Although the meteorological autumn It began on September 1st, astronomical level will take place next Sunday, September 22, when the so-called officially starts “autumn equinox”.
The autumnal equinox, as it is also known, marks the end of summer and the beginning of autumn. However, this date is not fixed and can vary from year to year, falling between September 21 and 24.
According to the National Aeronautics and Space Administration (POT)the event occurs when the Sun’s rays directly illuminate the equator line and the northern and southern hemispheres receive the same amount of sunlight.
“The equinoxes are the moment in the Earth’s orbit when the tilt of the Earth’s axis is not pointing towards or away from the Sun, but exactly sideways. The Earth’s axis is then perpendicular to the direction of the Sun. The dividing line between light (day) and darkness (night) then runs from pole to pole.” says NASA on its website.
The word “equinox” comes from Latin, whose original word is “aequinoctium”, which is divided into “aequus”, which means “equal” and “nox or noctis”, which means “night”, according to the Royal Spanish Academy (RAE).
This year’s autumn equinox will be at 8:43 a.m. (Puerto Rico time) on September 22, and from then on, nights will begin to last longer than days in the Northern Hemisphere, due to the movement of the light field toward the Southern Hemisphere.
However, every six months, once in March and once in September, an equinox divides the day on planet Earth almost in half, giving about 12 hours of daylight and 12 of night, the magazine highlights. National Geographic.
The equinoxes occur around March 21 (“spring equinox” or “vernal equinox”) and September 22 (“autumn or autumnal equinox”), when the field of illumination from the sun’s rays is tilted toward latitudes 23.5 degrees South and 23.5 degrees North, respectively, NASA says.
After the autumn equinox, the northern hemisphere will have its winter season, while the southern hemisphere of the Earth will have its summer period.
Therefore, the northern hemisphere will have shorter days, while the southern hemisphere will have longer days.