Solar flares are the most enigmatic of the displays that the Sun puts up for us mortals. Huge wisps of gas erupt from the solar surface, unleashing impressive displays of electro-magnetic storms, that often knock out earth-orbiting satellites, and interfere with our television broadcasts. But the processes that cause such flares are largely a mystery. Now scientists from Mullard Space Science Laboratory (MSSL) and University College London have discovered some new evidence that points to the cataclysmic events that trigger a solar flare and the mechanisms that drive its subsequent evolution.

A Solar Flare (Courtesy: SOHO)A really large solar flare was observed by the ESA-NASA SOHO spacecraft on 15 July 2002. A detailed analysis of the flare, just published by Louise Harra of MSSL, shows that the flare was a complex event with three eruptions -each one triggering the next one like a domino effect. The solar flare's explosive power was 5,000 million times greater than an atomic bomb, hurling a billion tonnes of hot gas towards the Earth at speeds of around half a million miles an hour :):).
The analysis showed that the explosion was triggered by the sudden emergence of plasma from below the Sun's surface, close to an existing region of strong magnetic field. The two magnetic fields collided, releasing tremendous energy in form of the flare. This contradicts the current understanding of flare creation, which asserts that flares form when a magnetic line entangles and reconnects in the corona.
Now, it looks like flares can also occur when magnetic lines of force collide with each other. Since scientists can observe the growth of these lines of force on the surface of the Sun (by tracking the radiation emitted by the charged particles going around these lines), they should be able to predict when two lines will collide. This will allow scientists to predict the occurrence of such flares.
Such predictions are important, since a large flare can destroy expensive satellites, and can also be a hazard for astronauts on the International Space Station. By predicting the flares before they occur, they will have a much greater chance of hiding when the flare reaches the Earth.