Astronomy Guide with the Newbury Astronomical Society
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Welcome to the Newbury Astronomical Society’s Beginner’s monthly astronomy guide to the night sky.
The chart above shows the night sky looking south at about 20:00 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 (in red) 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 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) just moving over the western horizon, Aquarius (the Water Carrier), Pisces (the Fishes), Aries (the Ram), Taurus (the Bull), Gemini (the Twins), Cancer (the Crab) and Leo (the Lion).
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. Saturn is currently in Sagittarius but has moved over the western horizon.
The summer constellations are still prominent in the early evening sky in the west. Only just visible is 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 through Altair in the lower part of the Summer Triangle.
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 and down through Auriga and Orion to the south eastern horizon.
Prominent in the south 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 stars can be seen within the square there seeing should be good. If no stars can be seen then seeing will not be good.
Coming into view in the south east is the constellation of Taurus (the Bull). The most obvious star in Taurus is the lovely Red Giant Star called Aldebaran. It appears slightly orange to the ‘naked eye’ but it is very obviously orange when seen using binoculars or a telescope. Aldebaran is located at the centre of the ‘flattened’ X shape formed by the brightest stars in Taurus. At the end of the top right (upper west) arm of the ‘X’ is the beautiful ‘naked eye’ Open Star Cluster Messier 45 (M45) known as the Pleiades (or the Seven Sisters). It really does look magnificent using binoculars.
Following Taurus is the constellation of Gemini (the Twins). The two brightest stars in Gemini are Castor and Pollux and they are named after mythological twins.
To the south of Taurus and Gemini is the spectacular constellation of Orion (the Hunter). Orion is one of the best known constellations and hosts some of the most interesting objects for us amateur astronomers to seek out. We will be having a closer look at Orion in the January issue of this magazine.
Planets visible this month: Uranus and Neptune in the evening. Mars will be rising in the east at dawn and Venus will be setting in the west at sunset.
Follow this link to see to see the full ‘Monthly What’s Up’ guide to the night sky: http://naasbeginners.co.uk/Whats_up/2019_2020/December 2019.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 18th December 2019, for details click on the link below.
For details visit the NAS website at: www.naasbeginners.co.uk