Constellation: Gemini

Gemini

Gemini constellation is located in the northern hemisphere of the sky. Its name means “the twins” in Latin.

Gemini is one of the zodiac constellations, first catalogued by the Greek astronomer Ptolemy in the 2nd century. The constellation represents the twins Castor and Pollux (Polydeuces), also known as the Dioscuri in ancient times, in Greek mythology. The constellation’s symbol is .

Gemini is known mainly for its two bright stars, Castor and Pollux, the neutron star Geminga, and several notable deep sky objects, among them the open cluster Messier 35, the Eskimo Nebula, the Jellyfish Nebula, and the Medusa Nebula.

Gemini is one of the constellations of the zodiac. It was one of the 48 constellations described by the 2nd century AD astronomer Ptolemy and it remains one of the 88 modernconstellations today. Its name is Latin for "twins," and it is associated with the twins Castor and Pollux in Greek mythology.

MYTH

Gemini constellation – Johannes Hevelius, Prodromus Astronomia, volume III: Firmamentum Sobiescianum, sive Uranographia, table DD: Gemini, 1690.

Gemini constellation represents the twins Castor and Polydeuces in Greek mythology. The brothers were also known as the Dioscuri, which means “sons of Zeus.” In most versions of the myth, however, only Polydeuces was Zeus’ son, and Castor was the son of the mortal King Tyndareus of Sparta.

The twins’ mother, Spartan Queen Leda, was raped by Zeus, who visited the queen in the form of a swan, associated with the constellation Cygnus (the Swan), and she became pregnant with Polydeuces and Helen (who would become the famous Helen of Troy). Leda later also became pregnant with Castor and Clytemnestra (who would later marry Agamemnon and eventually murder him and be killed by her own son Orestes). Castor and Clytemnestra were fathered by Tyndareus and, unlike Zeus’ children, they were mortal.

Castor and Polydeuces grew up together and were very close. Castor was an excellent horseman and proficient at fencing – he is said to have taught Heracles himself to fence – and Polydeuces was famed for his boxing skills. The two were part of the Argonauts’ expedition to get the Golden Fleece. Polydeuces’ boxing skills came in handy when Amycus, a son of Poseidon who ruled Asia Minor, refused to let the Argonauts leave until one of them fought him in a boxing match. Polydeuces accepted the challenge and easily won.

The twins came to the crew’s rescue on a number of occasions. They have been known as the patron saints of sailors, and were said to have been given the power to rescue sailors who were shipwrecked by the sea god Poseidon himself, who also gave them two white horses, which the twins often rode.

The Dioscuri are associated with St. Elmo’s fire, an electrical phenomenon that occurs during thunderstorms, when a coronal discharge from a pointed object in a strong electric field creates luminous plasma. The phenomenon is named after another patron saint of sailors, St. Erasmus of Formiae. St. Elmo’s fire would appear to sailors as a glowing ball of light during thunderstorms and they considered it as a sign that their guardian saint was with them.

Castor and Polydeuces eventually clashed with Idas and Lynceus, who were also twins and former Argonauts, over two women, Phoebe and Hilaira. The other two brothers were engaged to them, and Castor and Polydeuces carried the women off. Idas and Lynceus pursued them and in the end there was a fight between the four. Lynceus stabbed Castor with a sword and when Polydeuces saw this, he killed Lynceus. When Idas saw his brother die, he attacked Polydeuces, but Zeus intervened and sent a thunderbolt which saved his son. Polydeuces asked Zeus to share his immortality with his dead brother and the god placed them both in the sky, where they remain inseparable as the constellation Gemini.

The two brightest stars in the constellation, Alpha and Beta Geminorum, mark the twins’ heads.

Not everyone identified the constellation as Castor and Polydeuces in ancient times. Hyginus and Ptolemy associated the two stars with Apollo and Heracles, who were half-brothers and both sons of Zeus.

FACTS, LOCATION & MAP

Gemini is the 30th largest constellation in the sky, occupying an area of 514 square degrees. It lies in the second quadrant of the northern hemisphere (NQ2) and can be seen at latitudes between +90° and -60°. The neighboring constellations are Auriga, Cancer, Canis Minor, Lynx, Monoceros, Orion and Taurus.

Gemini belongs to the Zodiac family of constellations, along

with Aries, Taurus, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricornus, Aquarius and Pisces.

Gemini contains a Messier object – the star cluster Messier 35 (M35, NGC 2168) – and has seven stars with known planets. The brightest star in the constellation is Pollux, Beta Geminorum, with an apparent magnitude of 1.14. There are two meteor showers associated with the constellation; the Geminids and the Rho Geminids. The Geminids are usually bright and peak around December 13-14.

Gemini Constellation Map, by IAU and Sky&Telescope magazine

References:

http://www.constellation-guide.com/constellation-list/gemini-constellation/ https://en.wikipedia.org/wiki/Gemini_(constellation) /