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.
Cited for: The rule the reference applies to eclipses: the observances that attach to an eclipse (sūtaka, the bath, restrictions on food) apply where the eclipse is visible above the local horizon, and not elsewhere. The Dharma Sindhu is read the same way.
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:
The instant the penumbra or umbra first touches the solar or lunar disc. Scriptural Sparśa Snānam (purificatory bath) is prescribed.
Maximum obscuration. Classical texts declare meditation and mantra japa performed during Madhya Kaal yield Ananta Phala (thousands of times greater efficacy).
The instant the celestial discs completely disengage. Prescribes Mokṣa Snānam, charitable giving (Dāna), and kitchen purification.
Eclipse Magnitude & Obscuration
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):
Sūtak commences strictly 4 Praharas (12 hours) prior to the local Sparśa Kāla.
Sūtak commences strictly 3 Praharas (9 hours) prior to the local Sparśa Kāla.
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.