📅 When's a Good Day To…: Pick a Date by the Traditional Rules

Pick what you are about to start (sign a contract, launch something, start a job, move house, a first date, propose, travel, have a hard conversation, begin a habit) and a stretch of calendar, and Umbriel ranks the days by the old electional rules, with a good few hours inside each and the reasons beneath. Traditional rules, calculated exactly. It picks the sky, not the outcome.

• What you'll needNothing
• What you getThe best day in your window, a good stretch of hours inside it, the receipts behind it, and one day to steer round
• CostThe best day is free, with no account. The full ranked list and the version that checks your own chart are part of Membership.

Traditional rules, calculated exactly. It picks the sky, not the outcome. Nothing on this page can tell you how a contract or a first date will go. What it can do is tell you what the Moon and the planets are doing on each day, and what astrologers made of that when the date was theirs to choose. Your own calendar, your boss and the other person's diary come first.

The practice is called electional astrology: choosing a moment to begin something, rather than reading a moment that has already happened. It is one of the oldest jobs astrology was given. Almanacs listed good and poor days for centuries, and the rules are remarkably consistent from one author to the next.

The Moon does most of the work, because it moves fastest and sets the timing. The first rule is that it should not be void of course, the stretch between its last aspect and its move into the next sign, when tradition held that a beginning would come to little. Umbriel finds those windows to the minute, so a day that is void for two hours in the small hours is not treated like a day that is void from breakfast to bedtime.

The second is the phase. A waxing Moon was matched to beginnings and a waning one to endings, so a new job or a new habit wants the first half of the cycle, and the dark of the Moon, the day or so before it is new, was kept clear for most things. A hard conversation is the exception, since nothing is being grown, and the page treats phase as neutral there.

Then the Moon's sign and aspects. The Moon is at home in Cancer and exalted in Taurus, and at a low ebb in Scorpio and Capricorn. A friendly trine or sextile from the planet that rules the thing you are doing helps: Mercury for contracts and conversations, Venus for love, a house move or a first date, Jupiter for a job or a journey, Mars for a bold launch, Saturn for a habit meant to last. A hard aspect from Mars or Saturn to the Moon counts against an hour, and the good stretch is drawn around it.

For anything to do with signing, moving, travelling or launching, tradition also asks that Mercury be direct. Umbriel checks Mercury's real speed and takes retrograde days out of the running for those purposes, ranking them under every open day. For a proposal or a hard conversation it counts against a day without ruling it out, because authors disagree about how much it matters there, and the page says so.

With your chart added (a Membership feature), the slow planets are checked against your own Sun, Moon, Ascendant and Midheaven. A day that looks lovely for everybody can still land Saturn square your Sun, and that is worth knowing before you sign anything.

Nothing here is new astronomy, and no birth details are needed for the basic version. Every figure comes from the engine that casts the birth charts: the Moon's position for each hour of each day in your range, voidOfCourseMoon for the windows when it is between its last aspect and its next sign, and the positions of Mercury, Venus, Mars, Jupiter and Saturn at noon, with Mercury's speed checked to see whether it is retrograde. Each day is scored against the rules for the thing you are starting, the good stretch inside it is the longest run of hours when the Moon is neither void of course nor under a hard aspect from Mars or Saturn, and the days are ordered by score with any day held back by a rule that bars it (a Moon void for most of the day, Mercury retrograde where the purpose asks for it) placed below every open one. The receipts are the same numbers, written out, so you can check any line against an ephemeris. With your chart, the slow planets are also checked against your own Sun, Moon, Ascendant and Midheaven, to two degrees.