Reference: 13 Steps to Compute Classic Orbital Elements
Seq.  Name  Symbol  Equation 

1.  Distance 
r
 
2.  Speed 
v
 
3.  Radial velocity 
vr
 
4.  Specific angular momentum 
h
 
5.  Magnitude of specific angular momentum  
6.  Inclination  i  
7.  Node line 
N
 
8.  Magnitude of N  
9.  Right Ascension (RA) of ascending node 
Ω
 
10.  Eccentricity vector  
11.  Eccentricity  
12.  Argument of perihelion  
13.  True anomaly. 
ν

Auxilliary Circle is the circumcircle of an orbit. The circle's centercoincides with the orbit's center, and the circle's radius equals the orbit's semimajor axis.
 E=Eccentric Anomaly: Angle originates from elliptical center and starts with line to perihelion.
 a=semimajor axis. For Apollo, a = 1.47 AU
 b=semiminor axis. For Apollo, b = 1.22 AU
 c=focal length. For Apollo, c = 0.82 AU, distance of Sun from orbit center.
 ν=True Anomaly: Angle originates from Sun and starts with line to perihelion.
Source material: Fundamentals of Astrodynamics, by Roger R. Bate, Donald D. Mueller, Jerry E. White. Observing enclosed figures described above, determine areas of certain figures.
ECCENTRIC ANOMALY. If we assume this figure to be a circular sector defined by points, C, P, and A_{CIR}. Points are shown in figure in above table and defined below.
 C is center of Auxiliary Circle which coincides with orbital center.
 P is perihelion of orbit.
 A_{CIR} is Apollo's position superimposed upon Auxiliary Circle as described in preceding text.
 This area is a circular sector and easily computed.
TRUE ANOMALY. The outline of this figure vaguely resembles previous figure but with some significant differences. The three points which define the border of this area are shown in above figure and described below.
 S, Sun, is a focus of the orbit and the apex of the angle ASP.
 P is perihelion of orbit.
 A_{ORB}, Apollo's position in orbit.
 This area is not so easy to compute.
 The enclosing arc is a portion of an ellipse, thus not circular.
 The angle apex is at a focus, not at the center.
MEAN ANOMALY. Observing the above figure which shows both of above, it seems the area of eccentric anomaly must always contain area bounded by true anomaly. Intuitively, it seems there must be a circular sector with area less then that of eccentric anomaly which equals area of the true anomaly figure, a noncircular sector. Once we determine this circular sector, then computing its area would be a simple task.
In fact, Kepler discovered this circular sector and named it, Mean Anomaly. It's computed as follows.
 M = E  e sin E
 M = mean anomaly (radians)
 E = eccentric anomaly (radians)
 e = eccentricity
MEAN MOTION. As the positional vector, r, sweeps out areas during Apollo's orbit, areas per time can be related to motion of Apollo throughout it's elliptical orbit.
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