The symbol index is arranged alphabetically, giving English and then Greek symbols. Astrological symbols appear immediately following the English alphabet. The final portion of the index consists of the most commonly used subscripts. The section and equation numbers appearing in the central column refer to the first use of that symbol. Where one symbol has several distinct usages, each meaning is given with a section reference. For subscripted symbols that do not appear in the main body of the symbol index, the meaning may be determined by looking up the symbol and subscript in the separate portions of the index.
A 
Sec. 8.3 
Apocenter 
A 
Sec. 6.4 Eq. (6.4.13) 
Variable of substitution 
a 
Sec. 2.1 
Length of semimajor axis 
Sec. 6.4 
Point label  
Sec. 7.2 
Variable of substitution  
B 
Sec. 5.3 
Magnetic field 
B_{Tp} 
Sec. 19.2 
The transplanetary magnetic field (the magnetic field strength in the region of space outside Pluto) 
B 
Sec. 6.4 Eq. (6.4.14) 
Variable of substitution 
b 
Sec. 4.3 
Point label 
Sec. 7.2 
Variable of substitution  
C 
Sec. 2.1 Eqs. (2.1.1)(2.1.3) 
Orbital angular momentum per unit mass 
C_{M} 
Sec. 2.1 
Orbital angular momentum 
Sec. 13.1, Eq. (13.1.1) 
Spin angular momentum  
c 
Sec. 5.3 
Velocity of light 
Sec. 6.4 
Point label  
Sec. 7.2 
Variable of substitution  
D 
Sec. 6.7, Eq. (6.7.4) 
Net transport of guiding centers 
d 
Sec. 8.3 
Point label 
Sec. 21.8 
Distance between electrodes  
E 
Sec. 4.3, Eqs. (4.3.4)(4 3 5) 
Proper eccentricity 
Sec. 5.3 
Electric field  
Sec. 9.3 
East  
E_{ion} 
Sec. 21.4.3, Eq. (21.4.4) 
The value of the electric field at which discharge and ionization of gas become possible 
E_{} 
Sec. 15.3 
Electric field parallel to the magnetic field 
e 
Sec. 2.1 
Eccentricity 
Sec. 5.5 
2.718 (the base of the natural logarithms)  
Sec. 15.3 
Charge on the electron  
F 
Sec. 17.2, Eq. (17.2.4) 
Sum of the gravitational, centrifugal, and electromagnetic forces per unit mass 
f 
Sec. 3.2 
Force per unit mass 
f_{ap} 
Sec. 6.4, Eq. (6.4.3) 
Force per unit mass due to apparent attraction to the guiding center of motion 
f_{B} 
Sec. 17.2 
Electromagnetic force per unit mass 
f_{c} 
Sec. 3.2, Eq. (3.2.2) 
Centrifugal force per unit mass 
f_{G} 
Sec. 3.2 
Force per unit mass due to gravitation 
f_{per} 
Sec. 6.4, Eq. (6.4.4) 
Force per unit mass due to a gravitational perturbation 
f_{q} 
Sec. 5.3 
Electromagnetic force per unit mass 
f_{t} 
Sec. 18.3, Eq. (18.3.2) 
Tidal force per unit mass 

Sec. 5.5 
Force per unit mass due to impinging energy flux; radiation pressure 
G 
Sec. 2.1 
Universal gravitational constant 
g 
Sec. 4.3 
Absolute visual magnitude 
Sec. 8.2 
Acceleration due to Earth's gravitationa field  
h 
Sec. 2.2 
Height above a specified surface 
Sec. 9.2 
Height of tides on a celestial body  
I 
Sec. 4.3, Eqs. (4.3.6)(4.3.7) 
Proper inclination 
Sec. 15.4 
Electric current  
i 
Sec. 2.1 
Orbital inclination to the ecliptic plane 
i_{eq} 
Sec. 2.2 
Inclination of equator to the orbital plan. 

