Night sky guide for January 2017

January 2017 hosts one of the most intense annual meteor showers – the Quadrantids, known for producing spectacular fireballs. The timing favors western parts of North America and islands across the Pacific. The peak of Quadrantids is brief, typically lasting no more than an hour or so, and it does not always occur at the forecasted time.

The Earth's annual orbit around the solar system will carry it to its closest point to the Sun, at a distance of 0.98 AU at 14:19 UTC, on January 4. Technically speaking, this marks the moment when the Sun appears larger in the sky than at any other time of year, and when the Earth receives the most radiation from it. In practice, however, a 3% difference in the Earth's distance from the Sun is barely noticeable. Annual changes in our weather, for example between the summer and winter, are caused entirely by the tilt of the Earth's axis of rotation, rather than by any change in its distance from the Sun.

The Moon will reach its full phase at 11:35 UTC on January 12. At this time in its monthly cycle of phases, the Moon lies almost directly opposite the Sun in the sky, placing it high above the horizon for much of the night. This full moon was known by early Native American tribes as the Full Wolf Moon because this was the time of year when hungry wolf packs howled outside their camps. This moon has also been known as the Old Moon and the Moon After Yule.

New Moon, the best time of the month to observe faint objects because there is no moonlight to interfere, is on January 28.

• January 1 – M41 well placed for observation. The open star cluster M41 (NGC 2287) in Canis Major will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -20°43', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 49°N. At magnitude 4.5, M41 is too faint to be seen with the naked eye from any but the very darkest sites but is visible through a pair of binoculars or a small telescope.

• January 1 – Conjunction of Mars and Neptune – 06:32 UTC. Mars and Neptune will share the same right ascension, with Mars passing 0°01' to the south of Neptune. At around the same time, the two objects will also make a close approach, technically called an appulse. Mars will be at mag 0.5, and Neptune at mag 7.9, both in the constellation Aquarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible through a pair of binoculars.

• January 1 – Close approach of Mars and Neptune – 06:48 UTC. Mars and Neptune will make a close approach, passing within 0°01' of each other. Mars will be at mag 0.5, and Neptune at mag 7.9, both in the constellation Aquarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible through a pair of binoculars. At around the same time, the two objects will also share the same right ascension – called a conjunction.

• January 2 – Close approach of the Moon and Venus – 08:23 UTC. The Moon and Venus will make a close approach, passing within 1°50' of each other. The Moon will be 4 days old. The Moon will be at mag -10.7, and Venus at mag -5.0, both in the constellation Aquarius. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars. At around the same time, the two objects will also share the same right ascension – called a conjunction.

• January 2 – Conjunction between the Moon and Venus – 09:20 UTC. The Moon and Venus will share the same right ascension, with the Moon passing 1°54' to the north of Venus. The Moon will be 4 days old. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -10.7, and Venus at mag -5.0, both in the constellation Aquarius. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars.

• January 3 – Close approach of the Moon and Neptune – 04:01 UTC. The Moon and Neptune will make a close approach, passing within 0°22' of each other. The Moon will be 5 days old. The Moon will be at mag -11.1, and Neptune at mag 7.9, both in the constellation Aquarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible through a pair of binoculars.

• January 3 – Close approach of the Moon and Mars – 06:40 UTC. The Moon and Mars will make a close approach, passing within 0°13' of each other. The Moon will be 5 days old.The Moon will be at mag -11.1, and Mars at mag 0.5, both in the constellation Aquarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible to the naked eye or through a pair of binoculars.

• January 3 – Quadrantid meteor shower ~ 14:00 UTC. This is an above average shower, with 60 – 200 meteors per hour at its peak. However, big hourly rates assume a perfectly dark sky and that the radiant of the meteor shower is directly overhead, among other things. In practice, the number of meteors you are likely to see is lower than 80. Unlike most meteor showers which originate from comets, the Quadrantids originate from an asteroid: asteroid 2003 EH1. It takes 5.52 years for this asteroid to orbit the Sun once. It is possible that 2003 EH is a "dead comet" or a new kind of object being discussed by astronomers called a "rock comet." 2003 EH1 was discovered on March 6, 2003 by the Lowell Observatory Near-Earth Object Search (LONEOS). 2003 EH1 is a small asteroid – its diameter measures only about 3 km (1.8 miles) across. It was astronomer and research scientist Peter Jenniskens who realized that 2003 EH1 is the source for the Quadrantid meteors. The radiant of the Quadrantid meteor shower is at around right ascension 15h30m, declination +50°. All of the meteors will appear to be traveling directly outward from this point. The Moon will be 6 days old at the time of peak activity, presenting minimal interference. To see the most meteors, the best place to look is not directly at the radiant itself, but at any dark patch of sky which is around 30–40° away from it. It is at a distance of around this distance from the radiant that meteors will show reasonably long trails without being too spread out. This meteor shower is known for producing spectacular fireballs.

