Sky Tour Podcast for October 2023
This month’s episode is sponsored by Celestron, manufacturer of high-quality telescopes and an industry leader in developing exciting optical products with revolutionary technologies.
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I’m Kelly Beatty of Sky & Telescope magazine, and tonight we’re going on a tour of the stars and planets that you’ll see overhead during December. First let’s keep tabs on the Moon’s whereabouts, then we’ll watch for some impressive shooting stars, track down four planets, and gaze at a tall tower of bright evening stars. So bundle up, grab your curiosity, and come along on this month’s Sky Tour.
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December is the month of the solstice, when the Sun appears farthest south in the sky. This term — first used in the 14th century — comes to us from the Latin word solstitium, meaning “Sun standing still.” These days it signals the beginning of winter for those of us north of the equator and summer for Australians. This year’s December solstice comes at 10:27 p.m. Eastern Standard Time on the 21st. If you have a chance, watch where sunset occurs on this date — that will mark the spot on the horizon where the Sun sets its farthest southwest for the entire year. 
Y’know, virtually every culture has celebrated the winter solstice as a seasonal “turning point,” a sign that brighter, longer days lie ahead. But none of them celebrates the solstice because it’s the longest stargazing night of the year. Hmph! The truth is that December is one of the best times of the year to watch the stars. For one thing, unlike much of summer, you step outside and the air just looks clean. And clean air makes the stars and planets easier to see. Then you factor in what this season has to offer overhead — which is a lot. And it gets dark early, by 5 pm in most places. Heck, I sometimes try to sneak in a little stargazing before supper.
But before we get to the stars and planets of this holiday season, let’s check on the Moon’s whereabouts. As December opens, you’ll find it in the morning sky before dawn. Last quarter is on December 5th. Then New Moon follows on the 12th, after which you can watch for a slender crescent rising in the southwest after sunset. Filling out the lunar calendar, first quarter falls on the 19th and the full Cold Moon on the night of the 26th. By the way, during December, the full Moon can appear directly overhead — or nearly so — around midnight as it arcs across the sky. Last quarter follows on the 26th. As you’ll hear in a moment, these dates have a bearing on what’s arguably the best meteor shower of the year.
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The annual Geminid meteor shower peaks this month. Pretty much everyone knows about the Perseid meteors that arrive each August. But the Geminids are under-appreciated, because often they produce the year’s best meteor event. Ordinarily you can count on the Geminids to deliver maybe one meteor per minute from a really dark location, and these can often appear bright and intensely colored. This shower gets its name because the shooting stars you’ll see all seem to streak across the sky from the direction of the constellation Gemini. 
This shower has a broad maximum, meaning that it can be appreciated over a few nights, but if you had to pick one night to brave the cold to watch them, that’d be either the 13th or 14th. The Moon, just past new, is nowhere to be found this year, so it won’t wash out the faintest meteors. Gemini rises by about 7 pm, so that’s a big plus because the show should be well under way by 9 pm with the shower’s radiant, near the star Castor, about 30° high in the east. This radiant is the point in the sky from which all these meteors will seem to radiate as they flash all over the sky. So you really don’t need to face Gemini — just look in whichever direction your sky is darkest. You can park yourself in a comfortable chair or even lie flat and, heck, watch the show all night long if you want. Just make sure you dress very warmly.
So why do we see these particular meteors every mid-December, like clockwork? Meteor showers happen when our planet plows though a stream of fine particles that have been shed by a comet and spread out along its orbit. Earth crosses the Geminids’ orbit each December. But in this case the source isn’t a comet but an asteroid, called Phaethon. This object has a looping orbit that passes only 13 million miles from the Sun, and temperatures on its rocky surface can climb to more than 1,300° Fahrenheit. Astronomers think the searing sunlight causes its surface to crack and crumble, and then the Sun's radiation pressure then drives these particles off into space. Wow!
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While you’re waiting for the Geminids to appear, or any other time this month in early evening, you can easily track down a couple of planets. The most obvious is Jupiter, a brilliant beacon that you can spot well up in the east even in twilight. The king of planets was its brightest back in early November, but even so, wow, you can’t miss it now.
The other bright planet to look for is Saturn, which right now looks much dimmer than Jupiter — but it’s not hard to find. At nightfall, it’s roughly due south and not quite halfway to overhead, roughly as high up as Jupiter but well to its right by about six times the width of your clenched fist. If you still aren’t sure you’ve found it, head outside on the evening of December 17th, when a beautiful crescent Moon will sit just a bit to its lower left.
Now, there is one more evening planet you can hunt for early this month, and that’s Mercury. But spotting it will be a little tricky. This fast-moving world has been creeping up through late November, and the best time to look for it will be the first 10 days of December. Find a viewing spot that has a completely unobstructed view toward west, and go out when the afternoon sky is especially clear. Watch where the Sun sets, and then look just to the upper-left of that spot, just a few degrees above the horizon, beginning about 45 minutes after sunset. Mercury is there, quite bright but lurking in the twilight. If you don’t spot it, don’t fret — you’ll have a much better opportunity next month before sunrise.
