Orbit angle

[Aniruddh]

I'm writing a program that finds the distance between two spacecraft in ksp using the cosine rule. This is a quick question about orbital elements- which orbital element denotes the current angle of the planet/spacecraft around the orbit? Is that the mean anomaly? Thanks.

[Vanamonde]

There is a term for that. Which I do not remember. But the folks in the Science sub will, and so your question has been moved. 

[RealKerbal3x]

@Aniruddh Isn't it the inclination? Unless I'm misinterpreting your question.

[Aniruddh]

4 minutes ago, RealKerbal3x said:

@Aniruddh Isn't it the inclination? Unless I'm misinterpreting your question.

Inclination is the orbital equivalent of latitude, the one I'm looking for is the orbital equivalent for current longitude of the spacecraft. I'll try find a diagram to make it clearer.

[HebaruSan]

Referring you to everyone's favorite wikipedia graphic...

I believe what you want (for comparing two bodies in different orbits) is the longitude of the ascending node plus the argument of periapsis plus the true anomaly. Note that I believe some of those are in degrees while others are in radians, so some conversion is needed.

https://github.com/HebaruSan/Astrogator/blob/9e27f1e9653ed6cee22a36934eb24df81a6a976b/src/PhysicsTools.cs#L135-L164

[Aniruddh]

The Wikipedia graphic is really good! For some reason I didn't realise that orbits are 3d, which means I'd have to use multiple angles rather than a single angle. I just found out the game uses vectors as well which are easier to use than angles & the cosine rule, to find distances in 3d between 2 vessels.

I might still have to use the cosine rule later in the plugin I'm creating, but for now I'm good. Thank you all for the explanations.