Formation and evolution of the Solar System depletion period that brought the asteroid belt down close to its present mass is thought to have followed when Jupiter and Saturn entered a temporary 2:1 orbital resonance (see below). The inner Solar System's period of giant impacts probably played a role in the Earth acquiring its current water content (~6 kg) from the early asteroid belt. Water is too volatile to have been present at Earth's formation and must have been subsequently delivered from outer, colder parts of the Solar System. The water was probably delivered by planetary embryos and small planetesimals thrown out of the asteroid belt by
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