The Ten Best Things to Look for in the Summer Sky
Summer’s here, which means the days are long, but the nights are short. Good for barbecues but not for astronomy! Why not turn your bar-b-que into a star-b-que and wow your guests with some summer constellations in addition to your prowess with the grill? This top ten list of summer constellations, clusters, and stars is sure to be a stellar success with young and old alike.
Unlocking the Keystone Cluster
Let’s start with an object that’s almost certainly on every amateur astronomer’s top ten list of summer constellations: the Keystone Cluster in the Hercules constellation. Conveniently located between Eta and Zeta Herculis, this globular cluster lies an estimated 26,000 lightyears away, and appears on the very edge of naked eye visibility. That being said, while you should have no problem catching a glimpse of it with binoculars, the cluster comes alive through a telescope.
A small scope at only 100x will make it seem as though a drop of starry paint has fallen upon the sky. Keep looking and you’ll soon see chains of stars snaking out from the cluster’s center. What do you see?
Lyra Strikes a Chord
Moving eastward, we come to the small summer constellation of Lyra, the Lyre. Its brightest star, Vega, is almost impossible to miss and can be easily seen glinting in the summer skies. Close to this brilliant beacon is another easy target for astronomers of all levels - Epsilon Lyrae, the famous “double double” star.
If you’re looking for another naked eye challenge like the Keystone Cluster, the Double Double might just be the ticket. The vast majority of us will only see a single star, but those with good skies and exceptional eyes might just be able to split the star in two.
If you’re not one of the lucky ones, there’s no need to worry. Binoculars will easily show the two brightest components of this multiple star system. Both appear white and of almost equal brightness, but a telescope will reveal the double’s ultimate secret: each star is itself made up of two white stars of equal brightness.
This pair is a little trickier for smaller scopes and you’ll need higher magnification, but it can still be done. You might just be able to split them both at a little over 100x, but you’ll need to crank it up to over 150x to get a comfortable view. What’s amazing is that this is a true quadruple star system that lies about 162 light years from Earth.
Let’s move on to a star that’s been dying for several thousand years now. The Ring Nebula, also in Lyra, can be found nestled almost midway between the two bright stars of Sulafat (Gamma Lyrae) and Sheliak (Beta Lyrae).
This is a planetary nebula, which means it’s the shell of gas and dust expelled by a dying star. A small scope with a relatively low magnification of about 75x is enough to reveal its ring shape. Some think it resembles a slightly flattened donut, but to many others its gray color clearly gives it the appearance of a smoke ring in space.
The Secrets of the Scorpion
If we turn our attention away from the stars of the east, we might be lucky enough to see the constellation of Scorpion scuttling across the southern horizon. Antares, the brightest star in this summer constellation, is a red supergiant that marks the creature’s beating heart. It also marks the location of our second summer globular cluster, known simply as Messier 4, or M4.
You’ll find M4 between Antares and Alniyat, the relatively bright star slightly to its west. If you look carefully, you can catch it with binoculars, but turn a small scope toward this beautiful cluster and you might see something unusual. Globular clusters are so-called because they appear spherical - like a globe - but M4 is a little different.
A modest magnification of about 75x will reveal a bar of concentrated stars across its center. It’s not quite the shape of Saturn and its rings, but it can certainly evoke the memory of our solar system’s most famous planet.
Scorpius appears as an elongated S-shape of stars and M4 lies at the western end of the constellation, near the scorpion’s head. Follow the stars toward the south-east and you’ll come to the sting in the tail and two very fine open star clusters.
M6 and M7 lie close to the border with Sagittarius, the Archer, and can be seen together within the same binocular field of view. Neither rise very high above the horizon so you’ll need to be quick if you want to catch them before they sink into the southwest. Of the two, Messier 6 is smaller but is arguably the better suited for small telescopes.
Known as the Butterfly Cluster, a low power of only 30x is all that’s needed to identify the butterfly pattern of M6 & M7 and enjoy the cluster in its entirety. In particular, look out for a grouping of five stars that looks like a flattened version of the famous Pleiades star cluster.
The Steam of the Teapot
We’re nearly halfway through our mini tour of the summer sky - let’s take a step back and enjoy the wider view. To the east of Scorpius lies the constellation of Sagittarius, whose brightest stars form a famous teapot-shaped asterism.
Look just above the spout of the teapot and you might spy a little steam escaping from the pot. This faint, gray misty patch marks the very heart of our own Milky Way galaxy, some 25,000 light years away. Follow the path of the mistiness upwards, towards the stars above and allow yourself to absorb the splendor of our own galaxy.
Returning to the spout of the teapot, we have an opportunity to see something relatively rare from the northern hemisphere: a naked eye nebula. Messier 8, the Lagoon Nebula, can be barely glimpsed directly above the teapot’s spout, but you’ll need dark skies to see it.
Even low powered binoculars will reveal a faint patch of elongated light, broken into two equal parts by a dark rift that runs from north to south. Both binoculars and small telescopes show stars in both hemispheres, with the eastern half appearing brighter and more densely populated.
Flying High with the Swan
Let’s return to the stars now rising toward the zenith overhead. Cygnus, the Swan, is soaring majestically, its head marked by Albireo, one of the most famous and popular double stars in the entire sky.
If you have powerful binoculars and a steady tripod, you might barely split this star, but you’ll most likely need a telescope. A modest magnification of only about 35x is all that’s needed to see one of the most beautiful sights in the heavens.
The slightly brighter of the two stars appears golden, while its companion is a sapphire blue. Its double-star status was first discovered by the English astronomer John Flamsteed in 1681 and we can only imagine how he must have felt upon first seeing these striking colors!
Chasing Down the Fox
Moving away from Albireo we venture toward the faint summer constellation of Vulpecula, the Fox, home to the last two stops on our celestial sightseeing tour. First of these is the Coathanger, a curious grouping of stars that can be glimpsed with the naked eye under dark skies.
This is one object that’s best observed with binoculars. A low telescopic magnification of 30x will still fit the stars within the field of view, but with very little room to spare. Regardless of how you choose to observe it, there’s no mistaking its shape. Until the late 20th century, it was believed to be a true cluster, but studies in 1998 determined it was merely a chance alignment.
And so, we come to our final showcase sight. Also found within the faint constellation of Vulpecula is the Dumbbell Nebula. Like the Ring Nebula in Lyra, this misty patch is the outer shell of a dying star pushed out into space. It’s larger and brighter than its summer companion and although it can be seen with binoculars, a telescope is the instrument of choice for studying this curiosity.
Again, just a low magnification of only 35x is enough to reveal its shape; at first it might appear rectangular, but after a few moments the two lobes can clearly be seen. This nebula, like the Keystone Cluster, allows your imagination to run wild. Is it a dumbbell? A bat? Or something else?
Summer Constellations to Remember
By now it’s late and the warm air is cooling. The last of your guests are saying goodbye and thanking you for a pleasant evening. Hopefully, as they drive home beneath the summer stars, they’ll feel satisfied by your food but astonished by the views of the night sky sights above. Next time it might be more than your company and your cooking that brings them back!