Amavasya (new moon) comes every month, but when it falls on a Monday (Somvar), it becomes Somvati Amavasya — one of the rarest and most spiritually significant tithis in the Hindu calendar. It is particularly sacred for ancestral rites.

Why Is Somvati Amavasya Rare?

The lunar calendar month averages about 29.5 days, while the Gregorian week is 7 days. The new moon falls on a Monday roughly once every 5–6 months. In many years, there may be only 1–2 Somvati Amavasyas. This rarity makes each occurrence especially auspicious.

Significance for Pitru (Ancestral) Rites

All Amavasyas are considered sacred for pitru puja — worship of ancestors. But Somvati Amavasya carries additional power because Monday is governed by the Moon (Chandra), which in Vedic astrology represents the mind, emotions, and the ancestral realm. The combination of Moon's day with the Moon's darkest phase creates a powerful opening for ancestral energy.

According to the Skanda Purana, performing tarpan on Somvati Amavasya on the banks of a sacred river is equal to the merit of a full year's worth of pitru karma.

How to Perform Pitru Tarpan on Somvati Amavasya

• Time: Begin before noon, ideally at sunrise or within the Kutup muhurta (midday window).
• Location: A riverbank is ideal. At home, use a clean copper vessel with water.
• Items needed: Sesame seeds (til), kusha grass, water, Gangajal, black flowers (if available), raw milk.
• Sankalpa: State your gotra and the names of ancestors you are offering tarpan for.
• Offering: With both hands cupped (using kusha grass), pour water mixed with sesame seeds toward the south (pitru direction), chanting: OM [ancestor's name] pitarah triptimetu
• Offer three times for each ancestor — father, grandfather, great-grandfather on the paternal side, and similarly on the maternal side.
• After tarpan: Donate food (especially kheer, sesame sweets) to Brahmins or the needy.

Other Observances

• Fast from sunrise to sunset, breaking with only one meal
• Visit a Shiva or Peepal tree temple — the Peepal is considered the abode of ancestors on Amavasya
• Married women perform circumambulation of the Peepal tree for the longevity of their husbands
• Light a sesame oil lamp at home in the evening for pitru shanti