01-12-2007 December Night Sky (Article 114)

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Simon Kenny
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Location: Shannon, Co. Clare, Ireland

01-12-2007 December Night Sky (Article 114)

Post by Simon Kenny » Wed Feb 04, 2009 11:36 am

December Night Sky (Article 114)

During December in the northern hemisphere, the nights are at their longest. Looking north the constellation Perseus is almost overhead, with the bright star Capella and its fellow stars of Auriga to its right. Gemini lies further east. The handle of the Plough points towards the horizon around 9.00pm, and coming over the NE horizon is Regulus and the stars of Leo, a herald of spring a few months away yet. To the NW are Cassiopeia and Cepheus, with the last visages of summer, in Deneb skirting the horizon.

Looking south, much of far south is dominated by constellations unknown to the ancient Greeks. That said, many of their best are on show at this time of the year, with Taurus high up, ideally placed now for viewing the Pleiades cluster, which this year has been covered by the Moon each month, though most occurred in daylight. Below it lies Eridanus the celestial river, while to its lower left mighty Orion is still rising. Later in the month brilliant Sirius and Procyon are also on view. The autumn stars of Pegasus and Pisces are now fast setting in the west.

Regular readers of this feature will have heard of the Summer Triangle, but did you know that there's also a Winter Triangle? Comprising the bright stars Betelgeuse in Orion, Procyon in Canis Minor and Sirius in Canis Major. Have a look for it in mid month, and in the cold months ahead.

The Winter Solstice occurs on the 22nd, around 6.00am, with the Sun at its lowest point as seen from the northern hemisphere, and it sits on the Tropic of Capricorn. Mars is closest to earth on 17th, at a mere 88 million miles away, and visible all night on the 24th when it is at Opposition, becoming a somewhat apt "Christmas Star". It lies in Gemini and shines brighter than any of the stars. Saturn rises in the east around 10pm in the constellation Leo, but is fairly faint. Early risers will find a brilliant Venus in the morning sky. The moon passes across the Pleiades cluster after 9.15pm on night of 21st, well worth looking for but binoculars will make the view much better and also show more stars in this wonderful cluster.

December 13th is the maximum of the Geminid meteor shower, which ranges from 7th to 16th, and this year moonlight will not interfere, as New Moon was on the 9th. A rare opportunity to see Neptune will occur on 14th around 6.30pm when if you focus a small telescope on the moon, follow a line connecting the horns of the moon upwards by 1.5 x moon's diameter. The middle of three faint stars in a row is actually the planet Neptune. Clear skies.

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