The myth of Gemini made simple: how Pollux shared his immortality with Castor, and what Japan and China call the twin stars

The myth of Gemini is the story of two devoted brothers, Castor and Pollux. In the winter sky, two bright stars shine side by side.

Yet the twins do not have just one father. Some stories make both of them sons of Zeus, while others say only one was.

How Castor died also depends on the ancient source. And people in Japan, China and Australia gave the same two stars quite different names and stories.

In this article you will find:

• The outline of the Gemini myth, including a short version for children
• Which twin is the elder, and who their parents were
• Why Castor died, and how the ancient versions of the shared immortality differ
• The Dioscuri, the Argonauts, and the twins as protectors of sailors
• Japanese names such as Kin-boshi and Gin-boshi (gold and silver stars), and the Chinese Beihe and Jing
• How to find Gemini using the Winter Triangle and the Winter Hexagon

The key point is this: the myth of Gemini turns the fact that two stars always stand together into a promise between brothers.

In short, what is the myth of Gemini?

The myth of Gemini tells how Castor died in battle and how his brother Pollux shared his own immortality with him.

Their mother was Leda, queen of Sparta. In most of the old stories, Pollux is a son of Zeus, king of the gods.

A son of Zeus could not die. Castor, however, was the son of the mortal king Tyndareus, and death was his fate.

When Castor fell in battle, Pollux begged Zeus. He did not want immortality if he could not share it with his brother.

Zeus granted his wish. From then on, the two spent alternate days in heaven among the gods and in the world below.

And the two, it is said, became a constellation of two stars shining side by side.

What changes from source to source is the name of the father and the reason Castor died. The sections below set out each version with its source.

How would you tell the Gemini myth to a child?

For children, the myth of Gemini is "the story of two brothers who did not want to be apart, even in death."

Long ago in Sparta, in Greece, there lived two brothers called Castor and Pollux. They never quarrelled, and they talked everything over before they did it.

Castor, the elder, was a fine horseman. Pollux, the younger, was a champion boxer.

Pollux was a son of Zeus, the king of the gods, and he could never die. Castor was an ordinary human.

One day Castor was killed in a fight. Pollux wept and begged Zeus.

"I don't want to be the only one who can't die. Please let my brother and me share it half and half."

Zeus turned the two brothers into stars in the night sky. Even now, the two stars shine next to each other.

Which is the elder, Castor or Pollux?

In Japanese guides to the Gemini myth, the fainter Castor is the elder brother and the brighter Pollux the younger.

The Gifu City Science Museum's newsletter says the same. It calls the white star big brother Castor and the yellow star little brother Pollux.

In the English translations of the ancient texts we checked, however, we found nothing that clearly says which twin was born first.

The twins go by several names.

• Castor: Kastor in Greek
• Pollux: Polydeukes in Greek; Pollux is the Latin form
• Together: the Dioscuri (Dioskouroi, "sons of Zeus") or the Tyndaridae (Tyndaridai, "sons of Tyndareus")

The two group names already show that the stories disagree about the father.

Was the twins' father Zeus or Tyndareus?

In the Gemini myth, the ancient sources describe the twins' father in three different ways.

Leda is said to have lain with Zeus, who came to her in the form of a swan. Around the same time she also lay with her husband, King Tyndareus.

In Hyginus's Fabulae 77, Leda bore Pollux and Helen to Zeus. To Tyndareus she bore Castor and Clytemnestra.

The star-lore writer Ian Ridpath calls the second version the most commonly accepted. Pollux and Helen are immortal, while Castor and Clytemnestra are mortal.

Why did Castor die in the Gemini myth?

In the Gemini myth, Castor died in a quarrel with their cousins Idas and Lynceus. The cause is told either as a cattle raid or as a fight over brides.

Idas and Lynceus were a pair of brothers too. Both pairs are said to have sailed together on the Argo.

In Apollodorus, the twins lay in wait, but Lynceus spotted Castor and Idas killed him. Pollux then killed Lynceus with his spear.

A rock thrown by Idas knocked Pollux senseless. At that moment Zeus struck Idas with a thunderbolt.

In every version Pollux avenges his brother, and Zeus's thunderbolt ends the fight. What differs is how the quarrel began.

How does Ovid tell the story in the Fasti?

In Ovid's Fasti, the myth of Gemini is told as a fight over brides.

