What is an Equinox? The Science Behind It!

Over time, the Earth’s position has changed, bringing about different seasons and climates. But do you know how these seasons are determined?

The reason is simple: the Earth does not rotate in a straight line, but on a tilted axis.

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Because different parts of the Earth receive different amounts of sunlight during the year, it causes the seasons to change. It also causes the equinoxes and solstices, marking important points in the Earth’s orbit around the Sun.

But do you know what an equinox is? When does it occur? And how does it differ from a solstice? There are many questions that need to be answered to truly understand the impact of Earth’s axis tilt on our planet’s seasons and weather patterns.

What is the equinox?

Imagine searching the internet for the meaning of the equinox and getting this result: “An equinox is an astronomical phenomenon characterized by a twice-yearly event during which the plane of the Earth’s equator passes through the geometric center of the Sun’s disk.

This celestial alignment leads to a transient state of equilibrium in which the day-night cycle behaves approximately isotropically, resulting in a quasi-bifurcation of the photoperiod for the entire Earth.”

That’s hard to understand, isn’t it? Unless you have a degree in astronomy or a strong background in scientific terminology, deciphering such a complex definition can be quite challenging.

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However, to make it easier for everyone to understand, here is the simplest explanation: the spring equinox is when the sun is directly above the equator, resulting in equal days and nights. This phenomenon occurs twice a year, in March and September.

Equinox = Spring Equinox

The Science Behind the Equinox

We all know that the Earth revolves around the Sun, but did you know that this motion is responsible for the change of seasons? The Earth does not rotate in a straight line, but rather on a tilted axis.

Because of this tilt, the Northern and Southern Hemispheres receive different amounts of light at different times of the year, creating the seasons we experience.

Sometimes the Northern Hemisphere receives more direct sunlight, creating summer, while the Southern Hemisphere receives less direct sunlight, creating winter. This phenomenon is called axial tilt.

But at some point, the sun hits the equator, creating an equal number of nights and day. This moment is called the spring equinox. This balance of light and darkness occurs twice a year and marks the beginning of spring and fall.

What is the difference between the solstices and the equinoxes?

The solstices and equinoxes occur because of the tilt of the Earth’s axis as it orbits the sun. However, their meanings and events are slightly different.

Before we dive into what the solstice is, there are three important latitudes you should first know about: the Tropic of Cancer, the Tropic of Capricorn, and the Equator.

The Tropic of Cancer is at 23.5 degrees north latitude. The equator is the circle where the sun shines directly at noon. The Tropic of Capricorn is at 23.5 degrees south latitude.

Due to the tilt of the Earth’s axis, the sun’s rays hit different latitudes at different angles throughout the year, causing seasonal changes. When the sun’s rays hit the Tropic of Cancer directly, the summer solstice occurs in the Northern Hemisphere, marking the longest day of the year.

Likewise, the Southern Hemisphere does not receive the maximum amount of sunlight, resulting in the winter solstice, the day with the shortest daylight of the year.

Conversely, the winter solstice, when the sun’s rays hit the Tropic of Capricorn, causes the shortest day of the year in the Northern Hemisphere. In the Southern Hemisphere, this marks the summer solstice, the longest day of the year.

When does the Spring Equinox occur?

There are two equinoxes each year, one around March 21 (the spring equinox) and one around September 23 (the autumnal equinox). During these times, the lengths of day and night are nearly equal because the Earth’s equator is aligned with the center of the Sun.

Source: https://dinhtienhoang.edu.vn
Category: Optical Illusion