Igea Borbonica: the 1849 discovery and naming of Hygiea

A Naples astronomer, a royal dedication, John Herschel's rival suggestion and a serpent-and-star symbol.

Published 2026-10-23

On the evening of April 12, 1849, Annibale de Gasparis, working at the Capodimonte Observatory in Naples, found a faint moving point of light. It was the tenth asteroid known: Hygiea.^[3]

Big but hard to spot

Hygiea is the fourth-largest asteroid, yet six smaller asteroids were discovered before it.^[3] The reason is its very dark surface — it reflects only about 7% of the light that falls on it — combined with its distance in the outer main belt.^[2][3] Its true rank as fourth-largest was not recognized until 1974, when David Morrison measured its size and albedo using its infrared heat.^[3]

“Igea Borbonica”

De Gasparis invited his friend Ernesto Capocci, director of the observatory, to choose a name. Capocci proposed Igea, the Italian spelling of Hygieia, Greek goddess of health and daughter of Asclepius. De Gasparis added Borbonica to honor King Ferdinand II of the Bourbons, who supported the observatory.^[3] By 1852 the royal adjective had been dropped.^[3]

Herschel's alternative

In England, John Herschel suggested Parthenope, after the siren who founded Naples in Greek mythology. By the time he wrote to de Gasparis, Hygiea had already been named. De Gasparis honored the suggestion anyway: on May 11, 1850, he discovered another asteroid and named it 11 Parthenope.^[3]

A serpent crowned with a star

Early asteroids had symbols, like the planets. In 1850 de Gasparis described Hygiea's as “a serpent (like a Greek ζ) crowned with a star” — the serpent being a traditional emblem of the goddess. Symbols like this soon fell out of use as discoveries multiplied.^[3] The informal names of Hygiea's two big craters, Serpens and Calix (snake and cup), nod to the same imagery.^[3]

Numbered citations link to the sources list on the Hygiea overview page.