Go out on any summer night anywhere in the temperate zone of the northern hemisphere and look to the south, near the horizon.
You won't be able to miss it, the curving tail of Scorpius, looking like the evil hook longshoremen use to manhandle cargo, even to the cross-grip at the end. Unlike most of the constellations named by the ancients, the scorpion does look like its namesake, from the bright double star marking the sting, through the curving sweep of tail, onto the stubby body with the red giant star Antares at the heart of the beast. Even the pinchers are there, the three stars at the hook's handle. The scorpion is one of the twelve constellations named as houses of the sun by our Mesopotamian ancestors, a tradition passed down through the cultures of the Mediterranean down to the modern day, from the newspaper astrology column to the astronomer's on-line star chart. As the Earth revolves about its parent star over the course of a year, the Sun appears to spend about one moon in each of these houses, the cycle of the Zodiac, or the path of the Sun. The other planets circling the Sun, confined to the flat plane of the Solar System like chariots on a race track, also creep from house to house along the Zodiac, from west to east throughout the year. Their motion is slow, not noticeable in a night, and it varies from planet to planet depending on its distance from us, its speed, and our own Earth's motion. But over the course of a year it is noticeable to the careful observer; the wandering planets prowl along the fixed unmoving stars, and they keep to one path. No one knows when primitive man first noticed this, it was certainly thousands of years before the hydraulic civilizations of the world's great river valleys first gave them the names that survive to this day. But from the first time it was known, we also learned that the heavens were not chaos, there was order there, and pattern. For better or worse, we still believe this.

But the Zodiac has little real significance, it is an illusion due to the geometry of the observer, more a function of the Earth's path than of any physical reality of its own. Still, there are other paths and other realities in the night sky, paths based on real objects and not chance alignments. Look again, O summer night observer, just there, to the left of the scorpion, just to the east of it. See the little group of stars? Modern-day amateur astronomers nickname it the Teapot, short and stout, it sits just to the left of the scorpion's deadly stinger, with stars marking the handle, lid, base, even the spout. It is obvious once it is pointed out. To our ancestors, however, it was Sagittarius, the archer. It's a bit of a stretch for a modern's fancy but the three stars of the Teapot's spout are the archer's drawn bow, an unseen arrow aimed directly at the throbbing red heart of the monster. Scorpius is easy to find and remember, but let us instead shift our attention to the archer, for in the starry depths of far Sagittarius lurks another monster, a real one, a destroyer of worlds. The constellations are not places, they are directions; when we say "in Sagittarius" it is like when we say the wind is "in the north".

Imagine yourself on a dark summer night, looking south towards an unobstructed sky, towards the Zodiac as it slices just above the horizon, the constellations of Libra, Scorpius, Sagittarius and Capricornus strung along from west to east. The sun has set, but in a few months it will creep along this path, spending roughly a month in each house as it pretends to circle a stationary Earth. That is how the ancients saw the Universe. The world was at the center of Creation. The ancients also saw something else, and you may also. If the night is clear and dark, as it sometimes still can get in the wilderness, or out at sea, and if there is no moon, you can see the Milky Way.

In our light-polluted world, where children must sometimes wait decades for an opportunity to see more than a handful of stars at any one time, the Milky Way is often unrecognized even when it is seen. It appears to be a whitish band of cloud , except upon closer inspection, it is dotted with stars rather than obscuring them. If your eyes are adapted to the darkness, it becomes a sight of almost unendurable beauty: not just a glowing band, but a knotted and clustered clumping of stars and the yawning gulfs of blackness between the stars. With even the slightest optical aid, even an opera glass, the Milky Way reveals its secret, it is made up of infinite millions of them, stars in heaps, stars in clouds, stars scattered across the unimaginable darkness. I can only cry for the barreness of the soul that cannot be moved by this sight and this realization. For sheer beauty, the Milky Way puts even the sea to shame.

With better eyes, the river of light only gets deeper and wider; with a good pair of marine or astronomical binoculars (perhaps the best instrument to use to appreciate the overall structure of the Milky Way), the eyes see a general background of an infinity of tiny stars. Superimposed on this are clusters of brighter ones, handfuls of multicolored jewels scattered across a black velvet dusted with powdered diamond. Here and there are fuzzy misty clouds, the nebulae, glowing wisps of stardust, and scattered amongst them are brooding black voids, places where there are few or no stars. They too, we will learn later, are nebulae, but unilluminated ones obscuring the light of the stars behind them. To the unaided eye the sheer spectacle cannot be denied. But that spectacle is the same that our ancestors glimpsed from their desert caravans and their flimsy ships. Today we know that this is the center of Creation.

