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 β3 M of ejecta, expanding at velocities of 10 9 cm s β1 , are powered by the newborn massive, fast rotating, magnetized white dwarf with a mass of 1.3M , a rotation period of 12 s, and a dipole magnetic field βΌ 10 10 G, born in the merger of a 1.0+0.8M 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.