• January 4 – Earth at perihelion – 14:19 UTC. The Earth's annual orbit around the solar system will carry it to its closest point to the Sun, at a distance of 0.98 AU. The Earth's distance from the Sun varies by around 3% over the course of the year because its orbit is slightly oval-shaped, following a path called an ellipse. In practice, this variation is rather slight, however, because the Earth's orbit is very nearly circular. The Earth completes one revolution around this oval-shaped orbit each year, and so it makes its closest approach to the Sun on roughly the same day every year. In 2017, this falls on January 4. Technically speaking, this marks the moment when the Sun appears larger in the sky than at any other time of year, and when the Earth receives the most radiation from it. In practice, however, a 3% difference in the Earth's distance from the Sun is barely noticeable. Annual changes in our weather, for example between the summer and winter, are caused entirely by the tilt of the Earth's axis of rotation, rather than by any change in its distance from the Sun.

• January 5 – Moon at first quarter – 19:48 UTC. The Moon will be prominent in the evening sky, setting around midnight. At this time in its monthly cycle of phases, it appears almost exactly half illuminated. Over coming days, the Moon will set later each day, becoming visible for more of the night. Within a few days, it will not make it very far above the eastern horizon before nightfall. By the time it reaches full phase, it will be visible for much of the night, rising at around dusk and setting at around dawn.

• January 6 – Conjunction of the Moon and Ceres – 11:11 UTC. The Moon and 1 Ceres will share the same right ascension, with the Moon passing 3°25' to the north of 1 Ceres. The Moon will be 8 days old. The Moon will be at mag -12.2 in the constellation Pisces, and 1 Ceres at mag 7.6 in the neighboring constellation of Cetus. The pair will be too widely separated to fit within the field of view of a telescope but will be visible through a pair of binoculars.

• January 6 – Conjunction of the Moon and Eris – 13:13 UTC. The Moon and 136199 Eris will share the same right ascension, with the Moon passing 8°56' to the north of 136199 Eris. The Moon will be 8 days old. The Moon will be at mag -12.2 in the constellation Pisces, and 136199 Eris at mag 18.7 in the neighboring constellation of Cetus.

• January 7 – Pluto at solar conjunction – 06:36 UTC. 134340 Pluto will pass very close to the Sun in the sky as its orbit carries it around the far side of the solar system from the Earth. At closest approach, 134340 Pluto will appear at a separation of only 1°00' from the Sun, making it totally unobservable for several weeks while it is lost in the Sun's glare. At around the same time, 134340 Pluto will also be at its most distant from the Earth – receding to a distance of 34.23 AU – since the two planets will lie on opposite sides of the solar system. If 134340 Pluto could be observed at this time, it would appear at its smallest and faintest on account of its large distance. It would measure 0.0 arcsec in diameter. Over following weeks and months, 134340 Pluto will re-emerge to the west of the Sun, gradually becoming visible for ever-longer periods in the pre-dawn sky. After around six months, it will reach opposition, when it will be visible for virtually the whole night.

• January 11 – Mercury at greatest brightness – 11:29 UTC. Mercury will be well placed for observation in the dawn sky, shining brightly at mag -2.2. Mercury's orbit lies closer to the Sun than the Earth's, meaning that it always appears close to the Sun and is very difficult to observe most of the time. It is observable only for a few days each time it reaches the greatest separation from the Sun – moments referred to as greatest elongation. Mercury's brightness depends on two factors: its closeness to the Earth, and its phase. Its phase varies depending on its position relative to the Earth. When it passes between the Earth and Sun, for example, the side that is turned towards the Earth is entirely unilluminated, like a new moon. Conversely, when it lies opposite to the Earth in its orbit, passing almost behind the Sun, it appears fully illuminated, like a full moon. However, at this time it is also at its most distant from the Earth, so it is actually fainter than at other times. Mercury reaches its brightest when it is still a crescent – with less than half of its disk illuminated. This is because it is much closer to the Earth during its crescent phases than at other times. As a result, during evening apparitions, Mercury reaches maximum brightness a few days after it is at greatest separation from the Sun, which always coincides with it showing half-phase (dichotomy). Conversely, during morning apparitions, Mercury reaches maximum brightness a few days before it is at greatest separation from the Sun.

