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Genitive: Draconis

Abbreviation: Dra

Size ranking: 8th

Origin: One of the 48 Greek constellations listed by Ptolemy in the Almagest

Greek name: Δράκων (Drakon)

Coiled around the sky’s north pole is the celestial dragon, Draco, known to the Greeks as Δράκων (i.e. Drakon). Legend has it that this is the dragon slain by Heracles during one
of his labours, and in the sky the dragon is depicted with one foot of Heracles
(in the form of the neighbouring constellation Hercules) planted firmly upon
its head. This dragon, named Ladon, guarded the precious tree on which grew the
golden apples.

Hera had been given the golden apple tree as a wedding present when she married
Zeus. She was so delighted with it that she planted it in her garden on the
slopes of Mount Atlas and set the Hesperides, daughters of Atlas, to guard it.
Most authorities say there were three Hesperides, but Apollodorus names four.
They proved untrustworthy guards, for they kept picking the apples. Sterner
measures were required, so Hera placed the dragon Ladon around the tree to ward
off pilferers.

Draco winds around the north celestial pole on Chart III of Johann Bode’s Uranographia star atlas (1801). The dragon’s long tail, labelled Cauda Draconis on this chart, extends between the two
bears.

According to Apollodorus, Ladon was the offspring of the monster Typhon and
Echidna, a creature half woman and half serpent. Ladon had one hundred heads,
says Apollodorus, and could talk in different voices. Hesiod, though, says that
the dragon was the offspring of the sea deities Phorcys and Ceto, and he does
not mention the number of heads. In the sky, the dragon is single-headed.

The great hero Heracles was required to steal some apples from the tree as one
of his labours. He did so by killing the dragon with his poisoned arrows.
Apollonius Rhodius recounts that the Argonauts came across the body of Ladon
the day after Heracles had shot him. The dragon lay by the trunk of the apple
tree, its tail still twitching but the rest of its coiled body bereft of life.
Flies died in the poison of its festering wounds while nearby the Hesperides
bewailed the dragon’s death, covering their golden heads with their white arms. Hera placed the
image of the dragon in the sky as the constellation Draco.

Stars of Draco

Despite its considerable size, the eighth-largest constellation, Draco is not
particularly prominent. Its brightest star is second-magnitude Gamma Draconis,
called Eltanin from the Arabic al-tinnin meaning ‘the serpent’; according to Ptolemy it lay on the top of the dragon’s head. Alpha Draconis, lying in the dragon’s body, is called Thuban, from a highly corrupted form of the Arabic ra’s al-tinnin, ‘the serpent’s head’. Beta Draconis, near the dragon’s eye, is called Rastaban, another corrupted form of the same Arabic name. The
stars Beta, Gamma, Nu, and Xi Draconis form a lozenge shape which we regard as
the dragon’s head, but which bedouin Arabs visualized as four mother camels with a baby
camel at the centre, the baby being represented by an unnamed 6th-magnitude
star. Mu Draconis, a 5th-magnitude double star which Ptolemy described as lying
on the dragon’s tongue, is known as Alrakis.

Chinese associations

Chinese astronomers imagined two walls enclosing the north polar region of the
sky, and Draco contains large parts of each. (For more about this circumpolar
region, see Ursa Minor.) The eastern wall started at Iota Draconis and continued via Theta, Eta, Zeta,
and one or two other uncertain stars into Cepheus. The western wall ran from
Alpha via Kappa and Lambda Draconis into Ursa Major and then Camelopardalis.

In far northern Draco, closest to the celestial pole, was Tianzu, ‘celestial pillars’, consisting of five faint stars, identities uncertain. These pillars were
supposedly used as noticeboards for posting government orders, although they
might also represent pillars supporting the sky. Just south of it was Nüyu (also given as Yunu), four stars representing the Emperor’s concubines; the stars concerned are uncertain. Next to this were Nüshi (Psi Draconis), a woman in charge of water clocks in the royal palace, and Zhuxiashi (also known as Zhushi), possibly Phi or Chi Draconis, an official recorder or scribe to the Emperor.
Farther along the eastern wall of the Central Palace five stars (possibly
Omega, 27, 19, 18, and 15 Draconis) formed Shangsu, the Emperor’s secretaries. Six faint stars on the borders of Draco and southern Ursa Minor
formed the Emperor’s bedroom, Tianchuang.

Just outside the western wall of the Central Palace, north of the Plough, 7 and
8 Draconis formed Neichu, a private kitchen for the Emperor and his family. A second kitchen, Tianchu, lay just outside the eastern wall, consisting of Delta, Sigma, Epsilon, Rho,
64, and Pi Draconis. This kitchen catered for government officers and the
Emperor’s guests.

Farther south lay Fukuang, formed by 39, 45, 46, Omicron, 48, 49, and 51 Draconis. This represented a
basket containing mulberry leaves to feed silkworms. On the southern border
with Hercules was Tianpei, also known as Tianbang. This represented either the Emperor’s advance guard or a flail for threshing grain, in another example of how a
Chinese constellation could have widely differing meanings. It consisted of the
four stars we know as the head of Draco (Beta, Gamma, Nu, and Xi Draconis) plus
Iota Herculis.



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