Krishna Tritiya and the Waning Light

Krishna Tritiya is the eighteenth tithi overall, the third day of the dark fortnight. It shares the character of the third tithi, a Jaya day associated with victory and with the goddess Gauri, but the Moon is now clearly waning. The panchanga treats the third tithi of either fortnight as generally favourable. In some regions particular dark-fortnight tithis carry festivals of their own, and the ongoing diminution of the Moon shapes which observances are chosen. These are the calendar tradition's conventions; the astronomical basis is simply the Moon closing the twelve-degree steps back toward conjunction with the Sun, each tithi marking one such step regardless of whether the light is growing or fading.

Gauri's identification with Tritiya persists across the waning fortnight exactly as it does in the bright half, and several regional fasting observances dedicated to her, kept by married women for the wellbeing of their husbands and households, are specifically timed to the dark-fortnight Tritiya in certain months rather than to the more widely known bright-fortnight Akshaya Tritiya, showing that the two Tritiyas of a month are not simply a bright, festive version and a quiet, unremarkable counterpart but each carry their own distinct devotional life in different regional traditions. As with every tithi in the waning half, its real clock-time duration is governed by the same Moon-Sun angular arithmetic as the bright fortnight, unaffected by which half of the month it falls in.