Speaking of sunrise, if you wake up to a clear sky before dawn on December 9th, poke your head outside — or just look out an east-facing window — to spot a beautiful pairing of brilliant Venus and a delicate crescent Moon just a bit to its right. It’ll be a stunning sight, easily worth a little bit of lost sleep.
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With all this planetary action going on, are there any stars worth viewing? You bet! We might be on winter’s doorstep, but the evening sky is still hanging on to some of the stars of summer. 
Look well to the upper right of where the Sun sets, about halfway up in the sky. That bright, icy-white star is VAY-guh, which is sometimes called the Summer Star because it rides high in the sky during the balmy evenings of July and August. But now it’s low in the west — as if deflated by the oncoming cold. Catch it soon after dark before it sets for good until next summer.
Above VAY-guh, by about 1½ fists, is a slightly dimmer star called Deneb. It forms the head of the Northern Cross, which stands more or less upright during the evening at this time of year. Do you see it? This is what astronomers call an asterism — a pattern of stars, like the Big Dipper, that’s easy to spot but not really a full-fledged constellation.  There are five main stars in this cross, which overall is about two fists tall. Deneb is brightest and at the top. Below it is a row of three stars, roughly the same brightness and more or less in a horizontal row. The middle on is called Sadr, Arabic for “the chest.” Down at the foot is Albireo, about half as bright as Sadr. And in between, along that line, are two more stars that are fainter still. If you can see all seven, you’ve got a decently dark sky. If all you see is Deneb, well, sadly, you’re dealing with an awful lot of light pollution.
Now swing completely around until you’re facing east. Around 8 p.m. early in December, and by 6 p.m. at month’s end, you can take in what S&T columnist Fred Schaaf calls a “tower of brilliance” that starts near the horizon and climbs all the way to overhead. Start low down by finding Orion and the easy-to-spot vertical trio of stars that mark his belt. To Orion’s left by a couple of fists are the twins of Gemini, anchored by the stars Castor and, below it, slightly brighter Pollux. That’s the general area from which the Geminid meteors will seem to originate as they zip across the sky
Above Orion is Taurus, the Bull, whose angry eye is marked by the reddish superstar Aldebaran. Look a little more than one fist above Aldebaran for a fuzzy patch of light. This is the Pleiades, a tight little nest of stars. Sometimes they’re called the Seven Sisters. If you’ve got decently sharp eyesight, you’ll see that the six brightest stars of the Pleiades form a tiny dipper shape. Don’t confuse this with the real Little Dipper, which is much bigger and located due north in the sky.
To Aldebaran’s left is the bright star Capella. This is the alpha star in the constellation Auriga (aw-RYE-guh) or sometimes pronounced aw-REE-guh, which you can make out as a broad, misshapen hexagon with Capella at its top. Now, Auriga has a split personality — he’s either a charioteer or a goat-herder, depending on whom you ask. Capella mean’s “she-goat”, and just to its right is a faint, narrow triangle of stars sometimes called The Kids, as in baby goats.
And still higher up is Jupiter, which is unmistakable. Right now it’s outshining every other star in the nighttime sky by a wide margin. 
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Now let’s end the evening tour by looking a bit west of directly overhead — well to the right of Jupiter and well above Saturn. Look for four medium-bright stars at the corners of a huge square that’s a bit bigger than the size of your clenched fist. That’s another asterism, called the Great Square of Pegasus, and it marks the body of a mythical horse that’s flying across the sky. But this isn’t much of a horse — it’s upside down as seen by us northerners, and it has no hindquarters.  Look for two loose strings of stars, stretching from the right corner, that trace the horse’s front legs. The neck and head extend westward from the bottom corner, ending in the star Enif, an Arabic word meaning “the nose.”
If you’re lucky enough to have good, dark skies, and if there’s no bright moonlight, look past Enif, toward lower right, for a parade of four small constellations: 
Equuleus (eh-QUOO-lee-us), the Little Horse; 
Delphinus, the Dolphin; 
Sagitta, the Arrow; and 
Vulpecula, the Fox.
Each of these is marked by only 3 or 4 dim stars, so they might be a challenge to spot. You can always use the star chart in center of every issue of Sky & Telescope to help you track them down.

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That’s about it for this month. If you want more tips for viewing the night sky, including a free, interactive star chart for any time or date, check out our website, SkyandTelescope.org.
If you haven’t already subscribed, you can find Sky Tour on Apple Podcasts, Spotify, Stitcher, or wherever you listen. And please leave a rating or review! It will help others find the show. 
And if you want to explore the solar system and universe more deeply, please do check out the full line of binoculars and telescopes available at Celestron.com.
Sky Tour is a production of Sky & Telescope, a division of the American Astronomical Society, and is produced by me, Kelly Beatty.
Next month we’ll spend some time with the easy-to-spot constellations Cassiopeia and Orion. Until then, I wish you clear skies.