The twins carried off Phoebe and her sister, daughters of Leucippus. The two women were betrothed to Idas and Lynceus.

The twins could have outrun their pursuers. But winning by flight seemed shameful, so they stood and fought at a place called Aphidna.

Lynceus's sword pierced Castor's chest. Pollux at once speared Lynceus where the neck meets the shoulders.

How did Pollux share his immortality in the Gemini myth?

In the Gemini myth, Pollux chose to share his place in heaven with his brother. The two pass alternate days in heaven and below the earth.

Pindar's Nemean Ode 10 tells the scene in detail. Pollux ran back to his brother and found him still breathing, but close to death.

Weeping, Pollux begged Zeus to let him die with his brother. Zeus offered him two paths.

• To live alone, free of death, beside the gods on Olympus
• To share everything with his brother, spending half his days below the earth and half in heaven

Pollux, the poem says, did not hesitate and chose the second. He gave up half of his immortality to share his brother's fate.

In Ovid's Fasti, Pollux asks his father to divide between the two of them the heaven reserved for him. Half of the gift, he says, will be worth more than the whole.

Which ancient texts tell of the alternate days in heaven and below?

The idea of the alternate days in the Gemini myth already appears in Homer's Odyssey.

Among the shades Odysseus sees in the underworld, the twins are said to be held by the earth, yet alive. One day they live, and the next they are dead.

In Homer's Iliad, book 3, Helen looks for her brothers from the walls of Troy. But they already lay in the earth of their homeland.

The Theoi Project, which collects translations of ancient myths, offers a guess. The coming and going between heaven and the underworld may reflect that Gemini is visible for only about half of the year.

Who were the Dioscuri, protectors of sailors and heroes of the Argo?

Dioscuri is the joint name for Castor and Pollux, meaning "sons of Zeus." In ancient Greece and Rome, people prayed to them as gods who rescue sailors on stormy seas.

The twins are also said to have joined Jason and the Argonauts on their quest for the Golden Fleece.

Ridpath retells a scene from the Argonautica of Apollonius of Rhodes. Amycus, king of a land where the Argo put in, challenged the crew to a boxing match.

Pollux accepted and felled Amycus with a single blow. His fame as a boxer runs through this story too.

Why did the twins become protectors of sailors?

In the Gemini myth, saving the Argo from a storm is told as the reason the twins became the sailors' protectors.

Diodorus of Sicily tells how the Argo was caught in a great storm. When Orpheus prayed to the gods of Samothrace, the wind dropped and two stars fell above the heads of the twins.

According to Diodorus, ever since then sailors caught in storms have taken the appearance of two stars as the twins coming to help.

Hyginus's Astronomica 2.22 explains it another way. Poseidon, god of the sea, gave the twins horses to ride and the power to save shipwrecked men.

What does St Elmo's fire have to do with Gemini?

Ancient sailors believed that St Elmo's fire, the glow on a mast during a storm, was the twins appearing.

St Elmo's fire is a bluish glow at the tips of masts and rigging during storms. It is caused by electricity in the air.

The Roman writer Pliny says in his Natural History that if two such lights appear, they foretell a safe voyage. They are called Castor and Pollux.

A single light was called Helena and was taken as a sign of disaster. Two lights together, like two stars together, were a sign that the twins were near.

Is Gemini sometimes Apollo and Heracles?

There is also an old view that the two figures in Gemini are Apollo and Heracles.

In the 3rd century BC the poet Aratus called the constellation simply "the Twins" without saying who they were. Later, Eratosthenes identified them as the Dioscuri.

Hyginus reports the alternative that they are Apollo and Heracles. Both are sons of Zeus, but they are not twins.

In Flamsteed's star atlas (1729), one twin holds a lyre and an arrow and the other a club, Ridpath notes.

The lyre and arrow belong to Apollo and the club to Heracles. The star charts kept this view alive in their pictures.

What are Gemini's stars called, and how do Castor and Pollux differ?

Source: SIMBAD (CDS Strasbourg), V magnitude

The brightest star in Gemini is Pollux, the younger brother. Castor, the elder, looks a little fainter.

Yet Castor carries the letter alpha, usually given to the brightest star, while Pollux is beta.

Ridpath explains that Johann Bayer, who assigned the letters, ordered them by position rather than by brightness.

Their colours differ too. Pollux looks yellow to orange, Castor white.

