Small comet hypothesis draws renewed attention



Five papers that will appear in the December 15 issue of the AGU publication Geophysical Research Letters (GRL) are heating up an ongoing debate about a hypothesis that small and watery comet-like objects, each about the size of a small house and most weighing 20–40 tons, bombard the Earth 10 million times each year and deposit water vapor into the upper atmosphere.

Louis Frank, physics professor at the University of Iowa in Iowa City, and John Sigwarth, senior research associate there, say that these small comets dissipate into water vapor and may have sprinkled enough water over the history of the planet to fill the oceans.