The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North Pole. Owing to the Earth's axial tilt, winter in the Northern Hemisphere lasts from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer lasts from the June solstice through to the September equinox (typically September 23 UTC). The dates vary each year due to the difference between the calendar year and the astronomical year. Its surface is 60.7% water, compared with 80.9% water in the case of the Southern Hemisphere, and it contains 67.3% of Earth's land.The Southern Hemisphere is the half of Earth that is south of the Equator. It contains all or parts of five continents (Antarctica, Australia, about 90% of South America, a third of Africa, and several islands off the continental mainland of Asia), four oceans (Indian, South Atlantic, Southern, and South Pacific) and most of the Pacific Islands in Oceania. Its surface is 80.9% water, compared with 60.7% water in the case of the Northern Hemisphere, and it contains 32.7% of Earth's land. Owing to the tilt of Earth's rotation relative to the Sun and the ecliptic plane, summer is from December to March and winter is from June to September. September 22 or 23 is the vernal equinox and March 20 or 21 is the autumnal equinox. The South Pole is in the center of the southern hemispherical region.
