Fast-moving solar eruptions that overtake and devour their slower-moving kin can trigger long-lasting geomagnetic storms when they strike Earth's magnetosphere.

A coronagraph on board the ESA-NASA SOHO spacecraft captured this example of CME cannibalism in action on June 6, 2000. (Click for a larger image.)

March 27, 2001 — Fast-moving solar eruptions apparently overtake and often devour their slower-moving kin. This discovery was made by a team of astronomers working with a pair of NASA spacecraft.

Strange radio fireworks were first heard by the team using NASA's Wind spacecraft. The link to the cosmic collisions came when researchers matched the timing of the radio outbursts to images of solar eruptions consuming each other. The dynamic pictures of the so-called "cannibal coronal mass ejections" were captured by the Solar and Heliospheric Observatory (SOHO) spacecraft from NASA and the European Space Agency (ESA).

Solar eruptions directed toward Earth are potentially harmful to advanced technology, including communications and power systems, and this "cannibalistic" behavior may result in longer magnetic storms. These collisions change the speed of the eruption, which is important for space weather prediction because it alters the estimated arrival time of Earthbound coronal mass ejections (CMEs).

"Coronal mass ejection cannibalism is the most violent form of interaction between CMEs," says NASA Goddard's Dr. Natchimuthuk Gopalswamy, lead author of a research paper presented during a meeting of the European Geophysical Society in Nice, France. "This happens when a slow CME is expelled before a fast one from the same general region on the Sun. The fast CME simply gobbles up the slow one," resulting in a single, complex outward-moving front.

Coronal mass ejections are billion-ton clouds of electrified, magnetic gas that solar eruptions hurl into space at speeds ranging from a few hundred to 2000 km/s. Earth-directed CMEs can trigger magnetic storms when they strike our planet's magnetic field, distorting its shape and accelerating electrically charged particles trapped within. The researchers believe cannibal eruptions may be larger and more complex in structure than typical eruptions. These traits cause "complex ejecta" CMEs to trigger protracted magnetic storms when they envelop the Earth.


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Additional Resources:

Learn more about NASA's Wind spacecraft.

Learn more about the Solar and Heliospheric Observatory (SOHO) spacecraft from NASA and the European Space Agency (ESA).