Grand scenes in nature are often accompanied by sound. Think of crashing waves, thunderstorms or a pond trilling with chorusing frogs. The summertime Milky Way possesses all that and more and yet rises in total silence. You'd expect the opening bars of Beethoven's 5th Symphony to play as the billowing star clouds cleared the treetops. But you'll strain to hear anything from those billions of suns. Like listening to the noiseless passage of a big ship through a narrow canal, perhaps the contrast between silence and size only enhances the Milky Way's grandeur.
You can "listen" for yourself in the coming week, from June 6-14, when the Milky Way rises at nightfall in the eastern sky with no moon to dilute its beauty. Late sunsets and long twilights now mean that the sky doesn't get dark until around 10:30 p.m. local time (later for northern locations). That coincides with the appearance of the northern half of the summer Milky Way led by the Summer Triangle. If you've never seen this giant figure defined by the bright stars Vega, Deneb and Altair, it's time to get acquainted.
Vega stands about 40° or four vertical fists high in the eastern sky as soon as it gets dark. It's THE dominant star in the east during June evenings. Deneb, at the head of the Northern Cross, shines two and a half fists to the lower left of Vega. Altair is much lower, well below Vega and about a fist high in the southeastern sky.
From the countryside, the interior of the Triangle is filled with the textured, grainy glow of countless stars, most so far away and faint they blend into a foggy glow. At nightfall, we see just a small section of the Milky Way band. As the clock ticks toward midnight, the Earth turns, and entire band slowly rises into view.
From the Triangle, the Milky Way extends north (left) to the W of Cassiopeia and south (right) through Aquila the Eagle and into Sagittarius the Archer. Dark patches along its length, where parts of the band appear to be missing, are in fact light-years-thick clouds of interstellar dust that obscure the stars behind them.
Every star in the sky is a member of the Milky Way galaxy, but only those that stack up across the distance when we gaze across the plane of the galaxy create the band of glowing star-fog so familiar on summer nights. The galaxy is shaped like a flat pinwheel. Not exactly flat but pretty close — it's about 10,000 light-years thick by 100,000 light-years across, a ratio of 10 to 1. That similar to a standard bicycle tire, with the central hub corresponding to the the Milky Way's "nuclear bulge," where additional stars congregate into a dense core.
The sun and its family of planets orbit about halfway from the hub within the flat disk of the galaxy. Yes, we're in the thick of it. When we look straight through the disk toward the hub, stars near and far stack up to create a misty ribbon extending from one end of the sky to the other. Its only looks like smoke or fog because most of the stars are too faint and far away for our eyes to see individually. Rather, they blend together into a uniform glow and create the band of the Milky Way, also the name for the galaxy as a whole.
When we look above or below the band we're literally looking above and below the plane of the galaxy into its star-poor halo. There aren't enough stars there to overlap and produce the "glowing band" effect. Instead we see spotty, individual suns that form constellations neighboring the band such as Hercules, Pegasus and Aquarius.
For a good look at our galactic home I suggest you use this Light Pollution Map to locate dark skies you can reach by car. Just zoom in by scrolling your mouse and look for a blue, purple or gray zone nearest your city.. Again, the best viewing times this month are June 6-14. Bring bug spray and binoculars. With the latter you'll see far more stars than are visible with the naked eye. The view always knocks me over.
Take an hour and get to know our quiet but awe-inspiring surroundings.
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.