In the solar year, there are four significant dates: the two solstices, where the Sun reaches the highest latitudes in the sky, and the equinoxes, where the Sun is directly over the equator at noon. These are pretty well-known, and tied to religious festivals (the date of Christmas, for example, was selected for its proximity to the traditional Yule festival on the winter solstice). In addition, there are four lesser-known festivals halfway between the major festivals: Halloween (moved like Christmas from its original date, celebrated in Mexico as Day of the Dead) is halfway between the autumnal equinox and the winter solstice, Groundhog Day (also known as Candlemas) is halfway between the winter solstice and the spring equinox, May Day is halfway between the spring equinox and summer solstice, and Lammas is halfway between the summer solstice and the autumnal equinox.
So Groundhog Day has drifted pretty far from its roots, but that’s OK by me. We don’t have to assign deep meanings to dates that simply are due to the natural motion of the Earth around the Sun, and I think all of us can enjoy a festival whose primary modern purpose is to look at small fuzzy animals.