The Astrolium void of course Moon tool flags every void window across your chosen range in your timezone, with start time, end time, duration, and the Moon's sign at both ends. Swiss Ephemeris precision; daylight saving handled automatically; 30 days of scan in under 600 ms.
This is the free preview. The full electional feature uses the same engine to scan 90-day windows and rank candidate moments by Lilly's 5 rules. For the related horary work where the void Moon is one of the 7 considerations before judgement, see horary astrology and the horary calculator. For the deeper reading method, read the horary astrology guide. For the $29 per month Pro plan, see pricing.
What the tool returns
Void of course Moon in 2026
The Moon changes signs every 2–3 days, producing roughly 160 void windows across the year. In 2026, several months stand out. When the Moon enters Cancer or Capricorn (both ruled by planets that move slowly), void periods can extend 12–18 hours. When it enters Aries or Scorpio, voids are typically shorter. Enter any date in the tool above to see the exact window for your timezone.
Notable patterns in 2026: Saturn's ingress into Aries in early 2026 shifts which signs produce longer void windows compared to prior years. Worth tracking if you do electional work with clients.
The output is a chronological list of voids. Each row shows:
- Start time. The moment the Moon completes its last Ptolemaic aspect in the current sign. Stamped to the minute in your local timezone.
- End time. The moment the Moon enters the next sign. Stamped to the minute.
- Duration. Total void length in hours and minutes (6h 14m, 1d 3h 22m, and so on).
- Sign at start. The sign the Moon is in when the void begins (and will remain in for the entire void).
- Sign at end. The sign the Moon enters at the end of the void; the sign of the next 2.3-day lunar cycle.
A typical 7-day scan returns 3 voids. A 30-day scan returns 12 to 14, since the Moon completes its 29.5-day cycle through all 12 signs roughly once per month.
What a void of course Moon actually is
The Moon is void of course when it has formed its last Ptolemaic aspect in its current sign and will not perfect any further aspect before changing sign. The Ptolemaic aspects are the 5 classical contacts: conjunction (0°), sextile (60°), square (90°), trine (120°), opposition (180°). The Moon transits a sign in about 2.3 days, forming 4 to 6 such aspects in transit. After the last one, the Moon is void until it changes sign.
The classical reading from Lilly's Christian Astrology forward is that ventures begun under a void Moon do not perfect. "Nothing comes of it." The doctrine is mechanical, not mystical: the Moon's next aspect carries the venture forward, and a void Moon has no next aspect to give.
How to use it
Three working patterns.
-
Avoiding voids for inception. Picking a date for a wedding, a contract signing, a business launch. Run a 30-day scan, mark the void windows, pick a moment outside them. The electional feature automates the broader rule set on top of this single check.
-
Choosing a void deliberately for temporary work. Short conversations, exploratory meetings, anything you want to be low-commitment. Lilly's gloss: "voids are useless for the purposes of perfection but harmless for the purposes of not-perfecting."
-
Horary radicality. A void Moon is the third of Lilly's 7 considerations before judgement. Frawley's strict reading: not a chart fit for judgement. Lilly's permissive: flag and proceed. The horary calculator runs this check automatically inside its 7-considerations panel.
Edge cases
Modern aspects. Al H. Morrison and some 20th-century practitioners include the quincunx (150°) and semi-sextile (30°) as aspects that can prevent the Moon from going void. The classical position from Lilly forward is that only the 5 Ptolemaic aspects count. Astrolium defaults to classical; a toggle in the full electional feature switches to Morrison's reading.
Out-of-sign aspects. A Moon at 28° Aries forming a square with a planet at 1° Capricorn is a partile square but out of sign. The classical position is that out-of-sign aspects do not count for void determination. Astrolium honours this by default.
Why this matters for a $300-question astrologer
The 30-day scan typically takes 5 minutes from question to confident answer. A client asks when to sign a contract within the next 2 weeks; you scan the window, mark 5 voids totalling 38 hours of bad inception time, and the client books outside them. The same scan answers when not to elect, which is most of the working week. Working horary practitioners use the same tool to clear a horary calendar: voids signal the questioner should ask again later, not now.
Two patterns to track over a year of use. Voids near the start or end of a sign tend to be brief (under 4 hours) because the Moon is moving past its last aspect close to the boundary. Voids in the middle of slow signs (Taurus, Scorpio) tend to be longer (12 to 30 hours) because the Moon's last aspect happens earlier in the transit. Astrolium does not weight voids by length; the classical reading treats any void as void. But the practical experience is that long voids correlate with more visible drift in the matter elected. For the year-frame timing inside which these void windows sit, see the profections calculator.
Cross-link
For the broader electional work that uses the void Moon as one of 5 rules, see electional astrology. For the horary application, the horary calculator and the horary astrology guide. For the $29 per month Pro plan with the full 90-day electional search, see pricing.