Photograph by Geoffrey Hoyle
The following day they walked up Bowfell stopping for lunch under a threatening sky. Chandra asked if it was going to rain. “Not necessarily” said Fred “ These clouds could be saturated with water vapour, but for rain to fall, condensation nuclei are required like molecular fragments (ions) or fine dust”. With a moment’s reflection he added, “Some people even argue that meteor dust could supply nuclei for rain.”
From this brief conversation the following evenings at the hotel were interlaced with speculation concerning the difficulties in forming water droplets. If it was difficult to form water droplets in the densities that prevail in the terrestrial atmosphere, how could ice particles condense in the exceedingly tenuous clouds of interstellar space. The direction of their research would now turn to find a denser place than the interstellar medium to resolve the problem of how interstellar dust grains were formed.