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,
Solid waste policy in the United States to more than 33%. The most recent numbers from the EPA indicate that in 2012 the US municipal solid waste recycle rate was 34.5%. This section describes the common methods of solid waste disposal practiced in United States and worldwide. Some of the main issues associated with waste are open dumping, odor, particulate matter emissions, leachate seepage from landfills, greenhouse gas (GHG) emissions that lead to air pollution, surface and groundwater pollution, food chain contamination, land area depletion, human health impacts, environmental degradation, and negative impacts on plant and animal life. All levels of government - federal, state, and local