Sky-watchers in high latitudes could be in for a good light show tonight, following a spectacular coronal mass ejection (CME) from the sun yesterday.
The sun blasted out an M-2 (medium-sized) solar flare, a minor S1-class radiation storm and a major CME from Sunspot complex 1226-1227. A huge cloud of particles ballooned out - but, unusually, fell back to cover almost half the solar surface.
The events lasted for several hours, peaking at 1:41 am ET, and were recorded by the Solar Dynamics Observatory (SDO).
The charged particles emitted by the CME are now traveling towards the Earth, at over three million miles per hour, though we're not lined up for a direct hit.
However, it should deliver a glancing blow to the Earth's magnetic field late tonight and tomorrow night. There could be some dramatic auroras, says NASA, and there may be some disruption to satellite communications and power, although the National Oceanic and Atmospheric Administration (NOAA) says this is unlikely.
But, it says, "The Solar Radiation Storm includes a significant contribution of high energy (>100 MeV) protons, the first such occurrence of an event of that type since December 2006."
Airlines are likely to reroute flights over the poles to less extreme latitudes in order to minimise the risk to in-flight communications.