Podcast for October 2022: Make Way for Jupiter

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 October. In the minutes ahead, we’ll ponder the Moon’s whereabouts; then give Jupiter a really close look, learn what Andromeda and Pegasus have in common, circle around the pole star Polaris, and watch for meteors shed by Halley’s Comet. So grab your curiosity, and come along on this month’s Sky Tour.
*****
New Moon occurred on September 25th, and by the time we flip the calendar to October, there’s a waxing crescent Moon well up in the sky. By the way, the word waxing means the sunlit portion of the Moon appears to get fatter, up until full Moon, and the word waning is used as it gets thinner after that. Whatever, I just love the sight of a crescent Moon no matter when it happens. This month it fattens early on, reaching first quarter on the night of October 2nd and becoming the full Hunter’s moon on the 9th. I suppose this is the time of year when it’s time to go hunting in preparation for the cold winter ahead. Last quarter is on the 17th, and the Moon returns to new — close to the Sun in the sky and hidden from view — on the 25th. So I can look forward to seeing that lovely waxing crescent again each evening as October draws to a close.
It’s easy to think of the Moon as just a circle in the sky, but it’s really a sphere. And its changing shape has nothing to do with Earth’s shadow, as some people mistakenly think. If you’ve ever wondered by the Moon shows different phases as it orbits around Earth, here’s something you can try with a golf ball or a ping-pong ball. Go outside just before sunset in early October, or you can do this at month’s end, and find the crescent Moon over in the southwest. Hold the ball up at arm’s length so it’s pointed in the Moon’s direction and in sunlight. Now look at the ball. You’ll see a slice of it on the right side illuminated by the Sun, in a crescent shape, while most of it is in shadow — exactly how the Moon looks! 
Do this a couple of nights later, again just before sunset, and you’ll notice that the Moon has moved around in its orbit and appears farther east. Point your ball toward the Moon, and its surface will look more fully sunlit than it did before. It’s waxing, just like the Moon is. Finally, on October 9th, when the Moon is full, hold your ball up in late afternoon sunlight one more time, toward east where the Moon is about to rise, and it will look “full”. Here’s the point: The ball and the Moon both show these different shapes because they’re spheres being illuminated by the Sun from different angles. So congrats, you’ve just mastered the mystery of why the Moon goes through its phases each month.
*****
Before twilight fades I want you to note where the Sun has set. That’s west, more or less. Not far above that spot on the horizon is the unmistakably bright star Arcturus. It’ll be easier to spot early this month, but by the Halloween it will be farther down and harder to find. Now make an about face from the sunset point, so that you’re facing east, more or less. You’ll have no trouble spotting Jupiter, perched above the eastern horizon. Jupiter is pretty bright considering that it’s nearly 400 million miles away. But when you’re the biggest planet in the solar system, more than 11 times the diameter of Earth, you’re going to be obvious even from that far away. 
There are two other bright planets waiting for you tonight. Look to the right of Jupiter by about four times the width of your clenched fist held at arm’s length. You’ll be looking south, more or less, and the bright “star” kind of on its own over there is actually Saturn, It’s not as nearly bright as Jupiter, 24 times fainter in fact, both because Saturn is a little smaller than Jupiter and it’s more than twice as far away. 
The second planet, Mars, won’t make its appearance until it rises over the northeast horizon. That’ll be around 10 pm early in October and sooner, around 8, late in the month. Mars is already pretty obvious early in October, and by the end of the month it will appear almost twice as bright. That’s because Earth and Mars are gradually coming closer as they circle the Sun.
You can use the Moon as a shortcut to finding these three planets. On the evening of October 5th, the slightly gibbous Moon is parked to the lower left of Saturn. The next night it’ll be farther left, or east, about halfway between Saturn and Jupiter. And on the 8th it’ll be just 4° from Jupiter, and they’ll be a striking duo in the sky. Stay up a bit late on the 14th, until 11 pm or so, and you can spot the waning gibbous Moon just 3ۥ° from Mars. That’s about the width of your two fattest fingers held at arm’s length.
