The GEMINI constellation - myths, facts and location

By Jake Riley, SR Senior Editor

Fun Facts

1. Gemini means ‘twins’ in Latin
2. The brightest star of Gemini, Pollux, is the closest giant star to Earth
3. The second brightest, Castor isn’t actually a single star, but a sextuple star system
4. Of the six stars that make up Castor, two are three times bigger than our Sun
5. Every December, a meteor shower—Geminids—occurs within Gemini’s borders

An overview

The constellation of Gemini makes up two almost straight lines, with said lines connecting at the top and diverging at the bottom. The constellation consists of 17 main stars, with the two brightest, Pollux and Castor, denoted as the heads of the twins. The former is nine times bigger than our sun and about double its mass, while the latter is actually a six-star system with its primary star having a radius and mass twice and thrice that of our sun.

It is one of the 12 Greek Zodiac constellations, though the Egyptians depict the very same constellation as twin goats rather than twin humans, and the Arabians depicting them as twin peacocks. It is visible in all of the Northern hemisphere and most of the Southern hemisphere, from winter to spring in the former and only in the summer months of the latter.

The myth

In Greek mythology, there was a set of twin brothers named Castor and Pollux. They were born from the same mother, Queen Leda of Sparta, but apparently had different fathers. Castor was fathered by the queen’s husband, the King of Sparta, while Pollux was the son of Zeus, who had ravished the Spartan Queen disguised as a swan.

Also, the twins were not born from orthodox childbirth, but had hatched from an egg along with two sisters, Clytemnestra and Helen of Troy. As the twins grew older, they formed a close bond with one another, and soon became known as a single entity, the Dioscuri.

However, in another land lived another related set of twin brothers, who—over time—saw the Dioscuri as their rivals. Both pairs of twins were involved in the voyage of Jason and the Argonauts, and briefly entertained a truce between them, though this didn’t last for long.

The mortal Castor was eventually killed by the other twin pair. Taking pity on Pollux, Zeus decided to reunite the twin brothers by placing both of them amongst the stars, and hence the Gemini constellation was birthed.

The constellation

The Constellation of Gemini is situated in the northern sky’s second quadrant, and is visible between latitudes -60 to +90 degrees. It lies between Cancer and Taurus, neighboring Orion, and is the 30th largest constellation in the Earth’s night sky.

Of the 17 main stars it consists, there exists nine celestial bodies of note: Pollux, the brightest star of Gemini and the 17th brightest star in the Earth’s night sky; Castor, the second brightest star of Gemini which is a six-star system; Wasat, which is a three-star system; Melbuda, a supergiant star with surface temperatures matching our sun; Mebsuta, a yellowish-orange supergiant that has twenty times our sun’s mass; Alzirr, a yellow-white star, Alhena, a white star, Tejar Posterior, a red giant 2,500 times more luminous than our sun; and Propus, a three-star system also referred to as Tejar Prior or Eta Geminorum.

Want to learn about other constellations aside from Gemini? Find out more about Cancer or Leo. Alternatively, you can simply click here for a full list of constellations.