The Moon is now waning, growing thinner and rising about an hour later each night. So on Friday, Groundhog Day – the traditional Imbolc, or winter’s midpoint – skies will be inky the first two hours after dusk. On Saturday night, February 3, we’ll have darkness the first three hours, until 8:30 p.m. Monday extends it to four hours, and so on.
Moonless winter nights are special around here. The air is the driest of the year and the winter stars are the most brilliant. Orion and his friends are conspicuous in the hours after nightfall. If you’re away from Kingston, New Paltz and all artificial lights, you’ll see why we have a planetarium-come-to-life.
This week we face into the winter Milky Way, the spiral arm that’s opposite the galactic core. Ever wonder how that odd two-word label came to designate one of the grandest things we can see?
“Milky Way” wasn’t coined in some modern moment of whimsy. Although it’s directly overhead the same week that trick-or-treaters are handed items with the same name, it predated the candy bar by at least half a millennium. The label has an interesting etiology.
Its story began with the sky itself, whose most dominant feature in olden days (and even today, for those away from urban light pollution) was the dramatic creamy band that bisects the heavens. This remarkable glowing belt is sadly invisible from cities and brighter suburbs; and when it is just barely glimpsed from outer suburbs, it still isn’t awesome in the traditional sense. But go to any desert, rural farm, isolated dirt road in the Southwest, or a sanctuary like Cherry Hill State Park in northern Pennsylvania on a moonless evening, and it takes one’s breath away. Fields and roadsides north of Margaretville do the trick around here, too. Its late-summer brilliance – great enough to cast shadows – is punctuated by countless inky-black Rorschach patterns, making its vastness and grandeur the centerpiece of the sky. The Aztecs and Mayas revolved their mythologies around this luminescent band, and regarded it as the path taken by the newly departed en route to heaven.
In medieval Europe it was called by its Latin name, Via Galactica, meaning “Milk Street” – or, perhaps a bit more grandly, “Boulevard of Cream.” It was a perfect description, since the sky-band really does resemble a brook of spilled milk – albeit one that is oddly glowing, as if radioactive. So our modern Milky Way is simply a direct translation of Via Galactica.
Its nature remained mysterious until Galileo pointed his first telescope at it in 1610. The cranky 46-year-old observer wrote that the glow merely came from innumerable little stars – nothing more to it than that – and added naïvely that we “could now dispense with wordy debates about it,” which of course didn’t happen. When, in 1929, Hubble proved that all the sky’s spiral nebulae were separate “island universes” that each resembled our own Milky Way, they were called galaxies, too. The term and its possessive adjectives like “galactic” contain “lactic,” suggesting that the entire cosmos is one vast dairyland. These were all direct consequences of that milky Via Galactica label, derived from its simple appearance.
These nights we see that record’s flip side: our galaxy’s less brilliant spiral arm. It’s far less bright than the September Milky Way, but it still pops with lots of stars. Check it out this week. Each night will be darker than the previous one. And the price is right.