This type of configuration occurs when two planets are in opposition (180° apart) from each other and both are square (90° apart) from a third planet. This third planet, known as the focal planet or apex, is situated around the midpoint of the opposition. All three aspects should be within an acceptable orb of each other (8°). The tension and awareness created by the two planets in opposition must be resolved by the planet receiving the double square. This third planet becomes a focal point of much importance in your chart.

 

Square aspects typically indicate that one will face challenges, obstacles and difficulties, and therefore the T-square embodies this and has traditionally been considered as being inauspicious. However, the T-Square configuration can also be viewed as imparting a strong driving ambition and ability to overcome a situation to the individual embodied by the planets and houses embodied by the T-Square. Living with the demands of a T-square can be very challenging, but when the energy of this configuration is well-directed by a mature individual, it often leads to significant accomplishments.

 

When a transiting planet passes through the spot in opposition to the focal point or apex, then the T-Square becomes a Grand Cross. The duration of the effects of this transit depend on the speed of the transiting planet. For the faster moving planets (Moon, Mercury), the effects would last for minutes or hours. Whereas for the outer planets, the effects might last for days, weeks or more.