Looking for a telescope for the next night sky event? We recommend the Celestron StarSense Explorer DX 130AZ as the top pick for basic astrophotography in our best beginner's telescope guide.
The night sky tonight and on any clear night offers an ever-changing display of fascinating objects you can see, from stars and constellations to bright planets, the moon, and sometimes special events like meteor showers.
Observing the night sky can be done with no special equipment, although a sky map can be very useful, and a good telescope or binoculars will enhance some experiences and bring some otherwise invisible objects into view. You can also use astronomy accessories to make your observing easier, and use our Satellite Tracker page powered by N2YO.comto find out when and how to see the International Space Station and other satellites. We also have a helpful guide on how you can see and track a Starlink satellite train.
You can also capture the night sky by using any of the best cameras for astrophotography, along with a selection of the best lenses for astrophotography.
Read on to find out what's up in the night sky tonight (planets visible now, moon phases, observing highlights this month) plus other resources (skywatching terms, night sky observing tips and further reading)
Related: The brightest planets in December's night sky: How to see them (and when)
Monthly skywatching information is provided to Space.com by Chris Vaughan of Starry Night Education, the leader in space science curriculum solutions. Follow Starry Night on Twitter @StarryNightEdu and Chris at @Astrogeoguy
Editor's note: If you have an amazing skywatching photo and would like to share them with Space.com's readers, send your photo(s), comments, and your name and location to spacephotos@space.com.
Calendar of observing highlights
Sunday, Dec. 1 - New Moon (at 06:21 GMT)
The moon will reach its new phase on Sunday, Dec. 1 at 1:21 a.m. EST or 06:21 GMT, which converts to 10:21 p.m. PST on Saturday. At that time our natural satellite will be located within Scorpius and 4.5 degrees south of the sun. While it’s new, the moon is travelling between Earth and the sun. Since sunlight can only reach the far side of the moon, and the moon is in the same region of the sky as the sun, the moon becomes unobservable from anywhere on Earth for about a day (except during a solar eclipse). On the evenings following the new moon phase, Earth's planetary partner will return to shine in the western sky after sunset.
Monday, Dec. 2 - Mars Buzzes the Beehive (overnight)
As December begins, the bright reddish planet Mars will be shining just above (or celestial north of) the large open star cluster in Cancer known as the Beehive, Praesepe, and Messier 44. Mars and the stellar "bees," which will be scattered across an area more than twice the size of a full moon, will fit into the field of view in binoculars (orange circle) for several weeks. The planet will be closest to the cluster from Sunday to Friday and then increasingly farther above the cluster on the subsequent nights (dotted path).
Tuesday, Dec. 3 - The Double Cluster (all night)
The northeastern sky on December evenings hosts the bright constellations of Perseus and W-shaped Cassiopeia, with the very bright yellowish star Capella gleaming below them. The sky between Perseus and Cassiopeia hosts the Double Cluster, a pair of bright open star clusters that together cover a finger’s width of the sky. They make a spectacular sight in binoculars (orange circle) or through a telescope at low magnification. The higher (more westerly) cluster, designated NGC 869, is dense and contains more than 200 white and blue-white stars. The lower (easterly) cluster NGC 884 is looser and includes a handful of 8th magnitude golden stars surrounded by many fainter ones. The clusters, which formed in the same part of the Perseus Arm of the Milky Way galaxy, are about 7,300 light-years away from us. They would be even brighter if they weren’t being dimmed by opaque dust in the galactic plane.
Wednesday, Dec. 4 - Crescent Moon Shines near Venus (after sunset)
As the sky is darkening after sunset on Wednesday, Dec. 4, look low in the western sky to see the pretty, waxing crescent moon shining several finger widths below (or several degrees to the celestial south of) the brilliant planet Venus. The pair will share the view in binoculars (orange circle) and will make a pretty photo until they drop into the trees around 6:30 p.m. local time.
