In the past day we had some astrological transits, as we always do. We have to keep up with the score, the universe is always in flux, something is always in motion and getting into an aspect with something else.
Today the lunar phase was 1st Quarter, which means the MOON was squaring the Sun. This happens twice in every month. So it's not rare. But on this occasion, it involved a Sun opposition to Jupiter, approaching. This added another Moon square. Thus a T-square formed. That is called an aspect pattern.
Meanwhile, the Sun was already in a slower-paced aspect pattern. Sun was quincunx to Pluto and quincunx to Neptune from the "other side" of the opposition axis. Therefore we have two aspect patterns which are overlapping. This creates a configuration of planets which are in a more complicated pattern (having no name). This is very rare and also very fleeting. If many planets are involved, it is more likely that it goes out of the pattern quicker.
What does this pattern mean, how can we interpret it? Of course you want to know. But it cannot be easily explained here. It works more in a practical sense when these planets are compared within another chart. It has to be affecting a pre-existing chart, usually a natal chart.
In general, what is a T-square aspect pattern? It brings a conflict between the two planets in the opposition, with the planet squaring the other two as the mediator or the instigator. In this case, it is the powerful Moon.
Take a look at these astrological images which are snipped from astro-charts, that handy website...