• January 12 – Full Moon – 11:35 UTC. At this time in its monthly cycle of phases, the Moon lies almost directly opposite the Sun in the sky, placing it high above the horizon for much of the night. The sequence of full moons through the year are often assigned names according to the seasons in which they fall. This month's will be the first to fall in winter 2017 – the Old Moon. Over the nights following January 12, the Moon will rise around an hour later each day, becoming prominent later in the night. Within a few days, it will only be visible in the pre-dawn and early-morning sky. By the time it reaches last quarter, a week after full moon, it will rise at around midnight and set at around noon. At the exact moment when the Moon reaches full phase, it will lie at a declination of +18°13' in the constellation Gemini, and so will appear highest in the northern hemisphere. It will be visible from all latitudes south of 61°S. Its distance from the Earth will be 366 000 km. This full moon was known by early Native American tribes as the Full Wolf Moon because this was the time of year when hungry wolf packs howled outside their camps. This moon has also been known as the Old Moon and the Moon After Yule.

• January 12 – Venus at greatest elongation east – 15:52 UTC. Venus will be well placed for observation in the evening sky, shining brightly at mag -5.1. Venus's orbit lies closer to the Sun than the Earth's, meaning that it always appears close to the Sun and is very difficult to observe most of the time. It is observable only for a few weeks each time it reaches the greatest separation from the Sun – moments referred to as greatest elongation. On these occasions, however, Venus is so bright and conspicuous that it becomes the third brightest object in the sky after the Sun and Moon. It is often called the morning or evening star. These apparitions take place alternately in the morning and evening skies, depending whether Venus lies to the east of the Sun or to the west. When it lies to the east, it rises and sets a short time after the Sun and is visible in early evening twilight. When it lies to the west of the Sun, it rises and sets a short time before the Sun and is visible shortly before sunrise. On this occasion, it lies 47° to the Sun's east.

• January 12 – Close approach of Venus and Neptune – 21:05 UTC. Venus and Neptune will make a close approach, passing within 0°21' of each other. Venus will be at mag -5.2, and Neptune at mag 7.9, both in the constellation Aquarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible through a pair of binoculars. At around the same time, the two objects will also share the same right ascension – called a conjunction.

• January 13 – C/2016 U1 (NEOWISE) reaches its brightest. Comet C/2016 U1 (NEOWISE) is forecast to reach its brightest, at around mag 5.6. It will lie at a distance of 0.33 AU from the Sun, and at a distance of 1.14 AU from the Earth.

• January 13 – Conjunction of Venus and Neptune – 01:41 UTC. Venus and Neptune will share the same right ascension, with Venus passing 0°24' to the north of Neptune. At around the same time, the two objects will also make a close approach, technically called an appulse. Venus will be at mag -5.2, and Neptune at mag 7.9, both in the constellation Aquarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible through a pair of binoculars.

• January 13 – Mercury at dichotomy – 22:02 UTC. Mercury will be well placed for observation in the dawn sky, shining brightly at mag -2.2. Mercury's orbit lies closer to the Sun than the Earth's, meaning that it always appears close to the Sun and is very difficult to observe most of the time. It is observable only for a few days each time it reaches the greatest separation from the Sun – moments referred to as greatest elongation. Mercury's phase varies depending on its position relative to the Earth. When it passes between the Earth and Sun, for example, the side that is turned towards the Earth is entirely unilluminated, like a new moon. Conversely, when it lies opposite to the Earth in its orbit, passing almost behind the Sun, it appears fully illuminated, like a full moon. However, at this time it is also at its most distant from the Earth, so it is actually fainter than at other times. Mercury shows an intermediate half phase – called dichotomy – at roughly the same moment that it appears furthest from the Sun, at greatest elongation. The exact times of the two events may differ by a few hours, only because Mercury's orbit is not quite perfectly aligned with the ecliptic.

