Cosmos - Carl Sagan [79]
But the Earth does move. Merton, if he lived today, would be obliged to deduce “infinite, habitable worlds.” Huygens did not shrink from this conclusion; he embraced it gladly: Across the sea of space the stars are other suns. By analogy with our solar system, Huygens reasoned that those stars should have their own planetary systems and that many of these planets might be inhabited: “Should we allow the planets nothing but vast deserts … and deprive them of all those creatures that more plainly bespeak their divine architect, we should sink them below the Earth in beauty and dignity, a thing very unreasonable.”*
These ideas were set forth in an extraordinary book bearing the triumphant title The Celestial Worlds Discover’d: Conjectures Concerning the Inhabitants, Plants and Productions of the Worlds in the Planets. Composed shortly before Huygens died in 1690, the work was admired by many, including Czar Peter the Great, who made it the first product of Western science to be published in Russia. The book is in large part about the nature or environments of the planets. Among the figures in the finely rendered first edition is one in which we see, to scale, the Sun and the giant planets Jupiter and Saturn. They are, comparatively, rather small. There is also an etching of Saturn next to the Earth: Our planet is a tiny circle.
By and large Huygens imagined the environments and inhabitants of other planets to be rather like those of seventeenth-century Earth. He conceived of “planetarians” whose “whole Bodies, and every part of them, may be quite distinct and different from ours … ’tis a very ridiculous opinion … that it is impossible a rational Soul should dwell in any other shape than ours.” You could be smart, he was saying, even if you looked peculiar. But he then went on to argue that they would not look very peculiar—that they must have hands and feet and walk upright, that they would have writing and geometry, and that Jupiter has its four Galilean satellites to provide a navigational aid for the sailors in the Jovian oceans. Huygens was, of course, a citizen of his time. Who of us is not? He claimed science as his religion and then argued that the planets must be inhabited because otherwise God had made worlds for nothing. Because he lived before Darwin, his speculations about extraterrestrial life are innocent of the evolutionary perspective. But he was able to develop on observational grounds something akin to the modern cosmic perspective:
What a wonderful and Amazing scheme have we here of the magnificant vastness of the universe … So many Suns, so many Earths … and every one of them stock’d with so many Herbs, Trees, and Animals, adorn’d with so many Seas and Mountains!… And how must our Wonder and Admiration be increased when we consider the prodigious Distance and Multitude of the Stars.
The Voyager spacecraft are the lineal descendants of those sailing-ship voyages of exploration, and of the scientific and speculative tradition of Christiaan Huygens. The Voyagers are caravels bound for the stars, and on the way exploring those worlds that Huygens knew and loved so well.
One of the main commodities returned on those voyages of centuries ago were travelers’ tales,* stories of alien lands and exotic creatures that evoked our sense of wonder and stimulated future exploration. There had been accounts of mountains that reached the sky; of dragons and sea monsters; of everyday eating utensils made of gold; of a beast with an arm for a nose; of people who thought the doctrinal disputes among Protestants, Catholics, Jews and Muslims