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Interesting Facts About the Gemini Constellation
Gemini is a constellation high in the winter sky, containing a number of interesting observing targets.
Credit: Starry Night Software

The sign of the twins in the zodiac, the Gemini constellation looks very much like its namesake. It’s easy to spot in the sky, located northeast of Orion and lying between Taurus to the west and Cancer on the east. It’s also the northernmost constellation in the zodiac.

The constellation derives its name from the Latin word for twins. One can easily see its two brightest stars, Castor and Pollux, as the heads of the twins while other stars make up faint outlines of the bodies.

Some interesting facts about Gemini:

  • The brightest stars, Castor and Pollux, are named after twin brothers in Greek mythology.
  • Pollux is an orange giant meaning it has used up all its core hydrogen fuel. Astronomers say such a star will likely slough off its outer shell and evolve into a white dwarf.
  • Castor is actually six stars that are gravitationally-bound to each other making it a sextuplet star system.  Light from Castor takes 50 light-years to reach us while Pollux, which is slightly brighter, takes 35 light-years.
  • Mekbuda, a super-giant star about 220, 000 times larger than our sun, also lies in Gemini. Other noted objects are the Eskimo Nebula, Medusa Nebula and Geminga, a neutron star.
  • A 100 million year old star cluster, Messier 35, lies near the “feet” of the twins.

The constellation of Gemini was spotted many centuries ago and recorded by the ancient Greek astronomer Ptolemy.  Depictions of the constellation typically show young twin boys seated close together. In the zodiac, the sign of Gemini represents the time between May 20 and June 20.