  We present an $O(n^{1.5})$-space distance oracle for directed planar graphs
that answers distance queries in $O(\log n)$ time. Our oracle both
significantly simplifies and significantly improves the recent oracle of
Cohen-Addad, Dahlgaard and Wulff-Nilsen [FOCS 2017], which uses
$O(n^{5/3})$-space and answers queries in $O(\log n)$ time. We achieve this by
designing an elegant and efficient point location data structure for Voronoi
diagrams on planar graphs.
  We further show a smooth tradeoff between space and query-time. For any $S\in
[n,n^2]$, we show an oracle of size $S$ that answers queries in $\tilde
O(\max\{1,n^{1.5}/S\})$ time. This new tradeoff is currently the best (up to
polylogarithmic factors) for the entire range of $S$ and improves by polynomial
factors over all the previously known tradeoffs for the range $S \in
[n,n^{5/3}]$.
