Kepler's 1st law: Difference between revisions

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The orbit of every planet is an ellipse with the Sun at one of the two foci.
The orbit of every planet is an ellipse with the Sun at one of the two foci.



Revision as of 09:54, 13 February 2020

Kepler1stlaw.png

The orbit of every planet is an ellipse with the Sun at one of the two foci.


Mathematically, an ellipse can be represented by the formula:

$${e r={\frac {p}{1+\varepsilon \,\cos \theta }},}{\displaystyle r={\frac {p}{1+\varepsilon \,\cos \theta }},}$$

where $$p$$ is the semi-latus rectum, ε is the eccentricity of the ellipse, r is the distance from the Sun to the planet, and θ is the angle to the planet's current position from its closest approach, as seen from the Sun. So (r, θ) are polar coordinates.

For an ellipse 0 < ε < 1 ; in the limiting case ε = 0, the orbit is a circle with the Sun at the centre (i.e. where there is zero eccentricity).


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