Simplify the following text for a Grade 9 native English-speaking person.
Original: Even in the late 17th century , after explorers had found that South America and Australia were not part of the fabled `` Antarctica '' , geographers believed that the continent was much larger than its actual size .
Simplified: In the late 17th century , people discovered that South America and Australia were not part of the mythical `` Antarctica '' . However , geographers still believed that Antarctica was much bigger than it really was .