Late Sunday, the sun aimed a huge coronal mass ejection (CME) at our planet, along with a "solar energetic particle" event – the largest since September 2005 – which is expected to cause a solar storm of highly energetic protons to hit us on Tuesday at 9am Eastern Time, plus or minus seven hours.

The solar storm, according to SpaceWeather.com, ranks S3 – "Strong" – on the National Oceanic and Atmospheric Administration (NOAA) Space Weather Scale. NOAA identifies the storm as being the strongest since May 2005.

NASA's Goddard Space Weather Lab provides an animation of the CME which shows that the leading edge of the disturbance will not only strike Earth, but also Mars, arriving there late Wednesday, our time.

Space.com reports that the eruption of the prosaically named sunspot 1402 – which has become increasingly active recently – was spotted by a number of NASA spacecraft, including the Solar Dynamics Observatory (SDO) in a geosynchronous orbit around our planet, the Solar Heliospheric Observatory (SOHO) flying between Earth and the sun, and the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft, which share our orbit, one in front of us and one behind.

Despite the comparatively large size, speed, and strength of the stream of particles shooting towards us at around 2,200 kilometers (1,370 miles) per second, the storm is expected to cause little if any harm. Perhaps a few satellites will need to reboot, but not much else – even ISS 'nauts are safe, though it's best if they stay inside.

Sunspot 1402 belches a big one

Those living in nothern climes may, however, enjoy spectacular aurora borealis displays as the particles pass through Earth's orbit, concentrating their energy on the northern parts of our planet. The power of the pulse is so great, in fact, that such displays may be visible in more-southerly locations than is the norm.

Don't expect to view those sky shows from a high-flying aircraft, however: a NOAA spokeswoman told the American Meteorological Society, now meeting in New Orleans, that polar flights will likely be rerouted. ®