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 from 01/10 2007 to 30/06 2009, offered all house owners in NSW a rebate on systems that were replacing existing electric hot water systems. The more efficient the system (emitting less Greenhouse gas), the more RECs the system was eligible for, generating a higher rebate. Power and Water Corporation, the principal water and electricity supplier in the Northern Territory, offers an REC buyback scheme on installations of solar water heaters. The buyback must be applied for and assigned less than one year after the installation. The Queensland Government's Solar hot water rebate scheme finished on 30 June 2005. No state