Astronomy Guide to the Night Sky – October 2017

With the Newbury Astronomical Society

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The chart above shows the night sky looking south at about 22:00 BST on 15th October.  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 Sagittarius (the Archer), Capricornus (the Goat), Aquarius (the Water Carrier), Piscis (the Fishes), Aries (the Ram) and Taurus (the Bull) is about to rise over the eastern horizon.

Just disappearing over the south western horizon is the constellation of Sagittarius (the Archer).  It is really a southern constellation but we can see the upper part creep along the horizon during the summer.  The central bulge of our galaxy is located in Sagittarius so the richest star fields can be found in the constellation along with many of the beautiful and interesting deep sky objects that we seek out.  The Open Cluster M11 the Wild Duck Cluster is well worth searching out with a telescope.

The summer constellations are still prominent in the night sky lead by Hercules (the Hunter).  Following Hercules is the Summer Triangle with its three corners marked by the bright stars: Deneb in the constellation of Cygnus, Vega in Lyra, and Altair in Aquila.  The Summer Triangle is very prominent and can be used as the starting point to find our way around the night sky.  The Milky Way (our Galaxy) flows through the Summer Triangle passing through Cygnus, down to the horizon in Sagittarius.  See the ‘SW’ point on the horizon on the chart above.

The Milky Way flows north from the Summer Triangle through the rather indistinct constellation of Lacerta (the Lizard), past the pentagon shape of Cepheus and on through the ‘W’ shape of Cassiopeia (the Queen).

To the East of the Summer Triangle 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.  The Great Square can be used to judge the condition of the sky for observing.  If five or more stars can be seen within the square then the sky should be good enough for some serious observing.  If only two or three stars can be seen it should be alright for observing.  If no stars can be seen it might be an evening to do something else.

Using the stars of the Great Square as a starting point there are a few interesting objects to search out.  From the star Markab at the bottom right corner follow the ‘kinked’ line of stars to the right (west) to the star Enif.  Using binoculars follow the line up from Enif about the same distance as Enif is from the previous star in the line and a small ‘fuzzy’ patch will be seen, this is a nice Globular Cluster M15.  From the upper left star Alpheratz follow the lower line of stars in Andromeda to the 2nd star Mirak.  From Mirak move up two stars and to the upper left of the second star is another ‘fuzzy’ patch, this is the M31 the Great Spiral Galaxy in Andromeda.

If we continue along the lower line of stars of Andromeda we come to the star called Almach.  This is a beautiful double star.  It is not a true associated double star the two stars are just a ‘line of sight’ double.  One star is golden colour and the other more distant star is blue similar to Albirio in Cygnus..

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

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 18th October 2017.

For details visit the NAS website at:


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