Thursday, Dec. 5 - Lunar Crater Piccolomini (evening)
On Thursday evening, Dec. 5, the curved terminator on the moon will fall just to the left (or lunar west) of ancient Mare Nectaris, the dark and roughly circular patch located just south of the moon’s equator. A prominent crater named Piccolomini is located in the lunar highlands a small distance to the lower left of Nectaris. The 55 miles (88 km) wide crater has a sharp rim and a tall central mountain peak. A backyard telescope will show that the central peak is complex and that the crater’s inner walls have collapsed to form terraces. Watch for the curved escarpment named Rupes Altai extending to the upper left (or lunar northwest) from Piccolomini. Piccolomini and Nectaris are highlighted every lunar month when the waxing moon is about 5 days past new and again when the waning moon approaches third quarter.
Saturday, Dec. 7 - Mars Enters Retrograde (overnight)
On Saturday, Dec. 7, Mars’ easterly orbital motion through the stars of Cancer will slow to a stop in order for it to begin a westerly retrograde loop that will last through its mid-January opposition and into late February. Tonight the bright, reddish dot of Mars will be positioned in the eastern evening sky in Cancer, just above the large Beehive Cluster and below the bright “twin” stars of Gemini, Castor and Pollux. Over the coming weeks, you can watch Mars travel upwards (celestial west) towards those stars (red path). Retrograde loops occur when Earth, on a faster orbit closer to the sun, passes more distant solar system objects “on the inside track”, making them appear to move backwards across the stars for a while. Mars’ loop will cover almost two fist widths, or 19 degrees of the celestial sphere.
Saturday, Dec. 7 - Jupiter at Opposition (all night)
On Saturday, Dec. 7, Jupiter will reach opposition while it gleams brightly between the horns of Taurus and a palm’s width to the left (or 7.5 degrees to the celestial northeast) of the bright star Aldebaran. At opposition, planets rise in the east at sunset and cross the sky all night long before setting in the west at sunrise. Jupiter will be at its minimum distance from Earth for this year of 380.1 million miles (611.8 million km) or 34 light-minutes, boosting its brilliance to magnitude -2.8. Viewed in a telescope (inset), the planet will display a generous, 48.2 arc-seconds-wide disk striped with brown equatorial bands. Around opposition, Jupiter and its four large Galilean satellites frequently eclipse and occult one another, and cast their round, black shadows on the planet – singly and in pairs. The Great Red Spot will cross the planet's disk for a few hours every second or third night.
Saturday, Dec. 7 - Moon Moves Past Saturn (evening)
On Saturday evening, Dec. 7 in the Americas, the waxing crescent moon will shine a palm’s width to the lower right (or celestial west) of Saturn. The pair will be due south after dusk and then set in the west around 11 p.m. local time. On Sunday night, the half-illuminated first quarter moon will hop east to shine to Saturn’s upper left. In the interim, observers located in a zone extending from eastern Indonesia and the Philippines, and northeast across most of Japan to the Aleutian Islands can see the moon occult Saturn on Sunday evening. Use an app like Starry Night or Sky Safari to look up the occultation timings for a specific location.
Sunday, Dec. 8 - First Quarter Moon (at 15:27 GMT)
The moon will complete the first quarter of its 29.53-day trip around Earth on Sunday, Dec. 8 at 10:27 a.m. EST, 7:27 a.m. PST, and 15:27 GMT. During the first quarter phase, the moon's 90-degree angle from the sun causes us to see it half-illuminated on its eastern side. First quarter moons always rise around mid-day and set around midnight, so they are also visible in the afternoon daytime sky. The evenings surrounding the first quarter are the best ones for seeing the lunar terrain when it is dramatically lit by low-angled sunlight, especially along the terminator, the pole-to-pole boundary that separates the moon's lit and dark hemispheres.
Tuesday, Dec. 10 - Mare Imbrium's Golden Handle (all night)
On Tuesday night, Dec. 10, the terminator on the waxing gibbous moon will cross Sinus Iridum, the Bay of Rainbows. The circular 155 mile (249 km) diameter feature is a large impact crater that was flooded by the same basalts that filled the much larger Mare Imbrium to its east – forming a round bay encircled on the north and west by the prominent Montes Jura mountain range. The "Golden Handle" effect, produced when sunlight strikes the mountain peaks while the floor of the bay remains dark, will appear for observers in the Americas. With each passing hour, more of the mountains will become illuminated, brightening the handle.
