Some explanation: The sun can develop a coronal hole when a portion of its magnetic field fails to loop back onto the surface, as it usually does. This allows more solar material to escape into space. In other words, it makes the solar wind even windier. That’s the stuff that’s flying out into space. The region looks dark because there’s simply less hot and bright solar material left behind.
Coronal Hole Seen Over Sun's North Pole By SOHO Spacecraft vedat şafak yamı - YouTube
Large coronal hole near the sun's north pole
Coronal holes are a typical feature on the sun, though they appear at different places and with more frequency at different times of the sun's activity cycle. The activity cycle is currently ramping up toward what is known as solar maximum, currently predicted for late 2013. During this portion of the cycle, the number of coronal holes decreases. During solar max, 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.The 'gigantic hole' in the SUN that's firing solar material into space and was spotted by a spacecraft | Mail Online
Spacecraft Sees Giant 'Hole' In the Sun - Yahoo! News
Coronal Hole Seen Over Sun's North Pole By SOHO Spacecraft
The $1.27-billion (1 billion euros) SOHO satellite was launched in 1995 and is flying a joint mission between NASA and the European Space Agency (ESA). It watches solar activity from an orbit about the Lagrange Point 1, a gravitationally stable spot between Earth and the sun that is about 932,000 miles (1.5 million kilometers) from our planet.