Editor's Summary

23 February 2006

Four's Company

In May 2005 Pluto was well placed for observation and the Hubble Space Telescope's survey camera was trained in its direction. The result was the discovery of two previously unknown satellites, called S/2005 P 1 and P 2 for now, making Pluto the first Kuiper belt object known to have multiple satellites. Two papers this week cover this milestone in detail. Weaver et al. describe the discovery process, and derive preliminary orbits and size estimates for both satellites. Stern et al. present work on the potential origin of the new satellites in the Charon-forming impact, on the likelihood of a ring system at Pluto, and the likelihood that there are many more multiple satellite systems in the Kuiper belt. On the cover, images of the Pluto-Charon system on 15 May (top) and 3 days later show the newly discovered moons on the move. Charon moves from one side of Pluto to the other between the two frames.

Letter: Discovery of two new satellites of Pluto

H. A. Weaver, S. A. Stern, M. J. Mutchler, A. J. Steffl, M. W. Buie, W. J. Merline, J. R. Spencer, E. F. Young and L. A. Young

doi:10.1038/nature04547

First paragraph | Full Text | PDF (190K) | Supplementary information

Letter: A giant impact origin for Pluto's small moons and satellite multiplicity in the Kuiper belt

S. A. Stern, H. A. Weaver, A. J. Steffl, M. J. Mutchler, W. J. Merline, M. W. Buie, E. F. Young, L. A. Young and J. R. Spencer

doi:10.1038/nature04548

First paragraph | Full Text | PDF (178K) | Supplementary information