Scientists observed a giant coronal hole covering the sun's North Pole, the phenomenon is a common occurrence.
The holes are "dark, low density regions of the sun's outermost atmosphere," a NASA press release reported. Coronal holes have much less solar material, and are much cooler than their surroundings. The areas appear darker than the rest of the sun.
The holes may look alarming, but are actually a natural feature of the sun. They move around and appear with more frequency depending on the solar cycle.
The current cycle is moving towards the solar maximum, set for the end of 2013. During this time less coronal holes are expected.
"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 press release, written by Karen C. Fox of NASA's Goddard Space Flight Center, said.
Scientists study the holes to learn more about space weather. The holes create high speed winds made up of solar particles. These winds fly off the sun at speeds of up to three times faster than in other solar areas.
"While it's unclear what causes coronal holes, they correlate to areas on the sun where magnetic fields soar up and away, failing to loop back down to the surface, as they do elsewhere," the press release said.
The hole was discovered by the European Space Agency and NASA's Solar and Heliospheric Observatory (SOHO).
The SOHO satellite stays in orbit using the combined gravitational pull of the Earth and Sun, a SOHO press release reported. SOHO was initially only approved for a two year mission, but has been renewed five times since its first assignment ended.
