Late summer is an ideal time to take a visual journey through our Milky Way. Credit: Stuart Atkinson
Summer in the Northern Hemisphere is a frustrating time for many amateur astronomers. The nights never get dark enough to easily see the faint, fuzzy galaxies and nebulas they enjoy gazing at through their telescopes, and there are also fewer bright stars in the sky. Occasionally, a show of electric-blue stars can be observed. noctilucent clouds They will decorate the northern sky, but only a dedicated group of observers will stay up late to watch and photograph them.
Thus, many northern sky watchers enter a kind of reverse hibernation in summer, catching up on lost sleep until the darker skies of autumn arrive.
But wait a minute… isn’t summer the “Milky Way season”? Don’t all the books and magazines say so?
They do, but what they don't tell you is that in early and mid-summer it's pretty hard to see the Milky Way even from a dark-sky location; the sky is so bright that its faint star clouds and darker dust lanes blur together. But in early August, the Milky Way is a magical sight from any location away from streetlights and light pollution: a wide, hazy contrail that cuts the sky in half.
The problem is that there is so much to see along the Milky Way that novice observers don't know where to start. I wish there were a guidebook that pointed out the most interesting and beautiful features, just as there are guidebooks to help tourists on long road trips across the U.S.
Well, that's it! We'll take you on an astronomical journey through the Milky Way, stopping at the most fascinating places along the way to stretch your legs and enjoy the views.
Coming out
You'll have to wait until the sky is fairly dark to begin our summer Milky Way road trip, which means staying up or getting up around 1 a.m. Then, looking northeast, you'll see a cluster of stars about the size of a thumbnail low in the sky. This is M45, the famous Milky Way galaxy. Pleiades star clusterKnown as the Seven Sisters because keen-sighted people can see the seven brightest of its hundreds of members, this star cluster is one of the closest to Earth, at just 445 light-years away. It's a beautiful sight with binoculars and through low-power telescopes.
Next, move left from the Pleiades to the bright golden star. ChapelAt magnitude 0.1, Capella is the sixth-brightest star in the sky and the closest first-magnitude star to the North Celestial Pole. At about 42 light-years from Earth, it is a binary system. If you have binoculars, move them slowly across the sky just below Capella and you'll find lots of pretty little star clusters.
From Capella, shift your gaze a little to the upper right, where you'll find what looks like an inverted letter Y of stars, or maybe even a pair of gardening shears. This is the constellation Perseuswhich represents one of the most famous heroes of Greek mythology. Again, if you move your binoculars over Perseus, you will see many beautiful blue and white stars.
Look just above the Y shape of Perseus, perhaps a couple of finger widths across, and you'll see a fuzzy, blurry patch out of the corner of your eye. Binoculars revealed a group of star clusters so close together they almost seem to touch. Collectively known, unsurprisingly, as he Double cluster, NGC 869 and NGC 884 mark the sword that Perseus used to cut off the head of the serpent Medusa. They were first catalogued by the Greek astronomer Hipparchus in 130 BC, but curiously, Charles Messier did not include them in his famous catalogue, although he did include many smaller, fainter clusters. Like the Pleiades, the Double Cluster, 7,500 light-years away, is best seen at low magnification.
Leaving the Double Cluster behind, tilt your head back a little until you reach a striking zigzag of stars that looks like a letter W on its side. This is the constellation Cassiopeiadepicting an extremely vain Ethiopian queen who was cast into the sky by the gods after claiming, quite unwisely, that she was more beautiful than them. As a circumpolar constellation orbiting the North Star, she now spends half the year upside down, clinging to her throne and desperately trying not to fall back to Earth.
The Summer Triangle
After viewing Cassiopeia, tilt your head back until you are looking straight up. There you will see a very bright white star. Denebthe brightest star in the constellation Cygnus, the Swan. At magnitude 1.3, Deneb — whose name means “tail” — is the 19th brightest star in the sky. It’s a real beast: a white supergiant, some 50,000 to 100,000 times brighter than our Sun and also more than 100 times wider. If it replaced our Sun at the center of our solar system, it would swallow Mercury and Venus, and possibly even Earth and Mars…
If you look closely, you'll see that Deneb sits on top of a very striking cross of stars that looks like a crucifix or perhaps a dagger. This is the Northern Cross asterism, and it is much larger than its southern hemisphere counterpart, the famous South Cross.
