Earth tide lunar and the solar tidal maxima and minima (bulges and depressions) add together for the greatest tidal range at particular latitudes. At first- and third-quarter phases of the moon, lunar and solar tides are perpendicular, and the tidal range is at a minimum. The semi-diurnal tides go through one full cycle (a high and low tide) about once every 12 hours and one full cycle of maximum height (a spring and neap tide) about once every 14 days. The development of a systematic theory of Earth tides was started by George H. Darwin in 1879, and was then furthered by
Full moon and the names "harvest moon" and "hunter's moon" for the full moons of autumn. The "harvest moon" and "hunter's moon" are traditional terms for the full moons occurring during late summer and in the autumn, in the northern hemisphere usually in September and October respectively. The "harvest moon" is the full moon closest to the autumnal equinox (22 or 23 September), coming anywhere from two weeks before to two weeks after that date. The "hunter's moon" is the full moon following it. The names are recorded from the early 18th century. The "Oxford English Dictionary" entry for "harvest moon" cites