The Milky Way is a great band that goes about the entire sky, intersecting the Zodiac in the constellation of Sagittarius, and again on the opposite side of the sky at the Taurus-Gemini border. Again, a chance alignment, an illusion caused by geometrical coincidence. It wasn't until the telescope was invented that we started to understand just what it was we were seeing at night. The great stellar system, of which our nearby Sun is just a tiny insignificant member, is a huge flat disk of stars, clusters of stars and great clouds of dust and gas: the Galaxy. From inside, it is visible as the Milky Way. The sheer immensity of this object can be described, but it cannot really be understood. The Galaxy is a thin disk one hundred thousand light years across and a thousand light years thick. Our own Sun lies thirty thousand light years from the center, or about halfway to the edge. It is about equidistant from the northern and southern sides of the disk, about five hundred light years from each. A light year, the distance a light beam can travel in a year, is the only way we can measure these distances, but it is an incomprehensible concept, even for the astronomer. Light can circle the Earth seven times in one second, it can go to the Moon and back in three seconds. Light takes eight minutes to get here from the Sun, and a beam of light would take five hours to get to Pluto, the cold and lonely outpost planet at the edge of our Solar System. But the stars which make up the Galaxy are, on the average, several light-years apart. Our nearest stellar neighbor, Alpha Centauri, in the same general part of the sky we are now gazing at, is over four light-years away. Every single star we see at night with the naked eye is within several thousand light years of Earth. Look up at the night sky, every thing you see, everything, is within the one tiny little piece of the Galaxy we can see. The Milky Way itself is an illusion. When we look into the the disk of the Galaxy, we see the combined light of all the stars; the Milky Way. If we look in other directions, we peer out of the disk, and the stars we see are only the relative few that lie between us and the empty void of extragalactic space.

The great disk of the Galaxy is not a solid object, it is composed of innumerable yet separate stars, there are over 100 thousand million of them: 20 times as many stars in the Galaxy as there are people on Earth. There are 10 times as many stars in the galaxy as there are people that have ever lived on Earth. And yet, they are separated, as we have seen, by vast immensities. But that is not empty either, a thin tenuous gas envelopes everything, thicker in some places, thinner in others. Great clouds of dust and gas also inhabit this silent emptiness, some of them stellar nurseries where new stars condense like raindrops in a thunderstorm. There are also great clusters of them, stellar broods where the hot young stars have blown away the remaining gas and dust to reveal themselves as burning jewels. Everywhere are scattered the wrecks and dying embers of failed and exploded suns, the chemical elements produced by the thermonuclear furnaces inside those burned-out stars now enriches the interstellar medium so that subsequent generations will have the iron and silicon and carbon and oxygen and all the other materials needed to construct the dust motes we call planets, and perhaps, the biospheres which cling to the thin films of moisture surrounding those specks. In the remote past, when the Universe was born, there was only the primeval hydrogen and helium; in the cores of stars is formed, through nuclear fusion, everything else.

The whole spectacle of galactic evolution unfolds on a huge stage, and it is a very long playing drama, a very slow one for creatures as fleeting and ephemeral as we. The Sun revolves about the galactic center every 250 million years, perhaps only twenty orbits since it formed out of its primeval dust and gas cloud. Several new stars are born every year, and several die, some by the cataclysmic explosions known as supernovae, every century. But this constant birth and death continuously stirs and mixes the flows of gas and dust, alternatively clumping and dispersing the huge back clouds which also race about the galactic center with the stars in a stately cosmic dance. Gravity ties the whole thing together, and magnetic fields are embedded in the medium. Exotic subatomic particles are carried by these fields, and hard radiation from massive young stars rips the electron shells from nearby atoms forcing them to flouresce in ghastly auroral colors. The whole system rotates, and great waves pulse through the disk, alternately compressing and relaxing the gas, forcing bursts of star formation which race themselves across the disk, masquerading as spiral arms. The Galaxy is alive, it is a living thing, evolving morphologically, chemically, and dynamically, but all at unimaginably slow rhythms. The speed of light is the fastest thing there is, but the Galaxy is so large that we see it as an instantaneous photograph of an explosion, an avalanche frozen in time. At other time scales, it is breathing and growing, and perhaps even evolving consciousness. Astronomers call this structure The Grand Design. In the sterile jargon of astrophysics, our galaxy is a Grand Design Spiral.

