Beltane and the Cross Quarter Days

On the earth, our weather, our calendars, agriculture and many other things are driven by our relationship with the sun, and traditional peoples thought about this relationship a lot. They needed to. For example, it's important to know when to begin planting in the spring: plant too soon and a frost may kill the young growth. Plant too late and the summer heat may dry them out.  This is especially critical in pre-irrigation agricultures. So they studied the seasons carefully and began splitting the year into fractions.

The year is traditionally divided up into four seasons of roughly 92 days, normally deliniated by their starting points: the solstices and the equinoxes. These are the days that the sun appears to reach the endpoints and midpoints in it's travel north and south over the course of the year. Modern astronomers have figured out exactly when these points occur. Since the match between the sun and the Gregorian Calendar is imperfect, some of the dates below may be off by a day or two in some years.

In addition, most cultures have divided the seasons into halves, around a mid-season day. These days are called Cross Quarter days. Since these days mostly coincide with various planting and harvest cycles, many traditional religions all over the world celebrate them, and many of them have some reflection in modern festivals in nearly all cultures around the world, although often transmuted beyond recognizability.

Here's a list of these days, including some of the many names they've gone by

Midwinter's day, Imbolc, Candlemas, Groundhog's day.	Feb 2	The centerpoint of the winter is generally the coldest time of the year, although the days have begun to get noticeably longer (in the north. Opposite in the south)
Spring Equinox.	Mar 21	The sun is at the midpoint of it's trip to the north. Practically every culture has some celebration related to this event: In the Northern Hemisphere, it's time to start planting. Passover/Easter (named for the Babylonian fertility goddess Ishtar) are derived from this.  (it's the first sabbath after the first full moon after the equinox)
May Day, Beltane, Midspring day	May 1	The first planting is complete and the first plants are starting to come up. This is a time of fertility festivals.  More recently it's become popular for pro-worker events.
Summer Solstice	Jun 21	The start of summer.
Midsummer's Day, Lunasa	Aug 1	The plants are up, the growing is at it's peak.
Autumn Equniox	Sep 21	The harvests begin.
Midautumn day, Samhain, Hallows Day	Nov 1	The harvests are complete or nearly so, and things are beginning to die back for winter. Hence the death imagery of Halloween (Hallows Eve). Once it's over, Harvest celebrations, Thanksgiving celebrations, etc., begin.
Winter Solstice, Saturnalia, Yule	Dec 21	Most cultures have a winter celebration of some sort. They often are designed to remind people of the rebirth to come, despite the long winter grind ahead. E.g. Christmas celebrates the birth of the Messiah, Chanuka celebrates the survival of the temple and the miracle of the oil, etc.

Note that I've used earth centered terminology--the sun travels north and south.  In fact what happens is the earth is tilted approximately 23 degrees relative to it's orbital axis around the sun.  In practical terms this means that the sun appears to travel north and south: it's in the north when the earth is in the part of it's orbit with the north pole is tipped toward the sun, and it's in the south at the other part of its orbit.

On the Equinoxes, (from the Latin for Equal Night) rotational axis of the earth is exactly perpendicular to the line to the sun. At these points, the day and night are approximately equal in length, hence the name. (The actual length of the day is based on how far north or south of the equator you are. In the spring, the actual equal day is a little early, and in the autumn it's a little late.)

I originally wrote this article in the late 90s, with a major rewrite in 2005.