Editing Parabolic trajectory (section)

{{Short description|Type of orbit}}
{{about|a class of Kepler orbits|a free body trajectory at constant gravity|Projectile Motion}}
{{More citations needed|date=September 2014}}
[[File:OrbitalEccentricityDemo.svg|thumb|right|The green path in this image is an example of a parabolic trajectory.]]
[[File:Gravity Wells Potential Plus Kinetic Energy - Circle-Ellipse-Parabola-Hyperbola.png|thumb|250px|A parabolic trajectory is depicted in the bottom-left quadrant of this diagram, where the [[gravity well|gravitational potential well]] of the central mass shows potential energy, and the kinetic energy of the parabolic trajectory is shown in red. The height of the kinetic energy decreases asymptotically toward zero as the speed decreases and distance increases according to Kepler's laws.]]
{{Astrodynamics}}
In [[astrodynamics]] or [[celestial mechanics]] a '''parabolic trajectory''' is a [[Kepler orbit]] with the [[Orbital eccentricity|eccentricity]] equal to 1 and is an unbound orbit that is exactly on the border between elliptical and hyperbolic. When moving away from the source it is called an '''escape orbit''', otherwise a '''capture orbit'''. It is also sometimes referred to as a '''C<sub>3</sub>&nbsp;=&nbsp;0 orbit''' (see [[Characteristic energy]]).

Under standard assumptions a body traveling along an escape orbit will coast along a [[Parabola|parabolic]] trajectory to infinity, with velocity relative to the [[central body]] tending to zero, and therefore will never return. Parabolic trajectories are minimum-energy escape trajectories, separating positive-[[characteristic energy|energy]] [[hyperbolic trajectory|hyperbolic trajectories]] from negative-energy [[elliptic orbit]]s.