Thursday, Dec. 12 - Bright Moon Points to Uranus (all night)
On Thursday night, Dec. 12, the bright, nearly full moon will shine near the planet Uranus. Use binoculars (orange circle) to look for the medium-bright star Botein (Delta Arietis) shining below the moon. If you place Botein just at the upper edge of the binoculars’ field of view, Uranus will appear as a dull, blue-green "star" near the bottom of the field of view. Uranus is far easier to see without a bright moon nearby, so take note of Botein’s location with respect to the nearby bright Pleiades star cluster and return to Uranus on another night. In a dark sky, you can see the magnitude 5.7 planet without optical aid. A backyard telescope will reveal its tiny disk.
Friday, Dec. 13 - Moon Crosses the Pleiades (at dusk)
On Friday evening, Dec. 13, the orbital motion of the bright, nearly full moon will carry it through the Pleiades star cluster (aka Messier 45, Subaru, and the Seven Sisters) for some parts of the world. While bright moonlight overwhelms fainter objects, viewing the encounter during evening twilight, especially through binoculars (orange circle), will make a pretty, and fascinating, sight. Skywatchers in Europe and Africa will see the moon among the Pleiades’ scattered stars. Observers in Asia and the Americas will have to settle for seeing the moon shining to their upper right (or celestial west) and lower left (or celestial east), respectively.
Friday, Dec. 13 - Geminids Meteor Shower Peak (overnight)
The Geminids, one of the most spectacular meteor showers of the year, is active from November 19 to Dec. 24 annually while Earth passes through the cloud of sand-sized grains dropped by the asteroid designated 3200 Phaethon. The number of Geminids meteors will gradually ramp up to a peak in the wee hours of Saturday morning, Dec. 15, and then decline rapidly on the following nights. Geminids meteors are often bright, intensely colored, and slower-moving than average. In the Americas, expect to see a good number of Geminids meteors beginning after dark on Friday evening and upwards of 120 meteors per hour around 2 a.m. local time on Saturday - the time when the sky overhead will be pointing toward the densest part of the debris field. True Geminids will appear to streak away from a position near Gemini’s bright stars Castor and Pollux, but the meteors can appear anywhere in the sky, so just keep looking up and around. Unfortunately, this year’s shower will be hampered by bright moonlight. Stand where the moon is blocked from view or head outside around 4 a.m. local time, when the moon will be sinking out of sight.
Saturday, Dec. 14 - Bright Moon Joins Jupiter (all night)
Shortly after the very bright moon clears the rooftops in the east after dusk on Saturday, Dec. 14, the brilliant planet Jupiter will rise to join it. The duo will make a lovely photo opportunity when composed with some nice foreground scenery. As the moon and Jupiter climb the eastern sky, the bright winter stars will surround them, including yellowish Capella on their upper left and reddish Aldebaran to their right, both part of the huge winter hexagon asterism. The bright pair will culminate due south towards midnight and set in the west before dawn. By then the diurnal rotation of the sky will lift the moon, now full, above Jupiter.
Sunday, Dec. 15 - Full Oak Moon (at 09:02 GMT)
The December full moon will occur at 4:02 a.m. EST, 1:02 a.m. PST, or 09:02 GMT on Sunday, Dec. 15. Traditionally known as the Oak Moon, Cold Moon, and Long Nights Moon, it always shines in or near the stars of Taurus and Gemini. The Ojibwe of the Great Lakes region call the December full moon Manidoo Giizisoons, the “Little Spirit Moon”. For them it is a time of purification and of healing of all Creation. Since it’s opposite the sun on this day of the lunar month, the moon is fully illuminated and rises at sunset and sets at sunrise. Full moons during the winter months reach as high in the sky at midnight as the summer noonday sun, and cast similar shadows.
