Equinox day

Equinox day

Hello friends. Today is a day of great importance from the physical and astronomical point of view for our planet. Today, March 20, the equinox occurred. The equinox (from the Latin aequinoctium, meaning equal night) is the time of the year when the sun is in the plane of the Earth's equator, or to put it more properly, the time of the year when the plane of the ecliptic intersects the celestial equator. For this reason, the angle of inclination between these planes is 0°, so the sun rises exactly at the cardinal point east and sets at the cardinal point west. In addition, the length of day and night is practically the same in both hemispheres.

For the northern hemisphere, spring begins today, and the sun changes from negative declination (with respect to the celestial equator) to positive declination. On the other hand, for the southern hemisphere, the sun changes from positive to negative declination, thus initiating the autumn season. From the poles, the sun does not rise above the horizon, but describes a grazing circle.

It is traditionally said that the Earth is today at the Aries point, because at the beginning of the Christian era, the Earth on this date was in front of the constellation Aries. But nowadays, due to the precession movement of the Earth, the point where the equinox occurs has retrograded on the ecliptic and the Earth is in front of the constellation Pisces.