• January 14 – M47 well placed for observation. The open star cluster M47 (NGC 2422) in Puppis will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -14°30', it is easiest to see from the southern hemisphere; it can be seen at latitudes between 55°N and 84°S. At magnitude 4.4, M47 is tricky to make out with the naked eye except from a dark site but is visible through a pair of binoculars or a small telescope.

• January 14 – NGC 2403 well placed for observation. NGC 2403, a spiral galaxy in Camelopardalis will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +65°35', it is easiest to see from the northern hemisphere but cannot be seen from latitudes much south of 4°S. At magnitude 8.4, NGC2403 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

• January 14 – C/2016 U1 (NEOWISE) at perihelion. Comet C/2016 U1 (NEOWISE) will make its closest approach to the Sun, at a distance of 0.32 AU.

• January 14 – 74P/Smirnova-Chernykh reaches its brightest. Comet 74P/Smirnova-Chernykh is forecast to reach its brightest, at around mag 12.9. It will lie at a distance of 3.76 AU from the Sun, and at a distance of 2.79 AU from the Earth.

• January 14 – Conjunction of Ceres and Eris – 12:51 UTC. 1 Ceres and 136199 Eris will share the same right ascension, with 1 Ceres passing 6°09' to the north of 136199 Eris. 1 Ceres will be at mag 7.7 in the constellation Pisces, and 136199 Eris at mag 18.7 in the neighboring constellation of Cetus.

• January 16 – NGC 2547 well placed for observation. Across much of the world, the open star cluster NGC 2451 in Puppis will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -37°58', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 32°N. At magnitude 2.8, NGC2451 is visible to the naked eye, but best viewed through a pair of binoculars.

• January 18 – Conjunction of the Moon and Makemake – 17:16 UTC. The Moon and 136472 Makemake will share the same right ascension, with the Moon passing 27°28' to the south of 136472 Makemake. The Moon will be 20 days old. The Moon will be at mag -12.1 in the constellation Virgo, and 136472 Makemake at mag 16.9 in the neighboring constellation of Coma Berenices.

• January 19 – Close approach of the Moon and Jupiter – 07:09 UTC. The Moon and Jupiter will make a close approach, passing within 2°33' of each other. The Moon will be at mag -12.0, and Jupiter at mag -2.1, both in the constellation Virgo. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars.

• January 19 – Mercury at greatest elongation west – 13:45 UTC. Mercury will be well placed for observation in the dawn sky, shining brightly at mag -2.0. Mercury's orbit lies closer to the Sun than the Earth's, meaning that it always appears close to the Sun and is very difficult to observe most of the time. It is observable only for a few days each time it reaches the greatest separation from the Sun – moments referred to as greatest elongation. These apparitions take place alternately in the morning and evening skies, depending whether Mercury lies to the east of the Sun or to the west. When it lies to the east, it rises and sets a short time after the Sun and is visible in early evening twilight. When it lies to the west of the Sun, it rises and sets a short time before the Sun and is visible shortly before sunrise. On this occasion, it lies 24° to the Sun's west.

• January 19 – Moon at last quarter – 22:15 UTC. The Moon will be prominent in the dawn sky, rising at around midnight. Over coming days, the Moon will rise later each day, so that it is visible for less time before sunrise and it less far above the eastern horizon before dawn. By the time it reaches the new moon, it will rise at around dawn and set at around dusk, making it visible only during the daytime. Its day-by-day progress is charted below, with all times are given below in Zagreb local time. Over the next few days, the distance between the Moon and the Sun will decrease, and it will rise later each day. By the time it disappears into the Sun's glare as it approaches new moon, it will only be visible very shortly before sunrise.

• January 20 – NGC 2516 well placed for observation. Across much of the world, the open star cluster NGC 2516 in Volans will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -60°52', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 9°N. At magnitude 3.8, NGC2516 is tricky to make out with the naked eye except from a dark site but is visible through a pair of binoculars or a small telescope.

• January 20 – Conjunction of the Moon and Haumea – 06:05 UTC. The Moon and 136108 Haumea will share the same right ascension, with the Moon passing 25°03' to the south of 136108 Haumea. The Moon will be 22 days old. The Moon will be at mag -11.8 in the constellation Virgo, and 136108 Haumea at mag 17.2 in the neighboring constellation of Bootes.

