Chaturthi, the Day of Ganesha

Chaturthi is the fourth tithi of the bright fortnight. In the fivefold grouping it is a Rikta tithi, one of the days classed as empty or unfavourable for auspicious beginnings, though this general rule is set aside for its own festivals. Its presiding deity is Ganesha, the remover of obstacles, and the fourth tithi is his across the calendar: Vinayaka Chaturthi is kept in the bright fortnight each month, and Ganesh Chaturthi, in the bright fortnight of Bhadrapada, is his great annual festival. The waning-side Chaturthi, Sankashti, is likewise devoted to him. So a tithi the panchanga marks as generally inauspicious is at the same time one of the most sacred to a beloved deity, a reminder that the fivefold rule is a broad convention overridden by devotion.

The apparent contradiction of a Rikta, or empty, tithi hosting a great festival is resolved in classical muhurta theory by a general principle: a day's dedication to a specific deity or a fixed annual observance overrides the tithi's default fivefold character, since the auspiciousness of an established rite rests on scriptural sanction and tradition rather than on the generic timing rules used to select an unspecified undertaking. The same override applies to several other Rikta tithis on this list wherever a major festival falls on them. Ganesha's association with the fourth tithi specifically, rather than with another number, has no single settled explanation in the sources, though commentators sometimes connect it to numerological readings of his name and epithets rather than to any astronomical reasoning.