In a dark July night sky you can hardly miss Vega, Altair, and Deneb, the three bright stars of the Summer Triangle – fully up and dominating the northeast and east. What else is there to see on a summer night?
Although it doesn’t get dark until late, this time of year has advantages for observing. For starters you don’t have to wrap up until you nearly choke. You can coax friends outside to view some of the delights on offer in the night sky as it is a pleasant experience. Nobody wants to stand in the freezing cold and look at the sky but a balmy summer’s night is another matter. You might even sow the seed for a lifelong hobby.
Continue to keep a lookout for nocilucent clouds this month (see June night sky) and in case you are not lucky enough to see this spectacular phenomena take a look at some beautiful images taken by Dr Andy McCrea at the Irish Astronomical Association’s website.
There are two New Moons this month, the first was on the 1July and the second is on the 31 July. The planet famine is coming to an end as some favourites are making a comeback. If you are coming home in the early hours look out for Jupiter which is visible in the east from 3am. Mars, in Taurus, peeps over the horizon in the north east just before dawn. Saturn is still visible in the west just after sunset. Neptune and Uranus are also hanging in there but not visible to the naked eye observer.
The stars of autumn are already beginning to appear with Pegasus and Andromeda above the horizon in the east while constant Cassiopeia is shinning brightly in the north-east. Blue white Vega, of Summer Triangle fame, and the brightest star in the constellation of Lyra, the Harp, is almost at the zenith this month.
Cast your eye east (left) from Vega and you will come to Deneb, also of Summer Triangle fame, the brightest star in Cygnus the Swan. Deneb represents the tail of the giant celestial bird flying across the sky. Once you pick out its shape it’s quite an impressive sight. It is distinctly cruciform in shape, gaining it the title of the Northern Cross, and unlike its famous cousin in the southern hemisphere, Crux (the Southern Cross), which is a small constellation, it is quite large, Albireo marks the foot of the cross, or head of the Swan (whichever takes your fancy) and is one of the most striking double stars in the sky. Viewed through a small telescope it is possible to identify a beautiful yellow primary star and a fainter blue companion.
If you have a clear dark sky and an unobstructed horizon to the south you should be able to pick out a group of stars that resemble a teapot. The teapot asterism is part of the constellation of Sagittarius, the Archer. Sagittarius dates back to Babylonian times. Pabilsaĝ, as they knew him was their god of war, and like Centaurus, he is a half man, half beast creature although in his case he was part-man and part bull. Some legends say that the more kindly Grecian semi-equine was placed in the heavens to guide the Argonauts in their travels.
Once you locate the ‘teapot’ notice the misty background. That is the centre of our Milky Way galaxy (28 000 light years away). Dark skies are essential to see the Milky Way in all its glory. On July nights it can be seen stretching across the heavens from its core in Sagittarius, over our heads through Aquila and Cygnus and continuing on through Cassiopeia to the northern horizon. Given good conditions a dark bar, known as the Great Rift in Cygnus, can be seen running along its centre. This giant rift is caused by interstellar dust which blocks starlight from beyond.
The constellations of Sagittarius and Scorpius beside it lie in the thickest part of the Milky Way and are packed with riches for binoculars or small telescopes. These riches include dozens of star clusters, globular clusters, nebulae and double stars.
There are lots to see with the naked eye but to see the hidden beauty of the heavens you will need your binoculars or telescope. So relax on a balmy July night and enjoy the riches of the night sky.
(Article by Mary Bulman)