Source of solar wind discovered

[hari]

An international team of scientists have found the source of the stream of particles that make up the solar wind.

Professor Louise Harra of the UCL-Mullard Space Science Laboratory explains how astronomers have used a UK-led instrument on the orbiting Hinode space observatory to finally track down the starting point for the wind.

The solar wind consists of electrically charged particles that flow out from the Sun in all directions. Even at their slowest, the particles race along at 200 km per second, taking less than 10 days to travel from the Sun to the Earth. When stronger gusts of the wind run into the magnetic field of the Earth there can be dramatic consequences, from creating beautiful displays of the northern and southern lights (aurorae) to interfering with electronic systems on satellites and sometimes even overloading electrical power grids on the ground.

From its launch in the autumn of 2006, scientists have used the Hinode mission to study the Sun in unprecedented detail. One of the instruments on the probe, the UK-built Extreme Ultraviolet Imaging Spectrometer (EIS) measures the speed at which material flows out from the Sun.

The Sun is a cauldron of hot gas shaped by magnetic fields, which create bright regions of activity on the solar surface. Using EIS, the scientists found that at the edges of these bright regions hot gas spurts out at high speeds. Magnetic fields connect the regions together, even when they are widely separated.

Professor Louise Harra of UCL-Mullard Space Science Laboratory says, "It is fantastic to finally be able to pinpoint the source of the solar wind it has been debated for many years and now we have the final piece of the jigsaw".