Mercury the nearest planet to the Sun is visible as both an evening and morning object during January. The small elusive planet can be seen for the first few days of the month low down above the southwestern horizon after sunset (mag. -0.3). During this time it's slightly easier to spot Mercury from tropical and southern locations. However it doesn't take long before the fading planet draws into the Sun and is lost to the bright twilight glare.
On January 14th, Mercury passes through inferior conjunction. Subsequently it re-appears in the morning sky and may be seen towards month's end low down above the ESE horizon, 45 minutes before sunrise (mag. +0.0). Much brighter Venus (mag. -3.9) is positioned 7 degrees west of Mercury.
Venus is now fading in brightness but continues to be visible as a brilliant morning object before sunrise towards the southeast (Northern Hemisphere) / east-southeast (Southern Hemisphere). The planet starts the month at magnitude -4.1, ending it at magnitude -3.9. Although now limbering towards the lower end of its brightness range it remains unmistakable, a dazzling beacon of light hovering above the horizon.
At the start of January, Venus rises up to 3 hours before the Sun although from northern temperate latitudes the visibility period shortens considerably as the month progresses. By the end of January it reduces to just over an hour. From Southern Hemisphere and equatorial regions it still rises up to 2.5 hours before the Sun at months end.
On January 6th, Venus passes 6 degrees north of red supergiant Antares (α Sco - mag. +1.0). The following day the thin 10% illuminated waning crescent Moon forms a nice pairing with Venus. Finally on January 9th, Venus makes a close pass north of Saturn (mag. +0.6). The minimum separation of 5 arc minutes is equivalent to only 1/6 the apparent diameter of the Moon. Venus acts as a useful guide in locating the much more distant and fainter Saturn.
The phase of Venus increases from 77 to 85% as the month progresses.
Earth reaches perihelion or closest point to the Sun on January 2nd at a distance of 147.1 million kilometres (91.4 million miles).
Mars begins the New Year in Virgo as a mag. +1.2 morning object rising between 2am and 3am local time from northern temperate latitudes but rather earlier from locations further south. As the month progresses the planet brightens to mag. +0.8 with its apparent size increasing from 5.6 to 6.8 arc seconds.
This year promises to be a great year for "Red planet" watchers with the highlight occurring on May 22nd when opposition is reached. On this day Mars will shine at magnitude -2.1 and therefore easily brighter than all of the night time stars. Its apparent size will be a healthy 18 arc seconds. In addition there is no hiding of Mars this year, for the whole of 2016 it will be at some time of the night always visible.
The waning crescent Moon passes 1.5 degrees south of Mars on January 3rd.
Jupiter is located in Leo and continues to increase in brightness and apparent size as it heads towards opposition in March. The Solar System's largest and dominant planet is a brilliant morning object that rises before midnight at the start of January, improving by a couple of hours by months end.
Binoculars will reveal the off white or creamy coloured disk of Jupiter but without detail. Also visible are the four large Galilean moons (Io, Europa, Ganymede and Callisto). They continuously change position as they orbit the planet. Sometimes all four are visible at once but on occasions some satellites will be hidden from view as they pass in front of or behind the giant planet's disk.
This month Jupiter brightens from magnitude -2.2 to -2.4 and it's apparent size increases from 39 to 42 arc seconds. On January 8th, it reaches its first stationary point which signals the start of the 2016 opposition period. Afterwards the planet commences retrograde motion.
The waning gibbous Moon passes 1.4 degrees south of Jupiter on January 28th.
Saturn, mag. +0.6, is now an early morning object moving direct amongst the stars of Ophiuchus. With a declination of 20 degrees south the beautiful ringed planet is currently better seen from southern and tropical latitudes where it rises 2 hours before the Sun at the start of the month. The visibility period increases as January progresses with the planet visible a couple of hours after midnight by months end. For northern temperate based observers the visibility of Saturn is not quite as good.
Through a telescope Saturn's most famous feature are of course its spectacular rings and even a small telescope will show them. They are currently displayed wide open with a 26 degree tilt. In addition small scopes will also show the brightest Moons including Titan, Rhea, Tethys and Dione.
The thin waning crescent Moon passes 3 degrees north of Saturn on January 7th. As previously noted on January 9th brilliant Venus (mag. -4.0) moves just 5 arc minutes north of Saturn.
Uranus is moving direct in Pisces southeast of the "Great Square of Pegasus" and 2 degrees south of mag. +4.3 star epsilon (ε) Psc. The distant cold ice giant is visible during the first half of the night, now setting around midnight. At magnitude +5.9 it can just be seen with the naked eye but dark Moonless skies away from light pollution are required. For most observers this is seldom the case and binoculars or a small telescope are needed to spot the seventh planet from the Sun.
