Ask many astronomers what they do during Summer and the answer is normally “not much!”
They’ll tell you that, frankly, it is not worth the time and effort to be out and about when the darkness is so short. This, I think, is a bit of a misnomer – granted the conditions are not necessarily the best with heat and haze, but you can still observe some worthwhile sights. Globular clusters and some planetary nebulae are good at any time of the year, not forgetting we also have Jupiter and Saturn, despite the ringed planet being low down at the moment.
Once you have familiarity with the Summer sky then the Autumn and Winter skies are easier to get to know, as you have some familiar constellations to use to get to new ones. Learning your way around the constellations is not a long process – not years by any means – but it does take dedication and practice. The big difficulty with small scale star maps and planispheres (remember that plastic coated wheel you never got the hang of?) is that you have to imagine them bent into a bowl above your head. Master these mental gymnastics, then the maps become much easier to use. Those with ipads, tablets and similar gadgets will probably snort that the days of paper maps are over and apps reign supreme, but I disagree, as do many visual observers. For one thing, maps do not need batteries and their screens are dimmer! I concede that for many, especially those who suffer light polluted skies or suffer with eyesight problems, sky apps do seem a great way to navigate, but I prefer a printed map for my navigation.
You’ll only have acquired “the Knowledge” when you can look up and know exactly what is where. I guess it is the same argument as learning map reading skills versus using a sat nav, an argument which will rage for a very long time indeed.
Having got a few constellations under your belt, you could now graduate to using binoculars, 7 x 50 or 10 x 50. Whilst I prefer 10 x 50 optics, the 7x offers a larger field of view so it is easier to relate what you see to your map. For example the Skymap sheet shows M13 (the Keystone Cluster) in the keystone of Hercules which is a simple target to locate with binoculars. M5 in Serpens (described later) is also marked. So having got the hang of a few constellations, where do we go from here?
Hercules is an obvious place to start, but not with the globular cluster Messier 13 (which you’ve hopefully found by now), but its nearby companion Messier 92. If it were not for the presence of M13, then M92 would probably have earned the title for the best Northern Hemisphere globular cluster. Observed by Messier in 1781, he called it a “fine conspicuous nebulae, very bright” which is a fair description as it shines at magnitude 6.5. You can locate M92 by taking a line from M13 through to Iota Herculis (Hercules’ left foot). Scan along this line with your binoculars and you can make it out fairly easily. Point a telescope at the cluster, and, with a high power, of between 150x to 240x you can start to resolve the cluster with a moderate aperture.
Those with telescopes may also like to hunt for NGC 6229, the third globular in Hercules, which sits roughly a third of the way from Tau Herculis to Iota Herculis.
Whilst you are in Hercules, why not have a look for the Backwards 5 asterism? Located a little south west of Zeta Herculis, it is visible in larger binoculars and wide field telescopes.
Moving down from Hercules takes you to Serpens Caput and its globular M5. This is fairly easy to locate in binoculars as it sits 20’ northwest of 5 Serpentis. Again, using a high power starts to resolve the globular, although resolve is a loaded term – you are only resolving the stars your eyes are capable of seeing and the telescope is capable of showing.
Still moving southwards, the summer skies bring Scorpius and Sagittarius again, both of which rise a little higher than most people seem to think.
Scorpius has the lovely globular M4, which lies close to Antares. Just point your binoculars or telescope to Antares and move a little south westwards to grab this globular. A good reason for visiting this cluster is that there is another one close by – NGC 6144. I have seen it in a 15” from a site near Salisbury, but viewing conditions do make a difference; on the first night we could not observe it, the next night we could. If you have a good horizon, then give it a try.
Sagittarius, of course, holds a deep treasure chest of objects; two of the easiest to find are M22 and M28, both globular clusters, placed either side of Lambda Sagittarii (named Kaus Borealis), which itself is the tip of the teapot shaped constellation. Both are easily spotted in binoculars and again using a higher power on your telescope begin to resolve the fuzzy blob into stars.
Moving to the west of Kaus Borealis and the Lagoon Nebula (M8) is located. At its best in late summer, it is still visible in binoculars and a moderate telescope. Observed by Messier in May 1764 he notes “A cluster of stars that appears to be a nebula.” The Lagoon’s name was probably first used by Agnes M Clerke in her work “The System of the Stars” and refers to the black furrow which runs east to west dividing its brightest regions.
In the North West of the sky lies Draco, whose tail bisects both Bears rather neatly, with the head of Draco lying above the keystone of Hercules. Within Draco is found NGC 6543, the Cats Eye Nebula, a planetary nebulae lying some 4,000 light years away. Observed by W. Herschel in February 1786, he noted it as “a planetary nebulae, very bright … but very ill defined edge”. Having a magnitude of 13, it is, for me,
a telescopic object, but there have been those who have seen it in large binoculars. It is worth hunting out as it is a bright little planetary that can show hints of colour to those with better eyes than mine.
Moving from Draco overhead in an easterly direction lies Cepheus. There are a couple of objects to look at here. Firstly Mu Cephei, Herschel’s Garnet Star, a red supergiant around 6,000 light years away. Around 1,000 times greater in radius than our Sun, it is one of the reddest stars in the sky that is visible in binoculars, and also demonstrates semi regular light fluctuations; over a period of 730 days it varies between magnitude 3.4 and 5.1.
Whist in Cepheus, have a go at NGC 6946 (Fireworks Galaxy) and NGC 6939 (open cluster), both are in the same area of the sky, not far from the Garnet Star. Although Cepheus is a little low at the moment, point your telescope and have a look. 6946 lies around 12,000,000 light years away and has a diameter of 40,500 light years; it also has had a large number of supernova detected, nine since 1917 – a galaxy worth keeping an eye on.
Open cluster 6939 was described by Herschel as “… a beautiful compressed cluster of small, stars”. The member stars are all around magnitude 12, so a small telescope is needed to observe it, although with its height, extra aperture may be needed. If you do catch it, then its estimated age is 1.8 billion years old and 4,000 light years away. Both objects appear in binocular guides, but I have not seen them using a pair.
Finally, to complete the brief tour, within the Little Bear (Ursa Minor) an easy binocular object is the diamond ring asterism around Polaris. Just point your binoculars to Polaris and look for a ring of 8th to 9th magnitude stars in a ring.
Along with the deep sky objects listed, Jupiter and Venus are well placed at the moment for observation. The equatorial bands on Jupiter are easily seen in a moderate aperture telescope and small binoculars show the moons as points of light. As with most other observers, Venus yields nothing to me, except its phase which is fascinating to follow.
If you don’t have your own star charts, I’ll put the finder charts in the Society forum under the “Observing Now” section as one download. Do please also suggest other targets for the summer evenings—I have deliberately omitted Cygnus from this article as there is enough in there for an article of its own!
So whatever you decide to look at this summer, constellations, the Moon, planets, or the brighter deep sky objects, just get out there and view!