In 1987 I described a technique call Multi-Conjugate Adaptive Optics (MCAO) as a way of increasing the size of the area on the sky over which Adaptive Optics corrects for atmospheric wavefront distortions. An essential component of MCAO is the estimation of this wavefront distortion at different heights in the atmosphere. The technique proposed to do so was called 'Atmospheric Tomography,' or AT, since it uses tomographic techniques using the wavefront distortions at the telescope entrance pupil of objects observed in a number of different directions in the sky to infer the 3-D wavefront behavior. This paper describes a program to do so using the small scale structure on the solar surface (sunspots, pores and granulation). The Sun has the advantage of being an extended object on which the wavefront can be observed in a large number of directions using correlation Hartmann-Shack wavefront sensing. The AT experiment described in this paper uses the 76 cm Dunn Solar Telescope at NSO, 69 sub-apertures, a 2 X 2 arcmin2 field-of-view and a wavelength of 411 nm. The MCAO-AT system is being developed for the future 4 meter aperture Advanced Solar Telescope.