Monday, Dec. 16 - Bright Moon between the Twins (all night)
Look low in the eastern sky after dusk on Monday, Dec. 16 to see the bright, waning gibbous moon gleaming just to the right (or celestial southwest) of Gemini’s brightest stars. Golden Pollux and the brighter, whiter double star Castor above it should still be visible against the moon’s glare. Binoculars (orange circle) will reveal a handful of smaller stars immediately to the left of the moon, marking where the brothers are grasping hands. Bright, reddish Mars will shine off to their lower left. As the night wears on, the moon’s orbital motion will carry it closer to Pollux while the diurnal rotation of the sky shifts the constellation to the moon’s right (or celestial northwest) and puts Mars above them all.
Tuesday, Dec. 17 - Moon Moves toward Mars (all night)
On Tuesday evening, Dec. 17, the bright, 90%-illuminated moon will shine a short distance above (or celestial WNW of) the prominent reddish dot of Mars. The moon and the reddish planet will be close enough to share the view in binoculars (orange circle), which will also show the widely scattered stars of the Beehive Cluster below Mars. As they cross the sky together all night long, the moon will move closer to Mars, and will actually occult the planet for observers located at far northern latitudes. In the Americas, the moon will be positioned very closely above the planet as they sink into the west around sunrise on Wednesday morning.
Wednesday, Dec. 18 - Watch Algol Brighten (starting at 6:47 pm EST)
The star Algol in the constellation of Perseus represents the glowing eye of Medusa from Greek mythology. Also designated Beta Persei, it is among the most accessible variable stars for skywatchers. During a ten-hour period that repeats like clockwork every 2 days, 20 hours, and 49 minutes, Algol dims noticeably and re-brightens by about a third when a fainter companion star with an orbit nearly edge-on to Earth crosses in front of its much brighter primary, reducing the total light output we perceive. Algol normally shines at magnitude 2.1, similar to the nearby star Almach (aka Gamma Andromedae). But while fully dimmed, Algol’s brightness of magnitude 3.4 is almost identical to Rho Persei (or Gorgonea Tertia or ρ Per), the star sitting just two finger widths to Algol’s lower right (or 2.25 degrees to the celestial south). On Wednesday evening, Dec. 18 at 6:47 p.m. EST or 23:47 GMT, Algol will be at its minimum brightness while it shines about two thirds of the way up the eastern sky, above and between the bright star Capella and Jupiter. Five hours later Algol will return to full intensity while it shines high in the western sky below Capella and Jupiter.
Thursday, Dec. 19 - Stellar Halo around Mirfak (all night)
On mid-December evenings the constellation of Perseus is climbing the northeastern sky. Just for 2024, bright Jupiter will also be gleaming to the lower right of Perseus. The outer rim of our Milky Way galaxy runs through Perseus’ stars, filling its territory with rich star clusters. The largest of those surrounds his brightest star, Mirfak, or Alpha Persei. That elderly yellow supergiant star has evolved out of its blue phase and is now fusing helium into carbon and oxygen in its core. Melotte 20, also known as the Alpha Persei Moving Group and the Perseus OB3 Association, is a collection of 100 or so young, massive, hot B- and A-class stars sprinkled over several finger widths (or 3 degrees) of the sky around Mirfak. The cluster can be seen with unaided eyes, but it’s especially dazzling in binoculars (orange circle). Its stars are approximately 600 light years from the sun and are moving as a group - Mirfak along with them.
Friday, Dec. 20 - The Hyades Cluster (all night)
Located only about 150 light years away from the sun, Taurus, the Bull’s triangular face is actually one of the nearest open star clusters to our solar system. Its stars are commonly called The Hyades, named for the five daughters of Atlas in Greek mythology. It also has the designations Melotte 25 and Caldwell 41. The cluster contains several hundred stars, with a half-dozen or so readily seen under moonless suburban skies, many as close-together pairs. It’s a superb target to view in binoculars (orange circle). The five brightest members, all naked-eye stars, are within a few light years of one another. The cluster’s stars likely formed together about 625 million years ago. The bright orange star Aldebaran, at the lower (or southeastern) vertex of the Hyades triangle, is actually not part of the cluster. It is less than half as far away! In mid-December, the Hyades climbs the eastern sky in early evening and reaches its highest point due south around 10:30 p.m. local time. This winter, Jupiter will be gleaming just a palm’s width to the left (or 6 degrees to the celestial northeast) of the bull’s face.
