Tomorrow, Tuesday, Sept. 22, 2009, at 4:19 p.m. Central Standard Time, the autumnal equinox will occur. The Earth’s axis of rotation will be perpendicular to a line connecting the centers of the Earth and the sun. That positioning leads to the lengths of day and night being approximately equal. “Equi-nox” literally means “equal night.”
So why should you care about this relatively obscure astronomical event? For one thing, you are riding through space on this ball of rock and should probably have some idea of your position in the universe. But a more “down-to-earth” reason is that, to an observer of the natural world, the coming fall will be rich with seasonal changes related to the equinox.
There are four important dates during each year that mark dramatic changes in the natural world: vernal or spring equinox (day and night of equal length), summer solstice (longest day of the year), autumnal equinox (day and night of equal length) and winter solstice (shortest day of the year). Not coincidentally, those dates also mark the changing of the four seasons of the year. Ancient peoples appreciated the significance of those dates, building monuments around the world to track the celestial events.
We modern humans have increasingly insulated ourselves from the extremes of heat and cold, but wild plants and wild animals are out there every day, surviving what nature throws at them, or not. Fall is a time of preparation for the coming winter and the transition can produce spectacular natural events for those who put themselves in the outdoors to observe them.
Because the fall is my favorite season in Missouri, I am particularly enthusiastic over the arrival of the autumnal equinox. The death of chlorophyll to reveal the bright fall leaf colors, the migrations of birds, bees feverishly working the last flowers of the year, ballooning spiders, deep blue skies, the beauty of a heavy frost, the warmth from a woodstove, the comfort of an old flannel shirt--all are highlights of the season to me. Outdoor experiences are more pleasant with the cooler temperatures and the diminished threats from mosquitoes, gnats, chiggers and ticks. I hope that you’ll enjoy Missouri’s outdoors this autumn with friends or family. Conservation area trails are great places to experience the season.