Is Pluto a planet?
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Pluto: Planet or not? Before we can answer this question we needto know what the word planet is for, and that takes us back to the ancient greeks who calledMercury, Venus, Mars, Jupiter, Saturn, the Moon and sun planets. Basically if it movedacross the sky and was bright, it was a planet. This is a terrible start for the word because,1) it excludes Earth from the list and 2) it groups wildly different things together.But the greeks couldn't know how different the Moon was from Saturn, because the besttechnology they had to observe the Universe was sadly limited.It would take several thousand years until the industrious Dutch made the first telescopesand astronomy became much more interesting. Astronomers could now confidently rearrangethe solar system -- an elegant...
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Pluto: Planet or not? Before we can answer this question we needto know what the word planet is for, and that takes us back to the ancient greeks who calledMercury, Venus, Mars, Jupiter, Saturn, the Moon and sun planets. Basically if it movedacross the sky and was bright, it was a planet. This is a terrible start for the word because,1) it excludes Earth from the list and 2) it groups wildly different things together.But the greeks couldn't know how different the Moon was from Saturn, because the besttechnology they had to observe the Universe was sadly limited.It would take several thousand years until the industrious Dutch made the first telescopesand astronomy became much more interesting. Astronomers could now confidently rearrangethe solar system -- an elegant...
