The Solar System in January 2016
Dates and times shown are NZDT (UT + 13 Hours) unless otherwise stated. Rise and set times are for Wellington. They will vary by a few minutes elsewhere in NZ.
Sunrise, sunset and twilight times in January
January 1 NZDT January 31 NZDT morning evening morning evening SUN: rise: 5.48am, set: 8.59pm rise: 6.21am, set: 8.45pm Twilights Civil: starts: 5.17am, ends: 9.31pm starts: 5.53am, ends: 9.14pm Nautical: starts: 4.34am, ends:10.14pm starts: 5.15am, ends: 9.52pm Astro: starts: 3.43am, ends:11.04pm starts: 3.33am, ends:10.34pm
January PHASES OF THE MOON (times as shown by GUIDE)
Last quarter: January 2 at 6.30 pm (05:30 UT) New moon: January 10 at 2.30 pm (01:30 UT) First quarter: January 17 at 12.26 pm (Jan 16, 23:26 UT) Full moon: January 24 at 2.46 pm (01:46 UT)
The Earth is at perihelion on January 3 at noon NZDT (Jan 2, 23 hrs UT). It will then be 147 million km from the Sun (0.9833 AU).
The planets in January
At the beginning of January only Mercury of the naked-eye planets will be in the evening sky. But, at best, it will be very difficult to see. After conjunction mid month, Mercury joins the other four naked eye planets in the morning sky. The early evening sky will then be bereft of naked eye planets. By the end of January, Jupiter will rise about 10.30 pm so be easily visible to the east by midnight.
Mercury starts January as an evening object setting some 80 minutes after the Sun. On the 1st its magnitude will be -0.3 but with an altitude only 3.5 degrees, 45 minutes after sunset, it will be a difficult object. The Sun will be 8 degrees below the horizon so the westerly sky will still be bright making the planet difficult to see.
During the next few days Mercury gets closer to the Sun, especially after it is stationary on January 5 when the planet will start moving to the west and so towards the easterly moving Sun. Inferior conjunction is on January 14 when Mercury will be just under 50 million km from the Sun with the Earth 100 million km further out.
After conjunction Mercury becomes a morning object rising shortly before the Sun. The planet's westerly movement will take it quite quickly further from the Sun making it visible in the dawn sky. It is again stationary on January 26 by which date its motion away from the Sun will have slowed. On the last morning of January Mercury will rise almost 2 hours before the Sun. An hour after it rises the planet will be 8 degrees above the horizon with Venus the same distance above and to its left. At magnitude 0.3 Mercury should be fairly easy to see especially with Venus to act as a guide. But this is at about 5.30 am.
Venus remains a morning object rising about 140 minutes before the Sun all month. It starts January in Scorpius but moves into Ophiuchus on the morning of the 6th. Venus moves into Sagittarius on the 21st. On January 8 Venus will be 6 deg from Antares and on the 30th 3 degrees from the 2.8 magnitude star lambda Sgr.
As it moves to the east through the stars, Venus will overtake Saturn on January 9. At their closest, at about 5 pm, the two planets will be just over 5 arc minutes apart, about 1/6th of the moon's diameter. From NZ on the 9th at 5 am the two planets will be just over half a degree apart with Venus to the left of Saturn. They will be a similar distance apart on the 10th but with Venus now on the right of Saturn.
The crescent moon is closest to the two planets on the morning of January 7 when it will be 5 degrees left of Venus and 7.5 degrees from Saturn. The following morning the moon as a thinner crescent will below and a little to the right of the planets.
Mars rises 4 hours before the Sun on January 1 and nearly 6 hours before it on the 31st. Mars will be considerably higher than Venus. The planet starts the month at magnitude 1.3 in Virgo, 6 degrees below Spica. On the 18th Mars moves into Libra where it ends month a little brighter, magnitude 0.8. The morning of the 31st finds Mars 1.5 degrees from the star alpha Lib, magnitude 2.73
The moon, 36% lit, is closest to Mars on the morning of the 4th. The moon will be 2.5 degrees to the left of Mars.
Jupiter starts January in Leo with the 65% lit moon less than a degree to its upper left. On the 1st Jupiter rises about 12.30 am, by the end of January it will rise just before 10.30 pm so becoming visible late evening.
The planet is stationary on the 9th so its position changes little during the month. It gets to within a quarter of a degree of the boundary of Leo with Virgo, but as it starts moving back to the west retreats from the latter constellation.
The moon, now 82% lit, returns to the vicinity of Jupiter towards the end of January. On the morning of the 28th the two will be close to 4 degrees apart just before sunrise. Later in the morning, well after they set, the two will be just over a degree apart
Saturn rises just under two hours before the Sun on January 1, over four hours before the Sun on the 31st. It is in Ophiuchus all month at magnitude 0.5. See the notes for Venus for further details.
Uranus remains in Pisces during January at magnitude 5.8 to 5.9. It is an evening object. By the end of January it will be setting about 11.30 pm.
Neptune is also an evening object throughout January, by the end of the month it will set at 10.00 pm. The planet, magnitude 7.9, is in Aquarius.
Pluto continues to be in Sagittarius throughout January at magnitude 14.4. It is at conjunction with the Sun on January 6, after which it becomes a morning object rising as much as 2 hours before the Sun by the 31st. At conjunction Pluto will be nearly 5.1 billion km, 34 AU from the Earth and just over 33 Au beyond the Sun.
BRIGHTER ASTEROIDS: (1) Ceres is an evening object setting just before midnight on the 1st. It starts January in Capricornus at magnitude 9.3; on the 15th it moves into Aquarius. By the 31st, when it sets at 10.18, Ceres will be just over 10 degrees from Neptune.
(4) Vesta is in Cetus during January. It fades a little during the month from magnitude 8.0 to 8.3. The asteroid will be 6 degrees from Uranus on the 31st when it will set just before midnight.
(15) Eunomia is an evening object in Pisces during January, its magnitude fading from 9.5 to 9.8. It sets just before 11 pm on the 31st.
(27) Euterpe starts January in Gemini at magnitude 8.8 and is in the sky almost the whole night. By the 31st it will be a magnitude fainter and sets by 3am. The asteroid moves into Taurus on January 6.
Brian Loader New Zealand