Transcript: Many cultures have used a solar calendar, and, in fact, Sun worship was a basic part of ancient civilizations. Solar calendar divides the year into seasons using 4 fixed points. The longest day in the year, the summer solstice, June 21, the shortest day in the year, December 21, the winter solstice, and the two midpoints, March 21 and September 21, the spring and autumn equinoxes, equinox from the Latin word “equal night,” equal times of day and night. These are the four markers of a solar calendar, but ancient cultures also used to celebrate the 4 midpoints between the solstices and the equinoxes, and celebrate festivals on those days as well. We can even see residues of this in some European cultures. For instance, in Ireland, they still celebrate Imbolc on February 1, Beltane on May 1, Lughnasadh on August 1, and Samhain on November 1. Two of these festivals, the 8 points of the cardinal points of the solar calendar, are festivals that are celebrated widely. May Day in many parts of Europe, November 1, of course, marks All Hallows Eve, or Halloween, or the Day of the Dead, a widely celebrated holiday. The solar calendar is still with us in our religious and festival days.