|
|
| Line 2: |
Line 2: |
| [[File:Kepler1stlaw.png|center|class=shadow|300px]] | | [[File:Kepler1stlaw.png|center|class=shadow|300px]] |
| </div> | | </div> |
| | '''Johannes Kepler''' (b. 1571) |
| | |
| | ''''' Kepler's laws of planetary motion''''' 1609-1619 |
|
| |
|
| 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. |
|
| |
|
|
| |
| 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).
| |
|
| |
|
|
| |
|