by Anne Holt Sunrise 1st: 08.01 31st: 08.25 Sunset 1st: 15.53 31st: 15.59 Astronomical darkness 1st: 18.02 to 05.54 31st: 18.09 to 06.14 Latest Sunrise 30th (08.25 from 28th - 31st) Earliest Sunset 13th (15.49 from 9th -17th) Winter Solstice: 21st at 22.22. This day is 9hrs 33mins shorter than at the Summer Solstice. The shortest day is also on the 21st - 7hrs 28mins 29seconds. The 22nd is less than 1 second longer. New Moon: 7th at 07.20 Full Moon: 22nd at 17.48 Lunar apogee 12th at 12.27 (distance of 405176km) Lunar perigee 24th at 09.53 ( " " 361059km) December's
full Moon is known as the Cold Moon, no explanation needed. The Old
English/Anglo-Saxon names are also self explanatory - The Moon before
Yule or the Full Long Nights Moon. In December, because of the
angle of the ecliptic, the full Moon takes its highest path across the
sky, opposite the lowest position of the Sun. The Winter Solstice this
year is only just over 19 hours before the full Moon. Highlights Lots
of lovely dark nights (fingers crossed for some cloud free skies) about
12 hours of astronomical darkness throughout the month. We have the
Winter Solstice and the shortest day - or, as astronomers prefer to
think of it, the longest night, with 12 hours more astro darkness than
in June. There is one major meteor shower, the Geminids, often
considered to be the most reliable of all, and several minor ones. There
should be a naked eye comet mid month, though it's failing to live up
to the spectacular predictions made earlier in the year and will
probably only be visible to the naked eye from a dark sky site - if
that. There are some bright early evening passes of the International Space Station in the first half of the month. And we have a Christmas Star in the East! Venus
is shining brightly in the morning sky in December. It will be
slightly past its best by 25th but will still be brilliant, maybe bright
enough to be seen in daylight, if you know where to look. It isn't
recommended that you try to follow it, however, even if you do happen to
have a camel and some gift wrapped gold, frankincense or myrrh. It's
unlikely to lead you to Bethlehem and, anyway, you'd be more than 2000
years late. And you would miss your Christmas lunch. Constellations Orion, with the stars of his belt pointing down to the brightest star in the sky, Sirius, is now well above the horizon by midnight, and is a beautiful sight especially from a dark sky site. By month end these will be visible from 10pm - weather permitting. Taurus and the Pleiades precede him across the sky. Gemini, including the 'twins' Castor and Pollux, and Auriga with the bright Capella are also very prominent. Aries and Pisces, while not particularly bright - or often not even visible in our light polluted skies - are both quite high this month. Perseus, Andromeda and the Great Square of Pegasus are also well placed for most of the night. The Plough starts the night quite low in the Northern sky, with Cassiopeia high overhead. Because of the long winter nights, these last two will have changed places before dawn as they rotate around the celestial north pole. Planets Mercury: in Libra. mag 3.0 A
morning object, but not easily seen in December, especially at the
beginning and end of the month. On 1st it rises at 07.04 just under an
hour before the Sun but separated from it by only 8 degrees. On 4th it
is 2 degrees above the horizon at dawn and the following morning, when
it will have brightened to mag 0.8, is just 7.5 degrees west of the 4%
Moon as they rise about an hour before Sunrise. It reaches greatest
western elongation on 15th, when it will be at mag -0.4 and have an
apparent separation from the Sun of 21 degrees. However, because of the
low angle of the ecliptic it will be only 8 degrees above the horizon at
dawn. On 16th it moves into Scorpio and into Ophiuchus on 21st, when it
rises at 06.31 and reaches 7 degrees in the east before the sky
brightens. After greatest western elongation it appears to move closer to Jupiter - on 21st and
22nd they are less than 1 degree apart. On 31st it rises at 07.10 and
is only 3 degrees above the eastern horizon at dawn. PLEASE
REMEMBER: Do not try to look at Mercury - or any other celestial object
- through a scope or binoculars when it is low in the pre-dawn sky.