All three of these planets, plus a lovely crescent Moon, will be up by late evening on Halloween. If it’s clear that night and you’ve got a telescope, set it up so that all the little spooks and goblins in your neighborhood — and their parents — can have a look. Better than fuzzy fake spiders for sure! 
*****
Aside from Arcturus, are any bright stars in view? I’m glad you asked! Look for the Great Square of Pegasus rearing up in the east as it gets dark. It’s a couple of fists higher up than Jupiter. The square, which looks tipped up on one corner, represents the body of the mythical horse which, right now, is on its back in the sky. Seems the gods never got around to finishing Pegasus; it’s got a neck and head extending off to the right, and its legs are sticking up toward overhead. But this horse has no behind — it ends at the square’s left corner, a star called or al-FEE-ratz or AL-fer-ratz — depending on who’s saying it. The gods also got a little crossed up here. Alpheratz is actually the anchor star for the constellation Andromeda, which extends off to the left from that point. 
Now make a generous quarter turn to your left, so that you’re facing northwest. See anything familiar over the horizon? It’s our old friend the Big Dipper. We’re used to seeing it higher in the sky, but here it is not far above the horizon. Actually, in this pose, it’s easy to see how the Dipper is just a part of the larger star pattern tracing out the Great Bear, Ursa Major. The bear’s pointy nose, marked by the star MUSS-i-duh, is about two fists to the right of the Dipper’s bowl. The bear’s legs dangle underneath, and the farther north you are the more of them you’ll see. Its tail is marked by the arc of three stars in the Dipper’s handle. I’ve never understood why this celestial beast has a long tail — because real bears have stubby ones — and yet many widely separated cultures have recognized this general pattern of stars as a bear. Some historians think its origin as such might date back more than 10,000 years.
Here’s something else to think about. As the starry sky wheels around through the changing seasons, old constellations sink into the sunset, like the Teapot in Sagittarius, and new ones like Pegasus rise in the east. But for star patterns like the Big Dipper, in the northern part of the sky, this seasonal shift becomes a slow counterclockwise rotation around Polaris, the North Star. Here’s your word for the day: circumpolar, which is what astronomers use to describe constellations near Polaris that never rise or set.
Polaris isn’t the brightest star in the sky, but it’s easy to find. Find the two stars on the right side of the Big Dipper’s bowl. Now draw an imaginary line through them, and follow that line upward and to the right until you spot a medium-bright star pretty much all by itself. And what might that be? it’s Polaris, the North Star.
Now use that clenched hand to measure three fists to the upper right of Polaris. You’ll see a group of five stars crudely shaped like a “3”. Or maybe you’ll see them as a broad “W” tipped up on its left corner. The whole pattern is a little bigger than your fist. This is the constellation Cassiopeia, who is a queen in Greek mythology. 
You’ll see that Cassiopeia and the Big Dipper are situated on opposite sides of the North Star. So when one is up high, the other is down low. The Dipper dominates in spring and summer, while Cassiopeia rules in fall and winter.
Now look to the upper left of Cassiopeia, and above Polaris, for a wide pattern of five stars looking a little like an upside-down house perched on the point of its roof. This is the constellation Cepheus, who is the husband of Cassiopeia and the mythical king of Ethiopia. About the same distance to the lower right of Cassiopeia are the stars of Andromeda, their daughter.
*****
And here’s one more thing. Two modest meteor showers peak during October. The Orionid shower peaks late on the night of October 20th. Now, Orion rises about 11 p.m. these nights, so that’s the earliest you could hope to see any of these shooting stars — which are actually bits of dust shed by Halley’s Comet. You might glimpse a few extra meteors per hour from a dark site late at night and in the hours before dawn. The other is called the Taurids, which are most active the last week of October through early November. Taurus rises in the east a little earlier, around 9 pm, so keep an eye to the sky when you’re out in late evening on Halloween.
*****
Thanks for letting me expand your celestial horizons for another 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 if you’ve enjoyed listening, please leave a rating or review! It will help spread the word about Sky Tour, and I really welcome your feedback.
And if you want to explore the solar system and universe more deeply, 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 I’ll explain why queen Cassiopeia is not a happy camper. Until then, I wish you Clear Skies.