We examine the nature of large-scale, coronal, propagating wave fronts (``EIT waves'') and find they are incongruous with solutions using fast-mode MHD plane-wave theory. Specifically, we consider the following properties: non-dispersive single pulse manifestions, observed velocities below the local Alfven speed, and different pulses which travel at any number of constant velocities, rather than at the ``predicted'' fast-mode speed. We discuss the possibility of a soliton-like explanation for these phenomena, and show how it is consistent with the above-mentioned aspects.
@article{arxiv.0704.2828,
title = {Are "EIT Waves" Fast-Mode MHD Waves?},
author = {M. J. Wills-Davey and C. E. DeForest and J. O. Stenflo},
journal= {arXiv preprint arXiv:0704.2828},
year = {2009}
}