THE SOLAR SYSTEM IN JANUARY 2018

Dates and times shown are NZDT (UT + 13 hours) unless otherwise stated. Times are for Wellington. They will vary by a few minutes elsewhere in NZ.

The Earth is at perihelion, its closest to the Sun for the year, on January 3. Earth will then be 147 million kilometres, 0.983 AU, from the Sun

January 1 NZDT January 31 NZDT
SUN: rise 5.48am, set 8.59pm rise 5.47am, set 8.59pm

Twilights morning evening morning evening
Civil: start 5.17am, end 9.31pm start 5.54am, end 9.14pm
Nautical: start 4.34am, end10.14pm start 5.16am, end 9.52pm
Astro: start 3.43am, end11.04pm start 3.42am, end10.34pm

JANUARY PHASES OF THE MOON (times NZDT, as shown by GUIDE)

Full moon: January 2 at 3.24pm (02:24 UT)
Last quarter January 9 at 11.25am (Jan 8, 22:25 UT)
New moon: January 17 at 3.17pm (02:17 UT)
First quarter: January 25 at 11.20am (Jan 24, 22:20 UT)
Full moon February 1 at 2.27am (Jan 31, 13:27 UT)

A total eclipse of the moon, fully visible from NZ, takes place on the night of January 31/February 1. The eclipse will be total between 1:51:25 am and 3:08:07 am on the morning of Feb 1. Further details can be found on the RASNZ web site.

THE PLANETS in JANUARY 2018

The five inner planets are morning objects throughout January, with the exception of Venus which becomes an evening object after conjunction with the Sun on the 9th. Mercury and Venus will be difficult objects to view all month, with Saturn coming into view in the morning sky during January.

Mars and Jupiter will be the most interesting planets to watch. They form a close pair early in the month.

MARS and JUPITER start January as a pair in the morning sky. On the 1st they will be 3° apart with Mars to the upper left of Jupiter. They are closest on the mornings of January 7 and 8. On the 7th Mars will be some 17 arc-minutes above Jupiter, the following morning Mars will be level with and to the right of Jupiter, the two now 22 arc-minutes apart. Mars will, of course, be much fainter than Jupiter, by over 3 magnitudes. Look for the pair of planets an hour before sunrise at an elevation of 30° almost due east.

During the rest of January Mars will steadily pull away from the slower moving Jupiter, by the end of the month they will be about 12° apart. Both will be in Libra all month, although on the 31st Mars will be poised to move into Scorpius with Antares 9° to its right.

On the 12th the crescent moon will be 6° below the planets as seen about 5 am.

MERCURY is in the morning sky. On January 1 it rises almost 90 minutes before the Sun. Forty-five minutes before sunrise the planet, magnitude -0.4, will be a mere 6° up, with the Sun 8° below the horizon. During the month the elongation of Mercury from the Sun reduces, so it will get even lower in the morning twilight.

SATURN, also in the morning sky, will emerge from the Sun during January. On the 1st it will rise about 40 minutes before the Sun, an interval increasing to almost 3 hours by the end of the month.

Similar to Mars and Jupiter, Mercury will move past Saturn during January. On the 13th Mercury will be just under a degree above Saturn, the following morning it will nearly 2° to the lower right of Saturn. Also the moon, as a thin crescent, will then be 5.5° to the left of Saturn. All will be difficult to see, some 7 to 8° up 45 minutes before sunrise, Mercury a little brighter than Saturn

VENUS rises only 10 minutes before the Sun on January 1. By the 9th it is at superior conjunction. At conjunction Venus will be half a degree south of the Sun but 109 million km beyond it. Two hours after Venus is at conjunction, Pluto is also at conjunction. Following their conjunctions Venus will become an evening object while Pluto becomes a morning object.

By the end of January, Venus will be setting only 25 minutes after the Sun, so it will remain a difficult object all month.

OUTER PLANETS

URANUS is an evening object in Pisces during January. It is best placed in the evening sky as soon as it is dark. Uranus will set at 12.45 am by the end of the month.

NEPTUNE is an early evening object in January. It sets at midnight on the 1st and 10 pm, before the end of astronomical twilight, on the 31st. The planet is in Aquarius at magnitude 7.9.

PLUTO, is at conjunction with the Sun on January 9.

BRIGHTEST MINOR PLANETS

(1) CERES is a morning object, at first in Leo then in Cancer from the 19th. During January it brightens from magnitude 7.5 to 6.9.

(2) PALLAS is an evening object with magnitude dimming slightly from 8.7 to 9.0 during January. It starts in Fornax, crosses a corner of Cetus between January 13 and 22, to end the month in Eridanus.

(4) VESTA starts January in Libra, crosses a narrow part of Scorpius between the 18th and 29th and then moves into Ophiuchus. Its magnitude changes little, from 7.9 to 7.8.

(7) IRIS is an evening object in Aries, dimming from magnitude 8.6 to 9.3 during the month. By the end of January it sets just after midnight.

(8) FLORA is in Gemini all month, starting January at magnitude 8.2. It is at opposition on the 2nd when it will be 155 million km from the Earth, 1.034 AU. After opposition it becomes an evening object but dims to magnitude 9.2 by the end of January.

(20) MASSALIA is in Taurus during January. It fades from magnitude 8.9 to 9.6 during the month.

Brian Loader

 

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