☽ Void of Course Moon Calendar: Today & Upcoming
TRADITIONALA traditional technique: in the books before 1700.
Umbriel shows today's void-of-course Moon periods and what is coming, free. The Moon is 'void of course' between its last major aspect in one sign and its entry into the next: traditionally a window where things started tend not to come to much.
- What you'll needNothing. It's the same sky for everyone
- What you getToday's void periods and the upcoming schedule, with start and end times in your own timezone
- CostFree, no account required
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4420+ people cast their chart here in the last 30 days.
What a void of course Moon is
The Moon moves fast, about thirteen degrees a day, and spends roughly two and a half days in each sign. On its way through, it makes aspects to the other planets. Once it has made its last major aspect before leaving that sign, it is void of course until it crosses into the next one.
The classical maxim is that 'nothing will come of it': matters begun during a void are said to fizzle, drift or simply not develop as expected. Horary astrologers took this seriously enough that a void Moon could invalidate a question entirely.
The practical version most people use: it's a poor window for launching, signing and starting, and a fine one for rest, routine, admin and anything already underway. Voids can last minutes or, occasionally, most of a day.
Whether you treat this as real or as a scheduling superstition, it has one genuinely useful property. It's a recurring, freely available prompt to not start something big at 4pm on a Tuesday just because you're impatient.
How Umbriel computes it
The Moon is void of course from its last major aspect to a planet until it enters the next sign, and Umbriel finds these windows by stepping through time. It computes the geocentric longitudes of the Moon, Sun, Mercury, Venus, Mars, Jupiter and Saturn every 20 minutes, from about 2.6 days before the chosen moment to several days after it; Uranus, Neptune and Pluto are not used. In each step it interpolates the exact time the Moon crosses a sign boundary or reaches 0, 60, 90, 120 or 180 degrees from any of those six bodies, on either side. The default rule is the medieval one: the void starts at the last aspect the Moon makes inside a sign and ends at the sign change, and a sign with no aspect is void all the way through. Three other rules can be chosen, a 30 degree orb, a 13 degree orb, and a moiety of the Moon's 12 degree orb with the other planet's own orb, and those find the end by bisecting on the Moon's own longitude. The result depends on the moment only, not on any birth data or place, and times are shown in the time zone of your device. The accuracy page gives the Sun as under 1 arcsecond, the Moon as 0.27 arcminutes and Mercury, Venus and Mars as under 0.2 degrees.
What's in your result
- When it startsThe Moon's last major aspect while in its current sign.
- When it endsThe moment the Moon enters the next sign: always the end of the void, without exception.
- LengthAnywhere from a few minutes to many hours, depending on where the last aspect falls.
- What it's used forTraditionally a poor window for beginnings; unremarkable for continuing what's already running.
- Your timezoneUmbriel converts every void to your local time, which is where most published tables go wrong.
Common questions
Is the Moon void of course today?
Umbriel's calendar shows today's void periods in your own timezone, along with the upcoming schedule, so you can see at a glance whether you're in one right now.
What does void of course mean?
It's the stretch between the Moon's final major aspect in a sign and its entry into the next sign. During it the Moon isn't 'talking to' any other planet, which is where the traditional reading comes from.
What shouldn't you do during a void Moon?
The traditional advice is to avoid starting things you want to go somewhere: launches, signings, first meetings, purchases. Continuing existing work, resting and routine admin are considered unaffected.
How long does a void of course Moon last?
It varies a great deal, sometimes only a few minutes, occasionally most of a day. There's no fixed duration; it depends entirely on when the last aspect happens to fall.
Do I need an account or an email address?
No. There is no sign-up, no email capture and no free trial. Enter your details and the result is drawn in your own browser.
What to look at next
- Moon PhasesLists every upcoming Full and New Moon with its date and sign.
- Retrograde CalendarShows which planets are retrograde now and the date each one turns.
- The Year AheadPuts eclipses, retrogrades, New and Full Moons and the seasons on one timeline.
Go deeper
Every one of these is a page in its own right, written out one at a time.
Related free tools
Umbriel offers every system here as a set of prompts to think with, never as a statement of fact about who you are. Take what's useful, leave the rest.