Editing True longitude

In [[celestial mechanics]], '''true longitude''' is the [[Ecliptic coordinate system#Spherical coordinates|ecliptic longitude]] at which an orbiting body could actually be found if its [[inclination]] were zero.  Together with the inclination and the [[ascending node]], the true longitude can tell us the precise direction from the central object at which the body would be located at a particular time.

==Calculation==
The true longitude {{math|''l''}} can be calculated as follows:<ref name=Moulton_1970>{{cite book|last=Multon|first=F. R.|date=1970|title=An Introduction to Celestial Mechanics|edition=2nd|pages=182–183|location=New York, NY|publisher=Dover}}</ref><ref name=Roy_1978>{{cite book|last=Roy|first=A. E.|date=1978|title=Orbital Motion|page=174|ISBN=0-470-99251-4|location=New York, NY|publisher=[[John Wiley & Sons]]}}</ref><ref name=Brouwer_Clemence_1961>{{cite book|last1=Brouwer|first1=D.|last2=Clemence|first2=G. M.|date=1961|title=Methods of Celestial Mechanics|url=https://archive.org/details/methodsofcelesti00brou|url-access=registration|page=[https://archive.org/details/methodsofcelesti00brou/page/45 45]|location=New York, NY|publisher=[[Academic Press]]}}</ref>

:{{math|1=''l'' = ''ν'' + ''ϖ''}}

where:
*{{math|''ν''}} is the orbit's [[true anomaly]],
*{{math|''ϖ'' ≡ ''ω'' + ''Ω''}} is the [[longitude of the periapsis|longitude of orbit's periapsis]],
**{{math|''ω''}} is the [[argument of periapsis]], and
**{{math|''Ω''}} is the [[longitude of the ascending node|longitude of the orbit's ascending node]],

==References==
{{Reflist}}

{{Orbits}}

{{DEFAULTSORT:True Longitude}}
[[Category:Orbits]]
[[Category:Equations of astronomy]]

{{Astrophysics-stub}}