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 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