Perseus

Lore & Background

In Greek mythology, Perseus was the son of Danaë, who was sent by King Polydectes to bring the head of Medusa the Gorgon—whose visage caused all who gazed upon her to turn to stone. Perseus slew Medusa in her sleep, and Pegasus and Chrysaor appeared from her body. He then continued to the realm of Cepheus, whose daughter Andromeda was to be sacrificed to Cetus the sea monster. Perseus rescued Andromeda by killing the monster with his sword, turned Polydectes and his followers to stone with Medusa's head, and appointed Dictys the fisherman king. Perseus and Andromeda married and had six children. In the sky, Perseus lies near the constellations Andromeda, Cepheus, Cassiopeia (Andromeda's mother), Cetus, and Pegasus. Some star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose asterism was named together as Perseus et Caput Medusae; however, this never came into popular usage. In non-Western astronomy, four Chinese constellations are contained in the area of the sky identified with Perseus: Tiānchuán (the Celestial Boat), Jīshuǐ (the Swollen Waters), Dàlíng (the Great Trench), and Jīshī (the pile of corpses). The Double Cluster had special significance in Chinese astronomy. In Polynesia, Perseus was not commonly recognized as a separate constellation; only the Society Islands named it Faa-iti, meaning 'Little Valley'. Algol may have been named Matohi by the Māori people, but the evidence for this identification is disputed.

Reader's Guide

Perseus holds significance as one of the ancient constellations cataloged by Ptolemy and as a modern IAU constellation. Its brightest star, Alpha Persei (Mirfak), is a yellow-white supergiant and member of the Alpha Persei Cluster. The best-known star, Algol (Beta Persei), is an eclipsing binary that varies in brightness noticeably to the naked eye, linked with ominous legends across cultures. The Double Cluster, comprising two open clusters, was known to the ancient Chinese. Perseus hosts the radiant of the annual Perseids meteor shower, one of the most prominent meteor showers in the sky. The galactic plane of the Milky Way passes through Perseus. In Chinese astronomy, the area contains four constellations representing celestial boats, flood waters, trenches, and corpses. The constellation's boundaries, set by Eugène Delporte in 1930, are defined by a 26-sided polygon, and the IAU adopted the three-letter abbreviation 'Per' in 1922.

Did You Know?

• Perseus is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy.
• The best-known star in Perseus, Algol, is an eclipsing binary rather than an intrinsically variable star.
• In Neo-Assyrian Babylonia, the constellation was known as the Old Man constellation (SU.GI).

Common Misconceptions (Editorial)

Some people think Perseus is a modern constellation, but it is actually one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy. Another common misconception is that the star Algol is intrinsically variable, whereas it is actually an eclipsing binary.

Why It Matters (Editorial)

Perseus endures as a link between the night sky and one of Greek mythology’s most celebrated heroic journeys, from slaying Medusa to rescuing Andromeda. Its annual Perseid meteor shower, radiating from the constellation, keeps Perseus relevant not just for astronomers but for casual stargazers around the world, reminding us that ancient stories still align with living celestial events.