Monday, February 28, 2011

2011 Constellation Guide: Gemini


Gemini


Symbolism:  The Twins
Main Stars: 17

Position in the Sky
  • Right Ascension: 7 hours
  • Declination:  20 degrees
  • Visible between latitudes 90 and -60 degrees
  • Best seen in February (at 9:00 PM)
Named Stars
  • Castor (Alpha Gem)
  • Pollux (Beta Gem)
  • Alhena (Gamma Gem)
  • Wasat (Delta Gem)
  • Mebsuta (Epsilon Gem)
  • Mekbuda (Zeta Gem)
  • Propus (Eta Gem)
  • Propus (Iota Gem)
  • Tejat (Mu Gem)
  • Alzirr (Xi Gem)
  • Propus (1 Gem)

Messier Objects
  • M35 - Open cluster

Meteor Showers
  • Geminids - A major annual shower.  Ranges from as early as December 6 to December 18, with maximum on December 13/14.  Zenithal Hourly Rate can range from 50-80.
  • Rho Geminids - A very minor shower.  Ranges from December 28 to January 28 with maximum around January 8.  ZHR less than 1.
Mythology
The proximity of Castor and Pollux drew attention of ancient astronomers around the globe, who almost always saw them as counterparts.  The Chinese saw them as the universal principals of Yin and Yang  The Egyptians saw them as a pair of plants, the Arabs as two peacocks, the Phoenicians as a pair of kids or gazelles.  The Romans sometimes associated them with Romulus and Remus, the founders of their nation.  The affiliation that has stuck depicts them as Castor and Pollux, known to the Greeks as the Dioscuri (sons of Zeus).  Members of Jason's crew of Argonauts, Castor and Pollux were 'half-twins' - their mother was Quen Leda of Sparta, but Castor's father was her husband King Tyndareus, while Pollux was fathered by Zeus, who came to Leda in the form of a swan.

Features
Gemini is pretty easy to locate thanks to its twin stars Castor and Pollux.  The Twins sit high above Orion, east of Taurus.  Castor may appear as a single star to the unaided eye, but a telescope will split the bright blue star into a pair, and may also reveal a third star, a magnitude 9.3 red dwarf.  Actually, Castor is a sextuple star system, but amateur equipment cannot reveal this.  Pollux is the brightest star in Gemini, and one of the brightest in the sky.  It is an orange super giant, and is known to have a planetary system.
Messier 35 is an open cluster, and a great object to see through your scope.  There are several hundred stars packed into an area of the sky about the size of the full Moon.  A faint object can be found east of Wasat, the Eskimo Nebula.  This is a magnitude 10 planetary nebula, and may be at the edge of vision for many suburban locations.  It will appear as a blue-green disc, but with large equipment you may be able to resolve the features in the gas


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