How can I use the Newton Method to find the eccentric anomaly for Mars?

  • Thread starter Thread starter smmSTV
  • Start date Start date
AI Thread Summary
To compute the Eccentric Anomaly (E) for Mars using the Newton Method, start with Kepler's equation, reformulated as M = E - e*sin(E). Implement the iterative formula E_{n+1} = E_{n} - f(E)/f'(E), where f(E) = E - e*sin(E) - M and f'(E) = 1 - e*cos(E). Initialize E with a value, such as 0 at perihelion, and update it in each iteration until the convergence criterion, f(E)/f'(E) < 0.00001, is met. Additionally, the distance of Mars from the sun can be calculated using r = a * (1 - e^2) / (1 + e * cos(TA)), where TA is the True Anomaly and a is the Semi-Major Axis. This approach will help generate the required table for the astronomy class.
smmSTV
Messages
2
Reaction score
0
So I'm in need of some more help for my astronomy class again.
My professor wants us to write a program that outputs a table with the distance of Mars from the sun (r) and it's true anomaly. The problem is that i need to compute the Eccentric Anomaly (E) from the Mean Anomaly (M). Kepler's equation is E = M + εsin(E), but I can't get it down in terms of E. Seeing as how I'm using c++, it is kind of a necessity. One website seemed to have an equation involving Einitial and Efinals, but it didn't do me any good. Is the idea to set the original Einitial equal to 0 at t=0 (the perihelion point) and find E final in terms of that? At the end of each iteration (I'm running a while loop) the Eintial of the next iteration would be set to the Efinal of the current loop. Anybody got any ideas? Thanks
 
Astronomy news on Phys.org
The correct equation is M = E - e*sin(E)

Solve using the Newton Method:

E_{n+1} = E_{n} - \frac{f(E)}{f&#039;(E)}
where f(E) = E - e * sin(E) - M
and f'(E) = 1 - e * cos(E)

Loop the above equations until:
\frac{f(E)}{f&#039;(E)} &lt; 0.00001Or some substantially low number not zero.

Also,r = \frac{a * (1 - e ^ 2)}{(1 + e * cos(TA))}
where TA - True Anomaly
and a - Semi-Major Axis of Mars
 
Last edited:
This thread is dedicated to the beauty and awesomeness of our Universe. If you feel like it, please share video clips and photos (or nice animations) of space and objects in space in this thread. Your posts, clips and photos may by all means include scientific information; that does not make it less beautiful to me (n.b. the posts must of course comply with the PF guidelines, i.e. regarding science, only mainstream science is allowed, fringe/pseudoscience is not allowed). n.b. I start this...
Asteroid, Data - 1.2% risk of an impact on December 22, 2032. The estimated diameter is 55 m and an impact would likely release an energy of 8 megatons of TNT equivalent, although these numbers have a large uncertainty - it could also be 1 or 100 megatons. Currently the object has level 3 on the Torino scale, the second-highest ever (after Apophis) and only the third object to exceed level 1. Most likely it will miss, and if it hits then most likely it'll hit an ocean and be harmless, but...

Similar threads

Back
Top