With a mean diameter of about 3 km (1.9 mi), Polydeuces is thought to have a smooth surface coated with fine, icy particles accumulated from the cryovolcanic plumes of Enceladus.

[4]: 223  The images were visually inspected through the blink comparison technique, which revealed any potential moons that moved relative to the background stars.

[4]: 223–226  Preliminary orbit determinations using these images confirmed that Polydeuces was a co-orbital trojan moon residing around Dione's L5 Lagrange point.

[8] Due to gravitational perturbations by other nearby moons of Saturn, Polydeuces's orbital radius can vary by ±7,660 km (4,760 mi) over time.

[4]: 231  Of Saturn's four known trojan moons, Polydeuces librates the farthest from its Lagrange point: its angular distance behind Dione oscillates from 33.9° to 91.4° with a period of 790.931 days (2.17 years).

[4]: 231 Polydeuces is thought to have formed by accreting out of leftover debris trapped in Dione's L5 Lagrange point, in a similar process experienced by Saturn's other trojan moons.

[13]: 7  Cassini's highest-resolution images of Polydeuces from 2015 show that it has an elongated shape, with a relatively smooth limb deviating from a simple ellipsoid.

Depending on the size-frequency of impactors in the Saturnian system, Polydeuces is predicted to have suffered at least one disruptive impact in the last one billion years.

[12]: 11  This implies that Polydeuces is either very young with an age of less than one billion years, or it is a primordial moon that has consistently reaccreted from each disruptive impact over the Saturnian system's 4.5 billion-year lifespan.

[12]: 13 Polydeuces has a bright and likely smooth surface due to the accumulation of fine water ice particles from the surrounding E Ring, which is generated by the cryovolcanic plumes of Enceladus.

[22][12]: 11  Because of its small size, any craters on Polydeuces would be completely buried in E Ring material, giving it a craterless appearance resembling Methone or Pallene.

[13]: 23  The reason for these brightness asymmetries in the trojan moons of Dione and Tethys remains unknown; possible explanations include an asymmetric distribution of E Ring particles or recent impacts that brightened Helene and Calypso.