Night Sky, January 2018: What You Can See This Month [Maps]

Calendar of Observing Highlights

Monday, January 1 – pre-dawn – Mercury at Greatest Western Elongation

On Monday, January 1, Mercury will reach its greatest angle west of the sun, when it will be visible low in the eastern sky for about an hour before sunrise. In a telescope the planet will exhibit a waxing gibbous phase. With Mercury well above a shallow morning ecliptic (green line), this apparition is a good one for northern hemisphere observers, but a poor one for observers in the southern hemisphere.

Monday, January 1 at 9:24 p.m. EST – Full Wolf Moon, Supermoon

The January full moon, known as the Wolf Moon, Old Moon, or Moon after Yule, always shines in or near the stars of Gemini. It rises at sunset and sets at sunrise, and the position of the ecliptic on winter nights causes January moons to culminate high in the night sky. This full moon occurs less than five hours after perigee, the point in the moon’s orbit when it is closest to Earth, making this full moon the largest and brightest supermoon of 2018. We’ll also experience extra high tides globally.

Wednesday-Thursday, January 3-4 – midnight to dawn – Quadrantid Meteor Shower Peaks

Named for a now defunct constellation near the north celestial pole called the Quadrant, the annual Quadrantid meteor shower runs from Dec 30th to Jan 12th. This is one of the most reliable showers of the year, producing up to 100 meteors per hour – many as bright fireballs. The shower peaks before dawn on Thursday. But bright moonlight from moon’s waning gibbous phase on the peak will reduce the number of meteors you see.

Friday, January 5 at 3 a.m. EST – The Moon meets Regulus

On the morning of Friday, January 5, the waning gibbous moon will pass very close to the bright star Regulus in Leo. The pair will be visible together in a telescope at low magnification (orange circle). For observers in Alaska, the eastern tip of Russia, northern Canada, Greenland, Svalbard, Iceland, most of Europe, and northwestern Africa, the moon will occult Regulus. Times vary by region.

Saturday, January 6 – pre-dawn – Mars close to Jupiter

In the pre-dawn eastern sky on Saturday, January 6, Mars’ eastward orbital motion will cause it to pass very close to distant Jupiter. On both Saturday and Sunday morning, observers in the Americas will see the two planets separated by about one-third of a degree (less than a full moon’s diameter). In a backyard telescope, the planets, plus Jupiter’s four Galilean moons, will fit within the field of view of a low power eyepiece (orange circle).

Monday, January 8 at 5:25 p.m. EST – Last Quarter Moon

At last quarter, the moon rises around midnight and remains visible in the southern sky during morning daylight. At this phase, the moon is illuminated on the eastern side, towards the pre-dawn sun. During last quarter, the moon is positioned ahead of the Earth in our trip around the sun. About 3½ hours later, earth will occupy that same location in space. After last quarter, the waning moon traverses the last quarter of its orbit around the earth, on the way to new moon.

Thursday, January 11 – pre-dawn – Moon meets Mars and Jupiter

In the eastern pre-dawn sky on the morning of Thursday, January 11, the waning crescent moon will sit less than 4 degrees to the upper left of dim reddish Mars and very bright Jupiter. The two planets will be separated by only 2 degrees. All three objects will fit within the field of view of binoculars (red circle).

Saturday, January 13 – pre-dawn – Mercury passes Saturn

On Saturday morning, January 13, Mercury’s sunward orbital motion will carry it past Saturn. Look for the two planets in the southeastern pre-dawn sky. Mercury will be 0.75 degrees (or 1.5 full moon diameters) below and slightly to the right of the ringed planet.

Monday, January 15 – pre-dawn – Mercury and Saturn meet the Old Moon

Low in the southeastern pre-dawn sky of Monday, January 15, the old moon’s very thin crescent can be glimpsed sitting three degrees to the left of Mercury. Meanwhile, Saturn will be positioned three degrees to the upper right of Mercury. All three objects will fit into the field of view of binoculars (red circle).

Tuesday, January 16 at 9:17 p.m. EST – New Moon

When new, the moon is travelling between the Earth and the sun. Since sunlight is only reaching the side of the moon turned away from us, and the moon is in the same region of the sky as the sun, the moon is hidden from view. A day or two after new moon, look low above the western horizon after sunset for the slender sliver of the young crescent moon.

Friday, January 19 at 4:43 a.m. EST – Double shadow transit on Jupiter

When the geometry is favorable, the round black shadows of Jupiter’s four large Galilean moons can be observed as they cross the face of the giant planet. Multiple moon shadow events are less common. On Friday, January 19 between 4:43 and 4:55 a.m. EST, the shadows of both Europa and Ganymede will be visible at the same time for observers in the Americas. (Single shadows will be visible on Jupiter from 2:45 a.m. to 6:30 a.m. EST that morning.) Other double shadow events in January occur on January 4 (visible in the Middle East region about 5:15 a.m. local time) and January 12 (visible in central Asia about 12:45 a.m. local time).

