Today begins the first equinox of the year, known as “spring or vernal equinox”. At this time of year, since the sun is above the equator, days equal nights across the Earth.
Two such events are held every year: The The autumn (which begins today) and the vernal or fall equinox, with approximate dates between March 20-21 and September 21-22, respectively.
concept “moderation” It comes from the Greek words Negus: equus and nox: night, which together form the phrase “same night”. And indeed, it will be, but other than the fact that on this date the duration of day and night will be the same, do you know what happens there during the equinox?
“When moderation occurs, The sun is located above the Earth’s equator“, says National Geographic magazine. Therefore, the northern and southern hemispheres receive the same amount of sunlight and shade.
Nat Geo notes that this causes the separator, the line that divides the day and night zones, to pass through the planet’s north and south poles.
This apparent division of our 24-hour day is related to the same reason why the Earth has seasons. The planet rotates on an axis tilted 23.5 degrees from its orbital plane. This means that While the Earth revolves around an orbit of 365 days, the two hemispheres are tilted and thus are closer to or farther from the sun’s rays.
In other words, During the equinox, the sun reaches its zenith, the highest point in the sky at an angle of 90 degrees with respect to an object on Earth. Therefore, the ecliptic, the curved line that the Sun travels around the Earth, coincides with the celestial equator, whose axis of inclination is 23.5 degrees with respect to the ecliptic.
“At that time, the north and south poles were at the same distance from the sun and you could discern the vertical line known as the terminator, which indicates the division between day and night,” explains Nat Geo.
This angle causes the entire planet to experience the same amount of light and darkness during one day twice a year. These biannual phenomena, along with the two solar solstices on planet Earth, represent the change of season.
In the northern hemisphere, the vernal equinox turns winter into spring, while in the southern hemisphere it turns summer into autumn.
At the North Pole, the sun travels from six months to six months a day.Meanwhile, at the South Pole, the sun goes from six months in the day to six months at night.
In Ecuador, the sun passes its zenith at twelve o’clock.
Earth is not the only one with equinoxes
“All the planets of our solar system experience the equinoxes with their own characteristics”Nat Geo says, citing Mars, which has an inclination very similar to Earth’s, so it experiences the same kind of seasons, but its distance from the Sun means that Mars’ winter can last 154 days.
Also on some planets, seasonal changes can change the appearance of these celestial bodies. During Saturn’s vernal equinox, which occurs every 15 Earth years, the sun rises directly over the planet’s famous rings, drenching them in shadows that reveal its three-dimensional structure.
Also a planet that would be a nightmare for anyone with seasonal affective disorder (SAD).No winter depression) is Uranus. Its axis is tilted about 90 degrees, which means that it rotates on one side during its 84-year orbit around the Sun. This translates to endless winters lasting 42 years.
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