  Observations of strong solar wind proton flux correlations with ROSAT X-ray
rates along with high spectral resolution Chandra observations of X-rays from
the dark Moon show that soft X-ray emission mirrors the behavior of the solar
wind. In this paper, based on an analysis of an X-ray event observed by
XMM-Newton resulting from charge exchange of high charge state solar wind ions
and contemporaneous neutral solar wind data, we argue that X-ray observations
may be able to provide reliable advance warning, perhaps by as much as half a
day, of dramatic increases in solar wind flux at Earth. Like neutral atom
imaging, this provides the capability to monitor the solar wind remotely rather
than in-situ.
