  Following the GRB 170817A prompt emission lasting a fraction of a second,
$10^8$ s of data in the X-rays, optical, and radio wavelengths have been
acquired. We here present a model that fits the spectra, flux, and time
variability of all these emissions, based on the thermal and synchrotron
cooling of the expanding matter ejected in a binary white dwarf merger. The
$10^{-3} M_\odot$ of ejecta, expanding at velocities of $10^9$ cm s$^{-1}$, are
powered by the newborn massive, fast rotating, magnetized white dwarf with a
mass of $1.3 M_\odot$, a rotation period of $\gtrsim 12$ s, and a dipole
magnetic field $\sim 10^{10}$ G, born in the merger of a $1.0+0.8 M_\odot$
white dwarf binary. Therefore, the long-lasting mystery of the GRB 170817A
nature is solved by the merger of a white dwarf binary that also explains the
prompt emission energetics.