• Pollux: first magnitude, yellowish, about 34 light years away
• Castor: second magnitude, whitish, about 51 light years away

They are twin stars, but not true siblings. They lie at different distances and only happen to appear side by side.

Among the other names, Propus means "forward foot." It marks the tip of Castor's leading foot.

What is Gemini called in Japan? What are Kin-boshi and Gin-boshi?

In Japan, the two stars of Gemini were called Kin-boshi (金星, gold star) and Gin-boshi (銀星, silver star) for their colours. Yellow Pollux is the gold star and white Castor the silver star.

The Gifu City Science Museum's newsletter for February 2026 introduces them as old names. It does not say which region used them.

The characters for Kin-boshi are the same as those for the planet Venus (kinsei), but the reading and the object are different.

Are there regional Japanese names for Gemini?

In Toyama Prefecture, in Yokata (Toyama City) and Shinminato, the two stars of Gemini were called Futatsu-boshi (フタツボシ, two stars).

The name comes from a Toyama science-education resource based on Masuda Masayuki's book on the star lore of Etchu (old Toyama).

In Greece two brothers, in Japan gold and silver. Both see the two stars as a matched pair.

For Japanese names of stars in other seasons, see our list of traditional Japanese star names.

Are "crab eyes" and "cat's eyes" real Japanese names?

Some guides list "crab eyes" (kani-me) and "cat's eyes" (neko-no-me) as Japanese names for Gemini. We could not confirm them in museum or research sources.

The two stars do sit like a pair of eyes, so such names would not be surprising. But since we could not find where or by whom they were used, we have left them out of our tables.

What is Gemini called in China? What are Jing and Beihe?

In China, the two bright stars of Gemini belong to the asterism Beihe (北河, Northern River). Castor is Beihe er (北河二) and Pollux is Beihe san (北河三).

The stars around the twins' legs belong to Jing (井宿, the Well), one of the 28 lunar mansions.

The National Astronomical Observatory of Japan's calendar guide lists Jing as the first of the seven mansions of the southern Vermilion Bird. Its western neighbour is Shen, the mansion of Orion.

According to Ridpath, the eight stars of Jing form a shape like the character for "well" (井). Jing spans 33 degrees, making it the widest of all 28 mansions.

Beihe and Nanhe lie north and south of the ecliptic, the Sun's path. So they were also seen as gates or sentries.

The two stars that were the twins' heads in Greece were river stars in China. The twins' legs, meanwhile, became a well.

How did other cultures see the two stars of Gemini?

Many cultures around the world have seen the two stars of Gemini as two people. Stories of a pair of figures come from Australia and North America too.

Were the two stars twins in Babylon as well?

The two stars of Gemini were seen as twin gods in Babylon, long before the Greeks.

The glossary of the International Astronomical Union's Office of Astronomy for Education (OAE) explains it this way. Gemini is named after its two brightest stars, which in Babylonian mythology were twins and minor gods.

Who were the two stars for Aboriginal Australians?

In Aboriginal Australian traditions, too, Castor and Pollux are told of as two men.

The Boorong people of western Victoria called Castor Yuree and Pollux Wanjel. The two are young hunters.

They chase a kangaroo and kill it at the start of the "great heat," meaning summer. This comes from Stanbridge's record of 1858.

Tasmania has a story of two men as well. In a tradition from an Oyster Bay person, Castor and Pollux are the two men who made fire.

The two stood on a mountaintop and "threw fire, like a star," as Milligan recorded in 1859. Both stories are discussed in a paper by Gantevoort, Hamacher and Lischick.

What is the Blackfoot story?

The University of Calgary's observatory tells a Blackfoot story on its Gemini page.

A man named Smart-Crow had two sons. The brothers lost their mother when they were small.

Later, it is said, they brought her back to life with buffalo meat. When they grew up, they had special powers.

At the end of their lives, one rose to the sky with a white robe and an eagle feather, and the other was carried up on the branches of a tree. The two became the twin stars.

In Greece, Australia and North America, the same two stars became "two young men." Two bright stars side by side may have looked like a pair of people everywhere.

How do the names for the same stars differ by region?

As the table shows, the same two stars became brothers, gold and silver, river stars and hunters.

"No record found" marks places where we could not confirm a source while writing this article. It does not mean no name existed.

We could not confirm Ainu names for these stars in our sources either.

How do you find Gemini? Where is it relative to the Winter Triangle and the Winter Hexagon?

