Shukra asta and Guru asta: why combustion cancels a perfect date
Whether the two grahas that gate the wedding calendar are visible today — on 31 July 2026 Venus is visible and Jupiter is combust, which is what opens or closes the wedding calendar before any tithi is considered.
Combustion is a visibility statement
Asta means set. A planet is asta — combust, heliacally set — when it lies close enough to the Sun in longitude that it can no longer be seen rising before dawn or lingering after dusk. This is an observational fact before it is an astrological one: the planet is physically lost in the solar glare for a period, then reappears on the other side of the Sun as a morning or evening star.
The classical judgement follows directly from that. A graha you cannot see is a graha whose significations are held to be temporarily unavailable, and the texts treat combustion as a suspension rather than a misfortune. Nothing bad is said to happen during Shukra asta; rather, the blessing that Venus supplies is described as absent, so a rite that depends on it waits.
Two grahas matter for muhurat above the rest. Venus is the karaka of marriage and of union; Jupiter is the karaka of sanction, of the guru, and of the auspiciousness a samskara draws on. When either is combust, most traditions stop weddings outright, and many stop the other major samskaras with them.
The degree limits and how long they last
The limits are stated as an angular separation from the Sun in longitude, and they differ by planet because the planets differ in brightness. A retrograde planet is held to set earlier and at a wider separation, because it approaches the Sun from the other side and its apparent brightness at a given elongation is lower. These are the values this site computes with.
| Graha | Direct | Retrograde | Typical duration | Muhurat consequence |
|---|---|---|---|---|
| Venus (Shukra) | 10° | 8° | ~5–10 weeks, roughly annually | Marriage and most union rites pause |
| Jupiter (Guru) | 11° | — | ~4–5 weeks, roughly annually | Marriage and major samskaras pause |
| Mercury (Budh) | 14° | 12° | ~1–3 weeks, several times a year | Noted for trade and study; rarely a hard bar |
| Mars (Mangal) | 17° | — | Several weeks, roughly every two years | Rarely applied to muhurat |
| Saturn (Shani) | 15° | — | ~3–4 weeks, roughly annually | Rarely applied to muhurat |
Venus retrograde sets at a NARROWER separation in some texts and a wider one in others; the values above follow the commonly printed set, which this site’s scorer uses for Venus and Jupiter only. The three lower rows are given for context — they do not gate any occasion here.
Why it overrides a good day
The combustion bar is one of the very few rules that outranks an excellent panchang. A date can carry Rohini, a Purna tithi, a Thursday, a favourable yoga and a clean karana and still be unusable for a wedding because Venus went combust three days earlier. Families discover this when a date that looked perfect on a calendar is rejected by a priest without discussion, and the reason is usually this one.
It is also the rule that most reliably surprises people planning around the seasons. Venus combustion moves through the calendar year on its own roughly nineteen-month rhythm, so it can land squarely in what would otherwise be the strongest wedding weeks, and the affected stretch can run five weeks or more. Two consecutive years can therefore have very different amounts of usable November.
Regional practice does vary in severity. Some traditions apply the bar to weddings alone; others extend it to upanayana, griha pravesh and other samskaras; a few relax it for a re-marriage or for rites where Venus is not the operative karaka. This site takes the conservative line and bars both Shukra asta and Guru asta for marriage, and applies neither to occasions where the classical texts do not ask for it.
Computing it, and the one honest caveat
The computation is straightforward: take the sidereal longitudes of the Sun and the planet, find the smaller of the two arcs between them, and compare it against the limit. This site does exactly that from the same ephemeris that produces the tithi and nakshatra, checks retrograde motion for Venus, and applies the result as a hard exclusion on the occasions that declare it.
The honest caveat is that longitude alone is a simplification of the underlying phenomenon. Actual heliacal visibility depends on latitude — the planet’s distance from the ecliptic — on the observer’s own latitude, on the season and on atmospheric clarity, which is why traditional almanacs record slightly different asta and udaya dates from one another and from a pure longitude calculation. The classical limits are themselves an idealisation of centuries of observation.
For planning purposes the simplification is fine, because the periods run for weeks and the boundaries move by a day or two at most between methods. If your date sits within two days of a published rise or set, though, that is exactly the case where the method matters and where the almanac your family follows should decide it rather than a website.
One structural consequence follows from all this and is worth planning around. Combustion is the only major bar on the wedding calendar that does not repeat on an annual rhythm, so it is the one you cannot predict from last year’s experience. Kharmas lands in the same weeks every December; Chaturmas moves by days, not months; but a Venus setting can arrive in January one year and in October two years later. Anyone booking a venue eighteen months ahead should check it before the deposit, not after.
Frequently asked questions
Can an engagement or a roka be held during Shukra asta?
Practice differs. The strict reading applies the same suspension to anything that pledges a union; the more common practice treats an engagement as a family agreement rather than a samskara and permits it. Because the two readings genuinely disagree, this site does not exclude those weeks from its engagement list and says so on the page — a family that follows the stricter view should skip them.
How far in advance can combustion periods be known?
Indefinitely, because they follow planetary motion that is computed rather than observed each year. Any ephemeris will give the rise and set dates for Venus and Jupiter years ahead, which is why muhurat lists for a future year can be produced with confidence. The only uncertainty is at the boundaries, where different visibility models differ by a day or two.
Related guides
How this guide is maintained
Everything computed on this site â the sunrise and sunset behind every window on this page, and the tithi, nakshatra, yoga and karana behind the date tables â comes from a Lahiri sidereal ephemeris and a NOAA sunrise model applied to the exact coordinates of the city shown, with New Delhi as the reference city for anything not city-specific. Where this guide describes a rule that genuinely varies between texts, regions or family traditions, it says so in the paragraph rather than picking a side quietly, and where the site’s own date scorer takes a documented shortcut, the shortcut is named.
What no guide on this site can do is weigh your own chart. The tables here are a panchang shortlist — the classical tests a calendar can settle — and the personal layer that decides between the surviving dates is a separate step. Start with the occasion pages for computed dates, and see how we compute muhurat for the full method.
Written and maintained by Savan Vyas. A rule applied wrongly here is a bug, and corrections are genuinely welcome.
For a full personalised muhurat matched to your own birth chart, ask Soma on AskSoma.