Posted: Mon, May 9, 2005, 6:51 AM ET (1051 GMT)
Planetary scientists reported last week that an outer moon of Saturn surveyed by NASA's Cassini spacecraft last year most likely originated in the outer solar system. In a paper published in the latest issue of the journal Nature, scientists said that Phoebe bears a closer resemblance to Pluto and members of the Kuiper Belt than the other moons of Saturn. Scientists reached that conclusion based on measurements of the moon's density made when Cassini flew by Phoebe in June 2004, shortly before entering orbit around Saturn: the relative proportions of rock and ice are more like those seen in the Kuiper Belt than Saturn's other moons. Scientists believe that Phoebe formed in the Kuiper Belt but strayed inwards, and was eventually captured by Saturn.
