X-ray photons travel at the speed of light and are the first indication we receive at Earth of solar magnetic eruptions and the associated flares. These flare related X-rays cause changes to the Earth’s ionosphere and can result in significant degradation of radio communications, including complete black outs at some frequencies, beginning only 8 minutes (time for light to travel from the Sun to Earth) after a flare.
The early warning given by the SXI observations comes at least 15 hours before the associated shockwave of the solar eruption arrives at Earth, allowing the forecasters at SWPC to issue the appropriate watches, warnings, and alerts for geomagnetic storming which is the cause of the most significant space weather effects at Earth.