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The 7 Planets of the Ancients

The 7 Planets of the Ancients - anything in common 2 Uranus...

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The 7 Planets of the Ancients The term "planet" originally meant "wanderer": it was observed long ago that certain points of light wandered (changed their position) with respect to the background stars in the sky. In ancient times, before the invention of the telescope and before one understood the present structure of the Solar System, there were thought to be 7 such wanderers or planets: Mercury, Venus, Mars, Jupiter, Saturn, the Moon, and the Sun. This list is different in several respects from our modern list of planets: 1. The Earth is missing, because it was not understood that the points of light wandering on the celestial sphere and the Earth on which we stood had
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Unformatted text preview: anything in common. 2. Uranus, Neptune, and Pluto are missing because they would only be discovered when the telescope made them easily visible. o Uranus is barely visible to the naked eye; it was discovered in 1781. o Neptune and Pluto are too faint to see at all without a telescope; they were discovered in 1846 and 1930, respectively. 3. The Sun and the Moon were classified as planets because they wandered on the celestial sphere, just like Mars and Jupiter and the other planets. A central theme of our initial discussion will be how the "7 planets of the Ancients" (only 5 of which are really planets) evolved into our present list of Solar System planets....
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