Saturday, Dec. 21 - Northern Winter Solstice (at 09:21 GMT)
Winter in the Northern Hemisphere will officially commence in the Americas on Saturday, Dec. 21 at 4:21 a.m. EST and 1:21 a.m. PST, or 09:21 GMT. At the solstice, the sun will attain its southernmost declination for the year, resulting in the lowest elevation in the sky of the noonday sun, the least amount of solar insolation, and the shortest amount of daylight of the year. Conversely, the Southern Hemisphere will see its highest sun and maximum daylight hours for the year. After the December solstice, the amount of daylight time will begin to increase for the Northern Hemisphere.
Saturday, Dec. 21 - Ursids Meteor Shower Peak (overnight)
The Ursids meteor shower, which is produced by particles of debris dropped by the periodic comet 8P/Tuttle, runs from Dec. 17 to 26 every year. The weak, short-duration shower will peak (usually with only 5 to 10 meteors visible in an hour) while Earth is traversing the densest part of the debris field on Sunday morning in the Americas, but the best time to watch for Ursids meteors will be Saturday evening, Dec. 21 before the bright, waning gibbous moon rises around midnight local time. True Ursids will streak away from a location near the North Star Polaris, but the meteors can appear anywhere in the sky.
Sunday, Dec. 22 - Third Quarter Moon (at 22:18 GMT)
The moon will complete three quarters of its orbit around Earth, measured from the previous new moon, on Sunday, Dec. 22 at 5:18 p.m. EST, 2:18 p.m. PST, or 22:18 GMT. At its third (or last) quarter phase the moon is half-illuminated, on its western, sunward side. It will rise around midnight local time, and then remain visible until it sets in the western daytime sky during early afternoon. Third quarter moons are positioned ahead of the Earth in our trip around the Sun. About 3½ hours later, Earth will occupy that same location in space. The week of dark, moonless evenings that follow this phase are ideal for observing fainter deep sky targets.
Monday, Dec. 23 - Two Shadows and the Red Spot Cross Jupiter (07:48 to 08:48 GMT)
From time to time, observers with good quality telescopes can watch the small, round, black shadows of the Galilean moons traverse Jupiter’s disk. On Monday morning, Dec. 23, sky-watchers located in the Americas can watch two of the shadows and the Great Red Spot crossing the southern hemisphere of Jupiter together for about an hour. At 2:48 a.m. Eastern Time (or 07:48 GMT), the red spot and the small shadow of Io will join the much larger shadow of Ganymede, which began its own crossing of the planet’s south polar zone 70 minutes earlier. Ganymede’s shadow will leave Jupiter at 3:48 a.m. EST (or 08:48 GMT), leaving Io’s shadow and the spot to continue on alone until 4:58 a.m. EST. Watch for Io itself to move off of Jupiter’s disk by 4:35 a.m. EST.
Tuesday, Dec. 24 - Crescent Moon Moves Toward Spica (pre-dawn)
Early risers on Tuesday morning, Dec. 24 will see the pretty sight of the waning crescent moon shining in the southern sky close to Libra’s brightest star, Spica. The star will be twinkling a few finger widths to the moon’s lower left (or celestial southeast) from about 3 a.m. local time to the onset of civil twilight. Hours later, observers in a zone extending from eastern China, most of Japan, and the northernmost islands of the Philippines and southeast through Micronesia, most of Melanesia, and Polynesia can watch the moon occult Spica. Use an app like Starry Night or Sky Safari to look up the times for the occultation.
