9a. Solstices

A solstice is an astronomical event that occurs twice a year, once in June, and once in December, currently around the 21st or 22nd of the month. The name ‘solstice’ comes from ancient Roman astronomers, who described the phenomenon as sol sistere, or ‘sun stands still.’ This is an accurate description, as during a solstice, the Sun does, indeed, appear as though it is standing still, at least from the point of view of observers here on Earth. This is because a solstice is when the Sun, on its path (the ecliptic), reaches its highest point in the sky for the year, as seen from the North or South Pole, before changing directions and going back down again. The highest point in the sky is defined as the greatest distance north or south between the Sun and the equator, and in astronomy it is called the zenith. At its zenith, the Sun is either directly above the Tropic of Cancer (23.44 degrees north) in the northern summer, or the Tropic of Capricorn (23.44 degrees south) in the northern winter (and the opposite in the southern hemisphere). Recall that the seasons occur because of the 23.44-degree tilt of the Earth’s axis, causing the northern hemisphere to be inclined towards the Sun from June to August, and the southern hemisphere to be inclined towards the Sun from December to February. The solstices occur at the points when the Earth is tilted at its maximum angle towards the Sun. This is called the subsolar point, when the rays from the Sun are perpendicular to the planet. In other words, the rays are striking the Earth at a 90-degree angle. This point moves north and south throughout the year, reaching the Tropic of Capricorn in December, and the Tropic of Cancer in June.

The solstices also are known as the longest and shortest days of the year, with the June solstice being the longest day of the year in the northern hemisphere, and the shortest day of the year in the southern hemisphere. The December solstice is opposite, being the shortest day of the year in the northern hemisphere, and the longest day of the year in the southern hemisphere. The longest day of the year is the day with the most hours of sunlight, and the shortest day of the year is the day with the fewest hours of sunlight. This phenomenon is easily observably, particularly for those at latitudes furthest from the equator. In fact, during the June solstice, places north of the Arctic Circle (66.56 degrees north) are able to see the Sun for a full 24 hours. This commonly is called the ‘Midnight Sun,’ because for one day, the Sun never sets. Furthermore, in places south of the Antarctic Circle (66.56 degrees south), the Sun will not rise above the horizon on the day of the June solstice. This is also known as the polar night, because the night last for longer than 24 hours. During the December solstice, the opposite is true, with the Sun never rising above the Arctic Circle, or setting below the Antarctic Circle.

9b. Equinoxes

Like solstices, there are two equinoxes a year, occurring halfway between the June and December solstices, with one on either side. This means the equinoxes fall in March and September, respectively. Currently, they tend to occur around the 20th to 22nd of the month. Equinoxes happen when the Earth is tilted neither towards, nor away from, the Sun. The name ‘equinox’ comes from the Latin aequus nox, which means ‘equal night.’ This is because during the equinoxes, the day and night do, indeed, appear to be the same length from anywhere on Earth. However, the equinoxes are not specific days, but rather specific points in time, when the celestial equator and the ecliptic intersect (0 degrees north or south). The places where this happens are called equinoctial points. There are two equinoctial points throughout the year, one at each equinox. At these times, the subsolar point is on the equator, causing the Sun to appear directly overhead. The actual days where the number of hours of light and dark are equal are called equiluxes. The amount of time the Sun spends both above and below the horizon is very nearly equal during the equinoxes, with the day being slightly longer than the night. This is because even when the centre of the Sun is below the horizon, the upper portion is still visible. As a consequence, at the equator, the day is approximately fourteen minutes longer than the night at the time of the equinox. The equiluxes occur on different dates of the year, depending on one’s location on the Earth.

Equinoxes happen on all planets, not just Earth. The most noticeable is on Saturn. During an equinox on Saturn, the sunlight strikes the planet’s rings at a direct angle. This causes them to appear as a thin line, nearly invisible to observers here on Earth.

9c. Why the Solstices and Equinoxes Matter

The solstices and equinoxes have played a huge role in many cultures throughout the ages. People as far back as the ancient Greeks have known about solstices, equinoxes, and the path of the Sun, and have been using them for navigation. Solstices can be used for navigation, for example, by sailors, who are able to measure the angle between the Sun and the horizon to locate their position on the Earth. The solstices and the position of the Sun are not only useful, but also a cause for celebration in numerous places. In some cultures, the solstices and equinoxes are used to mark the seasons. In the U.K. for instance, the June solstice marks the beginning of summer, the September equinox the start of fall, the December solstice the start of winter, and the March equinox the beginning of spring. The date of Christmas, one of the most celebrated holidays worldwide, was chosen to coincide with the December solstice. Other popular holidays and celebrations with dates close to the December solstice are Hanukkah, Kwanza, and Yalda. For many witches and wizards, the December solstice is a day of feasting and celebration before the coming months of cold. The June solstice is also a day of festivity, but rather than preparing for the hardships to come, it is to celebrate the arrival of summer. The March equinox is associated with certain Muggle religious holidays such as Easter and Passover. The September equinox traditionally is associated with the coming of fall and harvest season, giving rise to holidays like the Mid-Autumn festival in China, and Harvest Festival in the U.K.

Apart from cultural significance, the solstices and equinoxes also can have an effect on the forces of magic. The solstices are known to Seers to be days with great importance. Seers have been known to predict momentous events on these days, and throughout history, many important events have taken place on the day of either the June or December solstice. An example would be during the June solstice of 1589, when Damian Muther, who would later become the first Minister for Magic, was born. Seers and Magical Historians are not the only ones who must pay attention to the solstices and equinoxes. They also play a part in wandlore, with certain wand woods being linked to these events. For instance, the wood vine is connected to the September equinox. This is because during the equinox, there is a balance between night and day. Those who are able to balance light and dark, achieving great things whilst seeking a greater purpose in life, frequently use vine wands. Apart from this, there are also certain plants and herbs used in potion making that need to be picked on a solstice or equinox.

9d. A Note About Names

Traditionally, the March equinox had been called the vernal equinox, and the September equinox has been called the autumnal equinox. These names come from the Latin words for spring and fall. More recently, there has been a shift towards using the names March equinox and September equinox, so as not to exclude the southern hemisphere, which has opposite seasons than the traditional names imply. This is also why the terms June solstice and December solstice are used, rather than summer and winter solstice.