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.
Alpha or
Castor at magnitude 1.9 is the second brightest star in Gemini lying 51 light
years from Earth, Castor is an A class star with a temperature of around
10,000’c much hotter the Sun at 5,800’C. Although it appears to the naked eye
as a single star there are in fact 6 stars that make up the Castor system
Beta or
Pollux with a magnitude of 1.1 is the brightest star, Pollux is 34 light years
away and is a K class orange giant star.
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’ lies 109 light years away and is of
magnitude 1.9, it is an A class star.
Eta or
Propus which means ‘Forward Foot’ is a M class red giant star, Propus is a
variable star and its brightness changes between 3.1-3.9 over a period of
around 230 days. The star lies at a distance of about 320 light years.
Epsilon or
Mebsuta which means ‘Outstretched Arm’ shines with a brightness of 3.1 and lies
at a distance of 840 light years. It is a G class class supergiant star.
Delta or
Wasat which means ‘Middle’ is a F class star lying at a distance of 60 light
years away, It shines at a magnitude of 3.5.
Zeta or
Mekbuda which means the ‘Outstretched Left Leg, it’s a Cepheid variable varying
brightness between magnitude 3.7 and 4.1 every 10.2 days, Mekbuda is 1,200 light years away and varies
between a F7 supergiant to a G class supergiant class star.
Mu or Tejat
which means ‘Back Foot’ is 230 light years away and is a M class red giant star
that varies very slowly between magnitude 2.7-3.0 in a period of around 70
days.
Messier M 35
is an open cluster around 3,800 light years away containing about 400 stars.
M35 can be seen in the sky near eta as a magnitude 5.1 mottled splash of light.
Charles Messier saw M35 in 1746.
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