Trigonometry related to Kepler's Equation

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SUMMARY

This discussion focuses on the derivation of Kepler's Equation, specifically the role of trigonometric functions in calculating the true anomaly (nu). The conversation highlights the importance of using the correct equations, particularly the first two equations, to compute 1 + cos(nu) and sin(nu)/(1 + cos(nu), which simplifies to tan(nu/2) using the half-angle formula. Participants emphasize the need for clarity in notation and the utility of provided resources, such as a PDF attachment and an external blog link for further understanding.

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  • Understanding of Kepler's Equation and its significance in celestial mechanics.
  • Familiarity with trigonometric identities, particularly the half-angle formula.
  • Basic knowledge of the true anomaly (nu) and its role in orbital mechanics.
  • Ability to interpret mathematical notation and LaTeX formatting.
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  • Study the derivation of Kepler's Equation in detail, focusing on trigonometric applications.
  • Learn about the half-angle formula in trigonometry and its implications in orbital calculations.
  • Explore resources on celestial mechanics and the significance of true anomaly in orbital dynamics.
  • Review LaTeX formatting for mathematical expressions to enhance clarity in communication.
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Astronomers, physicists, mathematicians, and students studying celestial mechanics or trigonometry who seek to deepen their understanding of Kepler's Equation and its derivation.

solarblast
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In deriving Kepler's Equation, there's a little trig work that gets at nu (see figure), which is the true anomaly. I'm curious how the third equation makes it into the 4th (last) equation. It's been a very long time since I've played with trig. nu of course is the atan of the last equation.
 

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solarblast said:
In deriving Kepler's Equation, there's a little trig work that gets at nu (see figure), which is the true anomaly. I'm curious how the third equation makes it into the 4th (last) equation. It's been a very long time since I've played with trig. nu of course is the atan of the last equation.


You should write down, with LaTeX, directly the equations here so that it'll be possible to check the notation and give, eventually, and answer, otherwise

it is way too cumbersome.

DonAntonio
 
See <http://rip94550.wordpress.com/2011/05/02/elliptical-orbits-%E2%80%93-deriving-keplers-equation/>. Attached is the part I was looking for.
 

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Last edited by a moderator:
You're using the wrong equation as the source. Use the first two. From the second, compute 1+\cos\nu. Next compute sin\nu/(1+\cos\nu). This is just \tan(\nu/2) per the half angle formula. Use the same formula to simplify the right hand side.
 
What source are you referring to? The link or one of the equations in the attachment? The link is 10 pages long.
 
Last edited:
I'm referring to the attachment in your first post.
 
Ah, that was produced by a CM "pdf book" on the web. I'm satisfied with the longer attachment. I may contact the author of the pdf.
 

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