Chasing Hubble's Shadows The Search for Galaxies at the Edge of Time

Excerpted fromChasing Hubble's Shadowsby Jeff Kanipe. Copyright 2006 by Jeff Kanipe. Published February 2006 by Farrar, Straus and Giroux, LLC. All rights reserved 1 HUNTING FOR SNARKS In the midst of the word he was trying to say, In the midst of his laughter and glee, He had softly and suddenly vanished away For the Snark was a Boojum, you see. Lewis Carroll, "The Hunting of the Snark" "The cup of the Big Dipper contains over four hundred galaxies," said the planetarium director, emphasizing his remark by rapidly circling the famous star grouping with his red pointer. "Just imagine," he continued, "if there are that many galaxies confined to just this tiny area, then there must be hundreds of millions of galaxies scattered across the entire sky, each containing tens of billions of stars." And with that, he turned a dial on his console, and the stars began to march majestically across the sky to the opening strains of Henry Mancini's "Theme fromA Summer Place." Fittingly, it was late summer 1968 and the first time I had ever set foot in a planetarium. My youthful interest in astronomy was still rudimentary, but already I had learned and could recognize on sight most of the constellations. I watched the familiar patterns rise in the east, drift overhead, and disappear in the west as the impossibly high strings of "Summer Place" soared in the background. Perhaps I am easily amused, but I was wowed. Thirty-six years later, with the public release of the Hubble Ultra Deep Field (HUDF)the deepest, farthest look into the universe ever mademy first-time planetarium experience came back to me and I was wowed all over again. Astronomers at the Space Telescope Science Institute in Baltimore announced that a region of sky just three thousandths the size of the cup of the Big Dipper contains at least ten thousand galaxies! That's an area you could easily cover with a pencil eraser held at arm's length. Assuming that the distribution of galaxies is similar across the sky, the number of galaxies embraced by the Big Dipper's cup would be well over 190 million, counting all those down to the faintest ones seen in the HUDF. If you extrapolate these values to the number of potentially observable galaxies across the entire sky, you get a truly mind-boggling number: 127billion! Of course, the true population, consisting of these galaxies plus those that cannot be, or have yet to be, detected with current telescopes, would be far greater. We know how deep Earth's oceans are. We know the width and breadth of the solar system. The size of the Milky Way is no longer in question; nor is the expanse of space lying between the nearby galaxies. But just how deep is the universe? Such a question has the most profound implications, because in this case,deepimplies more than size and distance on the grandest of scalesit implies age as well. Some of the galaxies in the Hubble Ultra Deep Field, for example, lie more than 12 billion light-years away. But that immensity also represents a span of timelookback timeof more than 12 billion years in the past, because it has taken that long for the photons from these remotest known galaxies to reach Earth, despite zipping along at a velocity of 300,000 kilometers per second. Hence the universe is far richer than people thought it was in the 1960s or, for that matter, in the three decades that followed. And today the answer still eludes astronomers. Not even the acute vision of the Hubble Space Telescope, the instrument used to make the remarkable HUDF image, can survey such realms. Still, the HubbKanipe, Jeff is the author of 'Chasing Hubble's Shadows The Search for Galaxies at the Edge of Time', published 2007 under ISBN 9780809034079 and ISBN 0809034077.