Spring Equinox: What is it?

The term ” equinox » comes from Latin aequinoctiumwhich binds aequs (equal to nox (night), and designates the moment when the duration of the day is equal to that of the night.

For the spring equinox, this generally occurs on the 20th or 21st of the month depending on the year (57 times on March 21 during the XX^and century). In 2016, Leap yearit was March 20 at 5:30 a.m. It hadn’t come this early since 1896. In 2018, the equinox is March 20 at 5:15 p.m. It will remain March 20 until 2044. By 20 occasions, it will take place on March 19 during the XXI^and century.

The beginning of spring in the northern hemisphere

For people in the northern hemisphere, this date marks the beginning of spring. The days keep getting longer until summer solsticeJune 21, the date of the end of the spring. In contrast, in the southern hemisphere, autumn begins. The length of the days gradually decreases until winter solsticeJune 21st.

The March Equinox occurs when, from Earth’s perspective, we observe that the Sun reaches the point (or knots) at the intersection of plane of the ecliptic where he walks – the plan of theorbit planets – andcelestial equator (projection in the sky of the terrestrial equator). I’star of the day then passes in the northern half of the celestial vault. Since our planet is tilted, the celestial equator crosses the plane of the ecliptic twice.

Seen from the Sun, during the two equinoxes, the blue planet appears equally illuminated in both hemispheres.