The astronomy of Halloween, 10.25.10

Many of the holidays we now celebrate have their roots in nature. Ancient peoples paid a great deal of attention to the world around them and many of them were far more familiar with their night sky than people in our day and age. As their own personal calendars and cues for when to plant or harvest their crops often came from signals in the stars, many were familiar with particular star patterns, lengths of daylight through the seasons, and when equinoxes and solstices would take place. While this generalization cannot be applied to every ancient people group, it does hold true for some ancient civilizations, such as the Mayans, Aztecs, Greeks, Romans, Celts, Arabs, Japanese, Egyptians, Chinese, and some Native North Americans people groups.


The origins of Halloween, however, have their roots in ancient Celtic culture. The Celts lived several thousand years ago throughout the area that is now Ireland, the United Kingdom, and Northern France. Prior to the arrival of the Romans into that area, the Celts held a celebration called “Samhain” (pronounced sow-in) on or near October 31. Samhain meant “summer’s end,” and was their marker for the transition from the bright sunlight and warmth of summer to the cold and darkness of approaching winter. There was great spiritual significance tied to the holiday, as it was a transition from light and dark, warmth and cold, life and death. The barrier between the physical and the spiritual world was thought to be loosened, and spirits of the dead were thought to walk the earth and visit those they had left behind. The tradition of dressing up in costume began as a way to hide from the spirits so they would pass by you without recognizing you and causing you harm. It was also believed that the spirits would go about causing mischief, but their presence was not entirely unwelcome as the Celts also thought their presence would assist their priests as they attempted to divine the future.


 With the coming of the Romans into the Celts’ territory, Samhain became melded with two of their celebrations, one of which honored the passing of the dead, called Feralia, and another which honored the goddess of fruit and trees, Pomona. It is thought that this may be another prevailing reason why death or the spirits of the dead are tied to Halloween. The celebration to honor the goddess Pomona may also be the origin of the traditional fall activity of bobbing for apples; the apple was considered to be the symbol of Pomona.


With the coming of the Roman Empire, Christianity also began to spread, albeit a little more slowly. It is thought that the Roman Catholic Church often interposed its own holidays either on or near “pagan” holidays in an attempt to cause the people to transition over to their Catholic beliefs, but more often than not the beliefs were simply mixed up in the Catholic holiday. Such is thought to be the case with Halloween. November 1 was celebrated by the Celts as their New Years Day. November 1 was also designated by Pope Boniface IV as All Saint’s Day, a day to honor all the Christian saints who did not have their own, individual holy day. It was also known as “All-hallows” or “All-hallowmas,” so naturally the day before was known as All-hallows eve. Eventually through translation differences and different ways of naming the holiday, “All” was dropped it and became known as Hallowe’en. More western spellings tend to drop the apostrophe. 


So why celebrate October 31? Why is that date important in astronomy? Because it is a cross quarter day. The Celts placed it on that date because they recognized the transition.

Image credit: NASA

Cross quarter days are days that are halfway between equinoxes and solstices.  Equinoxes are those two days during the year when the sun rises and sets exactly in the east and west. During the solstices, the sun is at its furthest northerly and southerly points. Cross quarter days recognize the transition between the two. While it may seem odd to us now to celebrate a new season during what we now consider autumn, it is important to remember that the Celts were recognizing a different transition. While we tend to celebrate our seasons based on the equinoxes and solstices, they placed theirs on the four cross quarter days of the year.  The three other cross quarter days were on February 2, May 1, and August 1. Sound familiar? February 2 for us is celebrated as Groundhog Day. May 1 is the day of our May Day celebrations. August 1 has no equivalent holiday in our culture and is probably lesser well known because of it, but it is recognized as Lammas Day, a festival of the wheat harvest. So remember the holiday’s origins this weekend as you go out and celebrate; you are carrying on traditions with very, very old roots.

Credit: NASA Science, Live Science, Digitalis Education Solutions Inc., the History Channel, and Utah State University.