As we stare at Sagittarius we are looking into the very center of the Galaxy. That is, the nucleus of the stellar system lies in the direction of the constellation of Sagittarius, thirty thousand light years away. Light cannot penetrate but a few thousand years into the dust and gas which permeates the system, but using exotic instruments and detectors, radio, infrared and microwaves, the energy given off by physical processes in the galactic core can be studied, and slowly a picture is being built up of what is happening there. What we see are events of unimaginable violence and colossal destruction. Matter is being annihilated in inconceivable amounts and being converted into energy, gamma and x-rays, in a continuous sputtering thermonuclear detonation without end, bathing the entire galactic nucleus in a deadly bath of hard radiation. At the core of our galaxy lies the Dragon, an immense black hole, perhaps of a million solar masses, continuously gulping down entire solar systems and huge clouds of gas. It is the eye of the beast. The center of the Galaxy is the site of Hell.

Look away from the center, out of the disk, and the number of stars suddenly decreases. After all, we are now looking merely five hundred or so light years to the top or bottom of the galactic disk. Telescopes have probed this extragalactic space, there are a few stars scattered out here, a galactic Halo, but nothing like the crowding of the disk itself. There is relatively little gas and dust here, except for the occasional fountain or explosion pushed up from the disk by an infrequent supernova every now and then. There are the great globular clusters scattered about, huge balls of hundreds of thousands of stars each, in random orbits about the galactic nucleus, relicts of some unknown process at the creation of the Galaxy, soon after the Big Bang. The globular clusters are very old, as old as the Galaxy itself. Perhaps even older. They fly about it like hundreds of swarms of angry bees, at dozens of miles per second; although to our short-lived eyes they seem frozen in place. They move quickly, but the distances are vast. But there is little else out in the Halo, it is mostly emptiness, our telescopes see no stars, our radio detectors do not catch the whisper of cold hydrogen, there are no glowing nebulae. But something strange lurks out here, too. Our studies of the motions of the stars and the currents of gravity which guide them tell us that much, perhaps most of the matter in the Galaxy is out in the Halo. We just can't see it, it gives off no light or other detectable radiation, and it is perfectly transparent, not obscuring the faint glow of more distant objects. It's gravitational attraction cannot be ignored, but it does not otherwise betray its presence, and no one has the faintest clue as to what it might be. Astronomers call it Dark Matter.

But when we peer outside the disk, through the nearby stars between us and the Halo, and through the scattered stars and great globular clusters, and past the Dark Matter and out into the depths of extragalactic space, we see other ghostly shapes, faint glows, fuzzy blobs of near nothingness, tiny smudges against the backdrop of eternal Night. A few of these faint objects, like the great Andromeda Nebula, can be seen with the naked eye, many more with optical aid. But again, the speculations of the philosophers and metaphysicians failed to anticipate the staggering reality revealed by the great telescopes of the twentieth century, aided by that quintessential Victorian invention, the photographic plate. Those faint dim glows, barely visible against the void, were other galaxies, very like our own: island universes. Andromeda was shown to be another Grand Design Spiral, even larger than our own,
and countless billions upon billions of others litter the emptiness, like snowflakes in a blizzard, to the end of eternity.

The ancient astrologer of the fertile crescent would not have believed it if we could somehow, magically transported back in time to the land between the rivers, tell him where his careful observations would eventually lead. His successors, young men and women huddled over computer monitors and keyboards, stare at flickering images collected from modern ziggurats on lonely mountain tops half a world away, or from automated observatories in orbit. The faint light from the edges of Creation piles up slowly on detector chips and photographic emulsion, slowly building up images of pastel galaxies, like colorful coquina shells resting on the black sands of the beaches of infinity. And we would see the same in every direction, for as Edwin Hubble once remarked,"...we are, by definition, at the very center of the observable region." Once again, we find ourselves at the center of Creation.