In William Lilly's definition, the Moon is void of course in the stretch after its last aspect in a sign and before it moves into the next sign. The idea comes from traditional astrology, and it describes a period of time, not a place in the sky.
Where does the term come from?
The term comes from horary astrology, the branch that casts a chart for the moment a question is asked. William Lilly's Christian Astrology, published in 1647, was the first book of its kind printed in English. On page 112, Lilly defines the term:
A Planet is voyd of course, when he is seperated from a Planet, nor doth forthwith, during his being in that Signe, apply to any other
In modern words: a planet has moved away from its last aspect and makes no new one before it leaves its sign. Lilly added that this is most usual with the Moon, and told readers to check for it when judging a question.
Which aspects count?
An aspect is an angle between two planets. The traditional major aspects, also called the Ptolemaic aspects, are the conjunction (0°), sextile (60°), square (90°), trine (120°) and opposition (180°).
Lilly's definition on page 112 doesn't name which planets or which aspects count, so this page gives no step-by-step method for finding when a void starts. Astrologers also allow a margin around each angle, called the orb, and different astrologers and traditions use different orbs. So two published lists can give different start times for the same void-of-course stretch. The end is easier to pin down: in Lilly's definition the void lasts only while the Moon is in that sign, so it ends at the latest when the Moon changes sign.
How long can a void-of-course Moon last?
No longer than the Moon's stay in one sign, which is about two to two and a half days. From late October to mid-December 2026, each stay lasts about 1.99 to 2.54 days, computed with Astronomy Engine, an open-source library (version 2.1.19). A void stretch can be much shorter, because it starts only after the Moon's last aspect in that sign.
The table shows only the Moon's sign changes. Each one is the latest possible end of a void stretch in the sign before it, not the actual start or end of a void, which depends on the Moon's last aspect:
| Moon enters | Date | Time (UTC) |
|---|---|---|
| Gemini | 28 Oct 2026 | 01:02 |
| Cancer | 30 Oct 2026 | 02:05 |
| Leo | 1 Nov 2026 | 04:18 |
| Virgo | 3 Nov 2026 | 08:28 |
| Libra | 5 Nov 2026 | 14:38 |
| Scorpio | 7 Nov 2026 | 22:40 |
Each change happens at the same moment everywhere. Your local clock time, and sometimes your date, will differ from UTC.
What this means for your day
For your day
Do
Check the Moon's next sign change in UTC and convert it to your time zone.
Don't
Don't cancel a plan only because the Moon is void of course.
Questions people ask
Is a void-of-course Moon bad luck?
That is a reading from tradition, not a measured effect. Lilly used it as one factor when judging a question in horary astrology; the astronomy only shows the Moon moving through a sign.
Is the Moon void of course at the same time everywhere?
Yes. It is one moment for everyone, but the clock time and date depend on your time zone, which is why this page gives times in UTC.
Sources
- William Lilly: Christian Astrology (London, 1647), page 112, Wellcome Library copy on the Internet Archive. Lilly's definition of "voyd of course" and his note that it is most usual with the Moon.
- Wikipedia: William Lilly. Christian Astrology (1647) as the first book of its kind printed in English, and horary astrology.
- Wikipedia: Astrological aspect. The five Ptolemaic aspects, and astrologers using different orbs.