Sec. 13.6 
Inclination of spin axis to the orbital plane 
K 
Sec. 11.2, Eq. (11.2.3) 
Constant, in cm/g 
Sec. 23.2 
Constant, in units of mass  
K_{r} 
Sec. 3.3, Eq. (3.3.9) 
Constant, in radians 
K_{z} 
Sec. 3.3, Eq. (3.3.17) 
Constant, in radians 
k 
Sec. 6.8 
Boltzmann's constant 
L 
Sec. 1.4, Eq. (15.1.1) 
Critical hydromagnetic parameter 
Sec. 8.5 
Lagrangian points one and two  
Sec. 16.3 
Electrostatic double layer  
Fig. 16.3.1  
Sec. 26.3 Eq. (26.3.2) 
Latent heat of fusion  
L_{4}, L_{5} 
Sec. 20.5 
Lagrangian points four and five 
l 
Sec. 8.2 
Length of a simple pendulum or the radial distance of a secondary body describing circular motion about a primary body. 
Sec. 15.1 
Length (linear extent of medium) 
M 
Sec. 4.1 
Mass of a macroscopic body 
MB 
Sec. 16.4 
Total mass of plasma suspended by the magnetic field at any one given time 
M_{H2O} 
Sec. 26.4, Eq. (26.4.2) 
Mass of water released by impacting planetesimals 
M_{j} 
Sec. 12.5 
Mass of a jet stream 
m 
Sec. 5.4 
Mass of a small particle or grain 
m_{a} 
Sec. 11.2 
Mass of an atom 
m_{e} 
Sec. 21.9 
Mass of the electron 
m_{H} 
Sec. 11.2 
Mass of the hydrogen atom 
m_{per} 
Sec. 6.4, Eq. (6.4.4) 
Small mass introducing a perturbative gravitational force 
N 
Sec. 4.3 
Number function 
Sec. 9.3 
North  
N 
Sec. 6.7 
Number density 
n 
Sec. 2.2 
Index of numeration 
Sec. 3.3 Eq. (3.3.15) 
The integers  
O 
Sec. 4.3 
The center or origin of motion 
P 
Sec. 8.3 
Pericenter 
P_{B} 
Sec. 15.1 
Magnetic permeability 
P_{0} 
Sec. 4.3, Eq. (4.36) 
Forced oscillation 
p 
Sec. 4.3 
Albedo 
p_{0} 
Sec. 4.3, Eq. (4.3.4) 
Forced oscillation 
Q 
Sec. 9.2 
An inverse function of the angle which a tidal bulge makes with respect to the tideproducing body 
Sec. 16.3 
Charge passing through a circuit during a given interval of time 
Q_{0} 
Sec. 4.3, Eq. (4.3.7) 
Forced oscillation 
q 
Sec. 2.5 
Ratio of the orbital distances of the innermost and outermost orbiting bodies in one group of secondary bodies 

Sec. 5.3 
Electric charge 
q_{n} 
Sec. 2.2 
Ratio of the orbital distances of adjacent secondary bodies 
q_{0} 
Sec. 4.3, Eq. (4.3.5) 
Forced oscillation 
R 
Sec. 2.2 
Radius of a solid body 
R_{G} 
Sec. 12.3, Eq. (12.3.4) 
Radius of growing embryo at transition point between nongravitational accretion and gravitational accretion 

Sec. 2.2 
Radius of gyration; inertial radius 
r 
Sec. 2.4 
Orbital radius 
Sec. 3.2 
Radial direction  
r_{B} 
Sec. 23.2, Eq. (23.2.2) 
Distance from the central body to a point on a magnetic field line from the dipole magnetic field of that body 
r_{ion} 
Sec. 21.4, Eq. (21.4.1) 
Ionization distance (radial distance at which infalling matter can become ionized) 
r_{L} 
Sec. 11.2, Eq. (11.2.4) 
Distance from a secondary body to its interior or exterior Lagrangian points one and two 
r_{min} 
Sec. 23.9, Eq. (23.9.6) 
Minimum value of orbital radius of condensed matter which is in orbit around the primary body 
r_{MR} 
Sec. 18.3 
The Modified Roche Limit (the radial distance at which matter orbiting a primary body cammot accrete to form a secondary body due to the tidal force of the primary) 
r_{orb} 
Sec. 2.1 
Radial distance from primary body to orbiting secondary body 
r_{per} 
Sec. 6.4, Eq. (6.4.4) 
Radial distance of the perturbing mass m_{per} from the guiding center of motion of another mass. 
r_{R} 
Sec. 18.3 
The Roche limit (the radial distance at which the tidal force of the primary exceeds the selfgravitational force of the secondary) 
r_{rel} 
Sec. 21.13.3 
Orbital distance at which ionization can take place for matter falling through a corotating plasma 
r_{s} 
Sec. 17.2, Eq. (17.2.13) 
Radius of the surface which is the demarcation for plasma falling in toward the central body or falling into the equatorial plane 
r_{syn} 
Sec. 23.9 
Orbital radius of a synchronous satellite; i.e., a satellite revolving with orbital velocity equal to the rotational velocity of its primary 
r_{Tp} 
Sec. 19.2, Eq. (19.2.2) 
The maximum radial distance at which angular momentum transfer from the Sun has ever occurred; furthest extension of the transplanetary magnetic field. 
S 
Sec. 6.4, Eq. (6.4.3) 
Displacement from the guiding center of motion of the particle executing that motion 

