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Night Sky, December 2019: What You Can See This Month [Maps]

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, often 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 beginner 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.com to find out when to see the International Space Station and other satellites. Below, 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).

The night sky is more than just the moon and stars, if you know when and where to look. (Image credit: Karl Tate/SPACE.com)

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.

Editor's note: If you have an amazing skywatching photo you'd like to share for a possible story or image gallery, you can send images and comments in to spacephotos@futurenet.com.

Night Sky Guides:

Calendar of Observing Highlights

Sunday, December 1 all night – Find Vesta using Alpha and Lambda Ceti

(Image credit: Starry Night)

The large asteroid Vesta is visible in binoculars and backyard telescopes. For several nights surrounding December 1, Vesta's rapid orbital motion (red path) will carry it closely past the naked-eye star Lambda Ceti (inset). First, look in the southeastern evening sky for Cetus' bright star Alpha Ceti (also named Menkar), and then locate the dimmer star Lambda Ceti positioned a slim palm's width to Alpha Ceti's upper left (or 5 degrees to the celestial north). Vesta will sit about a finger's width to the lower right of Lambda — or 1 degree to the celestial south of that star. Vesta and Lambda will appear together in the field of view of a telescope at medium power (red circle).

Wednesday, December 4 at 6:58 GMT — First Quarter Moon

(Image credit: Starry Night)

After the moon has completed the first quarter of its orbit around Earth, the relative positions of the Earth, sun, and moon cause us to see it half-illuminated — on its eastern side. At first quarter the moon always rises around noon and sets around midnight local time, so it is also visible in the afternoon daytime sky. The evenings around first quarter are the best times to view the lunar terrain through binoculars and telescopes — while it is dramatically lit by low-angled sunlight. 

Sunday, December 8 overnight — Bright Moon under Uranus

(Image credit: Starry Night)

Overnight on Sunday, December 8, the waxing gibbous moon will be positioned a palm's width below (or 7 degrees to the celestial southeast of) Uranus. The bright moon's light will overwhelm the dim planet, but you can note Uranus' location and view the planet on a night when the moon has left the scene.

Tuesday, December 10 after sunset — Venus Passes Saturn

(Image credit: Starry Night)

On the evenings surrounding Tuesday, December 10 the orbital motion of Venus (red curve) will carry it closely past Saturn. For about an hour after sunset, look low in the southwestern sky for very bright Venus positioned to the lower left (or celestial south) of medium-bright Saturn. With a separation of less than two finger widths (2 degrees) at closest approach, both planets will appear together in the eyepiece of a backyard telescope at low magnification on Tuesday and Wednesday.

Thursday, December 12 at 5:12 GMT — Full Oak Moon near Messier 35

(Image credit: Starry Night)

The December full moon, traditionally known as the Oak Moon, Cold Moon, Long Nights Moon, and the Moon before Yule, always shines in or near the stars of Taurus. 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 at mid-northern latitudes reach as high in the sky as the summer noonday sun, and cast similar shadows. On Thursday evening, the full moon will also pass within two finger widths to the lower right (or 2 degrees to the celestial south) of the rich, open star cluster Messier 35. To see that cluster's stars despite the bright moonlight, position the moon just outside your telescope's medium-power field of view (red circle).

Friday, December 13 all night — Comet PANSTARRS passes NGC 1528

(Image credit: Starry Night)

For several nights commencing on Friday, December 13, the path of comet C/2017 T2 (PANSTARRS) is predicted to carry it close to the north of a pair of bright open star clusters designated NGC 1545 and NGC 1528, also collectively named the M & M Double Cluster. This area of sky will be high in the eastern evening sky near the bright star Capella. Although it won't peak in visibility until early 2020, when viewed in a backyard telescope at medium power (red circle), the comet should be bright enough to be seen in December as a dim, greenish fuzzy patch next to the clusters' stars.

