Such flares — also known as coronal mass ejections — can release as much energy as a billion megatons of TNT or 300,000 power stations.

They are so powerful that they can wipe out communication satellites, disrupt aviation, bring down power grids and, potentially, kill astronauts.

However, despite the disruption they can cause, scientists have until now found them impossible to predict.

This week a consortium of the world’s space research agencies is due to launch Solar B, the first of three satellites designed to study such flares — and create the first early-warning system against them. Next month two more probes, the so-called Stereo mission, should follow Solar B into space.

“Currently, solar flares can cause huge damage with very little warning,” said Chris Davis of Britain’s Rutherford Appleton Laboratory, which is involved with both projects. “With these satellites we might predict them days beforehand and be prepared.”

Solar B, built by teams from Britain, America and Japan, is due to be launched on September 22 from the Uchinoura space centre in southern Japan. Its three instruments will try to find out what happens on the sun’s surface just before solar flares erupt. One of them, a telescope built by a team from University College London (UCL), will watch the sun’s atmosphere for signs suggesting the surface is building up to an explosion.

“Solar flares are fast and furious and can cause communication blackouts on Earth within 30 minutes of erupting from the sun’s surface,” said Professor Louise Harra, the UK Solar B project scientist based at UCL’s Mullard Space Science Laboratory. “It is imperative that we understand what triggers these events.”

The two Stereo probes, built and launched by Nasa, the American space agency, but also carrying British instruments, will have the complementary task of observing what happens to solar flares once they erupt into space.

If a flare appears to be heading for Earth, the probes will trigger alerts so satellites can be prepared for the blast.

The Stereo satellites will be launched together in a single rocket, but once in space they will move apart. Chris Eyles of Birmingham University, said: “One spacecraft will move ahead of the Earth, the other lag behind. The resulting offset will allow the two spacecraft to have stereo vision such as humans have.”

It also means the spacecraft will be able to generate high-quality three-dimensional “movies” of solar flares. If these are good enough they could be turned into Imax-style films and put on general release.

Solar flares are generated by the bizarre way in which the sun rotates, with its equator spinning every 25 days — while the poles take five days longer. This difference in speed slowly twists the sun’s powerful magnetic fields into giant knots. As these distortions build up, the magnetic forces become concentrated in certain parts of the sun’s surface, bottling up its red-hot plasma and radiation and so creating cooler areas known as sun spots.

Eventually, the repressed energy bursts out, resulting in an explosion of radiation, high-energy particles and associated magnetic fields that hurtle into space at millions of miles an hour.

Earth’s magnetic fields protect humanity from the direct effects of such storms, but growing dependence on satellites for communication and navigation means that a massive solar flare could spell disaster.

The collapse of satellite links could lead to a meltdown in stock markets and endanger aircraft and ships that depend on global positioning systems.

One of the most powerful solar flares on record happened in September 1859, when the sun doubled its brightness for some minutes. The surge in magnetism induced powerful electrical currents in telegraph wires across Europe, igniting widespread fires.

That event was three times more powerful than the strongest solar flare, or space storm, in modern memory, which occurred in 1989, but even that was able to burn out power cables and black out Quebec.

The Apollo moon programme narrowly escaped disaster in 1972 when a solar flare erupted just as one crew had returned from the moon and another was preparing for launch.

If it had happened during a mission the astronauts would have received a potentially fatal dose of radiation.

Professor Keith Mason, chief executive of Britain’s Particle Physics and Astronomy Research Council, said: “Predicting the timing and strength of solar eruptions is becoming vital and these observatories will be Earth’s new sentinels.”

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