A Square is an aspect between two planets that are 90° from eachother.
Aries & Libra are square to Capricorn & Cancer
Taurus & Scorpio are square to Leo & Aquarius
Gemini & Sagittarius are square to Pisces & Virgo

The Square gives friction, challenge and frustration, however it ignites action.
Inorder to find the solution to the endless annoyance one can feel under the square aspect, is by looking at the midpoint of those two planets in this aspect. Than look at the planet that rules over the midpoint.
if the midpoint is calculated in the sign of Virgo, than Mercury becomes the ruler of the midpoint and serves answers to the issues.


Examples 

Saturn in 11th, Capricorn square to Venus in 7th, libra.
The midpoint sits in the sign of Sagittarius in the 9th house.
 This specific square is about testing the structures of the relationship
The solution is Jupiter (ruler of the midpoint)
Look where Jupiter is placed (house & aspect) for better understanding
= By being adventurous & optimistic towards the restrictions, being openminded,
seeing new ways and opportunities to create pleasures. Educating yourself on the issues.

Uranus in 1st, Taurus opposing to Mercury in 7th, Scorpio.
The midpoint sits in the sign of Leo in the 6th house.
 This aspect makes restless, with an electric mind that never stops
The solution is the Sun
Look where the Sun is placed (house & aspect) for better understanding
= If the Sun is placed in the same sign and house of the midpoint than the solutions is to be found by structuring the creative expressions that result out of the busy mind,
finding ways to translate the ideas into creativity and incorporate them into the daily routine.

Mars in 8th, Aries square to Uranus in 5th, Capricorn.
The midpoint sits in the sign of Aquarius in the 7th house.
 This aspect brings sexual frustrations
The solution is the placement of Uranus & Saturn (house & sign)
= By being openminded and innovative (Uranus) with a steady (Saturn) approach

Mercury in 10th, Gemini square to Moon in 7th, Pisces.
The midpoint sits in the sign of Aries in the 9th house.
 This aspect bring difficulty in expressing & communicating emotions
The solution is Mars (house & sign)
= Find courage, be assertive, maybe be more physical and active


Type of Square

What i didn’t mention is the modality of the signs involved.
When you’re dealing with a square aspect it’s either one of these :
• Cardinal square 
• Fixed square 
• Mutable square 

A Cardinal square will bring new beginnings through letting go of the old.

A Fixed square will bring slow growth to the situation in which patience is a necessary element. Rushing through the square won’t benefit you on the long run. This square is here to ignite action in areas that need a solid foundation.

A Mutable square will bring change when you open your mind for new perspectives, by moving with the flow and improving your approach.

• Cardinal = Birth, initiating
• Fixed = Maintaining, stability, patience, steady, foundations
• Mutable = Adjusting, improvising, spreading, change

• Fire = Action, creation,  teaching, attitudes
• Earth = Effort, sustaining, steady
• Air = Communication, diplomacy, perspective
• Water = Processing, nurture, intense, essence