James Cook discovered Australia in 1770 and Britain sent prisoners and criminals to settle there. Europeans sold land belonging to Aboriginal people and killed thousands of them. Australia is located in the Southern Hemisphere south of the equator, making its seasons opposite those in Europe. It is the 6th largest country by size, an island continent surrounded by water, and has Canberra as its capital city with Sydney being the most populous. Australia has membership in international organizations and faces threats from terrorism, communism, and religious issues that impact its economic and demographic environment.