Stability of the Solar System essentially the distance from sun to earth). These are now known as the Kirkwood gaps. Some asteroids were later discovered to orbit in these gaps, but their orbits are unstable and they will eventually break out of the resonance due to close encounters with a major planet. Another common form of resonance in the Solar System is spin–orbit resonance, where the period of spin (the time it takes the planet or moon to rotate once about its axis) has a simple numerical relationship with its orbital period. An example is our own Moon, which is in a 1:1 spin–orbit resonance
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