What surprises you most about the Universe? 

I think what surprises me most are the surprises, the discoveries that are
unexpected. The results that suddenly turn the tables on what we
understood. This happens in many, many branches of astronomy: in my own
field of neutron stars, which are quite small, in planets and
understanding of the sun, right out to cosmology, studying the universe as
a whole. The surprises keep rolling in, in a quite dramatic way, and
that's I think what surprises me most: the uncertainty about astronomy.