Wednesday, January 24 at 5:20 p.m. EST – First Quarter Moon

At first quarter, the relative positions of the Earth, sun, and moon cause us to see the moon half illuminated – on the western (right-hand) side. First quarter moons rise around noon and set around midnight, so they are visible starting in the afternoon hours. The term quarter moon refers not to its appearance, but the fact that our natural satellite has now completely the first quarter of its orbit around Earth since the last new moon.

Friday-Saturday, January 26-27 overnight – Moon Crosses the Bull’s Face

Starting on Friday evening, January 26, the waxing gibbous moon’s orbital motion will carry it through the stars that form the triangular face of Taurus the Bull. The moon will pass the bull’s chin star Hyadum at about midnight EST. For most of the Americas, the moon will set mid-constellation. But observers in most of India, central Asia, most of China, Mongolia, most of Russia, Alaska, and northwestern North America will see the moon will occult Aldebaran, Taurus’ brightest star.

Wednesday, January 31 at 8 a.m. EST – Ceres at opposition

The dwarf planet Ceres reaches opposition on Wednesday, January 31. This is when it is at its brightest (visual magnitude 6.85) and closest to Earth for the year. It will be visible all night in binoculars and telescopes. At opposition, Ceres will be situated near the northern boundary of Cancer, about 10 degrees to the west of the naked eye star Algenubi in Leo. The celestial path of Ceres through June, 2018 is plotted in red.

Wednesday, January 31 at 8:27 a.m. EST – Full Supermoon, Total Lunar Eclipse, and Blue Moon

January ends with a treat – a total lunar eclipse of a full supermoon that is also a Blue Moon! Lunar eclipses are completely safe to look at because the sun is below the horizon. This total lunar eclipse occurs only 1.2 days after perigee (the moon’s closest approach to Earth), so the moon’s diameter will appear larger than average, making it super. The entire event will be visible from northwestern North America, across the Pacific Ocean, and as far as Eastern Siberia and Asia. Most of North America will see a portion of the eclipse before the moon sets and morning twilight arrives, while Eastern Europe and Central Asia will see the eclipse already in progress when the moon rises. During totality, the moon’s northern limb will pass just south of the center of the Earth’s shadow, darkening the Moon’s northern half more than its southern half. This full moon will also be a Blue Moon – the second full moon to occur within the calendar month.

Planets

On Monday, January 1, Mercury will reach its greatest angle west of the sun, when it will be easily visible low in the eastern sky for about an hour before sunrise. With Mercury starting well above a shallow morning ecliptic, this apparition is a good one for northern hemisphere observers. The planet will remain in view with increasing difficulty until about mid-month. Because Mercury crosses the ecliptic after mid-month, observers in the southern hemisphere can observe it throughout January, brightening over time.In a telescope Mercury will exhibit a waxing gibbous phase during January, and its apparent disk diameter will shrink as our distance from it increases.

Venus is hidden from view until well after solar conjunction on January 9. The best opportunities to see Venus during January are in the last few evenings of the month, when it will start to emerge from the twilight in the west-southwestern evening sky.

As January opens, reddish Mars is a distant and dim magnitude 1.5 object in the pre-dawn sky sitting only one degree above the bright double star Zubenelgenubi in Libra. On Saturday, January 6, Mars’ eastward orbital motion will cause it to pass very close to distant Jupiter. On both Saturday and Sunday morning, observers in the Americas will see the two planets separated by about one-third of a degree (less than a full moon’s diameter). During the month, Mars will grow in brightness and apparent disk size. On January 31, it crosses intoScorpius, ending the month about half a degree to the southwest of the claw star Acrab.

Bright Jupiter continues to climb the eastern pre-dawn sky during January, slowly moving eastward through central Libra. On Saturday, January 6, Mars will pass very close to Jupiter. On both Saturday and Sunday morning, observers in the Americas will see the two planets separated by about 0.33 degrees (less than a full moon’s diameter). A few mornings later on Thursday, January 11, the waning crescent moon will join Jupiter and Mars. All three objects will fit within the field of view of binoculars. Galilean moon shadow transits occur frequently during January, including several double shadow events.

Only recently past December’s solar conjunction, Saturn will be too close to the Sun to be seen during early January. Towards the middle of the month, it will reappear in the eastern pre-dawn sky among the stars of Sagittarius. On Saturday morning, January 13, Mercury’s sunward orbital motion will carry it past Saturn. Mercury, about twice as bright as Saturn, will be 0.75 degrees (or 1.5 full moon diameters) below and slightly to the right of the ringed planet.

During January, Uranus is well placed in the evening sky, positioned between the two chains of faint stars that link the fishes of Pisces. By month end, the planet will be setting about 10:30 pm local time. At visual magnitude 5.7, Uranus is bright enough to observe in binoculars under dark sky conditions.

Neptune spends January in the western evening sky in Aquarius, and setting in mid-evening. The naked eye star Lambda Aquarii, located only 0.5 degrees north of the planet, will aid you in finding it.

Skywatching Terms
Gibbous: Used to describe a planet or moon that is more than 50 percent 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.

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