Paul Gonwa, age 10, of Peoria, Illinois, for his question:
What does the Milky Way look like?
Human eyes see the Milky Way as a straggling ghostly white glow arching over the sky among the stars. On a clear winter night you can see it near the brilliant constellation Orion the Hunter. From there it loops down toward the southeast and northwest horizons. Telescopes reveal this ghostly glow to be a dense crowd of dazzling stars, too far away to be seen separately by human eyes. Astronomers have put the fine details together to give us a stupendous picture of its size, its true shape and its pinwheeling motions.
Our early ancestors beheld the beauteous Milky Way without the help of telescopes. It's still there, spanning the night sky, so let's take a look at what they saw. It still looks like a thin ragged scarf of ghostly white light, arching up and over the starry sky. In winter, it straggles up from the southeastern horizon, pinches between bright Procyon and dazzling Sirius and brushes lightly through the constellations Orion and Taurus, Auriga and Perseus. From the top of the sky it meanders through Queen Casseopeia and King Cephid and dips down below the northwest horizon.
The filmy white Milky Way actually circles the spacious skies around our entire globe. In winter we see only half of it. The wider, brighter half spans our summertime skies. Then it reaches up from the southwestern horizon to Sagittarius and Scorpius the Scorpion constellation, with its big red star Antares. As it climbs it splits into two ragged scarfs and straggles through Cygnus the Swan. From there it goes on up again through Cephus, Casseopeia and Perseus and hides below the northeastern horizon.
Early astronomers marveled at this gauzy circle around the celestial sphere. It was a mystery until about 360 years ago, when Galileo trained his small telescope upon it. He saw that the filmy haze is actually the blurred light from millions of crowded, faraway stars. Since then, astronomers have arranged the pieces to get a total picture of the gigantic star system called the galaxy.
They tell us that its shape is somewhat like an enormous wheel with a small hub of dense,, crowded stars and long spiralling arms thinning out toward the rim. Traveling at the unbelievable speed of 670 million miles per hour, it would take us 80,000 years to cross it from side to side. Meantime the vast star system with its spiralling arms rotates around like an enormous celestial pinwheel. Our sun is one of its 100 billion pinwheeling stars. We are far from the center and from the earth we have a rather flat, edgewise view out across the galaxy. We see, not a big wheel, but the hazy circle of faraway stars in the Milky Way.
Our sun is way out on a spiralling arm, sprinkled with stars and strewn with cosmic clouds of dust and hazy gases. The center of the galaxy is out beyond the summer constellation Sagittarius the Archer. Here the stars are thickest but, sad to say, much of the dazzling view is hidden behind dark cosmic clouds. Photographs of the Milky Way can be taken in sections throughout the year. When arranged in a line, they give a complete picture of the galaxy. This flat, picture of the Big Wheel shows the bulging center and dwindles down to nothing on each side.