Today is the autumnal cross-quarter day. Like equinox and solstice, a cross-quarter day identifies a place in the Earth’s orbit. Cross-quarters occur at the midpoint between solstice and equinox.
Image: Diagram of solstices, equinoxes and cross-quarter events. (Courtesy Archaeoastronomy.com — Click for an animated version)
Ancient Celtics celebrated cross-quarter days as significant events in their calendar. Samhain marked the end of the harvest and the end of summer. Samhain is the word for November in the Irish language. The same word was used for a month in the Celtic calendar, in particular the first three nights of this month, with the festival marking the end of the summer season and the end of the harvest. A modernized version of this festival continues today in some of the traditions of the Catholic All Saints’ Day, the secular Halloween, and in folk practices of Samhain itself in the Celtic Nations and the Irish and Scottish diasporas.
Archeoastronomy.com is an interesting site to visit. Go there and read about the ancient peoples celebration of celestial events. Also visit Old News and read about the possibility that ancient Native Americans may have been influenced by the Celtic calendar! Fascinating stuff.