Sun gives up secrets

The huge ejections contain twisted solar material

By Helen Briggs BBC News Online science reporter

The Sun spits out huge bubbles of super-hot electrified gas.

The solar eruptions blast out into space at speeds thousands of times faster than Concorde.

Sometimes they can even disrupt the Earth's magnetic field, leading to power black-outs.

Northern lights in Canada's Arctic North

They are also behind the most dramatic spectacle in the sky - the northern (and southern) lights.

The colourful light shows happen when solar eruptions strike the region of space shielded by our planet's magnetic field.

But despite their impact on Earth, it is not known exactly how the Sun spews out the giant bubbles of gas, known as coronal mass ejections (CMEs).

Now UK astrophysicists have found new clues. They think twisted magnetic fields deep within our star could be the driving force.

The evidence comes from data gathered by the SOHO and Yohkoh satellites.

Twisted structures

Twists within the Sun's magnetic field were studied by a team at the Mullard Space Science Laboratory (MSSL) in Surrey.

One theory is these twisted structures are caused by the Sun rotating faster at the equator than the poles, says Dr Lucie Green of MSSL.

But the new study, carried out with colleagues in France and Argentina, suggests a second option is more likely.

Prediction of space weather is still a long way off

Dr Lucie Green, MSSL

"The magnetic field doesn't get twisted enough by the differential rotation that happens on the surface," Dr Green told BBC News Online.

"The implication is that the magnetic field must get twisted deep within the Sun itself."

Scientists hope it will one day be possible to predict when the Sun is likely to emit CMEs as part of space weather forecasts.

"Prediction of space weather is still a long way off but our research is helping us understand why CMEs happen in the first place," says Dr Green.

Main image courtesy of SOHO/LASCO consortium. SOHO is a project of international co-operation between the European Space Agency and NASA.