Non User
Index: > A B C D E F G H I J K L M N O P Q R S T U V W X Y Z	Business Non User Industries Finance Tax

Home > Eccentricity

1 Mathematics

In mathematics, eccentricity is a parameter associated with every conic section, see Conic section#Eccentricity. It can be thought of as a measure of how much the conic section deviates from being circular. In particular,

• The eccentricity of a circle is zero.
• The eccentricity of an ellipse is greater than zero and less than 1.
• The eccentricity of a parabola is 1.
• The eccentricity of a hyperbola is greater than 1.
• The eccentricity of a straight line is infinity.

1.1 Ellipse

For any ellipse, where the length of the semi-major axis is a, and where the same of the semi-minor axis is b, the eccentricity is given by

The eccentricity is the ratio of the distance between the foci ( and ) to the major axis; i.e.

The term linear eccentricity is used for

1.2 Hyperbola

For any hyperbola, where the length of the semi-major axis is a, and where the same of the semi-minor axis is b, eccentricity is given by

1.3 External links

• MathWorld: Eccentricity

2 Astronomy and astrodynamics

In astrodynamics eccentricity of an orbit can be calculated from orbital state vectors as an absolute value of eccentricity vector or using other methods based on orbital energy and angular momentum.

For example, the eccentricity of the Earth's orbitFor other meanings of the term "orbit", see orbit (disambiguation In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. History Orbits were first analyse today is 0.0167. Through time, the eccentricity of the Earth's orbit slowly changes from nearly 0 to almost 0.05 as a result of gravitational attractions between the planets (see graph [1]).

Other values, PlutoPluto is the ninth planet from the Sun in our solar system. Because Pluto is also the smallest planet in our solar system and has a highly eccentric orbit (which takes it inside the orbit of Neptune) there has been some debate regarding whether Pluto shou 0.2488 (largest value among the planets of the Solar System), MercuryMercury is the closest planet to the Sun, and the second-smallest planet in the solar system. Mercury ranges from 0. 5 in apparent magnitude; Mercury is sufficiently "close" to the Sun that telescopes rarely examine it (the greatest elongation is 28. 0.2056, MoonFor other moons in the solar system see natural satellite. For other uses see Moon (disambiguation). The Moon is the only natural satellite of Earth. It has no formal name other than "The Moon" although it is occasionally called Luna ( Latin for moon to d 0.0554. For the values for all planets in one table, see .

Computation from apogee and perogee distance

(Note that when heights above the surface are given, the radius of the central body has to be added.)

2.1 External links

• World of Physics: Eccentricity

3 Mechanics

In mechanical engineering, an eccentric is a wheel that rotates on an axle that is displaced from the focus of the circle described by the wheel—in other words, a mechanical motion that can operate either as a cam or a crank, depending upon how it is driven.

Politics	Business	Finance

Topics: Eccentricity Axis Eccentric Conic Society Hyperbola Planets...

---

EccentricityMathematics In mathematics, eccentricity is a parameter associated with every conic section, see Conic section#Eccentricity. It can be thought of as a measure of how much the conic section deviates from being circular. In particular, The eccentricity of a Eccentric (mechanism)In mechanical engineering, an eccentric (mechanism) is a wheel that rotates on an axle that is displaced from the focus of the circle described by the wheel; in other words, a mechanical motion that can operate either as a cam or a crank, depending upon w Eccentric anomalyThe eccentric anomaly is the angle between the direction of periapsis and the current position of an object on its orbit, projected onto the ellipse's circumscribing circle perpendicularly to the major axis, measured at the centre of the ellipse. In the d Eccentricity vectorIn astrodynamics the eccentricity vector of a conic section orbit is the vector pointing towards the periapsis and with length equal to the orbit's scalar eccentricity. Calculation The eccentricity vector can be calculated from the orbital state vectors a Eccentricity (orbit)In astrodynamics, under standard assumptions any orbit must be of conic section shape. The eccentricity of this conic section, the orbit's eccentricity is an important parameter of the orbit that defines its absolute shape. Eccentricity may be interpreted Eccentricity (mechanics)In mechanical engineering, an eccentric is a wheel that rotates on an axle that is displaced from the focus of the circle described by the wheel; in other words, a mechanical motion that can operate either as a cam or a crank, depending upon how it is dri