■ The waxing gibbous Moon jumped over Jupiter in the last 24 hours and now shines at the planet's left, as shown below. This scene is drawn for early evening while it's still twilight. Later, as the Moon and Jupiter move westward, the orientation of the scene rotates clockwise like every sky pattern in the southern side of the sky as the hours pass. So, watch Jupiter swing down to the Moon's lower right. Keep an eye out, and by about 1 a.m. Jupiter hangs straight below the Moon.

Moon and Jupiter, Dec. 21-22, 2023
These sky scenes are always drawn for an observer near the weighted center of North America's population, near Peoria, Illinois. (They're exact for latitude 40° north, longitude 90° west).

The Moon here is always drawn about three times its actual apparent size, but you might not think so! The Moon's brilliance in the sky gives your eyes and brain the impression that it's larger than its actual, rather puny apparent diameter of ½°.

The same happens even more so with the Sun. Both the Moon and Sun are about the same apparent width as your little fingernail held at arm's length. Don't believe it? Try it!


■ The Moon is farther left of Jupiter now, off the left of the scene above. It's just a few degrees to the right of the Pleiades in early evening for North America. Binoculars will help pull in the Pleiades through the moonlight.

Watch the Moon draw closer to the Pleiades hour by hour. The Moon finally passes only about 1° or 2° south of them shortly before setting in the northwest around the first light of dawn Sunday morning the 24th, as shown below.

The Moon is close to the Pleiades by early dawn Christmas Eve morning, Dec, 24, 2023.
In early dawn on Christmas Eve morning, the bright Moon accompanies the Pleiades down in the west-northwest.


■ And now in early evening the bright gibbous Moon, two days from full, has jumped to the lower left (east) of the Pleiades. The Moon forms a flattened, nearly isosceles triangle with the Pleiades above and Aldebaran below.

Around 11 p.m. tonight the Moon shines just about as close to the zenith as you will ever see it (from your mid-northern latitude), giving "lustre of mid-day to objects below."

Your Moon shadow at that time will be as short as you'll ever see it. Go look. It's even a little shorter than your shortest Sun shadow, which happens at midday at the opposite solstice in June. Why? Because the Sun is always on the ecliptic (by definition), but the Moon is currently 3.5° north of the ecliptic. Go look.

The Moon will do practically the same close zenith pass about an hour later each night for the next few nights. The Moon will be full on the night of the 26th.

Sirius and Procyon in the balance. Sirius, the Dog Star, sparkles low in the east-southeast as evening advances. Procyon, the Little Dog Star, shines in the east about two fist-widths at arm's length to Sirius's left.

But directly left? That depends. If you live around latitude 30° (Tijuana, New Orleans, Jacksonville), the two canine stars will be at the same height above your horizon soon after they rise. If you're north of that latitude, Procyon will be higher. If you're south of there, Sirius will be the higher one. Your eastern horizon tilts differently with respect to the stars depending on your latitude. Because the Earth is round.


■ This evening the Moon, a day from full, forms a wide, shallow triangle with bright Capella to its left or upper left and Aldebaran to its the right or upper right. The Moon is only a degree or two from Beta Tauri (El Nath), which at magnitude 1.6 just misses being a classed as a first-magnitude star.

The Moon and Beta Tauri cross very near your zenith around 1 a.m. tonight. The time depends somewhat on your location.


■ Full Moon tonight (exact at 7:33 p.m. EST). Now shining above the feet of Gemini in the evening, the Moon forms a deeper triangle with Capella and Aldebaran than it did last night.

The Moon passes its very closest to the zenith around 1 a.m. tonight. For the record, it goes just a trace closer to straight overhead than it did last night or the night before.


■ As the stars come out, face due north and look high. Cassiopeia is now a flattened M shape canted at about a 45° angle (depending on where you live). Hardly more than an hour later, the M has turned horizontal! Constellations passing near the zenith appear to rotate rapidly with respect to your direction "up."


