Fall Equinox—Wonder Wedneday

It's WONDER Wednesday!

This week's WONDER is the fall equinox. Ah, yes, it's that apple-harvest-pumpkin-spice-decorative-gourd time of year! The calendar says it's fall, so we humans head back to school and get out our sweaters. But what cues the natural world, other than shifts in weather?

THE CELESTIAL CLOCK

The autumnal equinox is tomorrow, September 22. Equinox is Latin for "equal night," because this is the time of year when day and nighttime hours are roughly equal. When the sun crosses an imaginary extension of Earth's equator line, plants and trees slow down, critters hoard for winter, and birds and butterflies begin their migration south.

MOON MAGIC

Some research indicates that plants and animals have a biological response to the phases of the moon. The Harvest Moon occurred on September 10 this year and shone brightly for several consecutive nights. In Anishnaabe tradition, the Harvest Moon is known as Wabaabagaa Giizis, or Changing Leaves Moon.

ALL YOU CAN EAT

Fall marks the moment when hibernating animals start feasting to store fat for winter. Up north that includes woodchucks, chipmunks, skunks, the 13-lined ground squirrel, and some bat species. Michigan's only bear species–black bears–sleep in their dens from December through April, but they're not true hibernators because their body temperature only drops a few degrees and they're easily awakened. The body temperature of true hibernators matches that of their surroundings and they're down for the count until spring!

Pictured: a sugar maple leaf perfectly illustrates the transition from summer to fall.