GKO Not Where It Should Be?

[Astronut25]

While I was trying to calculate the SMa for a Semi-Synchronous Orbit for the Mün, I decided to make sure I got it right by calculating an orbit that I already knew (GKO @ 3,468,750m per the Wiki), but whenever I crunch the numbers I get 3,468,724m. What did I do wrong?

The Formula:

SMa = CUBEROOT( (GM p^2)/(4À^2) )

The Numbers from the Wiki:

r = 600000 m

p = 21600 s

M = 5.2915793e22 kg

G = 6.673848e-11 m^3 kg^-1 s^-2 (from http://en.wikipedia.org/wiki/Gravitational_constant)

[Fyrem]

so a 6 meter difference? which is the 7th least significant digit. could be that g=6.673848e-11 ... is only 7 digits.

[Fyrem]

sorry, my eyes fooled me, you are actually reporting a 26 meter difference. but I still hold that the G could use some more digits if you are really looking for that kind of accuracy.

[Astronut25]

AFAIK that is all the known digits of G, I played with the uncertainty of ± 8e-17 but that didn't account for the discrepancy.

the actual number is 6.67384e-11 ±8.0e-17

[Deltac]

Quick question, what does GKO stand for?

[JacenHan]

Geosynchronous Kerbin Orbit or thereabouts. GEO is the term used in real life for Geosynchronous Earth Orbit. It means that you are orbiting the object as fast as it rotates, essentially making it look like you are standing still above the object.

[Deltac]

Ah, well, that's where I'm getting confused: Geo means Earth. May I suggest KKO: Keosynchronous Kerbin Orbit? Apokee, Perikee(t), so and and so forth

(note: Half joking, half serious)

[tavert]

A) The wiki might be rounding to the nearest "nice" number

KSP might use hardcoded values for some physical constants that don't match reality. Pretty sure this is the case for standard acceleration due to gravity, maybe true for others.

[Stochasty]

I did some testing, and it seems pretty clear the either the game or the Wiki authors are rounding G to 6.674E-11.

[Jason Patterson]

Ah, well, that's where I'm getting confused: Geo means Earth. May I suggest KKO: Keosynchronous Kerbin Orbit? Apokee, Perikee(t), so and and so forth

(note: Half joking, half serious)

Not the curse of the unnecessary K's! Nooooooo! What's wrong with calling it a synchronous orbit and avoiding all of the alphabet soup excessive use of K foolishness?