A 'CANNIBAL CME' IS APPROACHING EARTH: A strong G3-class geomagnetic storm is possible later this week when a 'Cannibal CME' hits Earth's magnetic field. It's a 'cannibal' because it ate one of its own kind en route to our planet. The mash-up of two CMEs could spark naked-eye auroras visible from northern-tier US states. Full story @ Spaceweather.com.

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Above: This frame from a NASA animation shows one CME overtaking another. The resulting merger is called a 'Cannibal CME.'