99942 Apophis is a near-Earth asteroid with a mean diameter of approximately 340 metres. It attracted significant scientific attention after its discovery in 2004 because early orbital calculations indicated a measurable possibility of an Earth impact. At one point, the calculated probability associated with a 2029 impact reached 2.7%. Subsequent optical and radar observations progressively reduced orbital uncertainty, ruling out the previously considered 2029 and 2036 impact scenarios and, in 2021, eliminating the remaining significant 2068 impact possibility. [1–5] This paper investigates how observations changed the predicted impact risk of Apophis and examines the orbital consequences of its exceptionally close Earth encounter on 13 April 2029. Particular attention is given to orbital uncertainty, gravitational keyholes, radar observations, gravitational perturbation, and the expected change in Apophis's heliocentric orbit. The analysis shows that the changing assessment of Apophis was primarily a consequence of improved measurements and orbit determination rather than a physical change in the asteroid itself. Radar observations in March 2021 reduced the uncertainty in the asteroid's projected 2029 position from hundreds of kilometres to only a handful of kilometres and enabled scientists to rule out an Earth impact for at least the next 100 years. The 2029 encounter will nevertheless provide a valuable natural experiment in asteroid dynamics because Earth's gravity will alter Apophis's orbit and may affect its rotation and surface. [1–5]