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The Science Behind Mercury’s Retrograde

Source: New York Post

Mercury in retrograde is the phenomenon of Mercury seemingly moving backwards in the night sky, this is due to an optical illusion named Apparent retrograde motion. Apparent retrograde motion occurs when a planet seems to temporarily change the direction of its orbit, while realistically, it doesn’t actually move backwards. The illusion occurs in a span of weeks or months.

Both Mercury and Earth are in orbit around the Sun, though moving in the same direction, inner planets will move faster than those further from the star. This means that every so often, Mercury will lap our planet. Every 4 months when Mercury laps Earth, Apparent retrograde motion will take place. For about 3 weeks Mercury will seem to loop back its orbit as the planet passes us by and our line of sight shifts. Below are a series of photos demonstrating how the phenomenon takes place.

The small yellow circle represents the Sun, the smaller inner planet is Mercury and the other is Earth. The straight black line shows the Earth’s view of mercury against the stars we see in the night sky, and the yellow line represents the path or mercury which we observe.
During this period of the orbits, Mercury begins its retrograde illusion. From Earth Mercury will be seen moving backwards.
Here, Mercury would seem to slow down and turn back around.
After the Retrograde, Mercury continues to orbit forward.

Apparent Retrograde Motion also occurs with planets further from the Sun than Earth. In fact, though having a less common occurrence than Mercury, the Apparent Retrograde Motion of Mars can be tracked more easily than that of Mercury. This is because it lies on the dark side of our planet.

The retrograde motion of Mars in 2005

These images can be captured by combining several shots of the planet in the night sky, lining up the stars in the background throughout the period of the retrograde.

The same theory is applied when Mars is in retrograde. When our planet overtakes Mars, our faster motion makes Mars appear to orbit in the opposite direction. Earth’s orbit around the sun is about 24% further and faster than that of Mars. Even near perihelion (the point at which the planet is closest to the star in its orbital path), Mars only moves 10% faster than usual, this means it never moves around the Sun faster than Earth.

Aristotle’s geocentric model of the Solar System described the Earth as the centre of the system and the universe. This meant that the moon, the Sun, and all known planets of the Solar System were in orbit around the Earth. However, after discovering the phenomenon of planets retrograding, Aristotle’s model seemed flawed.

In the 3rd Century AD, mathematician, astronomer, astrologer, geographer and music theorist — Plotemy, improved on Aristotle’s model. He stated that planets moved in two revolutions, a deferent cycle and an epicycle. His theory explained the retrograde motion while remaining Aristotle’s model of Earth being the centre of the universe.

Figure of the heavenly bodies — An illustration of the Ptolemaic geocentric system by Portuguese cosmographer and cartographer Bartolomeu Velho, 1568 (Bibliothèque Nationale, Paris)

Later on, an astronomer Nicolaus Copernicus presented the Heliocentric Model, this would be known as the modern model that we use today. This Heliocentric Model presented the Sun as the centre of the Solar System. This Heliocentric Model solved the problem of the retrograding motion of the planets in a more elegant manner.

Astrological Beliefs began in Mesopotamian times. It developed its western form from Greek civilisation during the Hellenistic period. Greek tradition states that the heavens are divided according to the 12 constellations of the zodiac. The tradition believes that spiritual influences over human affairs are related to the bright stars that rise in intervals of the mentioned constellations.

Those who practise astrology, Mercury’s retrograde symbolises a period of renovation. The period of which Mercury is in retrograde is associated with confusion, delay, and frustration. Depending on which of the 12 zodiac constellations are seen in the background of stars, Mercury’s retrograde determines how differently or intensely it will affect the associated signs.

With more than half of Americans aged 18–24 believing that Astrology is a science, there are no known links proving the characteristics of personality to their natal charts. Astrological readings and horoscopes were infamous for being included in the back of magazines, however today’s generation of teens and millennials are all aboard the astrology bandwagon.

Source: The Atlantic

One reason Astrology has become so popular today is to do with its accessibility. Thanks to the internet, the world of astrology is at one’s fingertips: in a matter of seconds anyone is able to find their star signs and natal charts, along with the effects it has on their personality traits and the fate of their existence. It also provides comfort in times of stress, providing an explanation to individuals as to why their lives are heading south. This especially played a factor during the pandemic as more individuals suffered from anxiety and depression.

In recent times, a shift away from organised religion has been seen. Many young adults in today’s era have begun to stray away from their religion, thus the trends of astrology plays the role of a guiding belief system. Gaining insight from horoscopes and seeing how relatable the information is to themselves and the world feeds on the belief of Astrology.

On the other hand, today’s generation is far more logical in believing the fate of astrology. With all the information in the world in our back pockets, Gen Z is the most well informed generation. But despite understanding astrology is unlikely to mean anything, it doesn’t stop young adults and teens from cracking jokes about the stars when it relates to them.

[Written By: Nurrania Alfian. Edited By: Balvin Dhaliwal]



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TLMUN Herald

A not-for-profit publication under the Taylor’s Lakeside Model United Nations Club which focuses on amplifying the voices of the youth of today.