 a triple conjunction is an astronomical event, where two planets or a planet and a star meet each other three times in a short period either in opposition or at the time of inferior conjunction, if an inferior planet is involved. the visible movement of the planet or the planets in the sky is therefore normally prograde at the first conjunction, retrograde at the second conjunction and again prograde at the third conjunction. the meeting of three planets is referred to as a particular case of syzygy. there are three possible cases of triple conjunctions. == triple conjunctions between mercury and venus ==  at nearly every inferior conjunction there is a triple conjunction between mercury and venus. in most cases the second conjunction is not visible, because both planets have a too small elongation from the sun. triple conjunctions between mercury and venus are also possible, if mercury and venus are at the same time in inferior conjunction. this event is much rarer and the second conjunction between mercury and venus is also invisible. == triple conjunctions of inferior planets with superior planets or stars ==  if mars is in conjunction with the sun, there is often a triple conjunction between mars and mercury or between mars and venus. in the events in which mercury is involved, the second conjunction is invisible because of small elongation from sun; both other events are difficult to see because of the nearness to horizon and the relatively low brightness of mars, which is there always near its greatest distance from earth, barely visible. for a mars-venus triple conjunction all three events can almost always be seen, but mars is dim because of its great distance from the earth. triple conjunctions between the inferior planets mercury and venus and the superior planets jupiter, saturn, uranus, neptune, dwarf planet pluto or with stars take place when these objects are at the same time in conjunction to sun while mercury or venus are at inferior conjunction. frequently the second conjunction takes place when both bodies are too close to the sun in order to be seen, while the other conjunctions are easily visible, especially if the other body is jupiter, saturn or a bright star. with the dim planets uranus, neptune and dwarf planet pluto the visibility of such an event is difficult, because of the low elongation from sun. triple conjunctions of mercury and venus with the exterior planets jupiter, saturn, uranus, neptune, and dwarf planet pluto happen relatively frequently (approximately once in 10 years). during the movement in their inferior conjunction loop mercury and venus are always involved in triple conjunc
Astrological_aspects Astrometry Conjunctions_(astronomy_and_astrology)