■ Orion strides upward in the east-southeast after dinnertime. Above it shines orange Aldebaran, 1st magnitude, with the large, loose Hyades cluster in its background. Binoculars are the ideal instrument for this cluster given its size: its brightest stars (4th and 5th magnitude) span an area about 4° wide. Higher above, the Pleiades are hardly more than 1° across if you count just the brightest stars.

The main Hyades stars famously form a V. It's currently lying on its side. Aldebaran forms the lower tip of the V.

With binoculars, follow the lower branch of the V to the right from Aldebaran. The first thing you come to is the House asterism: a pattern of stars like a child's drawing of a house with a peaked roof. The house is currently upright and bent to the right like it got pushed.

The House includes three easy binocular double stars that form an equilateral triangle, with each pair facing the others. The brightest pair is Theta1 and Theta2 Tauri. You may find that you can resolve the Theta pair with your unaided eyes.


■ This is the time of year when M31, the Andromeda Galaxy, passes your zenith soon after dark (if you live in the mid-northern latitudes). The exact time depends on your longitude. Binoculars will show M31 as a small, dim gray elongated glow just off the knee of the Andromeda constellation's stick figure. See the big evening constellation chart in the center of the December Sky & Telescope.

Venus in bright dawn with much tougher Antares, Mercury, and Mars below and lower left of it, in the last mornings of December 2023.
Venus still shines brightly at dawn. As dawn swells, use binoculars or a wide-field telescope to try for much more difficult Antares and Mercury, and maybe even fainter, lower little Mars. For a sense of scale, Antares is 11° below Venus this morning and Mars is 5° below Mercury.


■ The brightest asteroid in the sky, 4 Vesta, is just past opposition and creeping toward Zeta Tauri, the dimmer horntip of Taurus near the top of Orion's club. Binoculars will show Vesta easily at magnitude 6.5. But you'll need a fine-scale finder chart to tell it from all the other faint pinpoints in the area! Use the chart with Bob King's article Vesta Sets Sail Across Orion.

Vesta will pass 0.2° from Zeta Tau on the nights of January 7th and 8th. Then it will cruise about ½° south of the dim Crab Nebula, M1, on January 11th, 12th, and 13th.


■ After the noise and celebration at the turning of midnight tonight, step outside into the silent, cold dark. The waning gibbous Moon will be shining high in the east, with the Sickle of Leo floating about a fist at arm's length above it.

In the south Sirius will be shining at its highest, with the other bright stars of Canis Major to its right and below it.

Sirius is the bottom star of the bright, equilateral Winter Triangle. The others are Betelgeuse in Orion's shoulder to Sirius's upper right, and Procyon the same distance to Sirius's upper left. The Triangle now stands upright on Sirius, just about in balance.

And look west of the zenith for Perseus now heading down. If you're in the Mountain or Pacific time zones, you'll find Algol, the prototype eclipsing variable star, near its minimum brightness of magnitude 3.4 instead of its usual 2.1. Algol takes several additional hours to fade and to rebrighten. Use our comparison-star chart to judge its brightness all through the night.

This Week's Planet Roundup

Mercury emerges into dawn view late this week. Starting around December 29th, look for it about three fists at arm's length lower left of Venus. On that morning Mercury is still only a difficult magnitude +1.3, but it's brightening and climbing daily.

Venus, magnitude –4.0 in Libra, shines as the bright "Morning Star" in the southeast before and during dawn. It's less high every week now. Closing in toward it from below is sparkly orange Antares, magnitude +1.0.

Mars is barely peeking over the eastern horizon in bright dawn, probably out of reach even with a telescope. It will very slowly get a little higher for the next five months!

Jupiter, magnitude –2.6 in Aries, is the bright white dot dominating the high southeast to south these evenings. It stands at its highest around 7 or 8 p.m. It has shrunk a little since opposition, but it's still a good 45 arcseconds wide in a telescope.

