Ocean Ocean An ocean () is a body of saline water that composes much of a planet's hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans. The word "ocean" is often used interchangeably with "sea" in American English. Strictly speaking, a "sea" is a body of saline water (generally a division of the world ocean) partly or fully enclosed by land, though "the sea" refers also to the oceans. Saline water covers approximately and is customarily divided into
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