Vaidhriti

Vaidhriti is the twenty-seventh and final nityayoga, closing the cycle. Its name is glossed as poor support or divided holding, and it is one of the inauspicious yogas, with Vyatipata, one of the two the tradition marks most strongly for avoidance, sometimes set aside for expiation and charity rather than ordinary activity. The panchanga counts it among the configurations most to be shunned for auspicious undertakings. Reckoned like the others from the summed longitude of Sun and Moon divided into twenty-seven parts, it completes the round before the cycle begins again at Vishkambha. These are the conventions of the calendar tradition, which fixes the malefic character of Vaidhriti; the astronomical basis is only the combined motion of the two lights through the lunar month.

Vaidhriti closes the cycle of twenty-seven immediately before it restarts at Vishkambha, and the two yogas most strongly marked for avoidance, this one and Vyatipata seventeen positions earlier, are sometimes treated together in classical muhurta literature as a linked pair of maximally inauspicious moments bracketing the sequence, comparable in the weight given to their avoidance to the way Vishti among the eleven karanas stands apart from its companions. Of the full twenty-seven nityayogas, nine in total are classed inauspicious in the standard reckoning, Vishkambha, Atiganda, Shula, Ganda, Vyaghata, Vajra, Vyatipata, Parigha and Vaidhriti itself, exactly a third of the set, with the remaining eighteen read as favourable to varying degrees.

A yoga is arrived at by addition, which sets it apart from every other reckoning in the almanac. Where the tithi measures the Moon's separation FROM the Sun, the yoga measures the two longitudes ADDED together, and cuts the resulting circle into twenty seven equal arcs of thirteen degrees twenty minutes. Vaidhriti is the arc from 346 degrees 40 minutes to 360 degrees 00 minutes of that sum. The sum climbs at roughly fourteen degrees ten minutes a day, so a yoga runs about twenty two and a half hours on average, a little shorter than a tithi, and like a tithi it can be skipped between two sunrises or carried across two of them.

The twenty seven arcs are the same width as the twenty seven nakshatras, and Vaidhriti is the twenty seventh arc of the grid in both schemes, which is why the two are often tabulated side by side. They are not the same thing and share nothing but their arithmetic: a nakshatra is a segment of the sky the Moon is physically standing in, while a yoga is a number derived from two positions and belongs to no part of the sky at all. Reading a yoga as a star group is the commonest confusion the term invites, and the shared name of the twenty seventh position, Revati, is where it usually starts.

Vaidhriti is one of the two yogas the almanac singles out beyond the ordinary auspicious and inauspicious grouping. Vyatipata and Vaidhriti are together called the maha pata yogas, and they are marked in almanacs that mark nothing else about the yoga at all: many printed panchangas carry the yoga column purely so that these two can be found. Both fall where the sum of the longitudes reaches a value the tradition treats as a break rather than a transition, and both are held to make the whole day unsuitable for anything undertaken for the first time.