An ancient constellation, Gemini a winter group represents a pair of twins holding hands. They are Castor and Pollux members of the crew of the ship Argo with Jason in search of the golden fleece. The fleece had come from a magic Ram which had been able to fly, after it died its fleece was placed in a sacred grove, guarded by a dragon which Jason killed and he took the fleece back to his own country.
Castor and Pollux were of mixed parentage although both sons
of Leda, Castor’s father was king Tyndareus of Sparta while the father of
Pollux was the god Zeus. When Castor died, because he was mortal, Pollux begged
his father Zeus to give Castor immortality, and he did, by uniting them
together in the heavens.
Gemini is a splendid zodiac constellation, and it was known
by a variety of names. The Anglo Saxons called the twins ge Twisan while the
Anglo Normas called them Frere.
The Arab astronomers knew Gemini as either Al Tau’ aman or
sometimes as Al Burj al Jauza. In the early Arabic period of astronomy, the two
bright stars of Gemini were seen as one of the fore paws of the great ancient
lion. The Persians called the two stars Du Palkar or the Two Figures while the
Khorasmians knew them as Adhupakarik which meant the same.
In India the twins were known as Acvini the Ashwins of
Horsemen, a name also found in other parts of the sky for other Hindu twin
deities.
The Gemini were the Ape of the early Chinese solar zodiac
and were known as Shih Chin. Later the constellation was known as the Yin Yang
the Two Principles.
Castor and Pollux the twins sailed on the ship the Argo with
Jason looking for the golden fleece and in helping their fellow crew in
surviving a storm that nearly overwhelmed the ship. they were often seen by
sailors as bringing good luck to a ship.
The incident in the storm associated with the twins was what
we would today call St. Elmo's Fire. This is a type of continuous electric
spark you've seen it many times before, since it is almost exactly the same as
the glows found inside fluorescent tubes. When it occurs naturally, we call it
St. Elmo's Fire, but when it occurs inside a glass tube, we call it a neon
sign.
St Elmo’s fire was seen as a good omen for sailors and would
bring good luck to their ship. St. Elmo's fire is named after St. Erasmus of
Formia (also known as St. Elmo), the patron saint of sailors.
A reference to Gemini can be found in the Bible, in The Acts
of the Apostles xxviii, 11 we read that: -
The twin Brothers were the sign of the figurehead of the
ship which St Paul and his companions travelled in on the eventful voyage that
ended with the shipwrecked on a small island near Malta.
Alpha or Castor to the Arabic astronomers it was Al Ras al
Taum al Mukaddim, or the Head of the Foremost Twin, an earlier Araic name was
Al Awwal al Dhira, the First in the Paw or Forearm.
The Babylonians said that Castor was Mash-mashu-Mahru, the
Western One of the Twins, while with Pollux the two constituted
Mas-tab-ba-gal-gal the Great Twins. In Assyria the twins were known as Mas-mas
and Tuamu.
Although Castor looks like a single star it is a multiple star containing six stars. The brightest is Castor with a magnitude of 1.9, it’s an A class star with a surface temperature of around 10,000 degrees and is 49 light years away.
Beta or Pollux to the early Arab astronomers it was known as
Al Thani al Dhira, the Second in the Forearm. Later Arab astronomers called it
Al Ras al Taum al Mu’ah-h-ar or the Head of the Hindmost twin.
The Babylonians referred to Pollux as Mash-mashu-arku, or
the Eastern One of the Twins.
Pollux has a magnitude of 1.1 making it brighter than
Castor, it is a K class giant star with a surface temperature of 4,600 degrees
and is 34 light years away.
There is a minor mystery here because Ptolemy in the 2nd
century stated that Castor was brighter than Pollux whereas now it is the other
way around, the Arab astronomers agreed with Ptolemy. So, if the old
astronomers were correct, we must suppose that either Castor has faded or else
Pollux has brightened up. It seems more likely that the change would have
occurred in Pollux.
Gamma or Alhena which means the Shining One, an early Arabic
Name is Al Maisan or the Proudly Marching One, however the Arab astronomer Al
Firuzabaldi said that this term could be applied to any bright star.
Alhena is an A class star with a magnitude of 1.9 and d a
surface temperature of 9,000 degrees, the star is 109 light years away.
Mu is occasionally known as Tejat Posterior or Rear Foot and
sometimes as Nuhata. Mu is 230 light years away and is a M class red giant star
with a surface temperature of 3,500 degrees. The star is a variable star; these
means it varies in brightness. These variations can be followed with the naked
eye. The light from the star varies between magnitude 2.7-3.0 in a period of
around 70 days.
Eta or Tejat Propus which means Forward Foot is another M class red giant star with a surface
temperature of about 3,500 degrees. This is another variable star. Eta varies
between magnitude 3.1-3.9 over a period of around 230 days. As with Mu these
variations can be followed with the naked eye. The star lies at a distance of
about 320 light years.
It was close to eta Gemini that William Herschel discovered
the planet Uranus in 1781
Delta or Wasat which is from the Arabic Al Wasat which means
Middle is an F class star with a surface temperature of 6,700 degrees and
is 60 light years away, It shines at a
magnitude of 3.5.
William Lassel of Liverpool gave a wonderful description of
M35 in 1846. He viewed it through his
24-inch reflector. A marvellously striking object one can see it for the first
time without exclamation so said William Lassell a 19th century astronomer who
discovered the largest moon of Neptune, Triton in 1846 from Liverpool.
But this 5th mag open cluster is equally exquisite when seen
through small telescopes or binoculars. It can be seen by the naked eye as a
mottled splash of hazy light. The cluster has a diameter of around 20 light
years. It has a decidedly rectangular shape. As it is an open cluster it is
made up of young stars, M35 is located 2,800 light-years from Earth,
Lying at the end of Gemini it is close to the 6th mag star 5
Gemini not too far from Mu and Eta. The number of stars in M 35 seem to vary
from observer to observer but there appear to be between 200-300 stars. The
central stars form the shape of the number 8
It was discovered by Philippe Loys de Chéseaux in 1745 and
independently discovered by John Bevis before 1750.
Observed by Messier in 1764 who described it as a cluster of
faint stars close to the left foot of Castor not far from the stars eta and mu.
I will just finish off with NGC 2392 a very well-known deep
sky object in Gemini, which used to be called the Eskimo Nebula but today is
known as the Clown Face Nebula. This is a Planetary Nebula discovered by
William Herschel in 1787. The Clown Face Nebula is around 6,500 light years
away.
www.theramblingastronomer.co.uk
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