Solar System
The overall structure of the charted regions of the Solar System consists of the Sun, four relatively small inner planets surrounded by a belt of mostly rocky asteroids, and four giant planets surrounded by the Kuiper belt of mostly icy objects. Astronomers sometimes informally divide this structure into separate regions. The inner Solar System includes the four terrestrial planets and the asteroid belt. The outer Solar System is beyond the asteroids, including the four giant planets. Since the discovery of the Kuiper belt, the outermost parts of the Solar System are considered a distinct region consisting of the objects beyond Neptune.
Solar phenomena
Space weather is the environmental condition within the Solar System, including the solar wind. It is studied especially surrounding the Earth, including conditions from the magnetosphere to the ionosphere and thermosphere. Space weather is distinct from terrestrial weather of the (troposphere and stratosphere). The term was not used until the 1990s. Prior to that time, such phenomena were considered to be part of physics or aeronomy.