Gemini the Twins
Gemini the Twins is another of the Zodiac constellations.   The constellation has been known as the twins since ancient times but the name Gemini is thought to originate with the Romans.   In the Southern Hemisphere they appear to us as standing on their heads in the northern sky during the warmer months of the year.

An excerpt from Johan van Keulen's Boeck zee-kaardt, 1709.
The black dashed line running through the Twins is the ecliptic,
the path the sun follows through the sky.  The symbol at
Castor's feet marks where the ecliptic meets the Tropic of Cancer.

The two bright stars, Castor and Pollux, mark the heads of the two brothers, one mortal and one the son of a god. Their mother was Queen Leda, the father of mortal Castor was her husband King Tyndarus and the father of Pollux was Zeus.  They were also brothers to Helen of Troy.  As most identical twins are, they were inseperable in both looks and actions.  Castor was a famed horseman and Pollux a reknowned boxer.  They were famous for being argonauts with Jason on the Argo and and after saving the mighty ship from a wild storm became the protectors of mariners.  The ghostly flame of St. Elmo's fire that sometimes appears on ships is also connected to them.  One day Castor was killed in a fight.  Distraught, Pollux pleaded with Zeus to let Castor reside with him on Mount Olympus.  Zeus took pity on his son and placed the brothers in the sky next to each other.  The Romans also connected this constellation with Romulus and Remus, the twins who founded Rome.

Astronomically Castor is an interesting star as it known to be a multiple system of six stars!  Few other stars come close to this number.  Not all are visible in a telescope though but the two main components are easily split. 

Alhena is the name for gamma (g) Geminorum, meaning a Brand or Mark.

Wasat, meaning the Middle, is the proper name for delta (d) Geminorum.  It is named so as it lies half way along the east side of the constellation. 

Mebsuta, epsilon (e) Geminorum, means the Outstretched [paw] and is a relic from ancient Arabian times when part of Gemini was contained in a larger constellation representing a lion, stretching from Gemini to Virgo.  Mekbuda, zeta (z) Geminorum, was the Contracted [paw].

The planet Uranus was in Gemini when on March 13th 1781 William Herschel first noticed a new star not on his charts.  He soon realised he could see a disk when he magnified it and it was moving across the sky.  The gas giant had been sighted several times before and even plotted on printed charts as a star but Herschel was the first to realise it wasn't an ordinary star. 

Two meteor showers are known to radiate from Gemini: The delta Geminids in early October and the Geminids in December.  The Geminids radiate from a point near Castor and are known to be the part of the debri stream following the asteroid 3200 Phaethon.  This is most unusual as most meteor showers are connected to comets.  You can read about the history of this shower here.

This article is ©2001 Stargazers Astronomy Shop

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