered the South Orkney Islands. Palmer later became a captain of packet ships and clippers.