• January 23 – NGC 2547 is well placed. Across much of the world, the open star cluster NGC 2547 in Vela will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -49°16', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 20°N. At magnitude 4.7, NGC2547 is too faint to be seen with the naked eye from any but the very darkest sites but is visible through a pair of binoculars or a small telescope.

• January 24 – Close approach of the Moon and Saturn – 10:53 UTC. The Moon and Saturn will make a close approach, passing within 3°36' of each other. The Moon will be at mag -10.3, and Saturn at mag 0.3, both in the constellation Ophiuchus. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars. The Moon will be 26 days old. 

• January 26 – Conjunction of the Moon and Mercury – 00:45 UTC. The Moon and Mercury will share the same right ascension, with the Moon passing 3°42' to the north of Mercury. The Moon will be at mag -9.1, and Mercury at mag -1.8, both in the constellation Sagittarius. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars. The Moon will be 28 days old.

• January 26 – Conjunction of the Moon and Pluto – 10:04 UTC. The Moon and 134340 Pluto will share the same right ascension, with the Moon passing 2°45' to the north of 134340 Pluto. The Moon will be at mag -8.7, and 134340 Pluto at mag 14.9, both in the constellation Sagittarius. The pair will be too widely separated to fit within the field of view of a telescope but will be visible through a pair of binoculars.

• January 28 – New Moon – 00:08 UTC. The Moon will pass close to the Sun and become lost in the Sun's glare for a few days. The Moon's orbital motion carries it around the Earth once every four weeks, and as a result its phases cycle from new moon, through first quarter, full moon and last quarter, back to new moon once every 29.5 days. This motion also means that the Moon travels more than 12° across the sky from one night to the next, causing it to rise and set nearly an hour later each day. At new moon, the Earth, Moon, and Sun all lie in a roughly straight line, with the Moon in the middle, appearing in front of the Sun's glare. In this configuration, we see almost exactly the opposite half of the Moon to that which is illuminated by the Sun, making it doubly unobservable because the side we see is unilluminated. Over coming days, the Moon will rise and set an hour later each day, becoming visible in the late afternoon and dusk sky as a waxing crescent which sets soon after the Sun. By first quarter, in a week's time, it will be visible until around midnight. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.

• January 29 – Conjunction of Mercury and Pluto – 17:20 UTC. Mercury and 134340 Pluto will share the same right ascension, with Mercury passing 1°11' to the south of 134340 Pluto. Mercury will be at mag -1.8, and 134340 Pluto at mag 14.9, both in the constellation Sagittarius. The pair will be too widely separated to fit within the field of view of a telescope but will be visible through a pair of binoculars.

• January 30 – M44 well placed for observation. The Beehive open star cluster (M44, NGC 2632, also known as Praesepe) will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +19°58', it is easiest to see from the northern hemisphere; it can be seen at latitudes between 89°N and 50°S. At magnitude 3.1, M44 is tricky to make out with the naked eye except from a dark site but is visible through a pair of binoculars or a small telescope.

• January 30 – IC2391 well placed for observation. Across much of the world, the Omicron Velorum open star cluster (IC 2391) in Vela will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -53°04', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 16°N. At magnitude 2.5, IC2391 is visible to the naked eye, but best viewed through a pair of binoculars.

• January 30 – IC2395 well placed for observation. Across much of the world, the open star cluster IC 2395 in Vela will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -48°12', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 21°N. At magnitude 4.6, IC2395 is too faint to be seen with the naked eye from any but the very darkest sites but is visible through a pair of binoculars or a small telescope.

• January 31 – Conjunction of the Moon and Venus – 14:35 UTC. The Moon and Venus will share the same right ascension, with the Moon passing 4°03' to the south of Venus. The Moon will be 3 days old. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -10.6 in the constellation Aquarius, and Venus at mag -5.4 in the neighboring constellation of Pisces. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars.

• January 31 – Close approach of the Moon and Venus – 16:53 UTC. The Moon and Venus will make a close approach, passing within 3°52' of each other. The Moon will be 3 days old. The Moon will be at mag -10.7, and Venus at mag -5.4, both in the constellation Pisces. The pair will be too widely separated to fit within the field of view of a telescope but will be visible to the naked eye or through a pair of binoculars. At around the same time, the two objects will also share the same right ascension – called a conjunction.

Video courtesy Hubble Space Telescope

Sources: InTheSky by Dominic Ford, NASA

Featured image credit: NASA. Edit: TW