Kiritimati is a Pacific atoll re-discovered by Captain James Cook on 24 December 1777, which explains its alternative name of Chistmas Island. It has the largest land area of any coral atoll and is also the oldest surviving atoll. Between 1956 and 1962 the island was used by the United Kingdom and United States governments as a base for nuclear tests. Today the island is part of the Republic of Kiribati. Photo credit: NASA |