Eclipses occur when the Sun, Moon, and Earth align at the lunar nodes — Rahu and Ketu. They are among the most astronomically precise and spiritually charged events in Jyotish, and the only phenomena where the mythological and scientific accounts tell exactly the same story.
During the Samudra Manthan (churning of the cosmic ocean), a demon named Svarbhanu disguised himself as a god and sat between the Sun and Moon to drink the amrita (nectar of immortality). The Sun and Moon recognised the imposter and alerted Lord Vishnu, who immediately hurled his Sudarshan Chakra — severing Svarbhanu's head from his body at the precise moment the amrita reached his throat.
The severed head became Rahu — the north lunar node — and the headless body became Ketu — the south lunar node. Both are immortal, having consumed amrita. In eternal vengeance, Rahu periodically swallows the Sun (solar eclipse) and Ketu swallows the Moon (lunar eclipse) — but each time, the Sun or Moon emerges unharmed from the severed neck.
This myth is not merely allegory — it is a precise astronomical encoding. Eclipses literally occur when the Sun or Full Moon is conjunct Rahu or Ketu (the lunar nodes). The ancient rishis had discovered the node-eclipse relationship and encoded it in a story that would be remembered across millennia.
The Moon's orbit is tilted approximately 5.15° with respect to the ecliptic (the plane of Earth's orbit around the Sun). This tilt means the Moon is usually above or below the ecliptic — so most New Moons and Full Moons pass without an eclipse.
The Moon's orbit crosses the ecliptic at exactly two points: the ascending node (Rahu in Sanskrit, ☊ in Western notation) where the Moon crosses from south to north, and the descending node (Ketu, ☋) where it crosses from north to south. At these crossing points, the Moon's ecliptic latitude equals zero degrees.
A solar eclipse requires a New Moon (Amavasya) occurring when the Moon is near a node — its shadow then falls on Earth. A lunar eclipse requires a Full Moon (Purnima) occurring near a node — the Moon then enters Earth's shadow. The closer the Moon is to the node at the moment of lunation, the deeper and more central the eclipse.
Our eclipse engine finds all eclipses for any year by building on top of the tithi table we already compute for the Panchang calendar. Here is the full pipeline, step by step:
Our Panchang calendar pre-computes ~370 tithi entries per year with precise start/end Julian Day numbers. Every Amavasya (tithi #30 — the New Moon) is a solar eclipse candidate. Every Purnima (tithi #15 — the Full Moon) is a lunar eclipse candidate. Because we already compute exact tithi times, we need no separate lunation scanning — we simply filter for tithis #15 and #30 and extract their midpoint times.
// Tithi #30 (Amavasya) → solar eclipse candidate
// Tithi #15 (Purnima) → lunar eclipse candidate
t_mid = (entry.startJd + entry.endJd) / 2
At each lunation midpoint, we query the ephemeris for the Moon's ecliptic latitude (β). This value tells us precisely how far above or below the ecliptic the Moon is at that moment. At a node (Rahu or Ketu), β = 0°, which would produce the deepest possible eclipse. As the Moon moves away from the nodes, |β| grows toward ±5.15°. If |β| is large enough, no eclipse occurs even at New Moon or Full Moon — the shadows simply miss.
// Query Moon ecliptic latitude
β = moonEclipticLatitude(t_mid) // degrees
// β = 0° at node, ±5.15° furthest from node
Whether an eclipse occurs depends on the Moon's latitude and its distance from Earth (which determines its apparent size). We use the Moon's angular velocity as a proxy for distance — a faster Moon is closer (larger apparent disk). The thresholds are:
For lunar eclipses, the contact times are universal — Earth's shadow is so large that the eclipse is seen from the entire night-side hemisphere simultaneously. We simply convert UTC contact times to the user's local timezone. For solar eclipses, the situation is more complex: the Moon's shadow is a narrow cone, and the contact times, totality path, and local magnitude all depend on the observer's geographic coordinates. We compute this using a standard geometric approach based on the Besselian elements of the eclipse. Sutak is then computed from the first contact (sparsha) time using classical timing rules.
Not all eclipses are equal. The type depends on the Moon's distance from the node, its distance from Earth, and the observer's location.
The most spectacular celestial event. Day turns to night for up to ~7.5 minutes along the path of totality. The solar corona — the Sun's outer atmosphere — blazes into view. Stars appear in daytime. Moon must be near perigee (close to Earth) so its apparent disk is large enough to cover the Sun completely.
