Portal de Periódicos da CAPES

The Forest and the Trees

1991; Cambridge University Press; Volume: 116; Issue: 2 Linguagem: Inglês

10.1017/s0252921100012896

2059-9137

Fred L. Whipple,

Space Exploration and Technology

Abstract Some 24 points are made concerning the author’s understanding of the cometary nucleus as developed in this colloquium. Comparisons with an earlier report are noted, and most of the earlier advances in concept are substantiated. The mean density of the Halley nucleus may have been underestimated. The dust/gas ratio apparently needs to be increased by as much as two times, perhaps to unity or higher. The nature of the rotation remains puzzling. CHON grains now appear to be more important sources of gas than thought earlier. A very low temperature at, and subsequent to, the formation of the nucleus continues to receive support, as does a solar-system composition. The 12 C/ i:3 C ratio may, however, be lower than expected.