Mabon is the name used by some traditions of Wicca, as well as some other forms of Neopaganism, for one of the eight annual sabbats central to their beliefs. It is celebrated on the Autumnal Equinox, which in the northern hemisphere occurs on or around September 23rd (occasionally the 22nd). Many celebrate on the 21st since most early Wiccan and Neopagan sources reference this date as Mabon. In the southern hemisphere, the Autumnal Equinox occurs usually around March 21.

Also called Harvest Home, the Feast of the Ingathering, Meán Fómhair, or as Alban Elfed by Neo-Druidic traditions, this holiday is a ritual of thanksgiving for the fruits of the earth and a recognition of the need to share them to secure the blessings of the Goddess and God during the winter months. The name may derive from Mabon ap Modron, a character from Welsh mythology, although the connection is unclear

Among the sabbats, it is the second of the three harvest festivals, preceded by Lughnasadh/Lammas and followed by Samhain.

The Autumnal equinox along with the other Equinox's were indeed celebrated in Celtic countries as part of the harvest festival,the Autumnal Equinox is an annual solar event likely commemorated by many ancient pagan cultures. Meanwhile, all that is known about Anglo-Saxon customs of that time was that September was known as haleg-monath or 'holy month.'

Mabon is a masculine personal name in Welsh; as well as being found as the given name of the mythological character Mabon fab Modron, it remains a popular name in Wales today.

* From the Latin word like nox, although the root is retained in English in the adjective: equinoctial — it is not commonly used for the plural, which is equinoxes, rather than equinoctes.
* One effect of equinoctial periods is the temporary disruption of communications satellites. For all geostationary satellites, there are a few days near the equinox when the sun goes directly behind the satellite relative to Earth (ie, within the beamwidth of the groundstation antenna) for a short period each day. The Sun's immense power and broad radiation spectrum overload the Earth station's reception circuits with noise and, depending on antenna size and other factors, temporarily disrupt or degrade the circuit. The duration of those effects varies but can range from a few minutes to an hour. (For a given frequency band, a larger antenna has a narrower beamwidth, hence experience shorter duration "Sun outage" windows).
* A folk tale claims that only on the March equinox day (some may add the September equinox day or may explicitly not), one can balance an egg on its point. However one can balance an egg on its point any day of the year if one has the patience.
* Although the word "equinox" implies equal length of day and night, as is noted elsewhere, this is not true. For most locations on earth, there are two distinct identifiable days per year when the length of day and night are closest to being equal. Those days are commonly referred to as the "equiluxes" to distinguish them from the equinoxes. Equinoxes are points in time, but equiluxes are days. By convention, equiluxes are the days where sunrise and sunset are closest to being exactly 12 hours apart. This way, you can refer to a single date as being the equilux, when, in reality, it spans sunset on one day to sunset the next, or sunrise on one to sunrise the next.
* The equilux counts times when some direct sunlight could be visible, not all hours of usable daylight, which is anytime there is enough natural light to do outdoor activities without artficial light. This is due to twilight, and this part of twilight is officially defined as civil twilight. This amount of twilight can result in more than 12 hours of usable daylight up to a few weeks before the spring equinox, and up to a few weeks after the fall equinox.
* On the contrary, the intensity of light near sunrise and sunset, even with the sun slightly above the horizon, is considerably less than when the sun is high in the sky. The daylight which is useful for illuminating daylit houses and buildings and for producing the full psychological benefit of daylight is shorter than the nominal time between sunrise and sunset, and is present for 12 hours only after the vernal equinox and before the autumnal equinox.
* It is perhaps valuable for people in the Americas and Asia to know that the equinoxes listed as occurring on March 21 that occurred frequently in the twentieth century and that will occur occasionally in the 21st century are presented as such using UTC, which is at least four hours in advance of any clock in the Americas and as much as twelve hours behind Asian clocks. Thus, there will be no spring equinox later than March 20 in the Americas in the coming century.

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