ASTRONOMY GUIDE TO THE NIGHT SKY – AUGUST 2021

Astronomy

ASTRONOMY GUIDE TO THE NIGHT SKY – August 2021

The chart above shows the night sky at 20:00 on 15th August 2021

Click on the chart to enlarge and click to the side of the chart to close

The chart above shows the night sky looking south at about 22:00 BST on 15th August.  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: Virgo (the Virgin), Libra (the Scales), Scorpio (the Scorpion) Sagittarius (the Archer), Capricornus (the Goat) and Pisces (the Fishes) rising in the east.

The constellation of Perseus appears in the north east (upper left) of the chart above but by midnight it will have moved to the northern horizon.  During the summer months Perseus is located in the north close the horizon so that is where it can be found this month when we are looking out for the Perseid Meteor Shower.  During the winter however it is located almost overhead and during November and December is actually host to the Zenith (the point in the sky directly over head).

In the west is the less obvious constellation of Virgo but it does have one fairly bright star called Spica.  Virgo gives its name to a large cluster of Galaxies that is also spread over into the neighbouring constellations of Coma Berenices (Berenices’ Hair) and into Leo.

To the north of Virgo is the bright orange coloured star called Arcturus in the constellation of Boötes.  Arctaurus is a star similar to our Sun but more advanced and is developed into a Red Giant star that is nearing the end of its ‘life’ as a normal star.  It has used almost all of its Hydrogen fuel and has expanded to become a Red Giant, 25 times the diameter of our Sun.  At the moment it shines 115 times brighter than our Sun but it is destined to collapse and become a White Dwarf.

Almost overhead is the constellation of Hercules (the Strong Man).  Hercules has a rather distinctive distorted square shape, at its centre, called the ‘Keystone’.  This is due to its resemblance to the centre stone of an arch or bridge.  The jewel of Hercules is without doubt is the Great Globular Cluster, Messier 13 (M13).  M13 can be found in the western (right) vertical imaginary line of the ‘Keystone’.  It is just visible using a good pair of 9 x 50 binoculars.  The spherical cluster, of about a million stars can be seen using a 90mm f10 telescope but will look even more impressive when using a larger telescope.

Prominent in the southern sky is the Summer Triangle that dominates the Summer Sky and was described in detail in the July magazine.  The triangle is defined by three obvious bright stars: Deneb in the constellation of Cygnus, Vega in Lyra, and Altair in Aquila.  The Milky Way (our Galaxy) flows through the Summer Triangle and passes through Aquila and Cygnus.  The Summer Triangle is bigger than may be expected but once it has been found it is very easy to find again.

As the Summer Triangle is so easy to find it is very useful to use as a starting place for finding our way around the night sky.

The Ecliptic is low in the sky during the summer months so the Moon and planets at appear close to the southern horizon.  Saturn and Jupiter are starting enter the night sky and are observable by midnight but due to their low altitude will not be at their best for observation this year.  The thick, murky and turbulent air close to the horizon will cause the planets to appear quite unsteady.

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

http://naasbeginners.co.uk/Whats_up/2020_2021/August2021.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 Magazines for Beginners on the Beginners website at: www.naasbeginners.co.uk.

All meetings of the Newbury Astronomical Society have been cancelled due to the Coronavirus.  However virtual meetings will continue on-line using Zoom.  Check the website above.

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