Monday 10th to Sunday 16th May 2021
On Monday, from about 11pm, there is an opportunity to spot the open cluster of stars known as M39 - Charles Messier added it to his catalogue in 1764.
M39 is in the constellation of Cygnus. Look to towards the north east with binoculars or a small telescope and the cluster will be about half way between the bright star Deneb in Cygnus and the constellation of Lacerta.
So why do we say it is in Cygnus when the cluster is actually nowhere near the familiar "swan shape" made by joining dots between Cygnus' major stars? The name "Cygnus" really refers to a whole area of the sky that contains the swan shape - joining the dots makes it easier to spot.
A good analogy is to think of a map of Somerset. It contains lots of features like towns, villages and beauty spots. The towns equate to major stars, the villages are minor stars and the beauty spots are deep sky objects. Now to make the whole area easy to find when looking at a map of the UK, join the dots between the big towns - Bridgwater, Taunton, Yeovil, Crewkerne and Chard for example - this produces an easy to recognise pattern, but Somerset is really the whole area around it.
Screenshot courtesy of Stellarium
Star chart courtesy of Wikipedia / Sky & Telescope Magazine
Copyright Adrian Dening and Radio Ninesprings 2021
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