Gemini lies just north of the Winter Triangle. Pollux is one corner of the Winter Hexagon (called the Winter Diamond in Japan).

From Japan, Gemini rises in the east on December evenings. Around 8 pm in February, it is almost overhead.

Start with the Winter Triangle: Betelgeuse in Orion, Sirius in Canis Major and Procyon in Canis Minor.

The stars of Gemini are not part of the Winter Triangle. To the north of Procyon and Betelgeuse, two bright stars sit side by side. These are Pollux and Castor.

The Winter Hexagon is a large six-sided figure joining six first-magnitude stars. The Saitama City Youth Space Science Museum lists them as follows.

• Pollux in Gemini
• Capella in Auriga
• Aldebaran in Taurus
• Rigel in Orion
• Sirius in Canis Major
• Procyon in Canis Minor

From the two stars, two lines of fainter stars run toward Orion. These are the twins' bodies and legs.

• December: the Geminid meteor shower, whose meteors appear to fly out from near Castor
• Orion: just west of the twins' feet
• Scorpius: not in the winter sky; look for it in the south on summer nights

You can read the Orion story in the myth of Orion.

Frequently asked questions about the Gemini myth

How would you explain the Gemini myth to a child?

The elder of two devoted brothers died, and the younger, who could not die, asked Zeus to let them share his immortality. The two became stars side by side.

Which is the elder, Castor or Pollux?

Japanese guides make the fainter white star, Castor, the elder and the brighter yellow star, Pollux, the younger. The ancient texts do not make the birth order clear.

Who were the parents of Castor and Pollux?

Their mother was Leda, queen of Sparta. The best-known version makes Zeus the father of Pollux and King Tyndareus the father of Castor.

What are the Japanese names for Castor and Pollux?

From their colours, Pollux was called Kin-boshi (gold star) and Castor Gin-boshi (silver star). In Toyama the pair was called Futatsu-boshi.

What is Gemini called in Chinese?

Castor is Beihe er (北河二) and Pollux is Beihe san (北河三). The area of the twins' legs belongs to the lunar mansion Jing (井宿).

When can you see Gemini?

From Japan and similar latitudes it is best seen on winter nights. It rises in the east on December evenings and is nearly overhead around 8 pm in February.

Sources

• Theoi Project, "Dioskouroi" (English translations of Hesiod (fragment), the Cypria (fragment), Pindar's Nemean Ode 10, Apollodorus's Bibliotheca 3, Hyginus's Fabulae 14, 77 and 80 and Astronomica 2.22, Ovid's Fasti 5 and Diodorus 4.43)
• Theoi Project: Homer, Odyssey 11, English translation (Leda's two sons by Tyndareus, alive and dead on alternate days)
• Theoi Project: Homer, Iliad 3, English translation (Helen looks for her brothers)
• Ian Ridpath, "Star Tales: Gemini" (the parentage, the Argonauts and Amycus, protectors of sailors and Pliny, Apollo and Heracles, star names, and the Chinese Jing, Beihe, Yue and Wuzhuhou)
• Gifu City Science Museum, "Hoshizora no Tayori", February 2026 (Gemini: the gold and silver stars, elder Castor and younger Pollux; in Japanese)
• Star names of Toyama (from Masuda Masayuki, Etchu no Hoshi Monogatari; a Toyama Prefecture science education resource, in Japanese)
• National Astronomical Observatory of Japan, Calendar Office, "Koyomi Wiki: the 28 lunar mansions" (in Japanese)
• IAU Office of Astronomy for Education (OAE), glossary entry "Gemini" (Chinese names Beihe er and Beihe san; the Babylonian twin gods)
• Gantevoort, Hamacher and Lischick, "Reconstructing the Star Knowledge of Aboriginal Tasmanians" (Journal of Astronomical History and Heritage 19(3), 2016; the two fire-makers of Tasmania, and Yuree and Wanjel of the Boorong)
• University of Calgary, Rothney Astrophysical Observatory, "Gemini and Indigenous Skylore" (the Blackfoot story of the twin stars)
• Saitama City Youth Space Science Museum, "The February sky" (2024; the Winter Triangle and the Winter Hexagon, in Japanese)
• Saitama City Youth Space Science Museum, "The December sky" (2024; the radiant of the Geminids, in Japanese)
• SIMBAD (CDS Strasbourg): star brightness (V magnitude) and proper names