Friday-Saturday, December 13 — midnight to dawn — Geminids Meteor Shower Peak

(Image credit: Starry Night)

The Geminids meteor shower, one of the most spectacular of the year, runs from December 4 to 16 annually. In 2019, it will peak before dawn on Thursday, December 14, when up to 120 meteors per hour are possible under dark sky conditions. Geminids meteors are often bright, intensely colored, and slower moving than average because they are produced by particles dropped by an asteroid designated 3200 Phaethon. The best time to watch for Geminids will be from full darkness on Wednesday until dawn on Thursday morning. At about 2 a.m. local time, the sky overhead will be plowing into the densest part of the debris field. The full moon in Gemini on the peak night will overwhelm the majority of the meteors for this shower in 2019.

Saturday, December 14 overnight — Moon Buzzes the Beehive

(Image credit: Starry Night)

Overnight on Saturday, December 14, the orbital motion of the waning gibbous moon (green line) will carry it toward the center of the large open star cluster known as the Beehive (and Messier 44) in Cancer. When Messier 44 becomes high enough to observe (after about 9 p.m. local time), the moon will be sitting less than a fist's width above (or 8 degrees to the celestial west of) the cluster. By dawn, the moon will close to within half that distance, and the rotation of the sky will place the moon to the cluster's lower right. Observers in Asia and the south Pacific can watch the moon pass through the northern edge of the cluster. Around midnight local time there, both objects will fit within the field of view of a telescope at low magnification (orange circle), although the bright moonlight will overwhelm the cluster's dimmer stars.

Thursday, December 19 at 4:57 GMT — Last Quarter Moon

(Image credit: Starry Night)

At its last quarter phase, the moon rises around midnight and remains visible in the southern sky all morning. At this phase, the moon is illuminated on its western side, towards the pre-dawn sun. Last 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. During the week following this phase, the waning moon will traverse the last quarter of its orbit around the earth, on the way to new moon and leave the evening skies dark for skywatchers worldwide.

Sunday, December 22 at 4:19 GMT Northern Winter Solstice

(Image credit: Starry Night)

On Sunday, December 22 at 04:19 GMT (or Saturday at 11:19 p.m. EST and 8:19 p.m. PST), the sun will reach the solstice — its southernmost declination for the year, resulting in the shortest day of the year for the northern hemisphere, and the longest day of the year for the southern hemisphere. After the solstice, the amount of daylight will increase daily for the Northern Hemisphere.

Monday, December 23 pre-dawn — Old Moon Meets Mars

(Image credit: Starry Night)

After it rises in the southeastern pre-dawn sky at 5 a.m. local time on Monday, December 23, the very old and slim crescent moon will be positioned a slim palm's width to the lower left (or 5.5 degrees to the celestial northeast) of reddish Mars. The duo will make a pretty sight in binoculars (red circle) until just before sunrise.

Sunday-Monday, December 22-23 midnight to dawn — Ursids Meteor Shower Peak

(Image credit: Starry Night)

The annual Ursids meteor shower, produced by debris dropped by periodic comet 8P/Tuttle, runs from December 17 to 23. It will peak during the early hours of Saturday, December 22, when seeing up to 20 meteors per hour is possible under dark skies. The best time to watch will run from midnight to dawn that morning. A waning crescent moon on the peak night will provide excellent viewing conditions for Ursids meteor watchers in 2019. True Ursids will appear to radiate from a position in the sky above the Little Dipper (Ursa Minor) near Polaris, but the meteors can appear anywhere in the sky.

Thursday, December 26 at 5:13 GMT — New Moon and Annular Solar Eclipse

(Image credit: Starry Night)

When at its new phase, the moon is travelling between Earth and the sun. Since sunlight can only reach the side of the moon facing away from Earth, and the moon is in the same region of the sky as the sun, our natural satellite becomes completely hidden from view. This new moon will occur when the moon is close to its descending node and also approaching apogee — setting up an annular solar eclipse. The track for the eclipse will commence near Riyadh, Saudi Arabia, where it will be 96 miles (or 154 km) wide. The eclipse will sweep southeast across southern India near Kannar (narrowing to 80 miles, or 129 km), cross through Malaysia, the southern Philippines, and Guam, and end in the North Pacific. A partial eclipse will be visible from southern Russia, down across Asia to northeastern Africa and over to northern Australia. Maximum eclipse of 94.11% solar disk coverage will occur for 3m39.9s southwest of Singapore starting at 05:24 GMT. Proper solar filters will be required to view any portion of this eclipse. 

