Continent Introductio", Waldseemüller noted that the earth is divided into four parts, Europe, Asia, Africa and the fourth part, which he named "America" after Amerigo Vespucci's first name. On the map, the word "America" was placed on part of South America. From the 16th century the English noun "continent" was derived from the term "continent land", meaning continuous or connected land and translated from the Latin "terra continens". The noun was used to mean "a connected or continuous tract of land" or mainland. It was not applied only to very large areas of land—in the 17th century, references were made to
Windows on Earth night cycles, night time lights, and other features that help make the exhibit realistic and interactive. Windows on Earth provides the user a view of Earth from an astronaut's viewpoint, with interactive photorealistic views of Earth as if seen from an altitude of 360 km. The program uses GeoFusion's digital Earth visualization system, which renders accurate views of Earth with terrain, satellite imagery, clouds, and other layers. The system is programmed for user interaction, allowing users to "fly" anywhere they wish to see, and zoom in or out to see details. The system's imagery is derived from Landsat, and features