WASHINGTON

ON

A ‘gigantic hole’ in the sun’s atmosphere, hovering over the solar north pole, has been photographed by a space telescope.

The dark spot, which covers almost a quarter of the sun, is a large ‘coronal hole’ - a dark, low density region of the sun’s outermost atmosphere, the corona.

It was spotted by the European Space Agency/NASA Solar and Heliospheric Observatory (SOHO) spacecraft between 13 and 18 July, during which time it was spewing out material including solar wind into space.

While the hole looks devoid of solar activity, it was in fact releasing violent blasts of solar wind and spewing out solar particles at around 500 miles per second. The holes have lower temperatures and therefore appear much darker than their surroundings.

Karen Fox of Nasa’s Goddard Space Flight Centre said that while coronal holes are a typical feature on the sun, they appear at different places and with more frequency at different times of the sun’s activity cycle, which typically takes around 11 years.  The sun’s activity cycle is currently ramping up toward what is known as solar maximum, predicted for late 2013 - during which time the number of coronal holes decreases.

During solar maximum, the magnetic fields on the sun reverse and new coronal holes appear near the poles with the opposite magnetic alignment.  

The coronal holes then increase in size and number, extending further from the poles as the sun moves toward solar minimum again.   At such times, coronal holes have appeared that are even larger than this one, which measures approximately 400,000 miles across, or the equivalent to 50 Earths in a row.