Solar System
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, such as the five dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury.
System
It is important not to confuse these abstract definitions. Theorists include in natural systems subatomic systems, living systems, the solar system, galaxies, and the Universe. Artificial systems include our physical structures, hybrids of natural and artificial systems, and conceptual knowledge. The human elements of organization and functions are emphasized with their relevant abstract systems and representations. A cardinal consideration in making distinctions among systems is to determine how much freedom the system has to select its purpose, goals, methods, tools, etc. and how wide is the freedom to select itself as distributed or concentrated.