Large Coronal Hole Spotted Near Sun's North Pole

There's a hole in our Sun's corona and now astronomers have imaged the phenomenon using the Solar and Heliospheric Observatory. The hole isn't something that should worry us, though; it's a natural part of the solar cycle. That said, the new image does reveal how massive these holes can become.

Coronal holes are dark, low density regions of the sun's outermost atmosphere, the corona. Containing little solar material, they have lower temperatures in comparison to the rest of the Sun. Because of this, they appear much darker than their surroundings in images that are taken.

These holes are typical features on our Sun, though they appear in different places and with more frequency at different times of the Sun's cycle. Currently, our Sun is reaching its 11-year peak in its cycle, what is known as the solar maximum. Although solar activity has been relatively low in comparison to other peaks, the number of solar holes usually decreases during this period of the Sun's cycle. During the 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.

The current hole, though, is still massive. It stretches across over the Sun's north pole, extending over a good portion of the solar surface. First detected on July 18, the hole can be seen in the form of a massive black spot in the current image.

These coronal holes aren't just an interesting phenomenon, though. They're also crucial to our understanding of space weather. These holes are the source of a high-speed wind of solar particles that streams off of the Sun at three times faster than other solar winds, affecting nearby spacecraft.

Currently, scientists aren't sure exactly what causes coronal holes. However, they seem to correlate to areas in the sun where magnetic fields soar up and away, failing to loop back down to the surface as they do elsewhere. Whatever the case, imaging these holes may give researchers a little more material to work with when it comes to understanding this phenomenon.