Even catching the frst few rays of sunlight is likely to cause permanent
eye damage. Venus: in Virgo, mag -4.7 At
its brightest at the start of December, totally unmissable for those
who can bear to leave their nice warm beds before sunrise. On 1st it
rises at 04.07 and reaches 22 degrees in the east as the sky brightens
at around 7.30. On this morning the 17% lit Moon passes close to the
planet. It begins to fade very slightly after the first few days, -4.6
on 4th, but a little higher at 23 degrees by dawn. It moves into Libra
on 14th when it rises at 03.59. On Christmas morning it will be a very
bright star in the east, rising at 04.06 and easily visible from around
5am, when all those with young children will, no doubt, have been
awakened At month end it will rise at 04.12 and reach 20 degrees by
dawn, still blazing away at mag -4.5. Mars: in Aquarius, mag 0.00 An
evening object in December, visible from around 16.30 and setting about
half an hour before midnight. Still easy to see despite it fading as it
is still getting higher in the sky. On 1st it culminates at 18.11, a
few minutes after the start of astronomical darkness, at an altitude of
27 degrees. On the evenings of 6th and 7th it passes less than one
degree north of Neptune. Moves into Pisces on 22nd, when it culminates
at 17.30, reaching 33 degrees in the south. By month end it culminates a
few minutes earlier and a couple of degrees higher but will have faded
to mag 0.4. Jupiter: in Scorpio, mag -1.7 A
morning object, not easily seen especially in early December, as it is
very low in the pre-dawn sky. On 1st it rises less than half an hour
before the Sun and appears only 3 degrees from it. Its position improves
during the month, on 7th it is only one degree above the horizon as the
sky brightens, on 14th,when it moves into Ophiuchus, it reaches 4
degrees. By 25th it might be visible from a site with a low, clear south
eastern horizon, at an altitude of 7 degrees at around 08.00. By 31st
it is slightly brighter at mag -1.8 and a little higher, 9 degrees in
the SE at 07.35. Saturn: in Sagittarius, mag 0.5 Very
low in the evening sky, on 1st it is only 6 degrees above the horizon
at dusk, setting at 17.47. Not likely to be visible after the first few
days of the month, by 18th it is on the horizon as the sky darkens and
on 31st sets only a few minutes after the Sun. Uranus: in Aries, mag 5.7 Still
very well positioned for binocular observation, especially in the
earlier part of December. It is also relatively bright - for Uranus -
so it's a good time to try to spot it with the naked eye from a dark sky
site. On 1st it culminates at 21 14, reaching 48 degrees above the
southern horizon, setting at 04.21. Its apparent motion is currently
retrograde (east to west) and it moves back into Pisces on 4th. By
month end it reaches its highest point, slightly lower at 46 degrees, at
19.14 in astronomical twilight. A reasonable sized amateur scope should
show the planet as a small blue/green disc. Neptune: in Aquarius, mag 7.9 An
early evening object. On 1st it reaches 28 degrees in the south at
18.27, during astronomical darkness. By month end it culminates at
16.30, an hour and a half before it gets fully dark. Still a good
amateur telescopic target during the early evening, though a much larger
scope is needed to show any markings on the blue disc. Dwarf Planets Ceres: in Virgo, mag 8.8 Should
be visible in amateur scopes, especially in the latter part of
December. On 1st it rises at 04.39 and only reaches 13 degrees by
dawn. On 5th it moves into Libra and is slightly fainter at mag 8.9.
