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Concept

Orbital Eccentricity

Orbital Mechanics and Spaceflight Engineering

Orbital eccentricity is a dimensionless parameter describing how much an orbit's shape deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 describe an ellipse, exactly 1 describes a parabolic escape or capture trajectory, and values greater than 1 describe a hyperbolic trajectory that will never return. It is one of the six classical orbital elements, alongside inclination, and follows directly from Johannes Kepler's description of planetary orbits as ellipses.

Facts
Concept Domain
Orbital Mechanics 1
Formulated Year
1609 1
Proposed By
Johannes Kepler 2
Kepler's first law, published in Astronomia Nova (1609), established that planetary orbits are ellipses rather than circles, which is what eccentricity quantifies.
Connections

Associated With

Apsis, Concepts
Heliocentrism, Concepts
Source Wikipedia (space and spaceflight articles)
Johannes Kepler, Pioneers
Source Wikipedia (space and spaceflight articles)
Additional Source Astronomia nova (Wikipedia)Astronomia nova article, lead section
Milankovitch Cycles, Concepts
Orbital Inclination, Concepts
Source Wikipedia (space and spaceflight articles)
Orbital Mechanics, Concepts
Source Wikipedia (space and spaceflight articles)
Sources
1. Wikipedia (space and spaceflight articles)
Wikimedia Foundation
  • Associated With: Orbital Mechanics
  • Associated With: Heliocentrism
  • Associated With: Orbital Inclination
View the Source
2. Encyclopedia Britannica: Space Exploration
Encyclopedia Britannica, Inc.View the Source
Orbital eccentricity (Wikipedia)
  • Orbital eccentricity, lead section
    A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic (escape orbit or capture orbit), and greater than 1 is a hyperbola.
  • In Group: Orbital Elements and Celestial Mechanics, Lead sentence
    In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle.
View the Source
Astronomia nova (Wikipedia)
Astronomia nova article, lead section
Quote, Astronomia nova article, lead section
is a book, published in 1609, that contains the results of the astronomer Johannes Kepler's ten-year-long investigation of the motion of Mars.
View the Source

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