History of Gemini Constellation

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One of 88 constellations defined by the Astronomical Union is the Gemini constellation. It is a group of galaxies and stars visible in northern and southern hemisphere during the winter and autumn. Two long spurs form the Gemini constellation joined at one end by the stars Castor and Pollux, and the other ends splits again into four short spurs. The constellation has four main stars that are visible to human eye, they are Wasat, Alhena, Pollux and Castor.

The name of the Gemini constellation is of Greek origin. However the stars forming Gemini as a constellation under different yet similar names and symbols were identified by other cultures of the near east and further away in the Indian subcontinent. It cannot be said with confidence that the ancient Greeks had more knowledge of stars and their positions, although it can be surely said that in modern times Greek names are continued to be used for the constellations.

More than 6000 years back, the Rigveda which is the Indian religious and historical text mentions the two primary stars of the Gemini constellation which appear as twin horseman early at dawn. They were part of the Ashvins known as Sahadeva and Nakula. During that time, the two stars were only visible at dawn during spring season. This led to the idea that they were twins and linked with the spring equinox. The two horseman were related to the two stars that are commonly known as Castor and Pollux. Mithuna is the Sanskrit name which means that the twins match almost the same as the modern Gemini constellation.

The constellation spreads from India to west to the ancient near east civilizations. The ancient Babylonian people had adopted the constellations for their own astronomy 5000 years back. They used it for navigations and to track the seasons. Gemini was known as Mastabba Galgal To the ancient Babylonian people. This is believed to be the translation for the great twins and heroes whose names were Gilgamesh and Enkidu. They fought with the gods in a series of epic battles on a quest for gaining immortality.

The twin stars were adopted by ancient Egyptians as an important part of their astronomy. They used two goats for symbolizing the two stars that were mentioned in the Ramissede Hour Tables which is a method to determine the time during any point at night which stars followed each other. These two Gemini constellation stars were known to rise at dawn.

The ancient Greek society was in its ascendency by the 1st millennium BC. However most of the ideas put forward by the Greek astronomers were not unique among the Gemini constellation's history. Many Greek constellations directly came from the astronomy of Babylonia although the legends about the origin of the constellation inspired from the Greek mythology. In particular, the Gemini constellation was believed to be the immortal twins called Castor and Polydeuces.

In Roman times, Castor and Polydeuces were known as Pollux. They were twin boys who were born to the Queen Leda of Sparta, the wife of King Tyndareus. The Greeks are of a view that Castor and Polydeuces were conceived on the same night along with their two sisters Helen and Clytaemnestra. Castor and Clytaemnestra were immortal and were the offspring of Tyndareus while Polydeuces and Helen were the offspring of Zeus, they were therefore immortal but not gods. The twins Castor and Polydeuces were inseparable in spite of having different fathers.

Castor and Polydeuces together had a lot of adventures which were a test of their different talents. Castor had the talent of horsemanship and archery while Polydeuces had the talent of his strength and boxing skills. Throughout known world, the twins were famous. They joined on his quest to find the Golden Fleece. The exact story behind the formation of Gemini constellation however relates to the tragedy of their love for two women who were promised to another man.

The two sisters were Phoebe and Hilaeira who were the daughters of Leucippus, he was an uncle of Castor and Polydeuces. He had made an agreement with Aphareus that his sons Lynceus and Idas would marry the daughters. The legend does not mention the love of Aphareus's daughters for Castor and Polydeuces. However in any event, they had found themselves in Sparta and they were married to Castor and Polydeuces, within a short time their sons were born. The unfortunate sons of Aphareus could not let this slight go unchallenged as it is definite in all great Greek tragedies.

Castor was ambushed and killed with spear by Idas who was returning from a cattle raid. Later it was felled by a thunderbolt hurled by Zeus in anger for Castors death. The immortal Polydeuces killed Lynceus in a fit of rage, he then pleaded with Zeus his father to let Castor live. Zeus agreed at a condition if he would either return to Olympus or share his immortality with Castor between Hades and Olympus. The constellation of Gemini is a picture of Castor and Polydeuces in the heavens.

Regardless of the knowledge of Gemini sign as representing the twin brothers, Castor and Polydeuces or Castor and Pollux as Romans used to know about them. The reality is that the story is not directly related to the two heroes.

The real meaning of the story is related to the stars having the same name of the boys which are the first to rise early in the morning at dawn. More importantly, the two stars only rise in the spring. Gemini sign has a particularly special position because of its association with rebirth and spring equinox.

Before the story of Castor and Polydeuces was told by the Greeks and Romans, other civilizations around were already aware of the twin stars. The twin stars were seen by Early Egyptians as two goats who return to their goat herd at dawn, including the two stars in their Ramissede Hour Tables. It was a useful scientific measurement of time during the day.

The name of Polydeuces was changed to Pollux by the Roman legends. All succeeding civilizations including the golden age of the Arab caliphate did not leave the Roman name for Pollux. Since then, the Gemini constellation has taken on a single personality owing to a legend that Castor and Pollux are the protectors of sailors and ships and manifested as St Elmo's fire. In ancient times, the sailors would call out 'By Gemini' for invoking their help. Today it has been corrupted to 'By Jimmy'.

In the Gemini constellation, Pollux is the brightest star. It is known as beta Geminorum in astronomical terms. It was announced in 1993 that Pollux, which is a bit more than 33 light years from the solar system has an extra solar planet which is thought to be nearly 2.3 times in size as compared to Jupiter. It takes 590 days to orbit Pollux. Astronomers were also expecting in 2006 that more technological advancement in telescopes and the search for other planets will surely verify planet covered by rocky water outside the habitable zone and further away from the star.

The term alpha Geminorum is also used for Castor. It is located nearly 51.6 light years away and is a featured star actually made up of six stars that are close to each other as a gravitational union. Giovanni Domenico Cassini discovered for the first time in 1678 that Castor is a visual binary star but the truth of this enigma was finally known in the 20th century when technological advancements in spectroscopy allowed astronomers to identify each star as a binary. These two sets of binary stars take 350 years to orbit each other fairly close together. While the third binary system orbits the four main stars from a bit greater distance but takes 10,000 years to complete.