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,
Solar hot water in Australia exported. Four of the original companies are still in business and the manufacturing base has now expanded to 24 companies. Water heating is the largest single source of greenhouse gas emissions from the average Australian home, accounting for around 28 per cent of home energy use (excluding the family car). The Australian government estimates that installing a climate friendly solar powered hot water system can save a family $300 to $700 off electricity bills each year. The solar hot water rebate program for financial year 2009 offered a $1600 rebate for the installation of solar powered hot water systems. The