Banner
    Gigantic Coronal Hole Caught Hovering Over The Sun's North Pole
    By News Staff | July 21st 2013 06:00 AM | 2 comments | Print | E-mail | Track Comments

    On July 18th, 2013, at 9:06 a.m. EDT, the Solar and Heliospheric Observatory (SOHO) captured an image of a gigantic coronal hole hovering over the sun's north pole.

    Coronal holes are dark, low density regions of the sun's outermost atmosphere, the corona, and contain little solar material and lower temperatures so they appear much darker than their surroundings.

    Coronal holes appear at different places and with more frequency at different times of the sun's activity cycle, which 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 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. Credit: ESA&NASA/SOHO)

    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.




    Comments

    Bonny Bonobo alias Brat
    Wow, absolutely fabulous photo!
    My article about researchers identifying a potential blue green algae cause & L-Serine treatment for Lou Gehrig's ALS, MND, Parkinsons & Alzheimers is at http://www.science20.com/forums/medicine
    MikeCrow
    Curious when added to all of the other goings on.


    This is a chart of the progression on cycle 24 sunspot number.

    Observation through June 2013


    Historical sunspot numbers



    Back a little bit further into the past:



    Coronal holes appear at different places and with more frequency at different times of the sun's activity cycle, which 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.


    Is this large hole a sign we are at or near solar max?


    Long-term Evolution of Sunspot Magnetic Fields

    Independent of the normal solar cycle, a decrease in the sunspot magnetic field strength has been observed using the Zeeman-split 1564.8nm Fe I spectral line at the NSO Kitt Peak McMath-Pierce telescope. Corresponding changes in sunspot brightness and the strength of molecular absorption lines were also seen. This trend was seen to continue in observations of the first sunspots of the new solar Cycle 24, and extrapolating a linear fit to this trend would lead to only half the number of spots in Cycle 24 compared to Cycle 23, and imply virtually no sunspots in Cycle 25.
    We examined synoptic observations from the NSO Kitt Peak Vacuum Telescope and initially (with 4000 spots) found a change in sunspot brightness which roughly agreed with the infrared observations. A more detailed examination (with 13,000 spots) of both spot brightness and line-of-sight magnetic flux reveals that the relationship of the sunspot magnetic fields with spot brightness and size remain constant during the solar cycle. There are only small temporal variations in the spot brightness, size, and line-of-sight flux seen in this larger sample. Because of the apparent disagreement between the two data sets, we discuss how the infrared spectral line provides a uniquely direct measurement of the magnetic fields in sunspots.
    Never is a long time.