Sec. 9.3 
South 
s 
Sec. 16.3 
Arc length 
T 
Sec. 2.1 
Sidereal period of revolution 
T_{e} 
Sec. 5.5, Eq. (5.5.10) 
efolding time (the time in which the value of a given parameter changes by a factor of e (2.718)) 
T_{gy} 
Sec. 5.4 
Period of gyration 
T_{gz} 
Sec. 2.2 
Sidereal period of revolution of a grazing satellite; i.e., a secondary body having an orbit of semimajor axis equal to the radius of the primary body 
T_{ion} 
Sec. 23.1 
Orbital period of a body orbiting at the ionization distance r_{ion} 

Sec. 4.3 
Period of variation in the proper elements of asteroid orbital motion 
T 
Sec. 6.8 
Temperature 
T_{e} 
Sec. 17.3 
Electron temperature 
T_{i} 
Sec. 17.3 
Ion temperature 
t 
Sec. 3.3 
Time 
t_{a} 
Sec. 12.3 
Time of accretion (time at which an accreting embryo would attain an infinite radius) 
t_{c} 
Sec. 12.6, Eq. (12.6.6) 
Time of catastrophic increase of an accreting embryo 
t_{es} 
Sec. 2.2 Eq. (2.2.3) 
"Time of escape" (the ratio of the radius of a body to its escape velocity) 
t_{I} 
Sec. 16.3, Eq. (16.3.5) 
Duration of a current flow 
t_{inf} 
Sec. 12.4 
Infall time (duration of infall of matter into the solar system) 
t_{j} 
Sec. 12.5, Eq. (12.5.8) 
Time at which the small radius of a contracting jet stream would reach zero 
t_{res} 
Sec. 16.5 
Residence time (the interval in which matter resides in the plasma state) 
t_{v} 
Sec. 6.8 
Time between occurrence of collisions; inverse of collision frequency 
U 
Sec. 12.2, Eq. (12.2.3) 
Volume of a toroidal jet stream 
u 
Sec. 6.8 
Relative velocity; "internal velocity" of a jet stream 
V 
Sec. 5.4 
Electrostatic potential; voltage 
v_{b} 
Sec. 21.8 
Burning voltage 
V_{Ion} 
Sec. 15.3 
Ionization voltage 
v 
Sec. 5.5 
Velocity 
v_{crit} 
Sec. 15.3, Eq. (15.3.1) 
Critical velocity at which an infalling atom can become ionized 
Sec. 21.8 
The experimental value of relative velocity of a plasma and a gas at which increased ionization occurs. 
v_{es} 
Sec. 2.2, Eq. (2.2.2) 
Escape velocity 
v_{imp} 
Sec. 12.10, Eq. (12.10.1) 
Impact velocity 
v_{ion} 
Sec. 21.4, Eq. (21.4.1) 
The value of infall velocity at which ionization of infalling matter can take place 
v_{m} 
Sec. 12.12, Eq. (12.12.1) 
Velocity capable of imparting sufficient kinetic energy to melt a specified mass 
v_{orb} 
Sec. 2.1 
Orbital velocity of secondary body 
v_{rel} 
Sec. 21.13, Eq. (21.13.3) 
Relative velocity 
W 
Sec. 8.2 
Energy (potential and/or kinetic) 
Sec. 9.3 
West  
W_{m} 
Sec. 12.12 
Energy needed to melt a specified mass 
W_{T} 
Sec. 17.3 
Thermal energy 
w 
Sec. 9.2 
Energy dissipation; power 
w_{T} 
Sec. 12.10, Eq. (12.10.2) 
Thermal power per unit surface area delivered by impacting mass 
X 
Sec. 13.4, Eq. (13.4.3) 
Variable of substitution 
x 
Sec. 3.2 
Rectilinear coordinate Iying in the horizontal plane 
Sec. 12.2 
Small radius of a toroidal jet stream  
x_{0} 
Sec. 6.4 
Magnitude of the x axis of the epicycle described about a guiding center 
Y 
Sec. 13.4, Eq. (13.44) 
Variable of substitution 
y 
Sec. 3.2 
Rectilinear coordinate Iying in the horizontal plane 
Z 
Sec. 13.3, Eq. (13.34) 
Variable of substitution 
z 
Sec. 3.2 
Rectilinear coordinate in the axial direction 

Sec. 2.3, Fig. 2.3.1 
Sun 

Sec. 2.1, Table 2.1.1 
Mercury 

Sec. 2.1, Table 2.1.1 
Venus 

Sec. 2.1, Table 2.1.1 
Earth 

Sec. 2.1, Table 2.1.1 
Moon 

Sec. 2.1, Table 2.1.1 
Mars 

Sec. 2.1, Table 2.1.1 
Jupiter 

Sec. 2.1, Table 2.1.1 
Saturn 

Sec. 2.1, Table 2.1.1 
Uranus 

Sec. 2.1, Table 2.1.1 
Neptune 

Sec. 2.1, Table 2.1.1 
Pluto 

Sec. 17.5 
Ascending node 

Sec. 17.5 
Descending node 

Sec. 6.8 
Dimensionless proportionality factor 
Sec. 7.2, Eq. (7.2.4) 
Dimensionless constant  

