IAS/PU Joint Astrophysics Colloquium
Saturn’s satellite Enceladus displays a bewildering array of thermal activity. I will describe our attempts to understand these phenomena in terms of tidal heating associated with the 2:1 mean motion resonance between Enceladus and Dione. Then I will argue that Enceladus and the other midsize satellites of Saturn are young.
Deviations from a uniformly expanding universe are of interest in modern cosmology, most particularly because the amplitude of such peculiar motions measures the strength of gravity on scales of roughly 10-100 Mpc. I will review various recent attempts to measure these velocity effects in leading galaxy surveys, together with new rapid approximate means of generating the simulated universes that are needed in order to extract validated results from the data.