A trajectory is the path a moving object follows through
space as a function of time.
In control theory a trajectory is a time-ordered
set of states of a dynamical system (see
e.
g. Poincaré map). In discrete mathematics, a trajectory is a sequence (f^k(x))_{k \in \mathbb{N}} of values calculated by the iterated application of a mapping f to an element x of its source.
The object might be a projectile or a satellite, for example. It thus includes the meaning of orbit—the path of a
planet, an asteroid or a
comet as it travels around a central mass. A trajectory can be described mathematically either by the
geometry of the path, or as the position of the object over time.