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The Planet That Wasn't. By Isaac Asimov

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My Comments/Review Of; The Planet That Wasn't - By Isaac Asimov - "In 1909, the American astronomer William Wallace Campbell went further, and stated categorically that there was nothing inside Mercury's orbit that was brighter than the eighth magnitude. That meant that nothing was there that was larger than forty-eight kilometers in diameter. It would take a million bodies of that size to account for the movement of Mercury's perihelion(2). With that, hope for the existence of Vulcan flickered nearly to extinction. Yet Mercury's perihelion did move. If Newton's law of gravitation was correct there had to be some sort of gravitational pull from inside Mercury's orbit. And, of course, there was, but it originated in a totally different way from that which anyone had imagined. In 1915, Albeit Einstein explained the matter in his General Theory of Relativity. Einstein's view of gravitation was an extension of Newton's--one that simplified itself to the Newtonian version under most conditions, but remained different, and better, under extreme conditions. Mercury's presence so close to the Sun's overwhelming presence was an example of the extreme condition that Einstein could account for and Newton not. Einstein's calculations showed that this effect just accounts for the motion of Mercury's perihelion, and accounted further for much smaller motions of the perihelia of planets farther out.After this, neither Vulcan nor any other Newtonian mass was needed. Vulcan was hurled from the astronomical sky forever. With a stone serving as a substitute for Zeus, you would surely be willing to allow the phrase "a stone" to be considered the equivalent of Zeus." Very well, then, who flung Hephaistos (the mythical Vulcan) from the heavens? Zeus! And who flung the planetary Vulcan from the heavens? Einstein! And what does ein stein mean in Einstein's native German? "A stone!" I rest my case." Isaac Asimov