This is not the best time of year for viewing the night sky because we are approaching the summer solstice when we have the maximum amount of daylight. However we have had some clear starry nights so let us not complain too much.
Okay, it is time to look at the stars. The following charts represent the night sky at 10.00pm BST on the 8th of June and at 9.00pm BST on the 23rd June.
We looked at the constellation Bootes- The Herdsman, last month and found its brightest star, Arcturus, by following the arc of The Plough handle downwards. As the night sky continues its westward journey we find two new constellations to the east of Bootes. First is the small but distinctive constellation, Corona Borealis- The Northern Crown. It consists of seven faint stars, the brightest Alphekka being of magnitude 2.2, in a horseshoe shape if you prefer that to a crown.
Secondly, and about 30 degrees (three clenched fists at arm’s length) to the left of Bootes you will see four relatively faint stars in the shape of a quadrilateral. This is an asterism called The Keystone (outlined in red on the chart) and is part of the constellation Hercules- the strong man in Greek mythology. Again, it is difficult to see any resemblance to a strong man but the Keystone asterism is another good signpost in the sky.
The second chart shows three constellations lying between Hercules and the horizon as you face south. They are named Ophiuchus- The Serpent Holder, Scorpius- The Scorpion and Libra- The Scales. The stars are mostly faint but these three constellations all lie on the zodiac; a region of the sky either side of the ecliptic and so by definition the sun passes through them. Historically the zodiac was divided into twelve equal regions each with its own zodiacal sign but in modern times the boundaries of the constellations were defined in terms of sky coordinates irrespective of the star patterns and the zodiacal constellations were no longer of equal size and there were thirteen rather than twelve. The odd one out is Ophiuchus which is a constellation but not a sign of the zodiac.
Follow a line from the right hand side of The Keystone down close to the horizon and after passing through part of Ophiuchus you will see a bright reddish star with a magnitude of about 1.4. This is Antares, the brightest star in the constellation Scorpius, and the 10th brightest star visible from the northern hemisphere. It is a red supergiant and if it were to replace our sun its surface would lie between the orbits of Mars and Jupiter. Antares was supposed to represent the heart of the scorpion. The fish-hook tail of Scorpius is not visible from out latitude.
Finally, to the right of Antares lies the small and faint constellation Libra. It is the only sign of the zodiac which depicts an object (a set of scales) rather than a living creature. Unfortunately it has little to offer the amateur with the unaided eye.
Something to look out for
There is always something special about the summer solstice and no doubt there will be news items about people going out early to catch the sun rise on the 21st June at Stonehenge or Glastonbury Tor. However, perhaps like me you have been missing the sight of the planets in the evening sky and a better reason for getting up early might be to catch an alignment of the planets from the 24th June to the end of the month. You will need a clear view of the horizon to the east-northeast from 3.00am BST onwards. As a bonus you might see a close approach of the Moon with Saturn on the 18th, with Jupiter on the 21st, with Mars on the 22nd and with Venus on the 26th.