Friday, December 27 after sunset — Young Moon meets Saturn

(Image credit: Starry Night)

In the southwestern sky for a short period after sunset on Friday, December 27, the very young crescent moon will be positioned a slim palm's width to the upper left (or 5 degrees to the celestial southeast) of Saturn. The duo will make a nice sight in binoculars (red circle). But use them only after the sun has completely set.

Saturday, December 28 early evening — Young Moon near Venus

(Image credit: Starry Night)

In the southwestern sky after sunset on Saturday, December 28, the very young sliver of the crescent moon will occupy a position less than 3 finger widths below (or 2.5 degrees to the celestial southwest of) Venus, making a lovely scene in binoculars (red circle). Observers in Antarctica and the southern tip of South America will witness the moon occult Venus. 

Monday, December 30 at 6:38 p.m. EST — Algol at Minimum Brightness

(Image credit: Starry Night)

The "Demon Star" Algol in Perseus is among the most accessible variable stars for beginner skywatchers. Its naked-eye brightness dims noticeably for about 10 hours once every 2 days, 20 hours, and 49 minutes when a small companion star orbiting nearly edge-on to Earth crosses in front of the much brighter main star, dimming their combined light output. On Monday, December 30 at 6:38 p.m. EST (or 23:38 GMT), Algol will shine at its minimum brightness of magnitude 3.4. At that time, for observers in the Eastern and Central time zones, the star will sit halfway up the eastern sky. Five hours later at 11:06 p.m. EST (04:06 GMT on December 31), Algol will be high in the western sky, and it will have brightened to its usual magnitude of 2.1.

Planets

(Image credit: Starry Night)

Mercury will spend most of December in the eastern pre-dawn sky descending sunward after greatest western elongation in late November. Due to Mercury's position north of the morning ecliptic, this has been an excellent appearance for Northern Hemisphere observers, and a poor one for those in the Southern Hemisphere. Early in the month, the best viewing times for mid-northern latitude observers will occur between 6 and 7 a.m. local time. By mid-December, the optimal viewing time will decrease to about 30 minutes centered on 7 a.m. local time. For the final week of the month, Mercury will be too close to the sun for observation. Viewed in a telescope during December, the planet will wax from a 71% illuminated disk on December 1 to nearly full. Meanwhile, Mercury's apparent disk diameter will shrink by 25%. On the morning of December 25, the old crescent moon will land 1.5 degrees to the left (celestial northeast) of Mercury, but the duo will be engulfed in morning twilight.

(Image credit: Starry Night)

During December, Venus will continue to climb away from the sun in the southwestern evening sky. The magnitude -3.9 planet will pass from Sagittarius into Capricornus on December 19. The shallow evening ecliptic has kept Venus from appearing very high in the sky, but the planet will be carried much higher by month's end – setting up a spectacular display during early 2020. Viewed in a telescope, Venus will show a waning gibbous phase all month long. Meanwhile, its apparent disk diameter will increase slightly as its orbit carries it closer to Earth. On December 2, Venus will pass 45 arc-minutes (or 1.5 full moon diameters) to the south of the bright globular star cluster Messier 22, and on December 19, it will land only 20 arc-minutes south of another, dimmer globular cluster Messier 75. On December 10-11, Venus will pass less than two finger widths to the lower left (or 2 degrees to the celestial south) of Saturn, making a nice binocular sight and widefield photograph. On December 28, the young crescent moon will be positioned 2.5 degrees below Venus; another pretty sight and photo opportunity.

