See what's up in the night sky for January 2020, including stargazing events and the moon's phases, in this Space.com gallery courtesy of Starry Night Software.
Wednesday, January 1 evening — Vesta Stands Stil
On Wednesday, January 1, the large main belt asteroid designated (4) Vesta will complete a retrograde loop that began in late September, and resume its regular eastward orbital motion (red path with dates). After dark, look for the magnitude 7.4 object halfway up the southeastern sky, within the circlet of stars that form the head of Cetus.
Friday, January 3 at 4:45 GMT — First Quarter Moon
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 conveniently positioned for observing before youngsters' bedtimes. The evenings around first quarter are excellent for looking at the lunar terrain while it is dramatically lit by low-angled sunlight.
Saturday, January 4 pre-dawn — Quadrantids Meteor Shower Peak
Named for a now-defunct constellation near the north celestial pole called the Mural Quadrant, the annual Quadrantids meteor shower runs from December 30 to January 12 – but the shower's most intense period, when 50 to 100 meteors per hour can occur, lasts only about 6 hours surrounding the peak, which is predicted to occur on Saturday, January 4 at 09:00 GMT (or 4 a.m. Eastern time). At that time, the Earth will be traversing the thickest part of the debris field. Many Quadrantids are bright fireballs owing to the shower's source, an asteroid designated 2003EH. The best time for viewing Quadrantids will be before dawn on Saturday morning, when the shower's radiant, which is beyond the tip of the Big Dipper's handle, will be high in the northeastern sky. The half-illuminated moon will set after 1 a.m. local time on the shower's peak date, leaving the pre-dawn sky dark for meteor-watchers.
Sunday, January 5 at 8:00 GMT — Earth at Perihelion
On Sunday, January 5, the Earth will reach perihelion, its closest point to the sun for the year. On that date Earth's distance from the sun will shrink to 91.401 million miles (147.096 million km). As winter-chilled Northern Hemisphere dwellers will attest, daily temperatures on Earth are not controlled by our proximity to the sun, but by the number of hours of daylight we experience.
Tuesday, January 7 all night — Gibbous Moon meets Aldebaran
As darkness falls in the Americas on the evening of Tuesday, January 7, the waxing gibbous moon will be positioned several finger widths to the left (or 2.5 degrees to the celestial north) of the bright orange star Aldebaran, which marks the southern eye of Taurus, the Bull. For the rest of the night, the moon will pull away from that star, and the motion of the sky due to Earth's diurnal rotation will lift the moon above Aldebaran. On that same date, Observers in Europe and Africa will see the moon pass through the triangular face of Taurus, and much closer to Aldebaran.
Friday, January 10 at 19:21 GMT — Full Wolf Moon and Penumbral Lunar Eclipse
The January full moon, known as the Wolf Moon, Old Moon, and Moon after Yule, always shines in or near the stars of Gemini or Cancer. It rises at sunset and sets at sunrise, and the position of the ecliptic on winter nights causes January moons to culminate very high in the night sky. This full moon will occur while the moon is close to the ecliptic, producing a penumbral lunar eclipse which will begin when the moon contacts the Earth's shadow at 17:07:45 GMT. The moon will enter almost completely into the Earth's northern penumbral shadow, subtly darkening the moon's southern limb more than its northern limb. However, the effect will be visible only within about 30 minutes on either side of greatest eclipse, which will occur at 19:10:01 GMT. The penumbral eclipse will end at 21:12:24 GMT. The entire eclipse will be visible from Europe, eastern Africa, and Asia. In North and South America, Alaska and the Canadian Maritimes will be treated to only the beginning and final stages of the eclipse, respectively.
Saturday, January 11 evening — Uranus Stands Still
On Saturday, January 11, the distant, blue-green planet Uranus will temporarily cease its motion through the distant stars of southwestern Aries — completing a westward retrograde loop that began in early August. After that date, the planet will resume its regular eastward orbital motion. Magnitude +5.77 Uranus can be seen in binoculars and backyard telescopes, and with unaided eyes under dark skies. Use the nearby naked-eye stars Omicron (o) Piscium and Eta (η) Piscium to guide you.
Saturday, January 11 evening — Bright Moon Buzzes the Beehive
When the bright, gibbous moon rises in the northeastern evening sky on Saturday, January 11, it will be sitting very close to the left side of the large open star cluster known as the Beehive. The brightest deep sky object in Cancer, this cluster is also called Praesepe and Messier 44 (or M44). The moon and the cluster will both fit within the field of view of binoculars (orange circle), although the bright moonlight will obscure the cluster's dimmer stars. For best results, place the moon just outside of the left edge of your binoculars' field of view and look for the cluster's many stars.
Monday, January 13 pre-dawn — Bright Moon near Bright Regulus
In the western pre-dawn sky on Monday, January 13, the waning gibbous moon will sit within three finger widths to the upper right (or 3 degrees to the celestial north) of the bright, white star Regulus, which marks the heart of Leo, the Lion. Also designated Alpha Leonis, Regulus' position is less than one degree from the ecliptic (green line), and the star is occasionally occulted by the moon and planets.
