Simplify the following text for a Grade 14 native English-speaking person.
Original: According to various organizations ( the National Science Foundation , NASA , the University of California , San Diego , and other sources ) , ships captained by three men sighted Antarctica in 1820 : Fabian Gottlieb von Bellingshausen ( an Estonian-born captain in the Russian Imperial Navy ) , Edward Bransfield ( a Ireland-born captain in the Royal Navy ) , and Nathaniel Palmer ( an American sealer out of Stonington , Connecticut ) .
Simplified: According to different organizations ( the National Science Foundation , NASA , the University of California , San Diego , and other sources ) , ships captained by three men saw Antarctica in 1820 . Fabian Gottlieb von Bellingshausen ( a captain in the Russian Imperial Navy ) , Edward Bransfield ( a captain in the Royal Navy ) , and Nathaniel Palmer ( an American seal hunter out of Stonington , Connecticut ) .