Pegasus

Lore & Background

In Greek mythology, Pegasus was a winged horse with magical powers. One myth says his hooves dug out the spring Hippocrene, which blessed those who drank its water with the ability to write poetry. Pegasus was born when Perseus cut off the head of Medusa, who was impregnated by the god Poseidon; he was born with Chrysaor from Medusa's blood. Eventually, Pegasus became the horse for Bellerophon, who was asked to kill the Chimera and succeeded with the help of Athena and Pegasus. After the death of his children, Bellerophon asked Pegasus to take him to Mount Olympus; though Pegasus agreed, he plummeted back to Earth after Zeus either threw a thunderbolt at him or sent a gadfly to make Pegasus buck him off. The Babylonian constellation IKU (field) had four stars, of which three were later part of the Greek constellation Hippos (Pegasus). Persia recognized the constellation. Pegasus was depicted by al-Sufi in the tenth century as a complete horse facing east, unlike most other uranographers who depicted Pegasus as half a horse rising out of the ocean. In Chinese astronomy, the modern constellation of Pegasus lies in The Black Tortoise of the north, where the stars were classified in several separate asterisms. In Hindu astronomy, Pegasus is contained within the 25th nakshatra lunar mansion Purva Bhadrapada, representing a bedstead that was a resting place for the Moon. For the Warrau and Arawak peoples in Guyana, the stars in the Great Square represented a barbecue taken up to the sky by the seven hunters of the myth of Siritjo.

Reader's Guide

It is bordered by Andromeda, Lacerta, Cygnus, Vulpecula, Delphinus, Equuleus, Aquarius, and Pisces. The constellation is dominated by the Square of Pegasus asterism, formed by Alpha (Markab), Beta (Scheat), Gamma (Algenib), and Alpha Andromedae (Alpheratz). The brightest star is Epsilon Pegasi (Enif), an orange supergiant varying between magnitudes 2.37 and 2.45. Twelve star systems within Pegasus have been found to have exoplanets; notably, 51 Pegasi was the first Sun-like star discovered to have an exoplanet companion, located just over 50 light years from Earth. The constellation contains variable stars such as AG Pegasi, described as the slowest nova ever recorded, and Tau Pegasi, a Delta Scuti variable. Its official boundaries, set by Belgian astronomer Eugène Delporte in 1930, are defined as a polygon of 35 segments, with right ascension between 21h 12.6m and 00h 14.6m and declination between 2.33° and 36.61°. The whole constellation is visible to observers north of 53°S.

Did You Know?

• Pegasus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy.
• The brightest star in Pegasus is the orange supergiant Epsilon Pegasi (Enif), which marks the horse's muzzle.
• 51 Pegasi was the first Sun-like star discovered to have an exoplanet companion.

Common Misconceptions (Editorial)

A common misconception is that the Great Square of Pegasus is the entire constellation; in fact, it is a notable asterism within Pegasus, not the full constellation. Another error is assuming Pegasus was always depicted as a half-horse rising from the ocean, but the 10th-century astronomer al-Sufi portrayed it as a complete horse facing east, differing from most other uranographers.

Why It Matters (Editorial)

Pegasus endures not only as a fixture in the night sky but as a symbol of poetic inspiration and mythical adventure, with its lore tying directly to the spring Hippocrene and the heroic tale of Bellerophon. Its scientific significance is equally lasting: 51 Pegasi made history as the first Sun-like star found to host an exoplanet, linking ancient mythology to modern discovery.