Etymology:

The word "equinox" was derived from Latin term "æquinoctium" which, in turn, came from "æquus" (equal), and "nox" (night). It refers to the time that occurs twice a year when the nighttime is equal to the daytime -- each being 12 hours in duration.

A multi-faith celebration:

Religious followers from around the world observe many seasonal days of celebration during late September. Most are religious holy days, and are linked in some way to the fall or autumn equinox. Common themes found worldwide are balance, harvesting, hunting, and remembrance of the dead.

People view other religions in various ways, and thus treat the celebrations of other faiths differently:

• Some people value the worldwide variety of fall equinox celebrations, because demonstrates the diversity of religious belief within our common humanity. They respect both their own religious traditions and those of other faiths for their ability to inspire people to lead more ethical and fulfilled lives. Religious diversity is, to them, a positive influence.
• Others reject the importance of all celebrations other than the holy days recognized by their own religion. Some go so far as rejecting some of their religion's holy days when they are discovered to have Pagan origins (e.g. Easter, Christmas, and Michaelmas).
• Some consider religions other than their own as being inspired by Satan. Thus the solstice and equinox celebrations of other religions are viewed as Satanic in origin, and intrinsically evil.

When and why the fall equinox happens:

The seasons of the year are caused by the 23.5º tilt of the earth's axis. Because the earth is rotating like a top or gyroscope, it points in a fixed direction continuously -- towards a point in space near the North Star. But the earth is also revolving around the sun. During half of the year, the southern hemisphere is more exposed to the sun than is the northern hemisphere. During the rest of the year, the reverse is true. At noontime in the Northern Hemisphere the sun appears high in the sky during summertime and low in the sky during winter. It is highest at the summer solstice (about June-21) and lowest at the winter solstice (about December-21).  The half-way points in the year are called the equinoxes. It is time of the year when the sun rises exactly in the east, travels through the sky for 12 hours, and sets exactly in the west. _1,2 Everywhere on earth experiences close to 12 hours of daylight, and 12 hours of nighttime.

The date and time of the fall equinox:

The exact date and time of the fall equinox, when the sun moves into the astrological sign of Aries, varies from year to year. Each year, the date/time moves progressively later in September until the year before leap-year is reached. On leap-year, it returns to an earlier date/time. This four-year cycle is then repeated. 

The above dates and times were derived from the astronomical calculations on The Dome of the Sky web site. ₁₅ Times are in UT (Universal Time). This used to be called Greenwich Mean Time or GMT. In North America, you can find your local time by subtracting:

• 3 hours 30 minutes for Newfoundland time
• 4 hours for ATL
• 5 hours for EST 
• 6 hours for CST
• 7 hours for MST
• 8 hours for PST
• 9 hours for ALA
• 10 hours for HAW

Fall celebrations by various faiths and countries - ancient and modern

• ANCIENT BRITAIN: Both the solstices and equinoxes "were the highly sophisticated preoccupation of the mysterious Megalithic peoples who pre-dated Celt, Roman and Saxon on Europe's Atlantic fringe by thousands of years." Stonehenge and other stone structures were aligned so that the solstices and equinoxes could be determined.
• ANCIENT IRELAND: The spring and fall equinox were celebrated in ancient times. A cluster of megalithic cairns are scattered through the hills at Loughcrew, about 55 miles North West of Dublin in Ireland. Longhcrew Carin T is a passage tomb which is designed so that the light from the rising sun on the spring and summer equinoxes penetrates a long corridor and illuminates a backstone, which is decorated with astronomical symbols. _21,22
• ASTROLOGERS: On the day of the fall solstice, the sun enters the sign of Libra -- the constellation of the balance or scales.
• CHRISTIANITY: The Christian Church replaced earlier Pagan solstices and equinox celebrations during Medieval times, with Christianized observances. Replacing the fall equinox is Michaelmas, the feast of the Archangel Michael, on SEP-29. "His feast was celebrated with a traditional well-fattened goose which had fed well on the stubble of the fields after the harvest. In many places, a there was also a tradition of special large loaves of bread made only for that day. By Michaelmas the harvest had to be completed and the new cycle of farming would begin. It was a time for beginning new leases, rendering accounts and paying the annual dues." ₃

  Other substitutions by the Church were:

  • Replacing the spring equinox by the Feast of Annunciation of the Blessed Virgin Mary. It is held on MAR-25, on the nominal date of the spring equinox according to the old Julian calendar. There was a "brief flirtation with calling the Vernal Equinox 'Gabrielmas.' "  This is the time when the angel Gabriel told Mary that she was pregnant. (Luke 1:26-38) ₄
  • Replacing the summer solstice, Midsummer Day, is the feast of St. John the Baptist, celebrated on JUN-24.
  • Replacing the winter solstice is Christmas, on DEC-25 when Mary is traditionally believed to have given birth to Jesus, while still a virgin. 