Wednesday, Dec. 25 - Mercury at Greatest Western Elongation (pre-dawn)
On the mornings surrounding Wednesday, Dec. 25, Mercury will reach its widest angle of 22° west of the sun, and peak visibility, for its current morning apparition. Starting around 5:45 a.m. in your local time zone, look for the planet shining very low in the east-southeastern sky, and climbing. The bright star Antares will sparkle a palm’s width to the planet’s lower right (or 6 degrees to the celestial SSW). In a telescope (inset) Mercury will exhibit a 64%-illuminated, waxing gibbous phase. Mercury’s position above the morning ecliptic (green line) will make this a good apparition for mid-northern latitude observers, and reasonably good showing for those located south of the Equator, too. The planet will continue to be well-placed for viewing for two weeks after greatest elongation. Turn all optical aids away from the eastern horizon before the sun rises.
Thursday, Dec. 26 - Night’s Brightest Star (late evening)
Sirius, the brightest star in Canis Major and in the entire night sky, too, is hard to miss once it clears the trees and rooftops in the southeast by 7:30 p.m. local time. Also known as the Dog Star, it will climb to its highest point in the lower part of the southern sky shortly after midnight local time. If you are walking through your darkened house in the middle of the night, Sirius might catch your eye out a window because it never climbs very high. Sirius is a hot, blue-white, A-class star located only 8.6 light-years from our sun. Its extreme brightness and its low position in the sky combine to produce spectacular flashes of various colors as it twinkles. A very large telescope may allow you to see Sirius B, a faint white dwarf companion star located just 10 arc-seconds to the east of Sirius.
Saturday, Dec. 28 - Earthshine Moon with Antares and Mercury (before sunrise)
If the weather forecast calls for clear skies to the southeast on Saturday morning, Dec. 28, it will be worth venturing outside around breakfast time to see the pretty spectacle of the old, waning moon’s slender crescent shining close to Scorpius’ bright star Antares and brighter Mercury. All three objects will clear the treetops by about 6:15 a.m. local time. Reddish Antares will sparkle just to the moon’s lower left. They’ll be extra close together for observers in westerly time zones. Mercury’s bright dot will be positioned nearly a fist’s diameter to the left (or 9 degrees to the celestial northeast) of Antares. The old moon should also display Earthshine, also known as the Ashen Glow and “the old moon in the new moon’s arms”. The phenomenon, sunlight reflected off Earth and back onto the moon, slightly brightening the dark portion of the moon’s Earth-facing hemisphere, appears for several days before and after each new moon.
Monday, Dec. 30 - Second New Moon of December (at 22:27 GMT)
The moon cycles through its phases every 29.5 days, allowing a phase to repeat if it first occurs early in a calendar month. For the second time in December, the moon will reach its new moon phase on Monday, Dec. 30 at 5:27 p.m. EST, 2:27 p.m. PST, and 22:27 GMT. At that time our natural satellite will be located within Sagittarius and 5.5 degrees south of the sun. Since sunlight is only reaching the far side of the moon, and the moon is in the same region of the sky as the sun, the moon becomes completely hidden from view. On the evenings following the new moon phase, Earth’s planetary partner will return to shine in the western sky after sunset.
Visible planets in December
Mercury
As December begins, Mercury will be visible briefly just above the southwestern horizon after sunset, especially from tropical latitudes where the ecliptic and the planet’s orbit are both nearly vertical. The closing days of its evening apparition will carry it down and sunward, rendering it invisible against the bright twilight after a day or two. Mercury will cross the sun and enter the eastern morning sky from December 6 onwards, but it won’t rise sufficiently long before the sun to make it observable until just before mid-December. Mercury’s morning apparition, which will be a good one for Northern Hemisphere observers, but a poor one from mid-southern latitudes, will peak when it reaches western elongation, 22 degrees from the sun, on December 24-25. At that time it will be best seen around 6:30 a.m. local time, when it will shine at a peak intensity of magnitude -0.41 in a location about 5 degrees to the east of Scorpius. Mercury can be safely viewed through a telescope before the sun begins to rise. During the second half of December, its illumination will wax in phase from a slim crescent to 77%-illuminated while it diminishes in apparent size. On December 28, the pretty, waning crescent moon will shine close to Antares off to Mercury’s right (or celestial WSW).
