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.I hate to imagine descriptive stellar astronomy today had that idea been adopted in the seventeenth century.The sky would be carved into two hundred tiny patches, one for each nation-state existing at the time.The naming of the solar system is fundamentally not a task for the exact sciences.It has historically encountered prejudice and jingoism and lack of foresight at every turn.However, while it may be a little early for self-congratulation, I think astronomers have recently taken some major steps to deprovincialize the nomenclature and make it representative of all of humanity.There are those who think it is a pointless, or at least thankless, task.But some of us are convinced it is important.Our remote descendants will be using our nomenclature for their homes: on the broiling surface of Mercury; by the banks of the Martian valleys; on the slopes of Titanian volcanoes; or on the frozen landscape of distant Pluto, where the Sun appears as a point of bright light in a sky of unremitting blackness.Their view of us, of what we cherish and hold dear, may be determined largely by how we name the moons and planets today.* Kowal has also recently discovered a very interesting small object orbiting the Sun between the orbits of Uranus and Saturn.It may be the largest member of a new asteroid belt.Kowal proposes calling it Chiron, after the centaur who educated many Greek mythological gods and heroes.If other trans-Saturnian asteroids are discovered, they can be named after other centaurs.CHAPTER 12LIFE IN THESOLAR SYSTEM“I see nobody on the road,” said Alice.“I only wish I had such eyes,” the King remarked in a fretful tone.“To be able to see Nobody! And at that distance too! Why, it’s as much as I can do to see real people, by this light!”LEWIS CARROLL,Through the Looking GlassMORE THAN three hundred years ago, Anton van Leeuwenhoek of Delft explored a new world.With the first microscope he viewed a stagnant infusion of hay and was astounded to find it swarming with small creatures:On April 24th, 1676, observing this water by chance, I saw therein with great wonder unbelievably very many small animalcules of various sorts; among others, some that were three to four times as long as broad.Their entire thickness was, in my judgement, not much thicker than one of the little hairs that cover the body of a louse.These creatures had very short, thin legs in front of the head (although I can recognize no head, I speak of the head for the reason that this part always went forward during movement) … Close to the hindmost part lay a clear globule; and I judged that the very hindmost part was slightly cleft.These animalcules are very cute while moving about, oftentimes tumbling all over.These tiny “animalcules” had never before been seen by any human being.Yet Leeuwenhoek had no difficulty in recognizing them as alive.Two centuries later Louis Pasteur developed the germ theory of disease from Leeuwenhoek’s discovery and laid the foundation for much of modern medicine.Leeuwenhoek’s objectives were not practical at all, but exploratory and adventuresome.He himself never guessed the future practical applications of his work.In May of 1974 the Royal Society of Great Britain held a discussion meeting on “The Recognition of Alien Life.” Life on Earth has developed by a slow, tortuous step-by-step progression known as evolution by natural selection.Random factors play a critical role in this process—as, for example, which gene at what time will be mutated or changed by an ultraviolet photon or a cosmic ray from space.All the organisms on Earth are exquisitely adapted to the vagaries of their natural environments.On some other planet, with different random factors operating and extremely exotic environments, life may have evolved very differently.If we landed a spacecraft on the planet Mars, for example, would we even be able to recognize the local life forms as alive?One theme which was stressed at the Royal Society discussion was that life elsewhere should be recognizable by its improbability.Take trees, for example.Trees are long skinny structures, above ground fatter at the top than at the bottom.It is easy to see that after millennia of rubbing by wind and water, most trees should have fallen down.They are in mechanical disequilibrium.They are unlikely structures.Not all top-heavy structures are produced by biology.There are, for example, pedestal rocks in deserts.But were we to see a great many top-heavy structures, all closely similar, we could make a reasonable guess that they were of biological origin.Likewise for Leeuwenhoek’s animalcules.There are many of them, closely similar, highly complex and improbable in the extreme.Without ever having seen them before, we correctly guess they are biological.There have been elaborate debates on the nature and definition of life.The most successful definitions invoke the evolutionary process.But we do not land on another planet and wait to see if any nearby objects evolve.We do not have the time.The search for life then takes on a much more practical aspect.This point was brought out with some finesse at the Royal Society discussion when, after an exchange remarkable for its rambling metaphysical vagueness, Sir Peter Medawar rose to his feet and said, “Gentlemen, everyone in this room knows the difference between a live horse and a dead horse.Pray, therefore, let us cease flogging the latter.” Medawar and Leeuwenhoek would have seen eye to eye.But are there trees or animalcules on the other worlds of our solar system? The simple answer is that no one yet knows.From the vantage point of the nearest planets, it would be impossible to detect photographically the presence of life on our own planet [ Pobierz całość w formacie PDF ]