The night sky in January 2017

posted 30 Dec 2016, 05:29 by Pete Collins
by Anne Holt

Sunrise.      1st:   08.25       31st:   07.55
Sunset         1st;  16.01       31st;   16.50

Astronomical darkness:
1st:    18.11  to  06.15
31st   18.52  to  05.54

Full moon 12th      New moon  28th

Highlights

The nights have now started to get shorter but we still have plenty of dark hours for astronomers to enjoy - even if they do tend to be somewhat chilly.
The Earth reaches perihelion, the closest point in its orbit to the sun, on Jan 4th at 14.18, when it will be at a distance of 147,100,997 km, or 0.9833 AU.  (one AU being the average distance).
We have one major and two minor meteor showers, a comet which should be visible in binoculars, and a chance to see the brightest and faintest of the major planets in the same binocular field of view.

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 Leo is above the south eastern horizon by 9pm.

Planets

Mercury - mag 0.5,  in Sagittarius. A morning object, rising around 7.30 at the start of January.  On 8th it is 7 degrees East of Saturn, rising at 06.46.  It reaches greatest Western elongation on 19th, when it rises 90 minutes before the sun and will have brightened to mag -0.1. However it is still very low - only 3.7 degrees above the SE horizon.   By month end it rises at around 7am.

Venus - mag  -4.4,  in Aquarius, moving into Pisces on 24th. Totally unmissable (clouds and tall buildings permitting) in the early evening sky.  Sets soon after 20.00 in early January. On Jan 1st it is 8 degrees East of the 11% waxing moon. On 12th, when it is at greatest Eastern elongation, it is only 22 arcminutes (two thirds of a full moon width) NW of Neptune.  At about 18.20 it should be possible to see both planets in the same field of view in binoculars or a small telescope. At the end of the month it sets about 4 and a half hours after the sun.

Mars - mag 0.5,  in Aquarius, moving into Pisces on 20th. Should be visible as an orange red 'star' in the early evening SW sky, setting around 21.30 throughout the month.. On 1st it is only 20 arcminutes East of Neptune - again, a good binocular target.

Jupiter - mag -1.9   in Virgo. At the start of January it rises soon after 1am, and by 23.30 at month end, when it will be slightly brighter at mag -2.2, and will reach its highest point in the sky just before 5am, in astronomical darkness.  It is just a few degrees from bright star Spica throughout the month.

Saturn - mag 0.4,  in Ophiuchus. A morning object, visible as a yellow 'star', low in the SE sky just before dawn. Rises only 90 minutes before the sun on Jan 1st, increasing to almost 3 hours by the end of the month.

Uranus - mag 5.9, in Pisces.  Best seen in early January when it reaches its highest point (45 degrees) at around 18.30, when the sky is getting really dark, and sets around 01.30.   By the end of the month it sets a few minutes before 11.30. Still at the limits of naked eye visibility - but not from anywhere near Manchester, unfortunately.   A telescope is needed to show its blue/green disc.

Neptune - mag 7.9, in Aquarius. On 1st it is just 20 arcminutes from Mars and, on 20th, 22'  SE of Venus.  By month end it sets less than two and a half hours after the sun, soon after the start of astronomical darkness.  It might be spotted in decent binoculars under ideal conditions but best viewed through a telescope, when its beautiful blue colour can be seen.

Minor planet Vesta, the second largest known object in the asteroid belt, reaches opposition, in Cancer, on Jan 18th.   At mag 6.2 it is outside naked eye visibility but should be a fairly easy binocular target, or a good photo opportunity if the skies are clear for a few days around that date - take a series of images and play 'spot the difference'. For its exact position on any night see . https://theskylive/vesta-tracker

We also have a binocular comet, 45P/Honda-Mrkos/Pajdusakova.  It is in Capricorn, visible low in the South during the first half of January.   It is expected to reach mag 7.1. See https://theskylive/45P-tracker

Meteor Showers

One major shower this month, the Quadrantids - named after the former constellation Quadrans Muralis, now part of Bootes after it was left out of the IAU's official list of constellations published in 1922. Active between late December and January 10th.  It has a very short peak on Jan 3rd, centred on 14.00. ZHR 80 - 120.These meteors don't usually leave trains but the shower could include some fireballs. These are usually best seen after midnight when the radiant is high in the sky.  Try looking between 4am and dawn on 3rd, just before the peak, which is in daylight. This shower probably originates from asteroid .2003 EH1 - thought to be the remains of the nucleus of defunct comet C1490/X1.

A couple of very minor showers

Delta Cancrids - active Dec 14th to Feb 14th, peak 16/17th,  ZHR 1-4.
 
Coma Berenecids - active Dec 8th to Jan 23rd,  peak 18th, ZHR 1-2 but occasionally produces a much higher rate, including bright fireballs, so might be worth looking out for.  These are among the fastest meteors recorded, reaching a speed of 65 km/sec.  Could originate from an unconfirmed comet observed in 1912 by astronomer B Lowe.  
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