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Massive Coronal Hole Spotted at Sun's North Pole

Jul 21, 2013 08:29 PM EDT
Coronal Hole
The European Space Agency/NASA Solar and Heliospheric Observatory, or SOHO, captured this image of a gigantic coronal hole hovering over the sun’s north pole on July 18, 2013, at 9:06 a.m. EDT.

(Photo : ESA & NASA/SOHO)

A gigantic coronal hole was spotted hovering over the Sun's north pole Thursday morning, NASA announced.

Dark, low density regions located in the outermost region of the Sun's atmosphere, coronal holes contain little solar material and are much cooler than their surroundings, resulting in their darker appearance.

Though a typical feature on the Sun's surface, where and how often they appear is dictated by the Sun's activity cycle. Currently, scientists report, the activity cycle is ramping up to what is known as solar maximum, which is predicted to occur later this year.

Solar maxes result about every 11 years when the magnetic fields on the Sun reverse and new coronal holes appear near the poles with the opposite magnetic alignment. During the present portion of the cycle, the number of coronal holes decreases. As time goes on, however, they will increase in both size and number, extending further from the poles as the Sun moves toward solar minimum again. During times like these, coronal holes even larger than the one scientists are observing now have been sited.

These holes are important pieces in understanding space weather, according to scientists, since they are the source of high-speed winds containing solar particles that stream off the Sun some three times faster than wind elsewhere.

At this point, it's unclear what causes them, though they appear to 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 images of the Sun's current coronal hole were taken by the European Space Agency/NASA Solar and Heliospheric Observatory, or SOHO.

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