Skip to content
Series 6 · Fasts & Observances

Astronomical Fasts & Observances

The astronomical principles behind sacred fasting days and cosmic cycles: Ekadashi, Pradosham twilight, Amavasya, Pournami, and Sankatahara Chaturthi.

Part 1
⏱️ 5 min read Intermediate

Ekadashi Fasting & Parana: The 11th Lunar Phase Science

How the 120°–132° lunar elongation defines the Ekadashi fast, the Harivasara rule, and the morning Parana break-fast window.

Read Guide →
Part 2
⏱️ 4 min read Beginner

Pradosham Explained: The Sacred Sunset Twilight Window

The astronomical calculation of the 3.75 Ghatika (90-minute) sunset sandhya on Trayodashi tithi, harmonizing Sri Lakshmi Narasimha twilight prayers and Shiva-Nandi worship.

Read Guide →
Part 3
⏱️ 5 min read Beginner

Amavasya & Pournami: The Astronomical Extremes of Lunar Syzygy

New Moon conjunction (0°) vs Full Moon opposition (180°): ocean tides, moonlit traditions, and ancestral tharpanam timing.

Read Guide →
Part 4
⏱️ 4 min read Intermediate

Sankatahara Chaturthi: The Moonrise Calculation Mystery

Why Sankatahara Chaturthi depends strictly on Moonrise during Krishna Chaturthi, leading to different calendar dates across cities.

Read Guide →
Part 5
⏱️ 6 min read Beginner

Thai Pongal & Makara Sankranti: Solar Ingress, Science & Rituals

The astronomical science of the Sun entering Makara Rasi, the sacred moment of Pongal boiling, and practical diaspora adaptations.

Read Guide →
Part 6
⏱️ 6 min read Beginner

Puthandu (Tamil New Year): Mesha Sankranti, Vishu Kani & Rituals

The astronomical science of the Sun entering 0° Aries, the sacred dawn Vishu Kani viewing, and the philosophy of 6-taste Mangai Pachadi.

Read Guide →
Part 7
⏱️ 6 min read Beginner

Deepavali & Ganga Snanam: Arunodaya Oil Bath, Science & Rituals

Why Tamil Deepavali is celebrated at pre-dawn Arunodaya (Krishna Chaturdashi), the sacred oil bath invokes Lakshmi and Ganga, and the role of Deepavali Marundhu.

Read Guide →
Part 8
⏱️ 6 min read Beginner

Karthigai Deepam: Cosmic Pillar of Fire, Krittika Star & Agal Vilakku

The astronomy of Karthigai Pournami and the Krittika star (Pleiades), home lamp arrangements, and Tiruvannamalai Maha Deepam.

Read Guide →
Part 9
⏱️ 8 min read Intermediate

Tamil Festivals & Sacred Observances: The Master Nirnaya Guide

Solar sankrantis, nakshatra alignments, and dawn/sunset tithi vyapti: cultural significance, checklists, recipes, and modern diaspora adaptations for all 16 major Tamil festivals.

Read Guide →
Covering 14,654 Cities Worldwide

Your City’s Panchangam, Every Day

Many printed calendars are computed for one town. Nava Panchangam computes sunrise, sunset and the windows that depend on them, such as Rahu Kalam, for your city, with a choice of Vakya or Drik; a tithi’s ending instant is the same everywhere.

Open Live Panchangam →