Astronomy

Astronomy
Astronomy Guide to the Night Sky – December 2018

With the Newbury Astronomical Society

A Comet for this Christmas!  Click on links Below

Click on the image to enlarge, ‘right click’ to copy the image or ‘click back or close window’ to return here

The chart above shows the night sky looking south at about 22:00 GMT on 15th December.  West is to the right and east to the left.  The point in the sky directly overhead is known as the Zenith or Nadir and is shown at the centre of the chart.  The curved brown line across the sky at the bottom is the Ecliptic or Zodiac.  This is the imaginary line along which the Sun, Moon and planets appear to move across the sky.  The brightest stars often appear to form a group or recognisable pattern; we call these ‘Constellations’.

Constellations through which the ecliptic passes this month are Aquarius (the Water Carrier), Piscis (the Fishes), Aries (the Ram), Taurus (the Bull), Gemini (the Twins), Cancer (the Crab) and Leo (the Lion).

The Milky Way (our Galaxy) flows up from the south eastern horizon through Orion and Gemini.  It continues up through Perseus and Cassiopea and on into Cygnus which is now disappearing over the western horizon.

Mars is still in a reasonable position in the constellation of Aquarius for observing in the early evening.  Above Mars is the constellation of Pegasus (the Winged Horse).  The main feature of Pegasus is the square formed by the four brightest stars.  This asterism (shape) is known as the Great Square of Pegasus.  The square is larger than might be expected but once found is easier to find again.

Attached to the upper left star (Alpherat) of the Square of Pegasus is the ‘>’ shape of Andromeda.  Following the lower line of stars to Mirach and then up to the second star, M31 the Great Galaxy can be found.

Along the Ecliptic is the constellation of Taurus (the Bull).  The stick figure representation of Taurus resembles a squashed ‘X’ with the bright orange coloured Red Giant star Aldebaran at its centre.  This is a lovely star to look at especially using binoculars or a telescope and does look noticeably orange in colour.

Following the western (right) and Northern (upper) arm of the ‘X’ shape of Taurus guides is to the beautiful Pleiades Open Star Cluster.  This is the bright Open Cluster of seven bright ‘naked eye’ stars known as M45 the Pleiades or ‘Seven Sisters’.

To the east of Taurus along the Ecliptic is the constellation of Gemini (the Twins).  The twin stars Castor and Pollux are easy to identify.

Below Gemini is Orion, one of the easiest constellations to recognise and dominates the southern sky at this time of the year.  There are many depictions of Orion shown on many different star charts.  Orion the Hunter appears in the winter sky, with his club held over his head and his shield (sometimes shown as a lion’s skin) held out in front of him.  His hunting dogs, Canis Major (the star Sirius) and Canis Minor (the star Procyon) following behind him.  Down from Orion’s very distinctive belt there is a line of stars, ending at the star Nair al Saif that looks very much like a sword attached to his belt.  Here can be found the main interest in Orion, the Great Nebula (M42).

A COMET FOR CHRISTMAS – Comet 46P/Wirtanen (click on the link below)

There is a good chance that we may have a fairly bright comet gracing our sky this month.  This comet is called 46P/Wirtanen and may be bright enough to see with our naked eye.  It should certainly be bright enough to see using binoculars.  The comet will climb up into Taurus on 10th December as it become brighter.  As 46P passes between the bright star Aldebaran and M45 (the Seven Sisters star cluster) on 16th December it makes its closest approach to Earth and will also be at its brightest.  It will continue up through the constellation of Auriga and pass close to the bright star Capella on 23rd December.  The main show will then over and the comet will begin to fade as it moves away from us.  Using binoculars it will appear as a large ‘faint and fuzzy’ patch of light but probably no tail.

THE GEMINID METEOR SHOWER (for more information click on the link below)

In the middle of this month, from 8th to 17th December, there will be an annual meteor shower known as the Geminid Meteor ShowerThe very best time to watch for the meteors will be during the early morning hours on Thursday 14thGeminids appear to radiate from the constellation of Gemini which is above the horizon from early evening.  The meteors can be seen for most of the night and in almost any part of the sky.  By midnight the constellation will be almost due south and high in the South Western sky.

Follow this link to see to see details about the comet, the meteor shower and a full ‘Monthly What’s Up’ guide to the night sky:

http://naasbeginners.co.uk/Whats_up/2018_2019/December2018.htm

To see a full version of this article and a guide to the night sky with charts, read the Newbury Astronomical Society (NAS) – Monthly Magazine for Beginners on the NAS website or come along to the next Beginners meeting on Wednesday 19th December 2018, for details click on the link below.

For details visit the NAS website at: www.naasbeginners.co.uk

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