Next, still looking toward Deneb, turn 180° in place and let the stars spin around your head until you are facing southwest and all the views you have seen so far are behind you. A short distance away, to the lower right of Deneb, at the four o'clock position, you will see an even brighter whitish-blue star. It is beautiful. Vegathe fifth brightest star in the sky. With a magnitude of 0.0, Vega is also known as the Harp Star because it is the brightest star in Lyra. At just 25 light-years away, it is one of the closest stars to us. Vega is a class A0 star that spins so fast (once every 12.5 hours) that it bulges at its equator. If it spun any faster, it would probably tear itself apart. If you are a fan of the sci-fi movie ContactYou'll know that Vega is the star that Ellie Arroway (Jodie Foster) traveled to in her alien-designed spaceship.
A short distance from Vega is the M57, the famous Ring NebulaThis is a planetary nebula, so named because when viewed through a low-power telescope it looks like the disk of a tiny planet. At high power it looks like a smoke ring with a darker center.
Look to the lower left of Vega, around seven o'clock, and you'll see another bright white star. This is Altairthe third star in a large asterism known as the Summer Triangle. At magnitude 0.8, it is the 12th brightest star in the sky and, at 16.8 light-years away, is another of the closest stars to our Sun.
If the sky is dark enough without light pollution (or moonlight), you'll see the Summer Triangle framed by a long, hazy vertical spot that looks like a patch of fog. Cygnus star clouda dense concentration of hundreds of thousands of distant stars. Look at it with binoculars or the lowest-powered telescope eyepiece you have and you'll see stars as thick as pollen grains.
Toward the bottom of this dense cloud of stars is a blue star much fainter than any of the stars in the Summer Triangle, but just as important. Marking the bottom of the Northern Cross, third-magnitude Albireo, 380 light-years away, is one of the most famous double stars in the sky. Look at it through a telescope and you'll see that it splits into a beautiful blue star and a beautiful gold-hued star that shine close together, looking like a sapphire next to a drop of molten gold. After stretching your legs by walking through the Cygnus Star Cloud and past Albireo, continue along the Milky Way, lowering your gaze until you're looking perhaps a third of the way up from the horizon to the zenith. You'll now notice another hazy area, much smaller than the Cygnus Star Cloud. This is the Scutum star cloud And if you look at it through binoculars or the eyepiece of a low-power telescope, you'll see that it's an area where faint stars are so close together that they look like a yellowish-white smudge of smoke. In the upper left corner of the cloud is a beautiful star cluster: M11, the Group of wild duckswhich early telescopic observers thought looked like a flock of ducks in flight.
Relaxing
We're running out of highway and our summer trip through the Milky Way is almost over. Look further down into the Milky Way's foamy trail and you'll see it begin to thicken and billow as it nears the horizon, like smoke rising from a distant campfire. You're now looking toward the constellation Sagittarius, about 28,000 light-years toward the center of our Milky Way galaxy and the Sagittarius star cloudsHere the stars are so densely packed that they really do look like thin clouds drifting in from beyond the horizon to cover the starry sky. But if you pass your binoculars or telescope above these clouds, you'll see stars as thick as dust, with many fascinating deep-sky objects embedded in them, including M20 or he Trifid NebulaThis is one of the most famous Messier objects in the sky. It is actually three nebulas in one: a red star-forming region, a blue reflection nebula, and a dark nebula. They are located about 5,000 light-years away from us. M20 is visible to the naked eye as a small patch of fog, but it looks much more impressive when observed through a telescope and especially in long-exposure photographs.
Just below the Trifid Nebula lies M8, he Lagoon NebulaThis stellar nursery, located 4,000 light-years away, is considered by many observers to be one of the most beautiful nebulae, and would undoubtedly be as popular as the Orion Nebula (M42) if it were higher in the sky and not marred by its proximity to the Milky Way's foamy center. It can be seen with the naked eye under good conditions, but a telescope can beautifully display the many faint billows of gas and the knots and strands of darker, dusty material within.
The final stop on our road trip is a striking orange-red star shining just above the southwestern horizon. Antaresthe brightest star in the constellation Scorpius. At 550 light-years away, Antares, which flickers and flutters in the summer sky like the flames of a distant campfire, at magnitude 1, is the 15th brightest star in the sky. Like the winter star Betelgeuse, ruddy Antares is a red supergiant that dwarfs our own Sun and would consume all the worlds out to Mars if dropped into the Sun’s place in our solar system.
And so our summer trip through the Milky Way ends. But there is much more to see. You will have to go out again another time, with a good star map or your favorite guidebook. planetarium appand enjoy your own leisurely ride along the paradise highway of summer.
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