Jupiter and Io on Dec. 2, 2023
Jupiter on December 2nd, imaged by Christopher Go. South here is up. Bright Europa is about to exit the planet's upper left (south preceding) limb. Its shadow follows along behind. Between them here and a bit above is the row of three white ovals in the South Temperate Zone. The gradually shrinking "Great" Red Spot is in view. To its preceding side, the south part of the South Equatorial Belt remains especially dark. We've adjusted color and contrast here to approximate Jupiter's visual appearance.

Saturn, magnitude +0.9 in Aquarius, is getting lower in the southwest just after dark. Don't confuse it with Fomalhaut, similarly bright, nearly two fists to Saturn's lower left. Saturn sets around 9 p.m.

Saturn on Nov 1, 2023, with Rhea and Dione
Saturn on November 1st, imaged by Christopher Go. South is up. Two of Saturn's moons were nearly in conjunction with it: Dione directly above it here, and larger Rhea upper left.

Uranus, magnitude 5.6 in Aries, awaits your binoculars in the darkness 14° east (left) of Jupiter. In a telescope at high power Uranus is a tiny but distinctly nonstellar ball, 3.8 arcseconds in diameter. Locate and identify it using the finder charts in the November Sky & Telescope, pages 48-49.

Neptune, fainter at magnitude 7.9, is at the Aquarius-Pisces border 22° east (upper left) of Saturn and is still high in the early-evening dark. Neptune is only 2.3 arcseconds wide: harder to resolve as a ball than Uranus, but definitely nonstellar at high power.

All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions and graphics that also depend on longitude (mainly Moon positions) are for North America.

Eastern Standard Time (EST) is Universal Time minus 5 hours. UT is also known as UTC, GMT, or Z time.

Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

This is an outdoor nature hobby. For a more detailed constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential magazine of astronomy.

Once you get a telescope, to put it to good use you'll need a much more detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows all stars to magnitude 7.6.

Pocket Sky Atlas cover, Jumbo edition
The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and hundreds of telescopic galaxies, star clusters, and nebulae among them. Shown here is the Jumbo Edition, which is in hard covers and enlarged for easier reading outdoors by red flashlight. Sample charts. More about the current editions.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, are the even larger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to mag 9.75). And read How to Use a Star Chart with a Telescope. It applies just as much to charts on your phone or tablet as to charts on paper.

You'll also want a good deep-sky guidebook. A beloved old classic is the three-volume Burnham's Celestial Handbook. An impressive more modern one is the big Night Sky Observer's Guide set (2+ volumes) by Kepple and Sanner.

Can computerized telescopes replace charts? Not for beginners I don't think, especially not on mounts and tripods that are less than top-quality mechanically. Unless, that is, you prefer spending your time getting finicky technology to work rather than learning the sky. And as Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."

But finding a faint telescopic object the old-fashioned way with charts isn't simple either. Learn the tricks at How to Use a Star Chart with a Telescope

Audio sky tour. Out under the evening sky with your
earbuds in place, listen to Kelly Beatty's monthly
podcast tour of the naked-eye heavens above. It's free.

"The dangers of not thinking clearly are much greater now than ever before. It's not that there's something new in our way of thinking, it's that credulous and confused thinking can be much more lethal in ways it was never before."
            — Carl Sagan, 1996

"Facts are stubborn things."
             John Adams, 1770


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December 22, 2023 at 6:17 pm

Re: ThetaTauri, Dec 28th -
December 13th was the Feast of St Lucy.
She was a virgin martyr of the early Christian Church. Born to a noble but poor pagan family in Syracuse Sicily, she was betrothed to the son of a wealthy pagan family to improve her families fortunes. While still a teenager she converted to Christianity made a vow of chastity, converted mother also and persuaded her mother to break the betrothal and give the dowry fund to charity. Her jilted suitor turned her over to the authorities who blinded her before executing her. Tradition holds that her sight was miraculously restored before she was killed.