It is about 3 degrees to the north of Venus on the morning of 29th and
on 31st rises at 04.39, reaching 19 degrees before the sky brightens. The other dwarf planets are so faint that they are only targets for experienced astrophotographers. Pluto, In Sagittarius, mag 14.7 Not
a good time for trying to catch this - it never gets higher than 14
degrees above the horizon during darkness. By month end its apparent
distance from the Sun is only 11 degrees. Eris: in Cetus, mag 18.8. Much fainter but might be a better bet. On 1st it reaches 34 degrees in the south soon after 21.00, on 31st culminates at 19.10. Haumea in Bootes, mag 17.4 On 1st it reaches 35 degrees by dawn, and by 31st is at 50 degrees as the sky begins to brighten. Makemake: in Coma Berenices mag 17.2 Should
be visible in the early hours, on 1st it reaches 51 degrees by dawn, on
31st culminates at 60 degrees soon after the end of astro darkness at
06.38. For more details and exact positions of all planets, asteroids and comets see: https:/theskylive.com Meteor Showers One major shower this month. Geminids:
active 4th to 19th. Some sources give the peak night as 13th/14th
others say 14th/15th. Actual peak, according to the IMO, is 12.30 on
14th with near maximum rates for several hours either side of this, so
either night is likely to be a good time to look. ZHR under ideal
conditions (dark sky, high radiant, no moon) is 150, so we might see as
many as 50 from a reasonable site, probably no more than 20 per hour
from Manchester. They are bright, often coloured, medium slow paced
meteors which don't usually leave trails. Unlike most other showers
these originate from an asteroid, 3200 Phaeton, rather than a comet.
The just past first quarter Moon won't interfere much, this year, setting
at 21.57 on 13th and 23.04 on 14th. Minor showers Monocerotids: Nov 27th to Dec 17th, peak 9th, ZHR 3 Weak, medium paced shower. Alpha Hydrids: active 3rd to 15th, peak 12th, ZHR 3 Mostly very faint but the shower does often include some brighter meteors which could be confused with Geminids. Coma Berenicids 12th to 23rd, peak 16th. ZHR 3 Another
weak shower, best seen around 1am when the radiant is high. These were
once thought to be part of the Leo Minorids but are now considered to
be a separate shower. Leo Minorids: Dec 5th to Feb 4th, peak 20th, ZHR 5 A very weak but long lasting shower. Ursids:
Dec 17th to 26th, peak 21st/22nd, ZHR 5-10 but there are very
occasional short outbursts of up to 50. These medium paced meteors
originate from debris left by comet 8P/Tuttle. The almost full Moon,
above the horizon all night, will seriously interfere. Comets One (probably - fingers crossed) naked eye comet. 46P/Wirtanen
starts the month very low down in Cetus at mag 6.1. On 1st it
culminates at 21.47 but is only 14 degrees above the southern horizon.
However it should brighten quite rapidly during the first half of
December, unfortunately not reaching the spectacular brightness
originally predicted but probably getting to around mag 4.8 between 15th
and 19th. It is also moving quickly northwards through Taurus (14th to
18th) Perseus (19th -21st), Auriga (22nd -28th) then into Lynx. On the
night of 16th, when it is at perihelion, it passes between the Pleiades
and the Hyades (the V shaped head of the bull) and should be quite high
in the sky for most of the night. It is at its closest to Earth on 18th
when it passes about 6 degrees to the east of the California nebula
(NGC1499). Sadly, the almost full Moon wll spoil the view on that
night. It becomes circumpolar on 21st and on the night of 23rd/24th
passes less than one degree from the bright star Capella. It fades
during the later part of the month, on 31st is predicted to be down to
mag 6 but almost overhead - 84 degrees above the northern horizon at 00
25. Even now, estimates of its brightness vary, some
sources say that it will only reach mag 5.5 at its brightest. Even when
it is at a theoretical naked eye magnitude it will still be difficult to
see without optical aid. The head and coma are quite large and
diffuse, so it will appear as a faint fuzzy blob rather than a star like
point of light. Comet 46p/Wirtanen during December 2018  38P/Stephan-Oterma
starts the month in Cancer at a mag of around 9.8. On 1st it reaches
its highest point, 65 degrees in the south, at 03.39 and should be
visible in a small scope and be an excellent subject for keen
astrophotographers. On 12th it moves into Lynx and is slightly higher,
69 degrees at 03.10. It's at its closest to Earth on 17th and on 19th
becomes circumpolar, reaching 72 degrees in the south at 02.45. Towards
the end of the month it is caught up by the much faster moving
Wirtanen, on 31st they are fairly close with Wirtanen about 30 degrees
to the west. |
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