Physical Prop erties of Comets
K. J. Meech
Institute for Astronomy, University of Hawai`i, 2680 Wood lawn Drive, Honolulu, HI 96822, USA
ABSTRACT
There have b een several recent reviews of the physical prop erties of cometary nuclei, most concentrating on
the sp eci cs of the rotation p erio ds, shap es, sizes and the surface prop erties. This review will presentan
up dated summary of these prop erties based on recent observations. There are nucleus parameters known for
26 nuclei. These comet nuclei are relatively small prolate ellipsoids of low alb edo. The axis ratios range
between 1.1{2.6 which when combined with rotation p erio ds constrains the densitylower limits. Typically
the nuclei are found to havevery small fractional active areas. Little direct observational evidence exists
for the internal physical prop erties, however, the results to date suggest a strengthless agglomeration of