How to Predict Solar Storms

French physicists have discovered the telltale calm before a solar eruption.

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Oct 22 2014, 5:00pm

A coronal mass ejection. Image: Tahar Amari/Centre de physique théorique. CNRS-Ecole Polytechnique. FRANCE.

The Sun has been fidgety recently. This morning, NASA announced that it had spat out its second substantial flare in a two-day period. These flares—which are sudden eruptions of bright, arcing radiation—have been preceded by months of increased activity as our star reaches solar maximum (the period of greatest solar activity in the Sun's 11-year-long cycle).

These eruptions can wreak havoc on satellites, ground-based communications, and human spaceflight plans, which calls for better methods of predicting their duration and intensity.

Fortunately, a paper published today in Nature takes on that challenge.

Led by physicist Tahar Amari at the Ecole Polytechnique, the paper is the result of several years of research into the events preceding solar flares. It's based on data obtained by the Solar Optical Telescope aboard the Hinode satellite to model a particularly active region of the Sun called NOAA 10930.

The Sun has been fidgety recently

Amari confirmed that flares were preceded by an elongation of sunspots, followed by the emergence of a "twisted rope" of magnetic flux. These flux ropes are basically kinks in the lines of magnetic fields, and are one of the major forces that power coronal mass ejections, which are like solar flares on steroids.

There are two existing theories for their formation: in the first, the flux rope is shifted out of magnetic equilibrium, and its reconnection to the field powers the eruption. In the second, the flux rope is only formed as a result of a magnetic reconnection.

A coronal mass ejection. Credit: Tahar Amari/Centre de physique théorique. CNRS-Ecole Polytechnique. FRANCE.

The new paper lends support to the first theory, which is good news, because it makes solar flares easier to predict. According to the study, about four days before eruption, the region will begin to accumulate magnetic energy resulting in the formation of a flux rope the day before a mass coronal ejection. If this process is detected in time, it could give everyone on Earth the better part of a week to prepare for the next solar barfathon.

Satellite operators and spaceflight engineers would be able to prepare "in the same way they are doing now, but might be able to do it sooner," Amari told me. Some examples include "postponing operations which depend on GPS, [and] modifying flight crew schedules and flight trajectories for near-polar flights."

The paper is a promising step towards reading the Sun's future moods, and it is especially topical given that the Sun is currently in a particularly manic phase right now. "The behavior of the Sun has recently changed and is now in a state not observed for almost 100 years," said physicist Nathan Schwadron, in a statement about his paper, released yesterday, which evaluated Sun's effect on human spaceflight.

"While these conditions are not necessarily a showstopper for long-duration missions to the moon, an asteroid, or even Mars, galactic cosmic ray radiation in particular remains a significant and worsening factor that limits mission durations," he said.

Along those lines, Amari and his colleagues hope to anticipate solar activity with even more precision moving forward. "Our next research concerns both applying these results to future prediction, and following a coronal mass ejection once it is produced," he said, "in particular studying the interaction with the Earth environment."

That's right, Sun: we're on to your games. The next time you try to mess up our spacecraft, we'll be ready.