The Euphrosyne family: two thousand steeply tilted siblings

A collision about 280 million years ago scattered fragments that still share Euphrosyne’s orbit — and maybe left it a moon.

Published 2026-10-23

Asteroid families are groups of asteroids that share similar orbits and are thought to be fragments of one parent body broken up in a collision.^[5] Euphrosyne heads one of the more unusual ones.^[2]

About two thousand members

The Euphrosyne family contains roughly two thousand asteroids with similar spectral properties and orbital elements.^[2] It is described as complex, and its second-largest body, 895 Helio, is most likely an interloper — an unrelated asteroid that happens to sit in the same region.^[2]

A young family

The family is thought to have formed in a collision about 280 million years ago — recent compared with the 4.6-billion-year age of the Solar System.^[2]

High-tilt orbits

All members have relatively high orbital inclinations, like Euphrosyne’s own 26°.^[2][1] This makes the family stand out from most of the main belt, where orbits are flatter.

Traces on the parent

Euphrosyne’s surface may be covered by a thick ejecta blanket from the same collision. VLT images show no deep basins; any craters wider than about 40 km must have flat floors, consistent with an icy surface — or with a young one.^[2]

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