This image captured by the Solar Dynamics Observatory shows an M9-class solar flare erupting on the Sun's northeastern hemisphere, just four days after a previous strong coronal mass ejection that sparked auroras around the world. A very fast coronal mass ejection (CME) travelling four million miles per hour (6.4 million kilometres per hour) is headed towards the Earth. A rush of radiation in the form of solar protons already has begun bombarding the Earth and is likely to continue through Wednesday. The radiation storm is the largest of its kind since 2005 but still ranks only a three on the scale of one to five, enough to be considered "strong" but not "severe".

Credit : NASA/SDO/AFP/Getty