Tonight's Sky
Sun
Sun
Moon
Moon
Mercury
Mercury
Venus
Venus
Mars
Mars
Jupiter
Jupiter
Saturn
Saturn

Tonight's Sky — Change location

OR

Searching...

Tonight's Sky — Select location

Tonight's Sky — Enter coordinates

° '
° '

Large coronal hole near the Sun’s north pole

Such holes are the source of a high-speed wind of solar particles that streams off the Sun some three times faster than the solar wind elsewhere.
RELATED TOPICS: SUN | SOLAR SYSTEM
Large coronal hole
The European Space Agency (ESA)/NASA Solar and Heliospheric Observatory (SOHO) captured this image of a gigantic coronal hole hovering over the Sun’s north pole July 18, 2013. // ESA & NASA/SOHO
The European Space Agency (ESA)/NASA Solar and Heliospheric Observatory (SOHO) captured this image of a gigantic coronal hole hovering over the Sun’s north pole July 18, 2013, at 9:06 a.m. EDT. Coronal holes are dark low-density regions of the Sun’s outermost atmosphere, the corona. They contain little solar material, have lower temperatures, and therefore appear much darker than their surroundings.

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 farther 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 holes are important to our understanding of space weather, as they are the source of a high-speed wind of solar particles that streams off the Sun some three times faster than the slower wind elsewhere. 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.
0

JOIN THE DISCUSSION

Read and share your comments on this article
Comment on this article
Want to leave a comment?
Only registered members of Astronomy.com are allowed to comment on this article. Registration is FREE and only takes a couple minutes.

Login or Register now.
0 comments
ADVERTISEMENT

FREE EMAIL NEWSLETTER

Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter.

ADVERTISEMENT
ADVERTISEMENT
BoxProductcovernov

Click here to receive a FREE e-Guide exclusively from Astronomy magazine.

Find us on Facebook

Loading...