Terrestrial planet from the original solar nebula. The Solar System has four terrestrial planets: Mercury, Venus, Earth, and Mars. Only one terrestrial planet, Earth, is known to have an active hydrosphere. During the formation of the Solar System, there were probably many more terrestrial planetesimals, but most merged with or were ejected by the four terrestrial planets. Dwarf planets, such as Ceres, Pluto and Eris, and small Solar System bodies are similar to terrestrial planets in the fact that they do have a solid surface, but are, on average, composed of more icy materials (Ceres, Pluto and Eris have densities of 2.17,
One of Our Aircraft Is Missing Submarines; a "" episode "One of Our Planets Is Missing"; the final episode of the US television series "Maverick", titled "One of Our Trains Is Missing"; the episode "One of Our Dogs is Missing" from the US television series "Lost in Space"; the episode "One of Our Assemblymen is Missing" from the US sitcom "Green Acres"; the episode "Two of Our Weirdos Are Missing" from the US sitcom "Laverne & Shirley"; the episode "One of Our Stately Homes is Missing" from the British spy-spoof cartoon series "Danger Mouse"; a 1991 text adventure game by Zenobi called "One of Our Wombats