I got two press releases in my email today — both touting the upcoming solstice as something newsworthy. Oohhhkayyy…. let’s look at this a bit deeper. First of all, “what’s the solstice?” you might ask. Simply put, it’s the day when the Sun reaches its southernmost point in the sky during the year. After that, its zenith point marches steadily northward. This year that special day is Monday, December, 22nd at 2:04 a.m. (for the folks on the East Coast of the U.S. — folks on the West coast start winter at 11:04 p.m. on the night of the 21st and for folks in England, it’s 7:04 a.m. on the 22nd.)

So, you might further ask, what’s the big deal here? Will the world tip over? The stock market surge on the news? The planets move into alignment? Will spiritual auras envelop everyone who waves a burning sage bouquet in front of a pyramid-shaped quartz crystal? Naw. The solstice isn’t a mysterious or metaphysical occurrence. It’s an entirely naturally-occurring twice-a-year event that has more to do with how the Earth moves around the Sun. Here’s what the good folks at Sky & Telescope have to say about the solstice:

“The seasons’ starting times are governed by the Earth’s motion around the Sun — or equivalently, from our point of view, the Sun’s annual motion in Earth’s sky. The start of winter (for the Northern Hemisphere) is defined as the moment when the Sun hovers over Earth’s Tropic of Capricorn (the line of latitude 23.5 degrees south of the equator) before heading north — a moment called, by Northerners, the winter solstice.

The Sun appears to move north and south in our sky during the year because of what some might consider an awkward misalignment of our planet. Earth’s axis is tilted with respect to our orbit around the Sun. So when we’re on one side of our orbit, the Northern Hemisphere is tipped sunward and gets heated by more direct solar rays, making summer. When we’re on the opposite side of our orbit, the Northern Hemisphere is tipped away from the Sun. The solar rays come in at a lower slant to this part of the world and heat the ground less, making winter.

North of the equator, the June and December solstices mark the beginning of summer and winter, respectively. The effect is opposite for inhabitants of the Southern Hemisphere; for them the December solstice signals the beginning of summer, while winter starts at the June solstice.

For a skywatcher on Earth (at north temperate latitudes), the effect is to make the Sun appear to move higher in the midday sky each day from December to June, and back down again from June to December. A solstice comes when the Sun is at the upper or lower end of its journey; an equinox comes when the Sun is halfway through each journey.”

So, if the solstice is a by-product of Earth’s motion around the Sun, what’s the big hoo-hah about? Why the press releases? It’s a fancy way of announcing that winter will be coming in on Monday and what clued us into that fact. For those of us north of the equator, it marks the longest night and the shortest day of the year. So, should you do anything to celebrate?

Well, yes, as a matter fact there IS something you can do. Parties, of course, are always in order. It’s a partyin’ time of year. In fact, solstice celebrations are some of the oldest known get-togethers in human history. But, the festivities don’t stop with solstice. Wait until December 25 (Christmas Day for those who celebrate that) and you’ll be rewarded with a great celestial sight. Dress up appropriately for the weather in your area, go outside and look toward the western horizon after sunset (in the dusk). If your skies are clear, you should be able to see the planet Venus and the thin crescent Moon low in the southwest. These aren’t really an effect of the solstice — they just happen to be visible a few days after solstice. If you’re lucky, as the sky grows darker you might be able to see the full moon glowing faintly in reflected Earthlight beyond the edge of the crescent. This is called the “Old moon in the new moon’s arms.” Have fun with your celebrations this year — and just remember: six months until the next solstice. Plan now!