About

Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union. Although it dates to antiquity, Sagitta has no star brighter than 3rd magnitude and has the third-smallest area of any constellation. Gamma Sagittae is the constellation's brightest star, with an apparent magnitude of 3.47. It is an aging red giant star 90% as massive as the Sun that has cooled and expanded to a radius 54 times greater than it. Delta, Epsilon, Zeta, and Theta Sagittae are each multiple stars whose components can be seen in small telescopes. V Sagittae is a cataclysmic variable—a binary star system composed of a white dwarf accreting mass of a donor star that is expected to go nova and briefly become the most luminous star in the Milky Way and one of the brightest stars in our sky around the year 2083. Two star systems in Sagitta are known to have Jupiter-like planets, while a third—15 Sagittae—has a brown dwarf companion.

History and mythology

The ancient Greeks called Sagitta Oistos 'the arrow', and it was one of the 48 constellations described by Ptolemy. It was regarded as the weapon that Hercules used to kill the eagle (Aquila) of Jove that perpetually gnawed Prometheus' liver. Sagitta is located beyond the north border of Aquila, the Eagle. An amateur naturalist, polymath Richard Hinckley Allen proposed that the constellation could represent the arrow shot by Hercules towards the adjacent Stymphalian birds (which feature in Hercules' sixth labour) who had claws, beaks, and wings of iron, and who lived on human flesh in the marshes of Arcadia—denoted in the sky by the constellations Aquila the Eagle, Cygnus 'the Swan', and Lyra 'the Vulture'—and still lying between them, whence the title Herculea. Greek scholar Eratosthenes claimed it as the arrow with which Apollo exterminated the Cyclopes. The Romans named it Sagitta. In Arabic, it became al-sahm 'arrow', though this name became Sham and was transferred to Alpha Sagittae only. The Greek name has also been mistranslated as [ὁ istos] Error: {{Lang}}: Non-latn text (pos 1: ὁ)/Latn script subtag mismatch (help) 'the loom' and thus in Arabic al-nawl. It was also called al-'anaza 'pike/javelin'.