'Citizen scientists' have discovered that a major solar storm is to hit the Earth today.
Tthe Solar Stormwatch web project, launched early last year by the Royal Observatory, Greenwich (ROG), encourages amateurs to help spot and track storms as they erupt from the sun. The measurements enable scientists to forecast the arrival of storms far enough in advance to issue effective pre-emptive alerts.
The current storm, or coronal mass ejection, was predicted to hit at 07.32 GMT this morning. It's the first time astronomers have been able to prediuct such an event more than a few hours in advance, with the Stormwatch program now able to give up to three days' warning.
"Solar Stormwatch is special in that it harnesses public interest in astronomy to provide data that is invaluable to scientists," says Dr Marek Kukula, public astronomer at the ROG.
"The more people that take part in 'stormwatching', the more we will learn, and the fact that the volunteers' work has now enabled us to predict when a storm will hit the Earth is a significant milestone, not just for the project, but for science as a whole."
Solar storms are comparatively frequent events, although most are pretty minor, and Earth is only affected if a coronal mass ejection happens to come in our direction.
On the down side, the storm could disrupt radio transmissions and GPS systems, and could also pose a small health risk for workers on the International Space Station and even airline passengers and crew. There's also a danger that power grids could be knocked out.
More pleasantly, though, sky-watchers have a good chance of seeing an impressive display of the Northern and Southern Lights further than usual from the poles.
Help spot the next bout of solar activity, here.