In A Nutshell: What Happens ON the Sun; Happens TO the Earth

One of the More Profound Insights regarding how the Sun Affects the Inhabitants of Earth
must be attributed to Maurice Cotterell
and his explanation of why we have:

12 Astroglogical Sun Signs

representing

12 different Personality Types

comprised of:

4 Different Groups of Commonality

THE SUN'S "CYCLE OF EXPOSURE"



At Its Equator:  the Sun Rotates completely
Once Every 26 Days

The Sun has a cycle that exposes its full face at each turn

and

that "face" has 4 Quadrants

... formed by the Sun's Equator being
Perpendicular to its Polar Axis

Each Quadrant exposes the Earth to Solar Radiation.

BUT:  Here on Earth ...

we only get exposed to "3"  parts of the Sun's Radiation at a time.

As a result;  during its
"Cycle of Exposure" to the Earth: 

it  takes 12 of these combinations of
"3 quadrants at a time" 
before the Sun gets to present the Earth with 
all of its 4 quadrants or faces during its 26 day cycle.

Three Different  Sides of the Sun Face Us Every 26 Days


Astrologically, we refer to these Mutations as:

THE 12 ZODIACAL SIGNS


We call the Four Faces of the SUN:

QUADRUPLICITIES 
(or 4 Elements)

[ Fire - Water - Air - Earth ]


We call the "3" Sides of the Sun that Face us each 26 Days:

TRIPLICITIES 
( or 3  Modalities of Expression;  also called The Qualities)

[ Cardinal - Fixed - Mutable ]

Note:  Both the Triplicities & Quadruplicites are determined by what sign a planet is in

Note :  A 26 Day Cycle of the Sun
would result in 13.8 months in a year.

It is interesting that there have been many
Astrologers who say there are in fact
"13" Zodiac Signs ... or should be. 

One author calls the 13th sign:  "Arachne"

For a more scholarly explanation of the Sun's cycles
and why there are 12 Sun Signs:

Here is a link to  →  Maurice Cotterell's Website