A · Canonical textChapter 5

Grahaṇam (Eclipses) & Sūtak Kaal

The astronomical physics of solar and lunar eclipses, contact phase timing, magnitude calculations, the scriptural Horizon Visibility Mandate (Dṛśya Niyama), and temple governance protocols.

Nirṇaya SindhuCh. Grahaṇa Prakaraṇa

A · Canonical text

यद्देशे नोपलभ्येत ग्रहणं सूर्य-चन्द्रयोः। तद्देशे नैव सूतकं न स्नानं न च भोजनम्॥

yad-deśe nopalabhyeta grahaṇaṃ sūrya-candrayoḥ | tad-deśe naiva sūtakaṃ na snānaṃ na ca bhojanam ||

Translation:In whatever territory an eclipse of the Sun or Moon is NOT visually observable above the local horizon, in that territory there is NO Sutak, NO ritual bathing requirement, and NO restriction on cooking or consuming food.

Note: The canonical Dharma Shastras (Nirnaya Sindhu, Dharma Sindhu) strictly anchor ritual dosha to physical local horizon visibility. Global eclipses occurring beneath the observer horizon carry zero religious validity.

1. Computational Astronomy & Contact Phases

Pūjāvāni computes solar and lunar eclipse geometries using high-precision Swiss Ephemeris topocentric algorithms (`swe.sol_eclipse_when_loc` and `swe.lun_eclipse_when_loc`). Every eclipse event is decomposed into its classical contact milestones:

Sparśa Kāla (t₁)

First Contact / Ingress

The instant the penumbra or umbra first touches the solar or lunar disc. Scriptural Sparśa Snānam (purificatory bath) is prescribed.

Madhya Kāla (t₀)

Peak Eclipse / Totality

Maximum obscuration. Classical texts declare meditation and mantra japa performed during Madhya Kaal yield Ananta Phala (thousands of times greater efficacy).

Mokṣa Kāla (t₄)

Last Contact / Egress

The instant the celestial discs completely disengage. Prescribes Mokṣa Snānam, charitable giving (Dāna), and kitchen purification.

Eclipse Magnitude & Obscuration

Magnitude = (Diameter_covered / Total_Diameter)

Obscuration = (Area_covered / Total_Area) × 100%

Magnitude ≥ 1.0 indicates a Total Eclipse. Magnitude < 1.0 indicates a Partial Eclipse. Annular eclipses occur when the Moon's apparent diameter is smaller than the Sun's, leaving an uncovered ring (antumbra).

Parameters & variables

Magnitude: Linear Fraction: Fraction of solar or lunar diameter occluded(dimensionless)
Obscuration: Areal Percentage: Percentage of total apparent disk area covered(%)

2. Sūtak Kaal Durations & Penumbral Exclusion

In Vedic tradition, an eclipse is characterized by temporary environmental disturbance (Aśaucam / Sūtak). Treatises define precise commencement horizons based on Praharas (3-hour intervals):

Sūrya Grahaṇam (Solar Eclipse)

Sūtak commences strictly 4 Praharas (12 hours) prior to the local Sparśa Kāla.

Candra Grahaṇam (Lunar Eclipse)

Sūtak commences strictly 3 Praharas (9 hours) prior to the local Sparśa Kāla.

Canonical Penumbral Exclusion (Chāyā Grahaṇam)

When the Moon passes solely through Earth’s faint outer penumbra without touching the central dark umbra, classical texts categorize it as a Chāyā Grahaṇam (shadow eclipse without disc occlusion / Bimba Grāsana). Treatises explicitly exempt penumbral eclipses from religious Sūtak: temples remain open, fasts are not required, and daily life proceeds normally.