Astronomy

Astronomy
Astronomy Guide to the Night Sky – December 2017

With the Newbury Astronomical Society

Click on the image above to enlarge, click on the  ‘Return arrow’ or close page to return here

The chart above shows the night sky looking south at about 21:00 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 and is shown at the upper 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 constellations through which the ecliptic passes are known as the constellations of the ‘Zodiac’.

Constellations through which the ecliptic passes this month are: Aquarius (the Water Carrier), Pisces (the Fishes), Aries (the Ram), Taurus (the Bull), Gemini (the Twins), Cancer (the Crab) and just off the chart to the east and soon to rise is Leo (the Lion).

The Milky Way (our Galaxy) appears to rise up from the western horizon through the Summer Triangle and Cygnus.  It continues up through Cassiopeia then down towards the East through Perseus and Auriga.  It then flows on through the constellations of Gemini, Orion and Monoceros at the bottom of the chart.

The outermost planet Neptune is in the constellation of Aquarius but looks small and faint and will need a telescope to see.  A beginner’s telescope will show Neptune as a rather fuzzy looking star with a blue tinge but a larger telescope will show it as a small blue disc.  Uranus is located in the constellation of Pisces and is slightly easier to see than Neptune as it is only half as far away as Neptune.  It appears twice the diameter of Neptune and four times as bright so it can be seen as a small disc using a beginner’s telescope with a magnification of 100x or more.

The planets Venus, Mars and Jupiter rise just before the Sun in the early morning in the east with Mercury and Saturn setting just after the Sun in the west in the evening.  None of these planets are well positioned for observing.

Sitting astride the ecliptic in the south east is the constellation of Taurus (the Bull).  The Taurus asterism (shape) looks like a squashed cross ‘X’.  At the centre of the cross is a large, faint Open Cluster called the Hyades.  It has the bright Red Giant star Aldebaran at its centre.  The real beauty of Taurus is the naked eye Open Cluster M45 the Pleiades (Seven Sisters).  See pages 7 and 8.

To the north of M45 (the Pleiades cluster in Taurus) is a line of stars defining the constellation of Perseus.  The whole asterism (shape) of Perseus looks like a horse rider’s stirrup.  At the top of the line of stars is the beautiful object ‘the Double Cluster’ best seen using binoculars.

Above and linked to the constellation of Taurus by the star Elnath is the constellation of Auriga (the Charioteer).  The shape of the ‘stick figure’ of Auriga is like a misshapen pentagon.  The brightest star in Auriga is the beautiful bright white star Capella.  It is the sixth brightest star in the night sky.  Cappella has a magnitude of approximately 0 (actually +0.06) so can be used as the base star when working out the brightness of other stars.  Auriga has three Messier Open Clusters: M36, M37 and M38.  They appear to form a straight line through Auriga which also appears to continue on in line to M35 in Gemini.  See pages 7 & 8.

Following Taurus along the ecliptic is Gemini (the Twins).  The twin stars Pollux and Castor are easy to find.  There is a lovely Messier Open Cluster M35 in Gemini just off the end of the line of stars emanating from the bright star Castor.  Castor is a double star when seen in a telescope.

Following behind Gemini is the faint and elusive stars of Cancer (the Crab).  Although Cancer itself is quite difficult to identify it is worth seeking out because at its centre is the lovely open cluster Messier 44 (M44) also known as Praesepe.  It is faint but lovely to see using binoculars.

In the middle of this month, from 8th to 17th December, there will be a meteor shower known as the Geminid shower.  The very best time to watch for the meteors will be during the early morning hours on Thursday 14th.

The Moon does not rise until 03:40 so conditions look very promising and weather permitting, the sky will be dark and moonless for most of the night.   The suggested hourly rate is 120 but this would be in a perfect dark clear sky.  Even with a perfect sky in the Newbury area we might expect less than that but it could still be well worth waiting for..

Follow this link to see the full ‘Monthly What’s Up’ guide to the night sky:

http://naasbeginners.co.uk/Whats_up/2017_2018/December2017.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 20th December 2017, for details click on the link below.

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

Leave a comment