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| | World Almanac for Kids |
 | | The discovery of Neptune was one of the triumphs of mathematical astronomy. |
 | | The average distance of Neptune from the sun is 4,498,252,900 km (2,795,084,800 mi), and its equatorial radius is 24,764 km (15,388 mi), or about 3.9 times that of the earth. |
 | | Neptune is never visible to the naked eye, but it can be observed in a small telescope as a small, greenish-blue disk without definite surface markings. |
| www.worldalmanacforkids.com /explore/space/neptune.html (404 words) |
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