The Moon Switch will switch a mains power line on and off depending on the light level. When it is light the power will be off and when it is dark the power will be on. The difference between the on and off levels has been adjusted so that the unit does not flicker at the triggering point nor will it switch on and off due to minor variations in brightness. Essentially the unit detects day and night and can therefore switch things on that are required during the night. The range of items that can be switched is only limited by a maximum load of 600 watts and the imagination. Most uses will include switching on heaters that are only required during the night. On of the major advantages of the Moon Switch is that the natural day/night cycle is duplicated including the seasonal variations of long day length summers and short day length winters.