The night sky in January 2018

posted 31 Dec 2017, 07:36 by Pete Collins   [ updated 31 Dec 2017, 07:40 ]
by Anne Holt

Sunrise:   1st   08.24          31st    07.55
Sunset:    1st   16.00          31st    16.49

Astronomical darkness
1st:   18.10  to  06.14       31st:   18.51  to  05.53

Full Moon:  2nd at 02.24    and  31st at 13.26
New Moon  17th at 02.18

The Earth reaches perihelion (closest point in its orbit to the Sun) on Jan 3rd at 05.35, when it will be at a distance of 147,097,000 km.

Highlights

This month we have 2 Supermoons, more correctly known as perigee-syzygy Moons:  perigee meaning closest point to Earth, syzygy meaning 3 celestial bodies in a straight line.  We have a reasonable meteor shower, ruined this year by bright Moonight (or, more likely, clouds), a dwarf planet at opposition, and the ISS is back in the evening sky from 26th.  We still have a good amount of astronomical darkness, a few minutes short of 12 hours at the start of the month and nearly 11 hours at the end - long enough to enjoy the beautiful rich winter skies.    We hope!

Constellations

There isn't much change in the prominent constellations since December,  just that everything rises, or sets, a couple of hours earlier. Orion is now well above the horizon by 8pm at the start of the month, with Sirius rising at this time.  By month end, Sirius will rise at about 6pm.  Auriga, Gemini and Cassiopeia are all high in the sky. The Summer Triangle is now setting earlier as the Winter Hexagon rises. Taurus and the Pleiades are still very prominent and the spring constellation of Leo is above the south eastern horizon by 9pm.


The Winter Hexagon
Planets

Mercury
:  in Ophiuchus, mag -0.3. Reaches Greatest Western Elongation on 1st but is still very low in the sky despite rising nearly 2 hours before the Sun. It might just be visible from a site with an unobstructed SE horizon.  It moves into Sagittarius on 9th and between 12th and 15th it appears very close to Saturn.  On 13th they are separated by a little over half a degree, both rising about an hour before the Sun.  It won't be visible at all in the later part of January, on 31st it rises only 15 minutes before the Sun.

Venus
:  in Sagittarius, mag -3.9. Not visible for most of January, on 1st it rises only 3 minutes before the Sun.  It reaches superior conjunction on 9th and moves into Capricorn on 18th.  By month end it will be an evening 'star' but still not easily seen as it sets only 17 minutes after Sunset.

Mars:  in Libra, mag 1.5. Another morning object, visible in the pre-dawn sky.  On 1st it rises at 03.34 almost 5 hours before sunrise.  During the first week of January it appears to move towards Jupiter, closest on the morning of 7th, when they are separated by only about a quarter of a degree.  By month end, when it rises 4.5 hours before the Sun, it will have brightened slightly to mag 1.3 and be close to Antares - the red supergiant in Scorpio.

Jupiter:  in Libra, mag -1.8. Increasingly conspicuous in the morning sky, on 1st it rises at 03.49 and culminates at 08.23, as the sun is rising.  By month end, when it will have brightened to mag -2, it rises at 02.15 and culminates only 45 minutes after the end of astronomical darkness.

Saturn
:  in Sagittarius, mag 0.5. Now a morning object but not visible for most of the month.  On 1st it rises only 43 minutes before the Sun.  By month end that is increased to 2 hours, so it might possibly be seen from somewhere with a low, clear SW horizon.

Uranus: in Pisces, mag 5.8. Only visible in the earlier part of the night this month. On 1st it is high in the sky, about 46 degrees, soon after the start of astronomical darkness and sets around 2am.  On 31st it sets just before midnight. Not really a naked eye object, except in ideal conditions.  Should be visible in decent binoculars. 

Neptune
:  in Aquarius, mag 7.9. Not easy to see after the first week in January.  On 1st it sets at 21.37, on 31st at 19.44 during astronomical twilight.

Recommended websites for more info on positions of planets and other Solar System objects
 https://in-the-sky.org         https://theskylive.com

The Moon

The Moon warrants its own section this month. We have 2 full Moons, the first on 2nd at 02.24. is known as the Wolf Moon - so called by Native Americans as this is the time when hungry wolves are likely to be howling.  On 31st at 13.36 we have the Snow Moon.  This is a Blue Moon, if we use the newer definition of the second full Moon in a calendar month. Both these full moons can be called Supermoons, as their apparent size is 90% or more of the maximum possible. The first of these is the largest of 2018,  slightly bigger than the one in December. It occurs only 4 and a half hours after perigee.

On 31st, there is a total lunar eclipse. unfortunately only visible on the opposite side of the Earth - parts of NE Europe, Asia, Australia, NZ and the Pacific Ocean. If you do happen to be in the right area at the time of totality, you will, weather permitting, be treated to the sight of a blood red blue Supermoon.  Or should that be a blood red Super blue Moon?

Meteor Showers

One fairly strong shower in January.

The Quadrantids, active 1st -10th, peak on the night of 3rd/4th,  Estimates of ZHR varies according to source used,  25,  40 or even more. This shower has a very short peak, only about 6 hours.  They are medium paced meteors not usually leaving trails.  The shower often includes bright fireballs.  It is named after the former constellation Quadrans Muralis, now part of Bootes, and is thought to originate from dust left by asteroid 2003 EH1, probably the remains of extinct comet C1490X1. This year only the very brightest meteors will be visible because of the proximity of the very bright just-past-full Moon.

Minor Showers

Ursa Minorids:  active 10th - 22nd,  peak 18th,  ZHR 3. Not much information about this one.  However conditions will be favourable, no Moon interference.

The Antihelion Source - meteors not belonging to any particular shower,  having their radiant on the ecliptic, opposite the position of the Sun - is active in early January.  ZHR around 3.

Kappa Cancrids: Again, not much information.  Possible activity around 21.00 on 9th.  The radiant of these is very close to the Antihelion Source but the meteors should be distinguishable as these are faster moving.

Comets

There are still several faint comets around,  none naked eye or even binocular
Well positioned are:
Pan STARRS (2016P2) mag somewhere between 10.5 and 13.2 (as always, sources fail to agree).   Moving in a NW direction through Taurus, in the first week of the month it passes below the bottom star of the Hyades, the V shaped group of stars in Taurus.  it's at its closest on 5th & 6th.  It ends the month a few degrees east of the Pleiades.

Heinze (2017T1) Currently mag 13 but expected to brighten during January, maybe to around mag 9.  Moving eastwards through Lynx, Camelopardis, Cassiopeia and finishing the month in Pegasus.

For details of all visible comets, see

Finally

Dwarf planet Ceres, in Cancer,  reaches opposition on 31st, at a distance from Earth of 1.6AU.  Best seen around midnight when it will will be at its highest point, about 42 degrees.  It will be at mag 6.8, so an easy target for amateur scopes and photographers.  However, even though it is by far the largest object in the Asteroid Belt, accounting for about 25% of the total mass, it is too small to appear as anything other than star like.
For exact position at any time, see
https://in-the-sky.org/news.php?id=20180131_13_100
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