David Hybl age 12, of Tuscon, Arizona, for his question;
What is the Milky Way System?
We can look up and see the Milky Way on clear starry nights. It is a pale hoop of glimmering light staggering over the sky. The Indians said it was the path to heaven for their departed spirits. The Romans said it was a stairway for visiting gods and goddesses. Almost 350 years ago, the great astronomer Galileo looked at the Milky Way through a telescope and knew it was neither of these things. He saw that it was made of countless bright pinpoints and knew that the Milky Way was a host of stars so far away that their light blended into a hazy glow.
We know now that the Milky Way is a vast and orderly system of billions of stars. Our brilliant sun is but one of those stars and our earth is a smallish planet of the Solar System. And the Solar System is but a small fragment of the Milky Way star system. Sometimes we call the vast system the Galaxy, a Spiral Nebula or an Island Universe. In any case, there are thousands of other such systems of stars scattered through the vast roaches of empty space.
Our Galaxy; or Milky Way system, is shaped somewhat like a pinwheel. The stars thickest towards the hub and scattered thinly towards the edges. The big wheel is wide and flat, somewhat thicker towards the center. Its size is staggering. Light, which travels non‑stop at about 186,000 miles a second: takes 100,000 years to cross from side to side. The Galaxy is 100,000 light years wide and 10 light years thick at the center. Our Solar System is far from the crowded center. We are about two thirds of the distance from the hub to the rim of the big wheel.
Our position gives us our special view of the Milky Way system. From the round earth, we can look out at the vast heavens in all directions. vie can see the thinly scattered stars towards the rim of the Galaxy. We also have a view of stars towards the center and across the big wheel. This is a flat; edgewise view of the system. We see it as the Milky Way, blurred with the light of a host of distant stars.
A telescope shows the stars of the Milky Way crowded together and almost touching. Actually, even the stars clustered at the center are far apart: Our view shows them on a more or less level plane. They seem to crowd because we do not see the flat space between them. We are looking at eye level across the vast wheel of widely separated stars.
The Milky Way is seen from above and below the equator. In places it is brilliant and in other places spattered with dark patches. The brightest span is in Sagittarius, the Archer. This constellation peeps over the horizon during the summer months. Here the distant stars are really thickest, for we are looking near the center of the Galaxy. In Orion the Hunter, the bright constellation of winter nights, the Milky Way is blotted with a shadowy horse head shape. This is a nebula of dark gases between us and the distant stars, The horse‑head nebula, the coal sack nebula and other dark clouds hide sections of the Milky Way from the earth,
Since most of the stars of our huge home in the heavens are in the Milky gay, we sometimes call it the Milky Way star system. It is a system in that all the stars are bound together by the laws which keep them in order. The whole vast wheel is turning around and around the central hub,