Kallichore.space

Measuring a tiny moon with a star

How a 2025 stellar occultation sized Kallichore.

Published 2026-10-23

Kallichore is only a faint dot of magnitude 23 — so how do we know its size?[1]

What an occultation is

An occultation occurs when one object is hidden from the observer by another that passes between them.[4]

Timing the blink

When a small moon passes in front of a star, observers on the ground see the star blink out. The length of the blink and where it is seen reveal the moon’s size.

Kallichore’s result

A 2025 occultation showed Kallichore is 3.5–6.1 km across, implying a dark albedo of about 3.7%.[1]

Still more to do

Further observations are planned to determine its orbit accurately ahead of Juice’s arrival.[1]

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