Equinox – Concept, characteristics and what is the solstice

We explain what the equinox is, some of its characteristics and history. Also, what are its differences with the solstice.

Equinox - Solstice
The equinox occurs twice a year, at the end of March and September.

What is the equinox?

Equinox is called any of the two moments of a year when 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 ground).

This happens twice a year, at the end of the months of March and September, depending on whether it is the spring or autumn equinox, respectively, and serves to formally mark the beginning of these seasons in each earth’s 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 alludes to the fact that that day, night and day have approximately the same duration throughout the world, since the parallel of the Sun’s inclination coincides with the equator in the middle of the planet.

The equinoxes are also used as a point of reference in astronomy, and in many human cultures has important significance in the religious or cosmological tradition, since it marked the rebirth of life after winter (spring), and therefore a time of celebration and fertility rites to start the harvest; but also the beginning of decay, cooling and death (autumn), and therefore a time of withdrawal, intimacy and reflection.

Equinox and solstice

Solstice - Equinox
The solstices are the opposite and complementary degree of the equinoxes.

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 hot to cold or vice versa (depending on the hemisphere), the solstices instead they are determined by the positioning of the Sun on the imaginary lines of the tropics terrestrial (Cancer and Capricorn, according to the constellations located in them) and thus producing the most extreme points of climate and temperature on the planet: winter and summer.

The solstices are thus the opposite and complementary degree of the equinoxes, in which the Sun transits instead 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.

Follow on: Solstice