   

• CHUMASH: This is a Native American tribe from Southern California. They celebrate their fall equinox sun ceremony during their month of Hutash (September). It takes place "after the harvest is picked, processed and stored....Kakunupmawa is a ritual name for the Sun. According to traditional Chumash lore, all humans were known as children of the Sun, or 'sons of Kakunupmawa.' " ₅ The spiritual thoughts of the tribe would become focused the importance of unity in the face of winter confinement, death and rebirth.
• DRUIDS: At this time of the year, the ancient Celts conducted a mock sacrifice of a large wicker-work figure which represented the vegetation spirit. This might have been the origin of Julius Caesar's comment in his Gallic Wars that the Druids performed human sacrifices. Although he never witnessed a human sacrifice and never met anyone who had, this story has been accepted and repeated often enough to be accepted as truth. The Celtic mock sacrifice has been reborn in the Burning Man Project, a yearly fall festival celebrated for one week in Black Rock Desert in Nevada. ₂₈ The movie "The Wicker Man" was based on the Celtic tradition; to say more would ruin the film if you are seeing it for the first time. ₆
• FRANCE: A new calendar was adopted at the time of the French Revolution in the late 18th century. The first day of the year, the 1st of Vendemiaire (the grape-harvest month), was the date of the fall equinox in the Northern Hemisphere. The year was divided into twelve months of 30 days each. That left five or six surplus days which were celebrations ending the year, in honor of virtue, genius, work, opinion, prizes and revolution.
• MAYAN: The ancient Mayans constructed a pyramid at Cihickén Itzá which displayed different patterns of triangles of light at the time of the solstices and equinoxes. The dates signaled the start of a harvest, planting, or a religious ceremony. On the fall equinox, seven triangles become visible on the pyramid's staircase. ₇
• NATIVE AMERICAN SPIRITUALITY: There are countless stone structures created by Natives in the past and still standing in North America. One was called Calendar One by its modern-day finder. It is in a natural amphitheatre of about 20 acres in size in Vermont. From a stone enclosure in the center of the bowl, one can see a number of vertical rocks and other markers around the edge of the bowl "At the winter solstice, the sun rose at the southern peak of the east ridge and set at a notch at the southern end of the west ridge." The summer solstice and both equinoxes were similarly marked. ₈
  
  "America's Stonehenge" is a 4,000 year old megalithic  site located on Mystery Hill in Salem NH. Carbon dating has estimated the age of some charcoal remnants at 3,000 and 4,000 years ago. Researchers have concluded that the site was erected either by Native Americans or an unknown migrant European population. ₉ The site contains five standing stones and one fallen stone in a linear alignment which point to both the sunrise and sunset at the and fall equinoxes. 
• NEOPAGANISM: This is a group of religions which are attempted re-creations of ancient Pagan religions. Of these, Wicca is the most popular; it is loosely based on ancient Celtic beliefs, symbols and practices, with the addition of some more recent Masonic and ceremonial magic rituals.
  
  Monotheistic religions, like Judaism, Christianity and Islam, tend to view time as linear. It started with creation; the world as we know it will end at some time in the future. Aboriginal and Neopagan religions see time as circular and repetitive, with lunar (monthly) and solar (yearly) cycles. Their "...rituals guarantee the continuity of nature's cycles, which traditional human societies depend on for their sustenance." ₁₀
  
  Wiccans recognize eight seasonal days of celebration. Four are minor sabbats and occur at the two solstices and the two equinoxes. The other are major sabbats which happen approximately halfway between an equinox and solstice. Wiccans may celebrate Mabon on the evening before, or at sunrise on the morning of the equinox, or at the exact time of fall equinox.
  
  Mabon is the second and main Wiccan harvest festival.
  • Selena Fox of Circle Sanctuary comments: "The Goddess manifests in Her Bountiful Mother aspects. The God emerges as the Corn King and Harvest Lord. Colors are Orange, Dark Red, Yellow, Indigo, and Brown. It is the festival of thanksgiving." ₁₁
  • Lee Wavedancer of Witch on the Go.com comments that the Wiccan God "has sacrificed the last of Himself to provide us with a final harvest of food before the winter begins. Celebrants gather to mark the turning of the wheel and to give thanks for the ultimate sacrifice of The God, recognizing that He will be reborn at Yule. This holiday has been called 'The Witches' Thanksgiving' and is a time for feasting together with family and friends." ₁₂
  • The author of the Pagan Family Circle writes: "While in the past, most all were farmers, this harvest festival traditionally applies to the harvest of foods, yet in this day and age, the 'harvest' may also apply to the 'seeds of dreams and wishes' that were planted many months earlier. Now is the time to see if they have come true. Whether they have come true or not ... a ritual to thank the growing energies of the God and the fertility of the Goddess should be preformed at this time. Lay upon your altar a sampling of your 'harvest'.... use it freely in your ritual. (Note: even if your 'harvest' came up empty, IE: your dreams were not fulfilled, the God and Goddess should still be thanked for the effort put forth in your name)" ₁₃
• JAPAN: "...the Spring and Autumn Equinox is observed as the six-day celebration the Higan-e. It is celebrated "for three days before and after the Equinox. Six days was chosen because it is based on the six perfections, giving, observance of the precepts, perseverance, effort, meditation and wisdom - needed before one goes from this shore of samsára to the further shore or nirvana. The literal meaning of Higan is 'other shore.' The ritual includes repentance of past sins and prayers for enlightenment in the next life. It also includes remembrance of the dead and visits to the family graves. It is thought that the Spring and Autumn Equinoxes, being the most temperate times of the year, are ideal moments to reflect on the meaning of life." ₁₄

Fall equinox traditions:

"The month of September also marks the 'Wine Moon,' the lunar cycle when grapes are harvested from the arbors, pressed and put away to become wine...The full moon closest to the Autumn Equinox is known as the 'Harvest Moon,' since farmers would also harvest their crops during the night with the light of the full moon to aid them." ₁₆

Teutonic tribes called the period from the fall equinox until Winter Night (OCT-15) by the name "Winter Finding." Winter Night was the Norse new year. ₁₇