Mean longitude

In astrodynamics or celestial dynamics mean longitude is the longitude at which an orbiting body could be found if its orbit were circular and its inclination were zero. The mean longitude changes at a constant rate over time. The only times when it is equal to the true longitude are at periapsis and apoapsis.

[edit] Calculation

The mean longitude $L\,$ can be calculated as follows:

$L=M + \bar{\omega} = M + \Omega + \omega\,$

where:

v • d • e

Types

General	Box · Capture · Circular · Elliptical / Highly elliptical · Escape · Graveyard · Hyperbolic trajectory · Inclined / Non-inclined · Osculating · Parabolic trajectory · Parking · Synchronous (semi · sub)

Geocentric	Geosynchronous · Geostationary · Sun-synchronous · Low Earth · Medium Earth · Molniya · Near-equatorial · Orbit of the Moon · Polar · Tundra

Other	Areosynchronous · Areostationary · Halo · Lissajous · Lunar · Heliocentric · Heliosynchronous

Parameters

Classical				Other
$i\,\!$	Inclination	$\omega\,\!$	Argument of periapsis	$\nu\,$	True anomaly	$L\,$	Mean longitude
$\Omega\,\!$	Longitude of the ascending node	$a\,\!$	Semi-major axis	$b\,$	Semi-minor axis	$l\,$	True longitude
$e\,\!$	Eccentricity	$M_o\,\!$	Mean anomaly at epoch	$\epsilon\,$	Linear eccentricity	$T\,$	Orbital period
				$E\,$	Eccentric anomaly

Maneuvers

Bi-elliptic transfer · Geostationary transfer · Gravity assist · Hohmann transfer · Inclination change · Phasing · Rendezvous · Transposition, docking, and extraction