Solar filament takes off

Stretching into space, larger than the Earth

By BBC News Online science editor Dr David Whitehouse

Nasa's Transition Region and Coronal Explorer (Trace) satellite has taken one of the most spectacular images of the Sun's surface.

Impression of Trace in orbit

A giant filament of gas was seen erupting from the Sun's "surface" on 19 July.

The filament measures over 100,000 km (62,000 miles) in height. The Earth could easily fit into its loops of superhot gas.

The hot gas in the filaments is confined by complex and changing magnetic fields emerging from beneath the Sun's surface.

Disruption

After rising above the Sun's surface, most of the gas will eventually fall back. More powerful solar eruptions than this one can eject particles into space that sometimes reach the Earth where they can disrupt satellites and cause aurorae.

Trace, launched in April 1998, enables solar physicists to study the connection between magnetic fields on the Sun's surface and the loops and arches of hot gas.

The Sun's surface is a seething mass of gas at a temperature of 6,000 C (10,800 F). Above the surface is a thin outer atmosphere called the corona which is much, much hotter.

Scientists are fascinated by this part of the Sun. They still fail to understand fully how the corona can be so hot.

They are also excited because the events and processes that take place in the hot gas on the Sun's surface occur in many places throughout the Universe.