Astrolium scans up to 90 days for candidate moments that pass Lilly's 5 electional rules, with planetary hours and void Moon overlays, ranked by how cleanly each candidate fits the venture. Weddings, business launches, surgeries, contracts. Electional turns a target month into a defended hour.
For the related question-chart technique, see horary astrology. For the planetary hours and void Moon engines as standalone tools, see the void-of-course Moon tool. For the underlying timing stack, see predictive timing. For the $29 per month Pro plan, see pricing.
What electional astrology actually is
Electional is one of the four classical branches of astrology (natal, mundane, horary, electional) and the only one that actively designs the chart. The astrologer's job is to find the moment when the relevant significator is strong, the Moon is helpful, the angles are clean, and the malefics are out of the way. The chart you elect is the chart the venture will live with.
Three foundational texts. Dorotheus of Sidon's Carmen Astrologicum (1st century CE) is the earliest Greek source on electional doctrine. Lilly's Christian Astrology Book IV (1647) is the working manual most practitioners still reach for. The modern adapters (Rachel Pollack, John Frawley, Anne Massey, and the late Joanne Wickenburg) translated the classical rules for 21st-century cases, with the muhurta tradition running in parallel for Indian practitioners.
Lilly's 5 rules, expanded
Astrolium enforces these 5 rules across every candidate moment in the search window. Each rule is scored 0 to 1, the sum ranks the candidates, and any candidate scoring below 3.0 out of 5.0 is flagged as ill-elected even if other criteria favour it.
Rule 1. Fortify the significator of the matter. Every venture has a significator. Marriage is Venus and the 7th house. Business launch is Jupiter or Mercury and the 10th house. Surgery is Mars (the cut) and the relevant body-part sign. Travel is the 3rd house (short) or 9th (long) and the Moon. The chosen significator must be in a good sign (its own domicile, exaltation, or triplicity), in a good house (preferably angular), and well-aspected (a sextile or trine from a benefic).
Rule 2. Strengthen the Moon. The Moon is the universal significator of the body, time, and movement. In every election it must be considered. A void-of-course Moon means the venture will move without traction, "nothing comes of it" in Lilly's phrase. The Moon should be applying to a benefic, in a good sign, and not at a critical degree (29th, 0th).
Rule 3. Avoid the malefics on the angles. Saturn or Mars on the Ascendant, IC, Descendant, or MC corrupts the foundation of the chart. A wedding chart with Saturn on the Descendant produces a marriage with Saturn on the partner. The angles are where the chart meets the world. Keep them clean.
Rule 4. Match the angles to the venture's nature. A wedding wants Venus or the Moon angular. A business launch wants Jupiter (expansion) or Mercury (contracts) angular. A surgery wants Mars angular and the Moon out of the relevant body sign. The angular planet sets the chart's voice.
Rule 5. Match the planetary hour. The Chaldean planetary hours run in order from sunrise: the day's ruler gets the first hour, then the next planet in the Chaldean sequence (Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon) for each subsequent hour. A Venus hour on a Friday afternoon is the classical wedding window. A Jupiter hour on a Thursday is the classical launch window. Astrolium overlays the planetary hours on every candidate moment, anchored to the location's actual sunrise to the minute.
Three working use cases
The wedding chart
The case astrologers get asked most. The bride and groom have picked a season (often "next September") and want to know the specific day and hour. Astrolium's wedding preset prioritizes Venus (sign and aspects), the 7th house (sign on the cusp, ruler placement, planets inside), and an applying lunar aspect to Venus or Jupiter.
A typical search across a 30-day window in September returns 8 to 12 candidate moments. The astrologer reviews the top 4, picks based on the couple's birth charts (avoiding the bride's natal Saturn on the wedding 7th, for example), and the final hour is locked. The chart of the marriage lives with the couple for as long as the marriage does, which is the case for electing carefully in the first place.
The business launch
A founder wants to incorporate a company. The chart of incorporation is the chart of the business. Astrolium's launch preset prioritizes Jupiter (expansion, philosophical mission) or Mercury (contracts, communication) on the Ascendant or MC, the Moon applying to a benefic, and the 10th house's ruler in a strong condition.
Frawley's worked examples in The Real Astrology Applied are useful here: tech ventures favour Mercury launches, consumer ventures favour Venus, finance ventures favour Jupiter. The classical doctrine is not arbitrary; it tracks the venture's nature. A 60-day search across a quarter typically returns 10 to 15 candidate moments. The founder usually has 2 to 3 they can hit; the astrologer picks the strongest of those.
The surgery date
Avoid the Moon in the sign ruling the body part being cut. Aries rules the head, Taurus the throat, Gemini the lungs and arms, Cancer the chest, Leo the heart, Virgo the gut, Libra the kidneys, Scorpio the reproductive organs, Sagittarius the thighs, Capricorn the knees, Aquarius the calves, Pisces the feet. The classical doctrine, repeated from Ptolemy through Lilly, is that the Moon on the body-part sign brings haemorrhage and slow healing.
Beyond the body-part rule: Mars (the cut) wants to be strong but not on an angle. The Moon should be waning (some traditions say waxing for healing) and not void. The planetary hour should be a benefic. A 14-day search around the surgeon's available dates typically returns 3 to 6 candidates. Astrolium runs the search; the surgeon and astrologer pick.
Search engine internals
A naive minute-by-minute scan across 30 days is 43,200 chart computations. Astrolium runs at a 1-minute resolution under 800 ms by caching the slow ephemeris terms (the outer planets move imperceptibly across a minute), recomputing only the Moon and the Ascendant in the inner loop, and pruning candidate windows where the Moon is void or a critical degree blocks the chart structurally.
A 90-day search at 1-minute resolution is 129,600 computations; Astrolium returns in under 2 seconds. For windows over 90 days, the $99 Business tier ships overnight batch search with email-on-complete.
What the workspace looks like
Open a client. Click 'New election'. Set the window (say, Sept 1 to Sept 30, 2026), pick a preset (wedding), and click search. The search runs in under 1 second across the 30 days at 1-minute resolution and returns the top 12 candidates as cards. Each card shows the moment, the planetary hour, the Moon's status, the relevant significator, the angles, and the composite score out of 5.0.
Click a candidate to render the election chart with the full justification underneath in prose: "Sept 18, 2:42 PM local time. Venus angular in the 7th house, applying Moon trine Venus at 3 degrees, planetary hour of Venus, no void Moon, no malefic on an angle. Composite score 4.6 out of 5.0." The client gets a 1-page PDF with the chart, the date and time, and the justification in language they can read.
Versus what you have now
By hand from Lilly: ~75 minutes per election for a 7-day window, mental scan only. Longer windows are typically not scanned. Mistakes in planetary hour computation are common.
Solar Fire or Astro Gold: Cast a chart for a date you guess; visually inspect; iterate. No search function. Planetary hours are correct when the software displays them but require manual cross-referencing for each candidate.
Astrolium: 30-day window scanned at 1-minute resolution in under 800 ms. Lilly's 5 rules scored automatically. Planetary hours overlaid. Void Moon and eclipse windows flagged. Client-ready PDF generated in 1 click. Election saved to the client's file with its written justification.
Cross-link
For the related question-chart technique, read horary astrology and the horary guide. For the void-of-course Moon as a standalone check, see the dedicated tool. For the planetary hours engine on its own, see planetary hours. For the comparison against Solar Fire's electional template, see Solar Fire vs Astrolium.