Visual binary Visual binary A visual binary is a gravitationally bound system that can be resolved into two stars. These stars are estimated, via Kepler's 3rd law, to have periods ranging from a number of years to thousands of years. A visual binary consists of two stars, usually of a different brightness. Because of this, the brighter star is called the primary and the fainter one is called the companion. If the primary is too bright, relative to the companion, this can cause a glare making it difficult to resolve the two components. However, it is possible to resolve the system if
The purpose of a system is what it does or sheer ignorance of circumstances." The term is widely used by systems theorists. It is generally invoked to counter the notion that the purpose of a system can be read from the intentions of those who design, operate, or promote it. From a cybernetic perspective complex systems are not controllable by simple notions of management, and interventions in a system can best be understood by looking at how they affect observed system behavior. When "side effects" or "unintended consequences" reveal that system behavior is poorly understood, then taking the POSIWID perspective allows the more political understandings of system behavior to