Issues Magazine

Scientists Detect the Cause of the Sun’s “Perfect Storm”


David Reneke

Astronomers have deduced the cause of a massive solar storm, and set standards to prevent profiteering from the naming of space objects.

An international team of scientists has uncovered the origin and cause of an extreme space weather event that occurred on the Sun in 2012 and generated the fastest solar wind speed ever recorded directly by a solar wind instrument.

The formation of the rare, powerful storm showed striking, novel features that were detected by an instrument on NASA’s twin satellite Solar TErrestrial RElations Observatory (STEREO) mission.

The storm on 22 July 2012 was so powerful that had it been aimed at Earth instead of at the STEREO spacecraft, which was located 120° off to the side of Earth, the consequences would have been dramatic – widespread aurora, satellite mal­functions, and the potential failure of electricity grids.

To date it has been unclear how extreme space weather storms form and evolve. Developing a better understanding of their causes is vital to protecting modern society and its technological infrastructures – one of the goals of the STEREO mission.

“These results provide a new view crucial to solar physics and space weather as to how an extreme space weather event can arise from a combination of multiple solar eruptions,” says research assistant professor Noé Lugaz of the University of New Hampshire (UNH).

The researchers suggest that a successive one-two punch of solar eruptions, known as coronal mass ejections, was the key to the event blasting away from the Sun at 3000 km/s – a speed that would circle the Earth five times in a minute!

In a sense, this was the “perfect storm”. The first eruption was a primer for the quick propagation of the subsequent eruptions through interplanetary space.

“Remarkably, this is reminiscent of the great solar flare in 1859, the famous Carrington Event, and the geomagnetic storm of unheard of intensity in Earth’s magnetosphere, or magnetic field, that occurred less than 1 day later,” said UNH research professor Charles Farrugia.

The STEREO mission, launched in October 2006, has dramatically improved our understanding of the powerful solar eruptions that can send more than a billion tonnes of the Sun’s outer atmosphere hurtling into space.