Bright Capella: A Lesson in Learning About the Universe
+ Von Del Chamberlain +
October 28, 1998
Things are not always the way they appear to be. In fact, usually they are not. Many stars glowing in the heavens can remind us of this. Mostly they appear as singular points of light, always in their places night after night, never seeming to change their courses. When we study them closely, however, we learn that every one of them has its independent motion. If we could just watch long enough we would see the patterns of constellations slowly modulate from old familiar figures into new ones. We simply do not live long enough to discern the changes in the patterns of heaven. Rest assured, however, that they are constantly changing.
In addition to their movements in space, stars often turn out to be quite different than the way they appear to just our eyes. A case in point is the brilliant star now present to the northeast in our evening sky. Sixth brightest in the night, Capella stands out with a golden-yellow color when compared with other stars. It is the brightest star in the constellation Auriga, the Charioteer, formed by a pentagon of stars. The name Capella marks it as the female goat of heaven, sometimes called the "mother goat." It was supposedly named to honor the goat that suckled none other than the infant Zeus. Near Capella, to the upper right as we see them in our current evening sky, is a slim triangle formed by three faint stars, the children of Capella, the kids, or baby goats.
Capella is a celestial symbol of abundance and beauty. Its upward flight in our evening northeast sky is accompanied by sounds of migrating birds, the bustle of gathering in the harvest, refreshing chilling of the air following hot summer days and the strokes of color on the landscape by the hands of greatest artist of all, Mother Nature.
Take special note of the color of Capella. Its light is very similar to that of the Sun. This is because Capella and the Sun have similar temperatures. In other ways, however, the two stars are quite different. Capella is a complex object that revealed its true nature as observational equipment became better and better. In 1899 it was discovered that what we see as Capella is really a pair of stars very close together. One of the stars is slightly cooler than the Sun while the other is hotter. Both are larger and brighter than the Sun and their combined output of light is about 160 times greater than the Sun's. Then it was discovered that a dim red star orbited this pair of stars and that this obscure companion is also actually a pair of stars closely orbiting each other. Thus, where our eyes see the one bright star, Capella, our instruments have helped us realize there is a little group of at least four stars. If that isn't enough, think of the possibilities of planets that might inhabit the system!
The group of stars we call Capella is located about 45 light years away from us, not really very far as star distances go. If we could go out to Capella and look back at the Sun we would see a star about the brightness of Polaris, our north star.
Capella is a lesson about increasing knowledge. When we go out and look around we find that many things are not what they first seem to be. We have learned that mountains, rocks, trees, every creature and even stars are made of tiny fundamental atomic particles. Under various conditions the elements form into molecules, crystals and cells that make up both the inanimate and animate kingdoms around us. Earth itself is a body composed of layers: a cool rocky mantle surrounds a hot molten core. The entire planet is one of a fleet orbiting a star, and that star along with a few hundred billion more compose the Milky Way galaxy. Billions of galaxies make up the universe. Wherever we look, smaller units build into larger and larger ones.
On the one hand, it is amazing to consider what we have learned from looking around, but at the same time it is humbling to realize how little we actually understand. Just when it seems we have ultimate answers we make discoveries that open grand new vistas that we knew nothing at all about. Pick any star in the sky and when you study what is known about it you will likely be surprised. Still, based on that little bit of information you can, without much effort, raise questions still unanswered. Capella is a good place to start. As J. B. S. Haldane once said, "The universe is not only queerer than we imagine, but queerer than we can imagine."