Astronomy

Astronomy
Astronomy Guide to the Night Sky – May 2018

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 May.  West is to the right and east to the left.  The point in the sky directly overhead is known as the Zenith.  It is shown (marked 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 constellations through which the ecliptic passes are known as the constellations of the ‘Zodiac’.

Constellations through which the ecliptic passes this month are: Gemini (the Twins), Cancer (the Crab), Leo (the Lion), Virgo (the Virgin), Libra (the Scales) and Sagittarius (the Goat) just appearing over the South Eastern horizon.

This month the planet Jupiter is in the constellation of Libra and is very easy to find later in the evening.

Ursa Major is almost directly overhead as can be seen by the location of the ‘Zenith’ (the point directly overhead) marked on the chart above.  It is one of the best known and easily recognised constellations.  It is also known as ‘the Plough’ or the ‘Big Dipper’ to the Americans.  It does actually resemble a saucepan more than anything else and is very easily recognised as a saucepan in the sky.

Ursa Major is very easy to find and because it is ‘circumpolar’ (never sets below the horizon) it is always somewhere in our night sky.  As it is so easy to find it is a good place to start exploring the night sky.  The two stars of the ‘pan’ opposite the ‘saucepan handle’ (known as the Pointers) can be used to find Polaris the Pole Star (or North Star) in Ursa Minor, see the chart above.  To find Polaris just follow the ‘Pointers’ up out of the pan.  By following an imaginary line off the end of the saucepan handle will show the way to Arctaurus the bright red star (it looks more orange) in Boӧtes, see the chart above.

The constellation of Boӧtes does not have anything interesting to search out but the bright star Arctaurus is very beautiful.  It is a Red Giant and appears distinctly orange to the naked eye and even more so when using binoculars or a telescope.  Boӧtes is also a good starting point to use to find other constellations like Hercules.  Hercules is to the east (left) of Boӧtes and is the constellation of the month.  See the link below.

By following the ‘Pointers’ in Ursa Major down they point the way to the constellation of Leo (the Lion), see the chart above.  The stick figure of Leo does actually look a little like a lion.  The bright star Regulus in Leo sits right on the Ecliptic and is often seen close to the Moon and sometimes the planets as they appear to move along the ecliptic.

To the west (right) of Leo is the faint and rather indistinct constellation of Cancer (the Crab).  The asterism (shape) of Cancer looks quite uninteresting.  However the Open Cluster Messier 44 (M44) ‘Praesepe’ or the ‘Beehive Cluster’ looks beautiful using binoculars and looks like a swarm of bees around an old style straw bee hive.

The constellation of Gemini (the Twins) and the twin stars Pollux and Castor are easy to find in the west along the Ecliptic past Cancer.  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 through a telescope.

To the east of Leo is the quite indistinct constellation of Virgo.  It does have one fairly bright star called Spica.  It is classified as a Class B1 Giant but is in fact a very close binary star.  The two stars are very close and orbit the common centre of gravity every four Earth days.  Their gravity pulling on each other has made them ‘egg’ shaped..

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

http://naasbeginners.co.uk/Whats_up/2017_2018/May2018.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 16th May 2018, for details click on the link below.

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

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