Lowell Observatory

The Origin and Evolution of Comets
David Schleicher

Dave Schleicher.jpg
Dave Schleicher

Dr. Schleicher's major research interests include the origins and evolution of comets, as discerned from studies of physical properties and chemical composition both as individual objects and as a class. The chemical composition is determined by first measuring the amount of light emitted by various molecules within a comet's coma or head. These photometric measurements are then converted to the number of molecules of each species which must be present to produce the measured light. Typically nearly a dozen comets are observed over the course of many months each year. Some are new comets while others have small orbits which return them near the sun repeatedly. These investigations can, therefore, examine how comets evolve over time, and separate evolutionary effects from inherent variations in composition due to differing conditions in the outer proto-solar nebula from which the solar system formed. Because comets are believed to be the most pristine objects remaining from the time of solar system formation available for chemical studies, comets provide a unique probe of these conditions. Five molecular species are routinely measured as part of the Lowell Observatory program of compositional studies of comets in the visible and near-ultraviolet portions of the spectrum.

For details on this analysis for one particular comet, see Comet 96/P Machholz 1 background.

For further information, see our Comet research at Lowell Observatory pages.