I LOVE AUTUMN BEST. The community bulletin board overflows with notices of fowl suppers, and there are hockey skates in the second-hand store.
Kitchens abandoned in summer's heat are busy and fragrant, as cooks produce goodies to share with friends and neighbours. The cooler weather makes my coffee taste especially good as I stroll, cup in hand, planning my day. There are tomatoes to can, potatoes and carrots to dig, tulips to plant with an eye to next spring. Nearby, great machines crawl across the fields night and day as farmers race to beat bad weather, bring in crops, and see what this summer's wager has paid.
In the wild, too, autumn is gathering time. Nature concentrates summer's explosion of life into great migrating flocks and herds, distills it into heady scents of ripe fruit and foliage beginning to decay. The abundance is emblazoned everywhere in red and gold.
A serene observer presides over autumn's rituals. The harvest moon, rising October 7th this year, is the full moon occurring closest to the autumnal equinox.
In autumn, the moon rises at a relatively low angle, making it appear to linger near the horizon as if reluctant to part from Earth. Because of this, the daily delay in moonrise is minimal - some 15 to 20 minutes, compared with more than an hour at the time of the spring equinox. Thus, the harvest moonrise happens at almost the same time several evenings in a row. In a cloudless sky, moonlight illuminates the landscape almost from sunset to sunrise. For farmers of yesteryear, light from the harvest moon added working hours at a critical time of year. It's still a welcome companion, although halogen lights have replaced kerosene lanterns.
With Halloween around the corner, the enormous orange moon always reminds me of pumpkins. The harvest moon appears orange for the same reason the rising or setting sun looks red. Earth's atmosphere scatters blue and yellow wavelengths, leaving orange and red. We're effectively peering through a thicker chunk of atmosphere when we gaze towards the horizon than when we look straight up, so the moon appears redder near the horizon than when it is higher. Extra dust in the air from harvest activities enhances the scattering effect.
That explains the harvest hue, but why does the autumn moon look so immense when it first appears? While moon's disc stays the same size throughout its nightly journey, our brain tells us otherwise. Primarily that's because we have trees, hills and other objects in the foreground to compare with the moon, and no points of reference as it climbs higher into the sky.
Scientists are still debating this effect, but there is an easy experiment to prove to yourself and any budding astronomers in your family that it is an illusion. Look at the moon when it has hefted its corpulent self just clear of the horizon. Now turn around, bend over at your waist and look at the same moon through your legs. Presto: the moon seems smaller.
Do take a walk beneath the harvest moon and enjoy the magic its ancient spell weaves across the landscape. Winter will arrive soon enough with its own enchantment but, as Nora Bayes and Jack Norworth wrote in 1903, "Snow time ain't no time to stay outdoors and spoon, so shine on, shine on harvest moon."