With the advent of powerful space-based infrared telescope facilities,
we are seeing a surge in the number of cometary nuclei whose thermal
emissions are being measured. This work has the potential to provide
insight into the ensemble structural and thermophysical properties
of comets and, ultimately, the circumstances of their formation and
evolution. Moreover, these studies are now happening while the
Rosetta spacecraft continues its detailed and lengthy study of comet
67P, giving us excellent context with which to try to understand
the wealth of remote observations of other comets. This is important
since for the forseeable future there will always be far more comets
observed remotely than in-situ, and we must understand what such
data are telling us about nuclei and near-nucleus comae so that we
are not fooled into misinterpretation. I will review some recent,
key results on cometary physical properties and on what we might
think of as a “typical” comet. I will also discuss some unanswered
questions that should be addressed in the future, and what the
observational limitations and opportunities are with regard to them.
Institute for Planets and Exoplanets
