  At intervals as short as ten thousand years, each white dwarf (WD) passes
within a solar radius of a planetoid, i.e., a comet, asteroid, or planet.
Gravitational tidal forces tear the planetoid apart; its metal-rich debris
falls onto the WD, enriching the atmosphere. A third of WDs exhibit atmospheric
"pollution". For roughly every hundred planetoid disruptions, a planetoid
collides with a WD. We simulate a small number of collisions, in which
"death-by-dynamics" refers to the fate of the planetoid. We also compute the
energies and likely durations of a broad sample of collision events, and
identify detection strategies at optical and X-ray wavelengths. Collisions with
the most massive planetoids can be detected in external galaxies. Some may
trigger nuclear burning. If one in $\sim 10^7-10^8$ of WD-planetoid collisions
creates the conditions needed for a Type Ia supernova (SN~Ia),
"death-by-dynamics" would also refer to the fate of the WD, and could provide a
novel channel for the production of SN~Ia. We consider the circumstances under
which the rate of SNe~Ia can be increased by interactions with planetoids.
