  A star passing within $\sim 10^4 \au$ of the Sun would trigger a comet shower
that would reach the inner solar system about 0.18 Myr later. We calculate a
prior probability of ~0.4% that a star has passed this close to the Sun but
that the comet shower has not yet reached the Earth. We search the HIPPARCOS
catalog for such recent close-encounter candidates and, in agreement with
Garcia-Sanchez et al. (1997), find none. The new result reported in this Letter
is an estimation of the completeness of the search. Because of the relatively
bright completeness limit of the catalog itself, V~8, the search is sensitive
to only about half the stars that could have had such a near encounter. On the
other hand, we show that the search is sensitive to nearly all of the past
encounters that would lead to a major shower in the future and conclude that it
is highly unlikely that one will occur during the next 0.5 Myr.
