This event is a rare astrological phenomenon that occurs when four or more planets align in a cross formation. During a Planetary Grand Cross of Mercury, the planet Mercury is at the center of the cross, with the other planets forming the four points of the cross. This alignment can bring about
From Wikipedia
In planetary astronomy, the grand tack hypothesis proposes that Jupiter formed at a distance of 3.5 AU from the Sun, then migrated inward to 1.5 AU, before reversing course due to capturing Saturn in an orbital resonance, eventually halting near its current orbit at 5.2 AU. The reversal of Jupiter's planetary migration is likened to the path of a sailboat changing directions (tacking) as it travels against the wind.