Saturday, May 30, 1998 Published at 07:58 GMT 08:58 UK
Massive quake hits the Sun
A solar flare causes ripples in the sun beneath it
A sunquake, tens of thousands of times bigger than any tremor on Earth, has been spotted on the surface of the Sun. It offers an insight into the cataclysmic events that may be occurring on the surfaces of even bigger stars. Our science correspondent David Whitehouse reports.
The sunquake released 40,000 times the energy of a strong terrestrial earthquake like the one which devastated San Francisco in 1906. About the same energy is required to power the United States for 20 years.
Evidence of the sunquake was found in data collected by the orbiting Soho solar monitoring satellite following a moderate solar flare last year.
A solar flare is an awesome spectacle on the face of the sun. It begins when magnetic fields generated in the solar interior rise up from below the surface.
The magnetic fields become coiled and twisted. Eventually the tension becomes too much and they rupture explosively heating gas to millions of degrees.
Superheated gas as well as shockwaves and sub-atomic particles are sprayed in all directions. Some escape the sun and can reach Earth. Some fall back on to the Sun's surface.
It was the disturbance on the solar surface that astronomers have seen.
Shortly after the flare, ripples appeared above the Sun's surface, looking like ripples in a pool of water. In one hour they had travelled 75,000 miles (120,000 kms). A distance equivalent to 10 Earth diameters.
Experts have said that this research could help predict solar flare which can affect electronic equipment back on Earth.
Writing in the journal Nature, scientists say the discovery of sunquakes suggests similar, but even bigger quakes may be discovered on some other stars.
As for the Sun itself, the scientists hope these latest findings will provide more insight into the energy-generating processes deep inside it.
As a further boost for this research, the European Space Agency has agreed to extend Soho's mission until the year 2003, so it can cover the expected peak in the 11-year cycle of solar activity.