Venus
Venus will continue to dominate the southwestern early evening sky during December, brightening even more from magnitude -4.2 to -4.46. As it increases its angle east of the sun from 44 to 47 degrees, it will add an hour to its viewing time and be carried higher in the sky as the ecliptic steepens daily. After commencing December among the stars of eastern Sagittarius, Venus will cross into Capricornus on December 6 and slip into Aquarius on December 31. That will bring it to within 17 degrees of Saturn, but the two planets will cozy up in a close conjunction in mid-January. Telescope views of Venus in December will show a waning, slightly gibbous phase on a disk that grows in apparent diameter from 17.25 to 22.2 arc-seconds over the course of the month. On December 6, Venus will pass just 0.8 degrees south of the distant globular star cluster Messier 75. The waxing crescent moon will shine just below (or celestial south of) Venus on December 4.
Mars
Mars will begin December by rising in mid-evening, chasing much brighter Jupiter across the night sky, and then shining high in the southwestern sky at sunrise. By month’s end, Mars will be only two weeks from its January 16 opposition, allowing it to rise soon after sunset and remain well placed for observing all night long. Mars will spend all of the month in Cancer. On December 7 it will commence a retrograde loop while positioned just 2 degrees to the northwest of the Beehive Cluster, Messier 44. During December, as Mars continues to reduce its distance from Earth, it will brighten from magnitude -0.52 to -1.19. Viewed in a telescope, the red planet will appear a small rusty-colored disk with hints of dark markings that grows in apparent size from 11.7 to 14.3 arc-seconds. It will display a gibbous phase that waxes from to 93% to 99%-illuminated. On December 17 the bright, waning gibbous moon will shine one degree to the west of Mars.
Jupiter
The extremely bright, white planet Jupiter will be well-placed for observing throughout most of the night during December. The gas giant will be marching westward between the horns of Taurus and decreasing its angular separation from the bright, reddish star Aldebaran to Jupiter’s southwest. On December 7, Jupiter will reach opposition for 2024. Since Earth will be positioned between the sun and the planet on that date, Jupiter will rise at sunset, remain visible all night long, and set at sunrise. At opposition, Jupiter will approach to 380.1 million miles, 611.8 million km, or 34 light-minutes from Earth, and it will shine at its maximum brightness for 2024 of magnitude -2.8. Jupiter passed perihelion in January, 2023, so the planet’s generous, 48.2 arc-seconds-wide disk will shrink a little more at each opposition for the next handful of years. Binoculars will reveal Jupiter’s four large Galilean moons flanking the planet on any night, and views of Jupiter in a backyard telescope will show its equatorial zones and belts. Better quality optics will reveal the Great Red Spot every 2nd or 3rd night. Around opposition, Jupiter’s Galilean satellites frequently eclipse and occult one another, and the round, black shadows they cast upon on the planet can be seen crossing Jupiter’s disk. The nearly full moon will shine to the upper right (celestial northwest) and upper left (celestial northeast) of Jupiter on December 13 and 14, respectively.
Saturn
Saturn will continue to shine in the southwestern sky during early evening in December, making it conveniently positioned for observing from dusk onwards - but the nightly westerly shift of the stars is carrying Saturn sunward, causing its set time for mid-northern latitude skywatchers to advance from 11:45 p.m. to only 9:55 p.m. local time at month’s end. Saturn is travelling retrograde westward through the stars of eastern Aquarius with far fainter Neptune following more than 10 degrees behind it on the ecliptic. Viewed in a telescope in December, Saturn will show an apparent disk diameter of about 17 arc-seconds, and its rings will subtend 39.5 arc-seconds. The wedge of shadow that its globe casts upon its rings on the east will steadily enlarge. Saturn’s rings have widened a little recently due to Earth’s orbital inclination, but they will become more and more edge-on to Earth until late March, 2025. Saturn’s moons will travel near the ring plane this year, allowing you to see the transits of them and their tiny black shadows across Saturn’s globe – sometimes in pairs – through high-quality telescopes. The waxing crescent moon will shine a palm’s width to the lower right (or celestial west) of Saturn on December 7. Observers located in a zone extending from eastern Indonesia and the Philippines, and northeast across most of Japan to the Aleutian Islands can see the moon occult Saturn on December 8.