The Moon covers the Sun's centre but its apparent diameter is slightly smaller (Moon is near apogee — far from Earth), leaving a brilliant ring of sunlight around the dark lunar disk. Annular eclipses produce no corona-viewing opportunity, but the "ring of fire" is striking. They are more frequent than total solar eclipses because the Moon spends more time near apogee.
The Moon passes across only a part of the Sun's disk. The penumbra (partial shadow) sweeps a wide region on either side of the central path. A partial solar eclipse is visible over a much larger geographic area than a total or annular eclipse. At maximum, the Sun appears as a crescent.
The Moon passes completely into the darkest part of Earth's shadow (umbra). The Moon does not go dark — instead it turns deep red or copper-orange. Earth's atmosphere refracts sunlight, bending red wavelengths (which scatter least) around the planet and onto the Moon. The exact colour depends on atmospheric conditions: clear air produces a bright orange-red; heavy volcanic dust can make the Moon nearly black.
Only part of the Moon enters Earth's umbral (dark inner) shadow. The umbral portion takes on a reddish-brown hue while the rest of the Moon remains its normal colour. The boundary between the lit and shadowed parts is visibly curved, demonstrating Earth's spherical shape — an observation known to ancient Indian astronomers.
The Moon passes through Earth's outer penumbral shadow — a region of partial sunlight, not total blockage. The dimming is subtle and often imperceptible to the naked eye except near maximum phase when the Moon's limb closest to the umbra may look slightly dusky. Not listed in most Panchang sutak observances because there is no visible "biting" of the Moon.
Every eclipse passes through defined phases, each with a Sanskrit name used in classical texts and modern Panchang calculations:
Shadow first touches the luminary. For lunar: penumbra touches the Moon (P1). For solar: penumbra touches Earth (C1). This is when Sutak is traditionally considered to begin (applying classical rules backward from this point).
Moon fully enters the umbral shadow (U1 for lunar) or Moon's disk fully covers the Sun (C2 for solar). Only for total/annular eclipses. The Khagras moment is recorded in classical texts as the deepest ritual restriction.
The deepest point of the eclipse — when the shadow's centre is nearest to the Moon (lunar) or when the Moon's centre is nearest to the Sun's centre (solar). This is the moment of greatest spiritual intensity in Vedic tradition.
Shadow fully leaves the luminary. The eclipse is complete. This is the moment for ritual bath (snan), ending of sutak observances, and beginning of eclipse-completion rituals. The name Moksha — liberation — signals the return to normal sacred time.
Sutak (also spelled Soothak or Sutak) is the period of ritual restriction that precedes and includes an eclipse. It is considered spiritually polluted time when certain activities are forbidden. Sutak only applies when the eclipse is visible from your location — an eclipse on the other side of Earth carries no Sutak obligation.
Classical texts disagree slightly on Sutak duration. The three main interpretations:
| Text | Solar Eclipse | Lunar Eclipse |
|---|---|---|
| Dharmasindhu | 4 day-prahars (~12 hours, scales with season) | 3 night-prahars (~9 hours, scales with season) |
| Nirnaya Sindhu | Fixed 12 hours before eclipse | Fixed 9 hours before eclipse |
| Muhurta Chintamani | From sunrise on the eclipse day | From sunrise on the eclipse day |
In natal astrology (Janma Kundali analysis), eclipses are treated as powerful activation events — not curses, but catalysts. An eclipse is a karmic spotlight, illuminating a specific area of life for deep transformation.
Transformation of identity, career, authority. Father-related themes. Leadership changes. A pivotal year for self-definition.
Emotional upheaval or breakthrough. Changes in home, mother, public standing. Inner world re-alignment. Often marks a powerful emotional turning point.
Major karmic reset. Past-life patterns surface for resolution. Sudden life direction changes. Spiritual awakenings or crises. The most intensely fated eclipse contact.
Physical appearance, health, and overall life direction transform. A new chapter begins. Identity shifts at a fundamental level. Others perceive you differently.
Events in the life area governed by that house: 1st = body, 2nd = wealth, 4th = home, 7th = relationships, 10th = career. Effects build over 6 months around the eclipse.
Transformative solar return year. Themes set at the eclipse activate through the next year. The year carries an intensified, fated quality. Often marks major life milestones.