Any quality made telescope at high powers will show the disk of Uranus, which appears green in colour and has an diameter of 3.5 arc seconds. The small apparent size means spotting any surface details is difficult even with the largest of amateur scopes.
On January 16th, the first quarter Moon passes 1.5 degrees north of Uranus.
Neptune, mag. +8.0, is an early evening object located in Aquarius that's visible above the western horizon for a short time as soon as it's dark enough. As January progresses Neptune will become more difficult to spot as it battles against the bright twilight sky. This month also offers the last realistic chance to catch a glimpse of the most distant planet in the Solar System before it reaches solar conjunction next month.
Neptune is positioned 30 degrees southwest of the "Great Square of Pegasus" and two degrees northeast of sigma Aqr (σ Aqr - mag. +4.8). The planet varies little in brightness from our perspective and even at opposition it's not bright enough to be seen with the naked eye but can be spotted with binoculars and small scopes.
The waxing crescent Moon passes 2 degrees north of Neptune on January 13th.
Solar System Data Table January 2016
|Date||Right Ascension||Declination||Apparent Magnitude||Apparent Size||Illum. (%)||Distance from Earth (AU)||Constellation|
|Sun||5th Jan 2016||19h 00m 07.8s||-22d 43m 04.0s||-26.8||32.5'||100||0.983||Sagittarius|
|Sun||15th Jan 2016||19h 43m 41.5s||-21d 18m 01.8s||-26.8||32.5'||100||0.984||Sagittarius|
|Sun||25th Jan 2016||20h 26m 09.7s||-19d 12m 12.3s||-26.8||32.5'||100||0.984||Capricornus|
|Mercury||5th Jan 2016||20h 11m 47.9s||-19d 43m 10.3s||0.2||08.2"||30||0.818||Capricornus|
|Mercury||15th Jan 2016||19h 37m 24.3s||-18d 24m 27.3s||5.2||10.1"||01||0.667||Sagittarius|
|Mercury||25th Jan 2016||19h 02m 39.3s||-19d 39m 53.6s||0.6||08.8"||28||0.761||Sagittarius|
|Venus||5th Jan 2016||16h 20m 46.0s||-19d 35m 05.6s||-4.0||14.0"||78||1.191||Scorpius|
|Venus||15th Jan 2016||17h 12m 19.1s||-21d 29m 39.3s||-4.0||13.3"||81||1.252||Ophiuchus|
|Venus||25th Jan 2016||18h 05m 08.3s||-22d 24m 07.3s||-4.0||12.7"||84||1.310||Sagittarius|
|Mars||5th Jan 2016||13h 55m 51.9s||-10d 15m 28.1s||1.2||05.7"||91||1.645||Virgo|
|Mars||15th Jan 2016||14h 16m 38.5s||-12d 05m 49.3s||1.1||06.1"||91||1.545||Virgo|
|Mars||25th Jan 2016||14h 36m 59.1s||-13d 46m 41.3s||0.9||06.5"||90||1.444||Libra|
|Jupiter||5th Jan 2016||11h 36m 16.2s||03d 56m 10.3s||-2.2||39.5"||99||4.988||Leo|
|Jupiter||15th Jan 2016||11h 36m 07.4s||04d 00m 09.6s||-2.3||40.7"||99||4.845||Leo|
|Jupiter||25th Jan 2016||11h 34m 47.9s||04d 11m 37.3s||-2.3||41.8"||100||4.716||Leo|
|Saturn||5th Jan 2016||16h 40m 11.4s||-20d 31m 21.8s||0.6||15.4"||100||10.826||Ophiuchus|
|Saturn||15th Jan 2016||16h 44m 31.7s||-20d 39m 04.6s||0.6||15.5"||100||10.726||Ophiuchus|
|Saturn||25th Jan 2016||16h 48m 29.9s||-20d 45m 30.9s||0.6||15.7"||100||10.605||Ophiuchus|
|Uranus||5th Jan 2016||01h 01m 20.0s||05d 51m 18.2s||5.8||03.5"||100||19.907||Pisces|
|Uranus||15th Jan 2016||01h 01m 48.1s||05d 54m 36.5s||5.8||03.5"||100||20.079||Pisces|
|Uranus||25th Jan 2016||01h 02m 34.8s||05d 59m 49.2s||5.9||03.5"||100||20.247||Pisces|
|Neptune||5th Jan 2016||22h 37m 40.4s||-09d 31m 12.3s||7.9||02.2"||100||30.533||Aquarius|
|Neptune||15th Jan 2016||22h 38m 42.3s||-09d 24m 57.9s||8.0||02.2"||100||30.663||Aquarius|
|Neptune||25th Jan 2016||22h 39m 52.5s||-09d 17m 54.9s||8.0||02.2"||100||30.772||Aquarius|