How Cassini found Polydeuces

Blink comparison, pre-discovery images and a quick confirmation.

Published 2026-10-23

Polydeuces was found in four wide-angle frames taken over less than six minutes on 21 October 2004.^[1]

Blink comparison

The team flipped between images to spot anything moving against the stars. Polydeuces moved 3–6 pixels per frame.^[1]

Looking back

With its orbit known, the team found 52 pre-discovery detections in images from April and May 2004; later, even earlier images from 2 April 2004 turned up.^[1]

Announcement

The IAU announced the discovery on 8 November 2004. Cassini found several other objects that year, including Methone and Pallene.^[1]

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