July to September
The combination of late sunsets combined with the Sun only just skimming below the northern horizon mean the sky barely darkens during the early summer months.
By September, conditions have improved and the darker skies we all know and love have returned once more.
Perhaps the most spectacular sight of summer is the Milky Way, the combined light from the stars in our own Galaxy stretching overhead. It can be seen running broadly from south to north although as the summer months creep by it slowly moves around the horizon running from south west to north east. Its brightest portions are in the south and a moonless sky will be needed to see it at its best. Give your eyes time to adjust to the darkness and then you may be able to detect the dark gaps in the gentle glow which are the result of vast galactic dust clouds blocking the more distant starlight from reaching us.
Looking due south at the Milky Way means you are looking toward the centre of our Galaxy where, at a distance of about 30,000 light years a giant black hole is thought to exist. The light that can be seen as the Milky Way comes from the 400 billion stars which make up its spiral structure although from a dark site only a few thousand are visible to the naked eye. Binoculars are a great way to explore the chains of stars and dark dust clouds, so sit back in a garden chair and explore the Galaxy.
Follow the line of the Milky Way to the north and you will be able to spot the giant stellar asterism known as the Summer Triangle. This shape of stars is not a true constellation and is a great starting point to navigate around the rest of the summer sky. The Triangle is depicted by the three bright stars, Deneb in Cygnus, Altair in Aquila and Vega in Lyra. Deneb is the highest of the three stars and marks the tail of Cygnus the Swan. Look closely and in the direction of the horizon you will see a large cross pointing down toward the horizon. The faint star at the centre of the Summer Triangle marks the head of Cygnus and it is known as Albireo. This insignificant looking star is a real beauty and well worth study through a telescope which will reveal that it is a stunning binary system made up of a blue star and yellow star.
The lowest star in the Summer Triangle is Altair in Aquila about 15 degrees to its north is a fine example of a planetary nebula, the Dumbbell Nebula. A telescope is needed to pick out this stellar corpse which somewhat resembles the fate that awaits the Sun. As its name suggests it looks like a ghostly dumbbell with the outer layers which have been expelled from the dying star creating the effect.
There are many other examples of planetary nebulae like this that have had the outer layers sculptured into all sorts of wonderful shapes by the star's magnetic field. The final star in the Triangle is Vega in Lyra and it is the brightest of the three. Lyra is a small constellation that represents a harp like instrument and with its main stars just to the lower left of Vega as you look at it. The stars are all fainter than Vega but roughly of equal brightness and form the shape of a parallelogram. Between the bottom two stars is another superb example of a planetary nebula, the Ring Nebula whose shape, not surprisingly resembles a ring! Just like the Dumbbell Nebula, the Ring Nebula is a stellar corpse whose shape has formed as a result of the outer layers of the star escaping off into space.
There is one final little treat among the Summer Triangle and to find it look closely again at Vega. Forming a triangle with Vega and the nearest star in the parallelogram is Epsilon Lyrae, the famous ‘double double star'. To the naked eye it looks like a faint star, but binoculars hint that there are two stars. Turn a telescope onto the system and the two stars you thought you saw have turned into a multiple star system of four stars.
The bright skies of the summer months need not be a write off for astronomy, you just need to know where to look. The objects already mentioned are easy enough to find but armed with a star map or an app on your smartphone, a pair of binoculars or a telescope and you will be amazed what delights the patient stargazer can uncover.
