We explain what the equinox is, some of its characteristics and history. Also, what are its differences with the solstice.
What is the equinox?
Equinox is called any of the two moments of a year in which the Sun is located on the equatorial plane of the Earth, reaching according to the point of view of an observer located in the terrestrial equator, its maximum point or zenith (at 90 ° with respect to the I usually).
This happens twice a year, at the end of March and September, depending on whether it is the equinox of spring or that of autumn, respectively, and serves to formally mark the beginning of these seasons in each terrestrial hemisphere: in March it is spring in the North and autumn in the South, and vice versa in September.
The term equinox comes from the Latin aequus nocte ("equal night"), which refers to the fact that that day, the night and the day have approximately the same duration throughout the world, since the parallel of the Sun's inclination coincides with the equator. to the middle of the planet.
The equinoxes are also used as a point of reference in astronomy, and in numerous cultures human beings has an important significance in the tradition religious or cosmological, since it marked the rebirth of the life after winter (spring), and therefore a time of celebration and fertility rites to start the harvest; but also from the onset of decay, cooling and death (autumn), and therefore a time of withdrawal, intimacy and reflection.
Equinox and solstice
If the equinox is the point where the plane of the Sun coincides with the Earth's equator, making the day and night have the same length and marking the transition from the hot to the cold season or vice versa (depending on the hemisphere), the solstices are instead determined by the positioning of the Sun on the imaginary lines of the terrestrial tropics (Cancer and Capricorn, according to the constellations located in them) and thus producing the most extreme points of weather Y temperature on the planet: winter and summer.
The solstices are thus the opposite and complementary degree of the equinoxes, in which the Sun instead transits the constellations of Aries and Libra. Solstices usually occur at the end of June (summer solstice) and December (winter solstice) in the Northern Hemisphere, and vice versa in the Southern Hemisphere.