Editing Elliptic orbit (section)

{{Short description|Kepler orbit with an eccentricity of less than one}}
{{inline citations|date=January 2021}}
[[File:Animation of Orbital eccentricity.gif|250px|thumb|Animation of Orbit by eccentricity<br>{{legend2| OrangeRed |0.0}}{{·}}{{legend2|Lime|0.2}}{{·}}{{legend2|Cyan|0.4}}{{·}}{{legend2|Gold|0.6}}{{·}}{{legend2|hotpink|0.8}}]]
[[File:orbit5.gif|thumb|250px|Two bodies with similar mass orbiting around a common [[barycenter]] with elliptic orbits.]]
[[File:orbit2.gif|thumb|250px|Two bodies with unequal mass orbiting around a common [[barycenter]] with circular orbits.]]
[[File:orbit4.gif|thumb|250px|Two bodies with highly unequal mass orbiting a common [[barycenter]] with circular orbits.]]
[[File:Gravity Wells Potential Plus Kinetic Energy - Circle-Ellipse-Parabola-Hyperbola.png|thumb|250px|An elliptical orbit is depicted in the top-right quadrant of this diagram, where the [[gravity well|gravitational potential well]] of the central mass shows potential energy, and the kinetic energy of the orbital speed is shown in red. The height of the kinetic energy decreases as the orbiting body's speed decreases and distance increases according to Kepler's laws.]]
{{Astrodynamics}}

In [[astrodynamics]] or [[celestial mechanics]], an '''elliptic orbit''' or '''elliptical orbit''' is a [[Kepler orbit]] with an [[orbital eccentricity|eccentricity]] of less than 1; this includes the special case of a [[circular orbit]], with eccentricity equal to 0. In a stricter sense, it is a Kepler orbit with the eccentricity greater than 0 and less than 1 (thus excluding the circular orbit). In a wider sense, it is a Kepler orbit with negative [[Specific orbital energy|energy]]. This includes the '''radial elliptic orbit''', with eccentricity equal to 1. They are frequently used during various astrodynamic calculations.

In a [[gravitational two-body problem]] with [[negative energy]], both bodies follow [[Similarity (geometry)|similar]] elliptic orbits with the same [[orbital period]] around their common [[barycenter]]. The relative position of one body with respect to the other also follows an elliptic orbit.

Examples of elliptic orbits include [[Hohmann transfer orbit]]s, [[Molniya orbit]]s, and [[tundra orbit]]s.