The wheel of the year
The Sun’s year rather than the calendar’s: one full turn of longitude from the March equinox back round to it. The wheel never changes. The dates written on it change every year, and this is where they fall in the turn you are standing in.
The eight points
Four turning points and the four midpoints between them. The midpoints are the astronomical cross quarters — the Sun at fifteen degrees of a fixed sign — which is a few days off the calendar dates the same festivals are usually kept on. Both are given, because the difference is real and everybody quietly picks one.
The twelve gates
Where the Sun steps from one sign into the next. These are the dates a newspaper column means by “Virgo begins”, and they move by a day or so from year to year for the same reason the equinox does.
How the dates are found
Nothing on this page comes from a table. It asks one question of the same astronomy the site’s charts use, twenty times over: when does the Sun reach this longitude? The March equinox is 0°, the June solstice 90°, the September equinox 180° and the December solstice 270°. The cross quarters are the halfway marks, 45°, 135°, 225° and 315°, which is fifteen degrees of Taurus, Leo, Scorpio and Aquarius, and each sign begins at a multiple of thirty. Every answer is given to the minute in this device’s time zone. The gold arc on the wheel is the part of the Sun’s year already travelled since the last March equinox, and the caption under it counts the days gone and the days left.
Reading the wheel, with an example
The wheel is drawn in degrees, so its four quarters look equal, but the dates written on them show that the seasons are not. The Earth moves fastest when it is nearest the Sun, in early January, so the Sun takes about eighty-nine days to get from the December solstice to the March equinox and about ninety-three and a half from the June solstice to the September equinox.
Take Samhain. The festival is kept on 31 October, but the astronomical cross quarter, the Sun at 15° Scorpio, usually comes around 7 November, a week later. Imbolc, Beltane and Lughnasadh are shifted the same way, by a few days to a week, and the list above gives each one’s moment beside the date it is usually kept.
Hemispheres, festivals and birthdays
The turning points are named by month rather than as summer and winter, because the June solstice is midsummer in Edinburgh and midwinter in Melbourne. The festival names are the old Gaelic ones of the northern calendar, and many people who keep them south of the equator move each one six months round.
The twelve gates matter most to anyone born close to the change of a sign. Newspaper dates such as “Taurus, 20 April to 20 May” are averages: the Sun enters a sign on a different day and hour from year to year, and the date also depends on the time zone. Someone born on such a day needs the minute and the place, which is what the birth chart works out. The signs themselves are on The signs, how they came apart from the constellations on Signs and stars, and every eclipse, station and change of sign in the year on the Almanac.
Why the dates move
A turn of the Sun takes about 365.2422 days, and a calendar year is a whole number of them. The leftover quarter of a day is what leap years are for, and it is why the equinox lands on a different day and hour each year, usually the 20th. Nothing here is rounded to a date: every line above is the moment the Sun reached that longitude, printed in your own time zone.
The signs on this wheel are measured from the equinox, not from the stars. They were the same thing about two thousand years ago and they are not now: the equinox drifts backwards against the constellations by about one degree in seventy-two years, so the sign of Aries currently sits in front of the constellation Pisces. Western astrology kept the seasons and let the constellations go, which is a choice worth knowing about rather than a mistake. Anybody telling you your sign is secretly the one before it has noticed this and stopped halfway.
What the wheel is for is orientation: where the light is in its year, how far it is to the next turn, and where you happen to be standing in it. It is not a forecast, and none of these dates predicts anything about a week.
Questions people ask
When is the next equinox?
The list under the wheel gives both equinoxes and both solstices of the Sun’s year you are in, to the minute and in this device’s time zone, and the caption counts the days left to the next March equinox. The March equinox usually falls on 20 March and the September equinox on 22 or 23 September, but the day and hour shift from year to year and between time zones, which is why the page works each one out instead of printing a fixed date.
What is the difference between an equinox and a solstice?
At an equinox the Sun crosses the celestial equator, so day and night are roughly equal everywhere and the Sun rises close to due east. At a solstice the Sun reaches its furthest point north or south, which gives the longest day in one hemisphere and the shortest in the other. On this wheel the equinoxes are 0 and 180 degrees of the Sun’s longitude, the starts of Aries and Libra, and the solstices 90 and 270 degrees, the starts of Cancer and Capricorn.
What are the cross-quarter days?
They are the four points halfway between a solstice and an equinox, known by their Gaelic names as Imbolc, Beltane, Lughnasadh and Samhain. Astronomically they come when the Sun reaches 15 degrees of Aquarius, Taurus, Leo and Scorpio, usually a few days to a week after 1 February, 1 May, 1 August and 31 October, the dates the festivals are generally kept on. This page gives both the moment and the traditional date, because people use both.
Why do the dates of the zodiac signs change from year to year?
A sign begins when the Sun reaches a multiple of thirty degrees of longitude, and the calendar does not fit the Sun’s year exactly. The Sun’s year is about 365.24 days, so each ingress comes roughly six hours later than the year before and jumps back after a leap day. That is enough to move the date by a day, which matters for anyone born near the change of a sign. The list of twelve gates gives this year’s moments.