(Image credit: Starry Night)

Visible in the eastern pre-dawn sky after it rises at about 4:45 a.m. local time, Mars will spend December traversing the stars of Libra while climbing away from the sun. The Earth-Mars separation will continue to decrease during December, but Mars will shine with a modest average magnitude of 1.65 and exhibit a small apparent disk size in telescopes. On December 12 Mars will pass a mere 11 arc-minutes to the upper left (or celestial north) of the pretty double star Zubenelgenubi, making a terrific sight in backyard telescopes. The old, waning crescent moon will be positioned a palm's width to the lower left (or 5 degrees to the celestial northeast) of Mars on December 23.

night sky december 2019

(Image credit: Starry Night)

During early December, magnitude -1.84 Jupiter will be low in the sky and sinking into the southwestern evening twilight at dusk. But the king of planets will become lost to view altogether after about mid-month, and solar conjunction will occur on December 27, close to the December Solstice point on the ecliptic.

night sky december 2019

(Image credit: Starry Night)

During December, Saturn will be visible in the southwestern evening sky — slowly moving eastward through northern Sagittarius, to the upper right of the stars that form Sagittarius' teapot-shaped asterism. During the beginning of December, Saturn will be setting in a dark sky shortly before 7:30 p.m. local time. But after mid-month, the modestly-bright magnitude 0.59 planet will become difficult to see within the evening twilight. To aid your search, on December 27, the young crescent moon will be positioned less than a palm's width to the upper left (or 5 degrees to the celestial southeast) of Saturn. But before then, on December 10-11, Venus will pass less than two finger widths to the lower left (or 2 degrees to the celestial south) of Saturn, making a nice binocular sight and widefield photograph.

(Image credit: Starry Night)

Blue-green Uranus will spend December moving slowly retrograde westward among the stars of southwestern Aries. Uranus will be visible from dusk until well after midnight local time during December, shine at magnitude 5.7, and will exhibit an apparent disk diameter of about 3.6 arc-seconds. To assist you in locating the planet, which can be readily seen in binoculars and backyard telescopes on dark nights, Uranus will be sitting less than 4 degrees above (or to the celestial north) of the naked-eye star Xi (ξ) Ceti. The bright waxing gibbous moon will land 7 degrees to the lower left of Uranus on December 8 — but wait until the bright moon has moved away to observe the planet.

(Image credit: Starry Night)

During December, blue Neptune will be positioned in the south and western evening sky moving prograde eastward through the stars of central Aquarius. At magnitude 7.9, Neptune will be visible in good-quality backyard telescopes. Its orbital motion will be slowly carrying it away from that constellation's naked-eye star Phi (φ) Aquarii and toward another naked-eye star named Hydor, also known as Lambda (λ) Aquarii. Neptune will be observable once full darkness arrives — but it will only be high enough for clear views until late evening in early December and until mid-evening by month's-end.

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 faint objects, such as meteors or dim stars, give your eyes at least 15 minutes to adjust to the darkness.

Light Pollution: Even from a big city, one can see the moon, a handful of bright stars and sometimes the brightest planets. But to fully enjoy the heavens — especially a meteor shower, the constellations, or to see the amazing swath across the sky that represents our view toward the center of the Milky Way Galaxy — rural areas are best for night sky viewing. If you're stuck in a city or suburban area, a building can be used to block ambient light (or moonlight) to help reveal fainter objects. If you're in the suburbs, simply turning off outdoor lights can help.

Prepare for skywatching: If you plan to be out for more than a few minutes, and it's not a warm summer evening, dress warmer than you think necessary. An hour of observing a winter meteor shower can chill you to the bone. A blanket or lounge chair will prove much more comfortable than standing or sitting in a chair and craning your neck to see overhead.

Daytime skywatching: When Venus is visible (that is, not in front of or behind the sun) it can often be spotted during the day. But you'll need to know where to look. A sky map is helpful. When the sun has large sunspots, they can be seen without a telescope. However, it's unsafe to look at the sun without protective eyewear. See our video on how to safely observe the sun, or our safe sunwatching infographic.

Further Reading

All About Space Holiday 2019

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