Is Kallichore a rubble pile?

What Hubble’s brightness changes reveal about its shape.

Published 2026-10-23

Kallichore is too small for gravity to pull it into a sphere.^[1]

A changing glint

Hubble observed Kallichore’s brightness change by Δm ≥ 0.461 within 1.25 hours, implying a moderately elongated shape with a/b ≥ 1.53.^[1]

Shaped by collisions

That elongation is expected for a kilometre-sized body shaped by collisions.^[1]

Rubble piles

A rubble pile is a body made of many pieces of rock held together by gravity rather than a single solid piece.^[5] Kallichore may have such an interior, like Ryugu and Bennu.^[1]

Unknown spin

Its rotation period is unknown because its brightness changes have not been watched long enough.^[1]

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