Halloween Celebration Has Key Celestial Origins

For some, Halloween is a day for scary stories, spooky costumes and an overdose of sugar, but for others, the holiday is an important marker in astronomy.

As the media site EarthSky reports, Halloween is a cross-quarter day, meaning it falls between the equinox and solstice. In the United States, October 31 serves as the midpoint between the autumn equinox and winter solstice. However, the exact cross-quarter day would be November 7—October 31 has become been adopted by tradition.

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Using astronomy, the year is divided into eight categories: spring and fall equinoxes, winter and summer solstices and four cross-quarter days. These cross-quarter days are Groundhog Day, May Day on the first of the month (also known as Beltane), Lammas on August 1 (or Lughnasadh) and Halloween.

The lesser-known May Day was the start of summer for the ancient Celts, and Lammas was a time for baking bread from the wheat harvest, according to The Farmer’s Almanac.

Our modern holiday is actually a spinoff of another spooky day, Samhain, and EarthSky says it was likely celebrated this time of year because it is a cross-quarter day. Thought to be the beginning of the new year on the Celtic calendar, this day was actually known as “summer’s end,” according to The Farmer’s Almanac. Farmers retrieved their cattle in from the pasture, many of which would supply the meat for the upcoming winter. As the day was a figurative death of the previous year, it was tied to ghosts and graveyards, much like our current Halloween. The seasonal apple bobbing tradition also comes from Samhain, but the activity was previously used to predict what would happen in the upcoming year. 

Halloween is also the darkest of the cross-quarter days, according to EarthSky, making it even more fitting for mischief. It was once thought that ghosts would wander the earth from sunset until midnight on Halloween. Then, on November 1, which is also All Saints Day, the spirits from the deceased would once again leave and find peace.

While you’re out haunting the streets this year, the night sky is set to deliver some treats, too. Space reports that trick-or-treaters can see the moon rising after 4 p.m. on the horizon facing east-southeast. At around 10 p.m., the moon will be at its highest point, so young ones might miss out on the view.

There is a small chance that the Taurid meteors, also known as the Halloween fireballs, could be seen tonight. But Saturn is set to descent in the west-southwestern region of the sky and can be glimpsed at twilight.