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| | Sun-Earth Day 2004 Venus Transit |
 | | Most people, when they think of a "planet", imagine a large roundish body with a rocky surface and an atmosphere, just the kind that cool science fiction stories are written about. |
 | | Pluto is a bit of an outlier, and generally considered a KBO or Kuiper Belt Object or TNO (Trans-Neptunian Object), referring to its probable origins outside the orbit of Neptune in a region where comets are thought to form. |
 | | Focusing now just on Earth and its closest neighbors, we can compare just the three terrestrial planets, Venus, Earth, and Mars, and we find that, although they have many things in common as we just mentioned, they are also worlds apart in many equally important respects. |
| sunearth.gsfc.nasa.gov /sunearthday/2004/vt_planetary_2004.htm (519 words) |
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