Why do eclipses repeat? Three orbital cycles align almost perfectly:
223 Synodic Months (New Moon to New Moon) = 6,585.32 days. This ensures the Sun-Moon phase (New or Full) repeats.
242 Draconic Months (node to node) = 6,585.36 days. This ensures the Moon returns to almost the same position relative to its nodes (Rahu/Ketu), so the eclipse geometry repeats.
239 Anomalistic Months (perigee to perigee) = 6,585.54 days. This ensures the Moon is at nearly the same distance from Earth, so the eclipse magnitude and type (total vs annular) are similar.
All three align within 0.04 days of 6,585.32 days — approximately 18 years, 11 days, and 8 hours. After this period, virtually the same eclipse recurs.
The 8-Hour Shift — The extra ⅓ day means Earth has rotated 120° further. So the repeat eclipse occurs ~120° west on Earth's surface. The same eclipse is visible from a completely different part of the world. After THREE Saros cycles (54 years 34 days, called the Exeligmos), the eclipse returns to approximately the same longitude — the same part of the world sees it again.
Each eclipse belongs to a Saros series — a family of eclipses recurring every 18.03 years over ~1,200-1,500 years. A typical Saros series contains 70-85 eclipses. The series begins with small partial eclipses near one pole, gradually intensifying to total/annular eclipses near the equator, then fading to small partials at the opposite pole before ending.
At any given time, about 40 Saros series are producing solar eclipses and about 40 are producing lunar eclipses (~80 total active series). Series are numbered: for example, the August 12, 2026 total solar eclipse belongs to Saros 126, and the March 3, 2026 total lunar eclipse belongs to Saros 133.
The Rahu-Ketu axis is not fixed — it rotates backwards (retrograde) through the zodiac, completing one full revolution in 18.6 years. This means Rahu and Ketu move through all 12 signs over 18.6 years, spending about 1.5 years in each sign. This is why eclipse "seasons" (when the Sun is near a node and eclipses are possible) shift earlier by about 19 days each year.
In Vedic astrology, this precession is one of the most important transit events — Rahu's ingress into a new sign affects mundane predictions, national events, and personal charts (especially for those running Rahu or Ketu Mahadasha). The current transit: Rahu is in Pisces and Ketu is in Virgo (2025-2026).
Let's trace a real Saros chain. The total solar eclipse of August 12, 2026 (Saros 126) is part of a family. Add 18 years, 11 days, 8 hours to each date:
Notice how the path shifts ~120° westward each time (the 8-hour rotation), and the magnitude slowly changes as the series evolves. This is how ancient astronomers could predict eclipses centuries in advance — by knowing the Saros pattern.
Similarly for lunar eclipses — the total lunar eclipse of March 3, 2026 (Saros 133) connects to:
Because the Rahu-Ketu axis precesses backwards, the times when the Sun aligns with a node (eclipse season) shift earlier by ~19 days each year. In 2026, eclipse seasons are in February-March and August. By 2030, they'll have shifted to approximately January-February and July. By 2035, to December-January and June.
| Year | Season 1 | Season 2 | Rahu Sign |
|---|---|---|---|
| 2024 | Mar-Apr | Sep-Oct | Pisces |
| 2025 | Mar | Sep | Pisces |
| 2026 ← NOW | Feb-Mar | Aug | Pisces → Aquarius |
| 2028 | Jan | Jul | Aquarius |
| 2030 | Jun | Nov-Dec | Capricorn → Sagittarius |
| 2033 | Mar-Apr | Sep-Oct | Scorpio |
| 2035 | Mar | Sep | Libra → Virgo |
An eclipse can occur at either node (Rahu or Ketu) and can be solar or lunar — giving us a 2×2 matrix of four distinct eclipse types. Classical texts like Brihat Samhita (Varahamihira), Surya Siddhanta, and Arthashastra (Kautilya) assign different mundane and personal significances to each combination. The node where the eclipse occurs determines its karmic flavour.
| ☊ At Rahu | ☋ At Ketu | |
|---|---|---|
| ☀ Solar | Power upheaval, deception, foreign influence | Ego fall, karmic reckoning, spiritual turning point |
| ☽ Lunar | Mass fear, mental fog, desire-driven illusion | Ancestral karma surfaces, grief, moksha, Blood Moon |
How to know which node? Check if the eclipse is near Rahu's longitude or Ketu's longitude (Rahu + 180°) in the sidereal zodiac. Our eclipse engine automatically identifies this.