 One of Walt Whitman's best-known poems is this one. When I heard the learned astronomer, when the proofs, the figures, were ranged in columns before me, when I was shown the charts and diagrams to add, divide, and measure them, when I, sitting, heard the astronomer where he lectured with much applause in the lecture room, how soon, unaccountable, I became tired and sick, till rising and gliding out I wandered off by myself, in the mystical and moist night air, and from time to time, looked up in perfect silence at the stars. I imagine that many people reading those lines tell themselves exultantly how true science just sucks all the beauty out of everything, reducing it all to numbers and tables and measurements. Why bother learning all that junk when I can just go out and look at the stars? That is a very convenient point of view, since it makes it not only unnecessary but downright aesthetically wrong to try to follow all that hard stuff in science. Instead, you can just take a look at the night sky, get a quick beauty fix, and go off to a nightclub. The trouble is that Whitman is talking through his hat, but the poor soul didn't know any better. I don't deny that the night sky is beautiful, and I have in my time spread out on a hillside for hours looking at the stars, and being awed by their beauty, and receiving bug bites whose marks took weeks to go away. But what I see, those quiet twinkling points of light, is not all the beauty there is. Should I stare lovingly at a single leaf, and willingly remain ignorant of the forest? Should I be satisfied to watch the sun glinting off a single pebble, and scorn any knowledge of a beach? Those bright spots in the sky that we call planets are worlds. There are worlds with thick atmospheres of carbon dioxide and sulfuric acid. Worlds of red hot liquids with hurricanes that could gulp down the whole earth. Dead worlds with quiet pockmarks of craters. Worlds with volcanoes puffing plumes of dust into airlessness. Worlds with pink and desolate deserts, each with a weird and unearthly beauty that boils down to a mere speck of light if we just gaze at the night sky. Those other bright spots, which are stars rather than planets, are actually suns. Some of them are of incomparable grandeur, each glowing with the light of a thousand suns like ours. Some of them are merely red hot coals doling out their energies stenchily. Some of them are compact bodies as massive as our sun, but with all that mass squeezed down into a ball smaller than the earth. Some are more compact still with the mass of the sun squeezed down into a volume of a small asteroid. And some are more compact still with their mass shrinking down to a volume of zero, the side of which is marked by an intense gravitational field that swallows up everything and gives back nothing with matters spiraling into that bottomless hole and giving out a wild death scream of X-rays. There are stars that pulsate endlessly in a great cosmic breathing. And others that, having consumed their fuel, expand and redden until they swallow up their planets if they have any. And someday, billions of years from now, our sun will expand and the earth will crisp and sear and vaporize into a gas of iron and rock with no sign of the life it once bore. And some stars explode in a vast cataclysm whose ferocious blast of cosmic rays hurrying outward at nearly the speed of light reaching across thousands of light years to touch the earth and supply some of the driving force of evolution through mutations. Those paltry few stars we see as we look up in perfect silence, some 2,500 no more on even the darkest and clearest night are joined by a vast horde we don't see up to as many as 300 billion to form an enormous pinwheel in space. This pinwheel, the Milky Way Galaxy, stretches so widely that it takes light, moving at 186,282 miles each second, 100,000 years to cross it from end to end. And it rotates about its center in a vast and stately turn that takes 200 million years to complete. And the sun and the earth and we ourselves all make that turn. Beyond our Milky Way Galaxy are others, a score or so of them bound to our own in a cluster of galaxies, most of them small with no more than a few billion stars in each, but with one at least the Andromeda Galaxy twice as large as our own. Beyond our own cluster, other galaxies and other clusters exist, some clusters made up of thousands of galaxies. They stretch outward and outward as far as our best telescopes can see, with no visible sign of an end, perhaps 100 billion of them in all. And in more and more of those galaxies we are becoming aware of violence at the center, of great explosions and outpourings of radiation, marking the death of perhaps millions of stars. Even at the center of our own galaxy there is incredible violence, masked from our own solar system far in the outskirts by enormous clouds of dust and gas that lie between us and the heaving center. Some galactic centers are so bright that they can be seen from distances of billions of light years, distances from which the galaxies themselves cannot be seen, and only the bright star-like centers of ravening energy show up as quasars. Some of these have been detected from more than 10 billion light years away. All these galaxies are hurrying outward from each other in a vast universal expansion that began 15 billion years ago, when all the matter in the universe was in a tiny sphere that exploded in the hugest conceivable shatter to form the galaxies. The universe may expand forever, or the day may come when the expansion slows and turns back into a contraction to reform the tiny sphere and begin the game all over again so that the whole universe is exhaling and inhaling in breaths that are perhaps a trillion years long. And all of this vision, far beyond the scale of human imaginings, was made possible by the work of hundreds of learned astronomers. All of it, all of it was discovered after the death of Whitman in 1892, and most of it in the past 25 years, so that the poor poet never knew what a stultified and limited beauty he observed when he looked up in perfect silence at the stars. Or can we know, or imagine now, the limitless beauty yet to be revealed in the future by science? Thanks for watching.