Sec. 2.2 
Ratio of radius of gyraffon to equatorial radius of body 

Sec. 2.2 
Normalized moment of inertia (moment of inerffa per unit mass and unit radius squared) 

Sec. 7.2, Eq. (7.2.5) 
Dimensionless constant 

Sec. 11.2 
Dimensionless proportionality factor 

Sec. 21.2, Eq. (21.2.1) 
Specific gravitational potential of secondary body with respect to the primary body 

Sec. 21.4, Eq. (21.4.2) 
Value of gravitational potential at which infalling matter can become ionized 

Sec. 5.5, Eq. (5.5.4) 
Dimensionless proportionality factor 

Sec. 7.2, Eq. (7.2.6) 
Dimensionless constant 

Sec. 16.5, Eq. (16.5.1) 
Dimensionless proportionality factor 
Sec. 3.3 
Indicating incremental change  
Sec. 6.7, Eq. (6.7.1) 
Geometrical factor  
Sec. 12.10, Eq. (12.10.6) 
Dimensionless proportionality factor indicating maximum in temperature profile of an accreting embryo  
Sec. 17.3 
Degree of ionization  
Sec. 23.5 
Dimensionless proportionality factor; the normalized distance (the ratio of the orbital radius of a body to the ionization distance for its primary body)  

Sec. 9.2 
An angle 

Sec. 23.1, Eqs. (23.1.4)(23.1.5) 
Dimensionless proportionality factor indicating degree of ionization of infalling matter 

Sec. 9.3 
Viscosity 

Sec. 2.2 
Mean density of a body 

Sec. 8.3 
An angle 
k 
Sec. 8.2, Eq. (8.2.3) 
Constant of integration 

Sec. 3.6, Eq. (3.6.1) 
Dimensionless constant 

Sec. 3.2 
Meridional angle or latitude 
µ 
Sec. 16.3 
Magnetic dipole moment 
µ_{lm} 
Sec. 16.4 
Lower limit of the magnetic dipole moment such that the tangential component of the magnetic field is equal to the magnitude of the total magnetic field strength 
v 
Sec. 6.8 
Collision frequency; number of collisions per unit time 

Sec. 13.1 
Moment of inertia 

Sec. 8.4, Eq. (8.4.1) 
Libration angle 

Sec. 2.1 
3.1415 (ratio of the circumference to the diameter of a circle) 

Sec. 6.8 
Density of dispersed matter 

Sec. 2.4, Eqs. (2.4.1)(2.4.2) 
Distributed density (density of a secondary body's mass when distributed along the orbit of that secondary) 

Sec. 2.1 
Indicating summation 

Sec. 5.5 
Cross section 
Sec. 6.8 
Collision cross section  
Sec. 12.3, Eq. (12.3.1) 
Capture cross section  

Sec. 15.1 
Electrical conductivity 

Sec. 12.7 
Cross section of a jet stream 

Sec. 2.2 
Spin period of a body 

Sec. 9.2, Eq. (9.2.1) 
Oblateness or ellipticity of a body 

Sec. 15.3 
Poloidal magnetic flux 

Sec. 4.3, Eqs. (4.3.4)(4.3 5) 
Longitude of proper perihelion 

Sec. 4.3, Eqs. (4.6)(4.7) 
Longitude of proper node 

Sec. 3.2 
Azimuthal angle or longitude 

Sec. 6.7, Eq. (6.7.5) 
Constant, in number/cm^{3} 
Sec. 11.2, Eq. (11.2.2) 
Constant, in cm K/g  

Sec. 7.2, Eq. (7.2.6) 
Constant, in units of number times a variable power of mass 

Sec. 7.2, Eq. (7.2.4) 
Constant, im units of number times a variable power of radius 

Sec. 7.2, Eq. (7.2.5) 
Constant, in units of number times a variable power of cross section 

Sec. 5.5 
Energy flux 

Sec. 8.2 
An angle 

Sec. 9.3 
Rotational angular velocity 

Sec. 13.3, Eq. (13.3.3) 
Rotational escape velocity 

Sec. 6.4 
Orbital angular velocity 
Subscripts  
.  
c 
Central or primary body 
sc 
Secondary body 
em 
Embryo 
gn 
Grain 
Lm 
Limiting value 
0 
Initial value or parameter values for the guiding center or circular motion 
K 
Denoting orbital parameters for a body describing Kepler (circular) motion 
A 
Apocenter, aphelion, apogee, etc. 
P 
Pericenter, perihelion, perigee, etc. 

Ascending (and descending) node 
x,y,z 
Components in the x, y, and z directions 

Components in the r, , and directions 

Sun, Mercury, Venus, Earth, Moon, Mars, Jupiter, Saturn, Uraus, Neptune, Pluto 