All About the Autumnal Equinox
Autumnal Equinox Definition
The autumnal equinox is the transitional point between summer and winter. It is the day where night and day are nearly equal in length. Before the autumnal equinox days are longer than nights, after the autumnal equinox days are shorter than nights. We can see this understanding from the roots of the word equinox which comes from Latin. Ã?Â? quus meaning equal and nox meaning night.
To put it in more scientific terms, an equinox is when the solar ecliptic (the path the Sun appears to take through the sky throughout the year) intersects with the celestial equator (a theoretical extension of the earth’s equator out into space). This happens twice a year, once at the vernal or spring equinox and the other at the autumnal equinox.
Generally the autumnal equinox comes on about the 22nd or 23rd of September. In the United States and many other countries it marks the first day of autumn (or fall). It is also known as the fall equinox for this reason.
What Causes the Autmnal Equinox?
Equinoxes are caused by the tilting of the earth as it revolves around the Sun. This is also the cause of the seasons. In summer the northern hemisphere is tilted towards the Sun and the southern hemisphere is tilted away. In winter the northern hemisphere is tilted away from the Sun while the southern hemisphere is tilted towards it.
As the tilt inverts itself each year it comes to a point where the earth’s equator is directly in line with the Sun. There is effectively no tilt and both the southern and northern hemispheres are at equal distance from the Sun. This occurs twice a year and are our two equinoxes. Because the earth is directly in line with the Sun there is no difference between the lengths of day and night.
This is described astronomically as the intersection of the solar ecliptic and the celestial equator. Although the Sun does not move with relation to the Earth, it appears to do so because of the tilting of the planet as each year progresses. Depending on the season we will see the Sun in different positions in the sky. If we charted the path that the Sun makes through the daytime sky we would see an elliptical path (as opposed to a circular one). This is referred to as the solar ecliptic.
The celestial equator is essentially an extension of the terrestrial equator out into space. When the solar ecliptic and the celestial equator intersect, then, the Sun is in direct line with the terrestrial equator and both northern and southern hemispheres are at equal distance from it. The autumnal equinox is the latter of the two points on the ecliptic where this intersection takes place.
Autumnal Equinox Celebrations
People throughout history have watched the Sun and the heavens for their understandings of the universe, and many celebrations have existed throughout history to celebrate different points of the solar year. The autumnal equinox is no exception.
Although the autumnal equinox is not as widely celebrated in the world or through history as either the summer or winter solstice or even the vernal equinox, there are many celebrations associated with it. The most commonly known to us are harvest celebrations, which are often celebrated around the time of the autumnal equinox. Many ancient peoples engaged in harvest celebrations around the equinox; some of these continue today.
The United Kingdom’s Harvest Day is celebrated around the time of the autumnal equinox. Canadian Thanksgiving is also somewhat related to the equinox. Our own harvest celebration, Thanksgiving, is not directly tied to the autumnal equinox, however, coming some two months after the autumnal equinox. Many American neopagan religions such as Wicca still celebrate a harvest festival on the equinox, it is known as Mabon.
Japan celebrates Autumnal Equinox Day as a national holiday. It is seen as a time of family and remembrance of dead loved ones. Autumnal Equinox Day is generally spent visiting graves of family members and holding family reunions.
