By Mike Glazier
I would like to begin by hoping you all have a very good astronomical Christmas and to say once again as before, that a good stocking filler for those with an astronomical mind is ‘Collins 2018 guide to the night sky’. It contains just about everything that is needed to be a good companion to a telescope.
December promises to be a fairly interesting month so far as the night sky goes and we begin with the annual Geminid meteor shower which although it is active between the 4th-16th of the month, it has its short maximum between 13th-14th. This particular shower ‘sports’ in excess of 100 meteors an hour when viewed under suitable sky conditions, and we all know what these should be. Little if any, light pollution and transparent skies.
The radiant of the shower lies midway between Castor in Gemini and the open star cluster M35 which can be found on any reasonable star chart. The Moon will be at a narrow ‘waning’ phase making it very useful for meteor watching.
Another shower which has a broad active span is the Ursids, which has its radiant in Ursa Minor, the small or lesser Bear. Activity runs from 17th-23rd but maximum occurs during the early hours of 22nd. This shower is in my opinion nothing at all to get excited about because the hourly rate is only anything up to 10 per hour. The parent comet responsible for this shower is comet 8PTuttle A thin waxing Moon will be well out of the way by the time of the maximum so that just leaves the question of sky conditions.
The Moon will be at Perigee on December 4th and at apogee on 19th with our neighbour being on that date at the furthest distance for the year 406,602kms.
The Winter solstice is on December 21st at 16.28. This marks the shortest day of the year in the northern hemisphere. The Sun will rise (Valencia) at 08:18 and set at 17:41 at 240ºW giving 9 hours, 22 minutes and 57 seconds of daylight.
The Moon will be full on December 3rd and close to Aldebaran in Taurus
On 8th of the month the Moon will pass just 0.7º South of Regulus but no occultation.
On December 13th until 15th a waning Moon will pass Mars in Virgo and Jupiter in Libra, but this will be a pre-dawn event. There are a number of occultations during December but none are visible from Spain.
Mercury will be close to the Sun passing into inferior conjunction by the 13th of the month.
Venus will be visible very low in the dawn sky at magnitude -3.9. but it will soon move too close to the Sun for any observations to be made.
Mars starts the month in Virgo, in fact very close to the star Spica and at magnitude 1.7. It will move eastwards into Libra by the end of the month brightening only slightly.
Jupiter at magnitude -1.7 to -1.8 in Libra will slowly move eastwards.
Saturn at magnitude 0.4 to 0.5 will be found in Sagittarius.
Planetary speaking there will not be a lot to whet the appetite, so astronomy will be relegated to constellations and clusters.
Constellations of the month
Looking South there are many constellations to locate, Orion the hunter and his two hunting dogs Canis major and Canis minor. Can’t be missed.
Gemini the twins will be located top left of Orion with the lovely open cluster M35 at the foot of the star Castor.
Above Orion is the group called Auriga the charioteer and its brightest star Capella.
To the South-West lies Andromeda the princess, daughter of Cassiopeia and Pegasus the flying horse. Above these two famous groups lie Perseus and Cassiopeia ( Cassiopeia is seen as an inverted W or M depending on the time of night).
To the North you will find Ursa Major, Ursa minor ( the small Bear) and of course Draco the dragon which winds its way around Ursa Minor.
Sweeping the skies with binoculars is a fascinating way to do astronomy, and without a doubt one will find small chains of stars, double stars, clusters like M35 and of course below Andromeda the famous galaxy M31.
Amongst the stars of the Winter night skies one will also see numerous satellites, meteors and other strange and often unidentified objects.