Über die Autorin bzw. den Autor

Jeff Kanipe (Derwood, MD), a respected science writer and editor, is the author of Chasing Hubble’s Shadow, The Arp Atlas of Peculiar Galaxies, and A Skywatcher’s Year, among other works. Formerly, he was the managing editor of Astronomy magazine, the editor-in-chief of StarDate magazine, and a columnist and feature writer for space.com.

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THE COSMIC CONNECTION

HOW ASTRONOMICAL EVENTS IMPACT LIFE ON EARTHBy JEFF KANIPE

Prometheus Books

Copyright © 2009 Jeff Kanipe
All right reserved.
ISBN: 978-1-59102-667-9

Contents

Introduction..........................................91. Tilt-a-Whirl World.................................152. An Imperfect Sun...................................393. A Temperamental Sun................................654. At Any Time........................................875. Keep Your Distance.................................1256. There Goes the Neighborhood........................1537. Keep Watching the Skies!...........................1858. Exotica............................................2239. The Ultimate Cosmic Connection.....................251Acknowledgments.......................................265Notes.................................................267Index.................................................289

Introduction

As sentient creatures, we humans have been looking at the heavens for tens of thousands of years, give or take, and yet civilization's reach has made little more than a chalk jot on the great wall of time. But during that time we've gone from fashioning stone tools to achieving scientific and technological breakthroughs bordering on the miraculous. In the twentieth century alone, old-timers could tell striplings that they lived in a time before the automobile and the airplane but also lived to see artificial satellites moving silently among the stars of the night sky, astronauts ambling on the Moon, and pictures taken from the surface of Mars. We now live in a period of on-the-verge science, typified by exciting new insights in quantum mechanics, genetics, nanotechnology, and stem cell research. One can only wonder what the next 10,000 years will bring!

Alas, if only humankind could be characterized by such positive strides. Unfortunately, there is no getting around the fact that our forward momentum has too often been severely compromised by our inherent impulses toward infamy beyond comprehension. While I certainly don't agree with W. S. Gilbert that humankind is "Nature's sole mistake," it does seem, sometimes, as if we are Nature's experiment-one that, hopefully, will turn out to be a success.

Our ascendancy as a species is usually credited to Darwinian processes, such as passing along traits from one generation to the next, genetic mutations that improve an organism's chances of survival, successful adaptations of organisms to different regions or environments, and the flourishing of one species over another. Nevertheless, evolution alone is not enough to explain the ascension of the human race on this amazing planet. In its most sweeping terms, life also results from conditions not of our world but of our universe. Some of these, like the motion of the Sun through the Galaxy, might be said to be mechanical in nature. Others, like the impact of a comet or asteroid on Earth, could be considered random, capricious events. In any case, evolution would have taken a two-dimensional path without them.

Long before protohumans dropped from the trees and began playing with fire and scribbling on cave walls, even before the Sun emerged from its chrysalis of dust and irradiated its nascent brood of planets, numberless and nameless astronomical events steered the course and direction of the Earth and its emerging life-forms. These astronomical factors contributed to giving the Earth its early advantage in the cosmic game of life. Others can be credited with maintaining, even nurturing, that life. These include the Earth's location in space, its stable orbit around the Sun, the fact that it has a satellite that prevents the planet's rotational axis from tipping wildly, and the even temperament of its star. We can literally thank our lucky stars we are here because as any astronomer will tell you, the developmental history of any planet, much less one with life sticking to it, is fraught with peril and uncertainty. You don't have to look very far into the Galaxy, or even our own solar system, to realize that were the Earth located someplace else, even by a small distance, our so-called habitable zone might not be so habitable. Stars are not, by and large, life-form-friendly. The vast majority are too cool to nurture anything beyond the most rudimentary organisms, while a smaller fraction are too short-lived and volatile to host habitable planets. In any galaxy, one of the biggest factors for successfully engendering life on an earthlike planet (never mind self-aware life) is that it maintains a comfortable distance from its home star, and especially from other potentially deadly stars in the vicinity, whose explosive deaths could result in the destruction of the atmosphere or in undesirable mutagenetic effects. Civilization might not have gotten very far had the Star of Bethlehem been a nearby supernova.

To be sure, no astronomical event can be said to have had any adverse biological or ecological impact at all during the last 2,000 or even 10,000 years. Comets may have buzzed past, asteroids skittered off our atmosphere, and stars exploded near enough to light up our skies during the day-but no cosmic event has lifted a deadly hand toward Earth and probably won't in our lifetime or a hundred lifetimes. Only when you assume an astronomical perspective does it become obvious that there is no such thing as cosmic isolation. A civilization that lives long enough won't have to go to the stars; the stars will come to it.

The effects of these cosmic interventions both giveth and taketh away. Dying stars are the seeds of life. Nitrogen, found in complex organic molecules called polycyclic aromatic nitrogen heterocycles, or PANHs for the rest of us, forms in abundance around dying stars and star-forming regions. Since interstellar space is full of dying stars and their nebulae, PANHs must exist in every corner of the Galaxy, including our own. And indeed they do, and not just in our Galaxy but throughout the universe. More important, however, since much of the chemistry of life requires organic molecules containing nitrogen, it stands to reason that the nitrogen in our DNA was sown across space by previous generations of indiscriminate, dying stars.

Comets, too, may have played a role in sowing life on Earth. When a comet called LINEAR strayed too close to the Sun in 2000 and broke up into a chain of icy debris, astronomers analyzed the fragments and discovered that they were not only made up of water but that the water had a chemical composition similar to water on Earth. This finding bolstered what has been a controversial theory, that comets in the early solar system seeded the Earth billions of years ago with water and essential molecular building blocks. These comets would not have formed in the frozen depths of the outer solar system but in the warmer environs around the planet Jupiter, where reactions in the primordial gases would have produced greater amounts of organic molecules as well as a just-right balance of "heavy water," which is composed of hydrogen, oxygen, and the form, or isotope, of hydrogen called deuterium. On the other hand, it's also apparent that the stars fell on the dinosaurs sixty-five million years ago in the form of an asteroid the size of Mount Everest, the impact of which resulted in their extinction. Had that asteroid's path through the inner solar system been even slightly different, it would have missed the Earth entirely, as countless asteroids do all the time, and perhaps might have been shunted off to some other nether region of the solar system. But as...