Terrestrial planet Terrestrial planet A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars. The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth ("Terra" and "Tellus"), as these planets are, in terms of structure, "Earth-like". Terrestrial planets have a solid planetary surface, making them substantially different from the larger giant planets, which are composed mostly of some combination of hydrogen, helium, and water existing in various
Solar hot water in Australia greenhouse gas and carbon emissions. In the case of Victoria, for example, converting from electric to solar hot water could save 20% of the state's total greenhouse gas emissions. Despite an excellent solar resource, the penetration of solar water heaters in the Australian domestic market is only about 4% or 5%, with new dwellings accounting for most sales. During the 1950s, Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) carried out world leading research into flat plate solar water heaters. A solar water heater manufacturing industry was subsequently established in Australia and a large proportion of the manufactured product was