Because the Julian Calendar did not correctly adjust for Century-year leap days, by the Middle Ages the solstice occurred on the calendar on or about her feast day.

Occurring so close to the #WinterSolstice - along with the miracle of her vision restoration and her name being derived from "lux", the Latin word for "light" - her feastday is a celebration of the eventual return of light after the dark nights of Winter.

In parts of Latin America the binary Theta Tauri system is called "los Ojitos de Santa Lucia"("the Eyes of Santa Lucia") since they pass almost directly overhead around midnight as seen from the region in the days near her feastday.

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December 22, 2023 at 6:28 pm

... a little backstory: Many years ago my Grandmother, who came from central Mexico, visited us for a month during summer. One night we went out stargazing together and I pointed out the "Cat's Eyes" in the "Stinger" of Scorpius. She said, "Esos son los Ojitos de Santa Lucia"("those are the Eye of Santa Lucia").
I thought it was strange to associate those stars with the saint, since the Sun passes through Scorpius in early December so those stars are only above the horizon during daylight hours and are not visible around St Lucy's Day. I didn't think to ask her more about it, but recently searching Google I did find "Cat's Eyes" references but also references to Theta Tauri as "the Eyes of Saint Lucy".

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mary beth

December 23, 2023 at 11:18 am

So interesting! We celebrate on December 13th and the information in your post will make it all the more enjoyable. Merry Christmas!

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December 24, 2023 at 11:31 pm

mary beth: weather permitting, don't forget to go out and look for the Full Moon on the nights of Dec 25 and 26th.
Around midnight it will be almost directly overhead as seen from southern Texas.

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mary beth

December 24, 2023 at 11:35 pm

Ok thank you! We are going to have a stretch of good weather starting tomorrow morning. I’ll give a report on here the morning of the 27th. My husband commented a couple of nights ago how odd it was to see the moon almost at the Zenith. It will be really nice when it is full.

Merry Christmas! Santa is almost here. I think I hear sleigh bells!

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December 23, 2023 at 10:23 am

misha17, thanks for this information you presented and astronomical info on Theta Tauri system and Scorpius, very good. Merry Christmas--Rod

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December 27, 2023 at 10:10 pm


"Around 11 p.m. tonight the Moon shines just about as close to the zenith as you will ever see it (from your mid-northern latitude), giving 'lustre of mid-day to objects below.'"

... there was little mention of it in the news, but this year was the 200th anniversary of the initial publication of the poem, "A Visit from St. Nicholas"
("Twas the night before Christmas ...").

It was published anonymously in the Troy (NY) Sentinel on December 23rd, 1823 with the title, "Account of a Visit from St. Nicholas". Clement Clarke Moore eventually claimed authorship when he included it in a published book of his poems, but there is still some dispute about whether he was the actual author.

(See: the Wikipedia entry,
... which is also the source of my notes)

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December 27, 2023 at 10:28 pm

... interestingly, on December 23, 1823, the Moon was about at Last Quarter, "21 days old", and didn't rise until about midnight.

Of course, since St Nick visited on the Night before Christmas (December 24), the author was writing about a prior year's visit. The Moon was 11 days old, a few days before full, the year before on the Night before Christmas in 1822.

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mary beth

December 29, 2023 at 10:55 am

Very interesting! Wish we could get weather records for that Christmas Eve as well. I don’t think records were kept regularly until turn of the last century. But I bet somewhere tucked away in an old desk in New York, is a letter or something that would give us that information if we could only find it,

We didn’t end up having as good of weather, as I had hoped on the 26th and 27th but you could still see the moon high overhead. It was beautiful although haloed and a little bit shrouded in clouds. I was wishing I could get a picture to post. Be nice if they would allow us to post pictures in the comments..

Happy New Year!

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