The Moon is void of course from its last exact major aspect in a sign until it enters the next sign. This tool lists every void period in the days you choose, with start and end times in your own time zone, using that modern definition. It happens often: in 2026 the Moon is void of course 160 times, for anything from a few minutes to almost two days at a stretch, about a fifth of the year in all.
The definition we use
We follow the modern definition, popularised in the 20th century by the New York astrologer Al H. Morrison and widely used in Western astrology today: the Moon is void of course once it has made the last of its major aspects while in a sign, and it stays void until it enters the next sign. The major aspects, often called the Ptolemaic aspects, are the conjunction and the four that Ptolemy names in the Tetrabiblos (book I, chapter 13): the opposition, trine, square and sextile. By default the tool counts aspects to the Sun and to every planet from Mercury to Pluto. If the Moon makes no aspect at all in a sign, it is void from the moment it enters that sign.
How it works
The Moon’s sign changes come from NASA JPL DE440 data in the tropical zodiac, found when our data files were built. Between one sign change and the next, the tool searches every two hours, and then to the second, for each moment the Moon stands exactly 0, 60, 90, 120 or 180 degrees from the Sun or a planet. The last of those moments before the Moon leaves the sign starts the void period. The sign change ends it.
A void period happens at the same moment everywhere on Earth. The place you give, or your device’s time zone if you leave it empty, only sets the clock the times are shown in.
Reading the result
The first line says whether the Moon is void now and, if not, when the next void period begins. The table lists each period with its start, its end (the moment the Moon enters the next sign), its length and the last aspect that started it, such as “Moon trine Saturn”. Lengths vary a great deal: in 2026 half of the void periods last less than about seven hours, and the longest lasts almost two days.
Astrologers who use the void Moon treat it as a time to finish, rest or tidy up rather than to start something new, sign a contract or launch a plan. That is a traditional rule of thumb for planning, not a forecast, and many people ignore it entirely.
Where traditions differ
Which bodies count. Uranus, Neptune and Pluto were unknown to the older astrologers. Counting them, as the modern form does, can make a void period start later. Tick the box in the form to see the older, seven-body version, which counts only the Sun, Mercury, Venus, Mars, Jupiter and Saturn.
The older definitions. William Lilly, in Christian Astrology (1647, book 1, page 112 of the first edition), writes that a planet is “voyd of course, when he is separated from a Planet, nor doth forthwith, during his being in that Signe, apply to any other”. Lilly judged applications by orbs, and readers of his work still differ on whether, in practice, he let an aspect within orb carry the Moon past the sign boundary. An older Hellenistic form, credited to Antiochus of Athens, looks a fixed 30 degrees ahead instead, whatever the sign. The times here follow the modern definition: exact aspects only, and the void period always ends at the sign change.
What it does not do
It does not tell you whether a plan will go well, and it does not say a void Moon is bad luck. It does not use minor aspects or the asteroids. It covers dates from 1900 to 2075, the range of our planet data.
Frequently asked questions
↳ What does void of course mean?
It means the Moon has made its last major aspect to the Sun or a planet before it leaves its current sign. Until it enters the next sign it has, in the old phrase, no course left to run.
↳ How often is the Moon void of course?
Once before every change of sign, which comes every two to two and a half days. In 2026 there are 160 void periods, from a few minutes to almost two days long, adding up to about a fifth of the year.
↳ Why do other calendars sometimes give a different start time?
Usually because they count a different set of bodies. A calendar that leaves out Uranus, Neptune and Pluto can start a void period earlier. The end time, when the Moon changes sign, should agree to a minute or so.
↳ Is the void Moon the same in every time zone?
Yes. It begins and ends at the same moment for everyone. Only the clock time and sometimes the date differ, which is why the tool asks for your place or uses your device's time zone.
↳ Should I avoid starting things when the Moon is void?
That is the traditional advice among astrologers who use it, and some people find it a helpful pause. It is a planning custom, not a proven effect, so treat it as one input among many.
↳ Does Vedic astrology use the void of course Moon?
It is a Western idea. Vedic astrology times things with the panchang instead: tithi, nakshatra, yoga and the other limbs of the day.