Continent with other islands in the Pacific into one continent called Oceania. This divides the entire land surface of Earth into continents or quasi-continents. The ideal criterion that each continent is a discrete landmass is commonly relaxed due to historical conventions. Of the seven most globally recognized continents, only Antarctica and Australia are completely separated from other continents by the ocean. Several continents are defined not as absolutely distinct bodies but as ""more or less" discrete masses of land". Asia and Africa are joined by the Isthmus of Suez, and North and South America by the Isthmus of Panama. In both
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