Uranus
Recently at opposition, Uranus will be an all-night target in a backyard telescope or binoculars during December. Its small, blue-green, magnitude 5.6 dot will be moving slowly retrograde westwards through western Taurus until it passes into Aries on December 29. The bright Pleiades Cluster will be positioned a palm’s width to Uranus’ left (or 7 degrees to its northeast). Far brighter Jupiter will be located about 20 degrees to its lower left (or celestial east). On December 12 the bright, waxing gibbous moon will shine a palm’s width to the upper right (or celestial WNW) of Uranus. (Image: Uranus - Dec2024.jpg)
Neptune
During December the distant planet Neptune will be observable on moonless evenings as a blue, magnitude 7.9 speck positioned just north of the stars 20 and 24 Piscium near the Pisces-Aquarius border and south of both the Great Square of Pegasus and the circle of stars that forms the western fish. The planet will be easiest to see while it is highest in the sky during early evening. Neptune’s westerly motion will slow to a stop when it completes its retrograde loop on December 8, and then it will ramp up to regular prograde motion. Much brighter Saturn will be shining about 13 degrees to Neptune’s lower right (or celestial west). In a telescope, Neptune’s tiny apparent disk will span 2.3 arc-seconds, but larger telescopes can also show Neptune’s large moon Triton. The first quarter moon will hop from west to east of Neptune on December 8-9.
Skywatching terms
Gibbous: Used to describe a planet or moon that is more than 50% illuminated.
Asterism: A noteworthy or striking pattern of stars within a larger constellation.
Degrees (measuring the sky): The sky is 360 degrees all the way around, which means roughly 180 degrees from horizon to horizon. It's easy to measure distances between objects: Your fist on an outstretched arm covers about 10 degrees of sky, while a finger covers about one degree.
Visual Magnitude: This is the astronomer's scale for measuring the brightness of objects in the sky. The dimmest object visible in the night sky under perfectly dark conditions is about magnitude 6.5. Brighter stars are magnitude 2 or 1. The brightest objects get negative numbers. Venus can be as bright as magnitude minus 4.9. The full moon is minus 12.7 and the sun is minus 26.8.
Terminator: The boundary on the moon between sunlight and shadow.
Zenith: The point in the sky directly overhead.
Night sky observing tips
Adjust to the dark: If you wish to observe fainter objects, such as meteors, dim stars, nebulas, and galaxies, give your eyes at least 15 minutes to adjust to the darkness. Avoid looking at your phone's bright screen by keeping it tucked away. If you must use it, set the brightness to minimum — or cover it with clingy red film.
Light Pollution: Even from a big city, one can see the moon, a handful of bright stars, and the brightest planets - if they are above the horizon. But to fully enjoy the heavens — especially a meteor shower, the fainter constellations, or to see the amazing swath across the sky that is the disk of our home galaxy, the Milky Way — rural areas are best for night sky viewing. If you're stuck in a city or suburban area, use a tree or dark building to block ambient light (or moonlight) and help reveal fainter sky objects. If you're in the suburbs, simply turning off outdoor lights can help.
Prepare for skywatching: If you plan to be outside for more than a few minutes, and it's not a warm summer evening, dress more warmly than you think is necessary. An hour of winter observing can chill you to the bone. For meteor showers, a blanket or lounge chair will prove to be much more comfortable than standing, or sitting in a chair and craning your neck to see overhead.
Daytime skywatching: On the days surrounding first quarter, the moon is visible in the afternoon daytime sky. At last quarter, the moon rises before sunrise and lingers into the morning daytime sky. When Venus is at a significant angle away from the sun it can often be spotted during the day as a brilliant point of light - but you'll need to consult an astronomy app to know when and where to look for it. When large sunspots develop on the sun, they can be seen without a telescope — as long as you use proper solar filters, such as eclipse glasses. Permanent eye damage can occur if you look at the sun for any length of time without protective eyewear.
