The dynamics of a system composed of three bodies system acting under their mutual gravitational attraction is complex. In general, the behaviour of a three-body system over long periods of time is enormously sensitive to any slight changes in the initial conditions, including even small uncertainties in determining the initial conditions, and rounding-errors in computer floating point arithmetic. The practical consequence is that, the three-body problem cannot be solved analytically for an indefinite amount of time, except in special cases. Instead, numerical methods are used for forecast-times limited by the available precision.