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among the wanderers。 We have found vast volcanic eminences that dwarf the highest mountain on Earth； ancient river valleys on two planets enigmatically one too cold and the other too hot for running water； a giant planet with an interior of liquid metallic hydrogen into which a thousand Earths would fit； whole moons that have melted； a cloud…covered place with an atmosphere of corrosive raids； where even the high plateaus are above the melting point of lead ancient surfaces on which a faithful record of the violent formation of the Solar System is engraved； refugee ice worlds from the transplutonian depths； exquisitely patterned ring systems； marking the subtle harmonies of gravity； and a world surrounded by clouds of plex organic molecules like those that m the earliest history of our planet led to the origin of life。 Silently； they orbit the Sun； waiting。
We have uncovered wonders undreamt by our ancestors who first speculated on the nature of those wandering lights in the night sky。 We have probed the origins of our planet and ourselves。 By discovering what else is possible； by ing face to face with alternative fates of worlds more or less like our own； we have begun to better understand the Earth。 Every one of these worlds is lovely and instructive。 But； so far as we know； they are also； every one of them； desolate and barren。 Out there； there are no 〃better places。〃 So far； at least。
During the Viking robotic mission； beginning in July 1976； in a certain sense I spent a year on Mars。 I examined the boulders and sand dunes； the sky red even at high noon； the ancient river valleys； the soaring volcanic mountains； the fierce wind erosion； the laminated polar terrain； the two dark potato…shaped moons。 But there was no life—not a cricket or a blade of grass； or even； so far as we can tell for sure； a microbe。 These worlds have not been graced； as ours has； by life。 Life is a parative rarity。 You can survey dozens of worlds and find that on only one of them does life arise and evolve and persist。
Having in all their lives till then crossed nothing wider than a layer； Leib and Chaiya graduated to crossing oceans。 They had one great advantage： On the other side of the waters there would be…invested with outlandish customs； it is true—other human beings speaking their language and sharing at least some of their values； even people to whom they were closely related。
In our time we've crossed the Solar System and sent four ships to the stars。 Neptune lies a million times farther from Earth than New York City is from the banks of the Bug。 But there are no distant relatives； no humans； and apparently no life waiting for us on those other worlds。 No letters conveyed by recent émigrés help us to understand the new land— only digital data transmitted at the speed of light by unfeeling； precise robot emissaries。 They tell us that these new worlds are not much like home。 But we continue to search for inhabitants。 We can't help it。 Life looks for life。
No one on Earth； not the richest among us； can afford the passage； so we can't pick up and leave for Mars or Titan on a whim； or because we're bored； or out of work； or drafted into the army； or oppressed； or because； justly or unjustly； we've been accused of a crime。 There does not seem to be sufficient short…term profit to motivate private industry。 If we humans ever go to these worlds； then； it will be because a nation or a consortium of them believes it to be to its advantage—or to the advantage of the human species。 Just now； there are a great many matters pressing in on us that pete for the money it takes to send people to other worlds。
That's what this book is about： other worlds； what awaits us on them； what they tell us about ourselves； and—given the urgent problems our species now faces—whether it makes sense to go。 Should we solve those problems first？ Or are they a reason for going？
This book is； in many ways； optimistic about the human prospect。 The earliest chapters may at first sight seem to revel overmuch in our imperfections。 But they lay an essential spiritual and logical foundation for the development of my argument。
I have tried to present more than one facet of an issue。 There will be places where I seem to be arguing with myself。 I am。 Seeing some merit to more than one side； I often argue with myself。 I hope by the last chapter it will be clear where I e out。
The plan of the book is roughly this： We first examine the widespread claims made over all of human history that our world and our species are unique； and even central to the workings and purpose of the Cosmos。 We venture through the Solar System in the footsteps of the latest voyages of exploration and discovery； and then assess the reasons monly offered for sending humans into space。 In the last and most speculative part of the book； I trace how I imagine that our long…term future in space will work itself out。
Pale Blue Dot is about a new recognition； still slowly overtaking us； of our coordinates； our place in the Universe and how； even if the call of the open road is muted in our time； a central element of the human future lies far beyond the Earth。
CHAPTER 1 YOU ARE HERE
The entire Earth is but a point； and the place of our own habitation but a minute corner of it。
—MARCUS AURELIUS； ROMAN EMPEROR； MEDITATIONS； BOOK 4 （CA。 170）
As the astronomers unanimously teach； the circuit of the whole earth； which to us seems endless； pared with the greatness of the universe has the likeness of a mere tiny point。
—AMMIANUS MARCELLINUS ACA。 330…395； THE LAST MAJOR ROMAN HISTORIAN； IN THE CHRONICLE OF EVENTS
The spacecraft was a long way from home； beyond the orbit of the outermost planet and high above the ecliptic plane—which is an imaginary flat surface that we can think of as something like a racetrack in which the orbits of the planets are mainly confined。 The ship was speeding away from the Sun at 40；000 miles per hour。 But in early February of 1990； it was overtaken by an urgent message from Earth。
Obediently； it turned its cameras back toward the now…distant planets。 Slewing its scan platform from one spot in the sky to another； it snapped 60 pictures and stored them in digital form on its tape recorder。 Then； slowly； in March； April； and May； it radioed the data back to Earth。 Each image was posed of 640；000 individual picture elements （〃pixels〃）； like the dots in a newspaper wire…photo or a pointillist painting。 The spacecraft was 3。7 billion miles away from Earth； so far away that it took each pixel 5？ hours； traveling at the speed of light； to reach us。 The pictures might have been returned earlier； but the big radio telescopes in California； Spain； and Australia that receive these whispers from the edge of the Solar System had responsibilities to other ships that ply the sea of space among them； Magellan； bound for Venus； and Galileo on its tortuous passage to Jupiter。
Voyager 1 was so high above the ecliptic plane because； in 1981； it had made a close pass by Titan； the giant moon of Saturn。 Its sister ship； Voyager 2； was dispatched on a different trajectory； within the ecliptic plane； and so she was able to perform her celebrate