Friday, January 17 at 12:58 GMT — Last Quarter Moon
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. After this phase, the waning moon will traverse the last quarter of its orbit around the earth, on the way to new moon.
Saturday, January 18 pre-dawn — Mars meets its Rival
In the pre-dawn southeastern sky on the mornings surrounding Saturday, January 18, the orbital motion of the Red Planet Mars will carry it within a palm's width to the upper left (or 4.5 degrees to the celestial north) of its rival, the bright, ruddy-colored star Antares. That star represents the heart of Scorpius, the Scorpion. Antares' name translates to "Rival of Ares". The star and the planet will shine with similar colors, but Mars will be somewhat brighter during this encounter.
Sunday, January 19 at 8:21 p.m. EST — Algol at Minimum Brightness
The "Demon Star" Algol in Perseus is among the most accessible variable stars for budding astronomers. Its naked-eye brightness dims noticeably for about 10 hours once every 2 days, 20 hours, and 49 minutes because a dim companion star orbiting nearly edge-on to Earth crosses in front of the much brighter main star, reducing the total light output we receive. On Sunday, January 19 at 8:21 p.m. EST (1:21 UT on Monday), Algol will reach its minimum brightness of magnitude 3.4. At that time, for observers in the Eastern time zone, the star will sit close to the zenith in the southwestern sky. Five hours later, at 1:21 a.m. EST, Algol will be over the northwestern horizon and will have brightened to its usual magnitude of 2.1.
Monday, January 20 pre-dawn — Old Moon near Mars
In the southeastern sky during the hours preceding dawn on Monday, January 20, the waning crescent moon will be positioned less than four finger widths to the upper right (or 4 degrees to the celestial northwest) of Mars. Both objects will fit into the field of view of binoculars (red circle).
Tuesday, January 21 all night — Comet C/2017 T2 (PanSTARRS) passes the Heart and Soul Nebulas
In the northern sky on the nights surrounding Tuesday, January 21, the orbital motion of Comet C/2017 T2 PanSTARRS will carry it past the Heart and Soul Nebulas (also designated IC 1805 and IC 1848) in Cassiopeia, setting up a wonderful astro-imaging and observing opportunity in moonless skies. The comet, which should be readily visible during January in binoculars as a dim fuzzy patch, possibly with a tail, is predicted to reach peak visibility in late spring, 2020.
Wednesday, January 22 before sunrise — Old Moon over Jupiter
Look just above the southeastern horizon before sunrise on Wednesday, January 22 for the very old, slim crescent moon sitting a generous palm's width to the upper right (or 7 degrees to the celestial west) of Jupiter. That bright planet will rise at about 6:30 a.m. local time. Appoximately fifteen hours later, the moon's eastward orbital motion will produce an occultation of Jupiter for observers in Madagascar, the Kerguelen Islands, southern and eastern Australia, New Zealand, southern and eastern Melanesia, and southwestern Polynesia.
Friday, January 24 at 21:42 GMT — New Moon
During its new phase, the moon is travelling between Earth and the sun. Since sunlight can only reach the side of the moon that faces 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 for about a day.
Saturday, January 25 after sunset — Young Moon near Mercury
Very low in the west-southwestern sky immediately after sunset on Saturday, January 25, the very thin crescent of the young moon will be positioned less than two finger widths to the left (or within 2 degrees to the celestial southeast) of Mercury. The best time to see the pair will be between 5:30 and 5:45 p.m. local time. But ensure that the sun has completely set before scanning the sky with binoculars (red circle) or a telescope.
Monday, January 27 early evening — Venus Kisses Neptune
In the western sky after dusk on Monday, January 27, the orbital motion of the very bright planet Venus (red path with dates and times indicated) will carry it very closely past the distant and far dimmer planet Neptune. Closest approach will occur at 20:00 GMT, when the two planets will be separated by only 4 arc-minutes! Observers in the Americas will have to wait until full darkness arrives a few hours later to see Neptune – by then sitting only 10 arc-minutes to the celestial north of Venus. Throughout the encounter, Venus and Neptune will appear together within the field of view of a backyard telescope (red circle), but Venus will far outshine Neptune's tiny blue disk. Note that your telescope's optics will likely flip and/or invert the arrangement shown here.
Tuesday, January 28 evening — Young Moon near Venus
In the southwestern sky after sunset on Tuesday, January 28, the young moon's slim crescent will be positioned a binoculars' field width to the upper left (or 6 degrees to the celestial southeast) of very bright Venus. By the time Venus sets at about 8:45 p.m. local time, the moon's eastward orbital motion will have carried it a bit farther away from Venus.
Friday, January 31 evening — Moon and Uranus
In the southwestern sky during the evening hours of Friday, January 31, the waxing crescent moon will be positioned a palm's width to the lower left (or 6 degrees to the celestial southwest) of Uranus. While bright moonlight will hamper views of far less bright Uranus, use the moon to identify Uranus' location and then look for that dim planet on a night when the moon is less intrusive.