What's going on with SDO images of the Sun? I'm not a physics buff but I do have an Astrophysics question regarding our Sun.  For the last week now the SDO telescope has been showing portions of the Sun going dark, at first it was in the UV and higher frequencies until today when more then 50% of our star was dark in all bands for 70 minutes.


Solar Dynamics Observatory (SDO) saw both the Moon (upper right) and the Earth (upper left) partially block the sun (Sept. 1, 2016 at 7:33 UT). Just before this image was taken, the Earth totally blocked the sun for a while. SDO orbits 22,000 miles above the Earth in a highly elliptical orbit that sometimes puts the Moon or Earth in front of the sun. The sun image was taken in a wavelength of extreme ultraviolet light. Only once before have both been there at the same time. Note that the edge of the moon is quite crisp because it has no atmosphere. Credit: Solar Dynamics Observatory, NASA


SDO Orbital Track
Every day the affected frequencies grow as well as the time duration of the effects.  So, can anyone explain what is going on with the satellite or am I missing something?  NASA won't respond so here I am.  Thank you very much for any help on this.


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*PD

 A: My answer is only a summary of what I have  read,  so hopefully someone current in the field will get us both up to date, although it still seems as though we have a lot of fundamental science to learn regarding this phenomenona. 
Perhaps to put things in perspective, on June 18, 2013, a large coronal hole was spotted in the Sun, spanning at least 400,000 miles across (almost half of the Sun's diameter), although I am not sure how this compares with the current events.


It was also revealing that none of the sites I checked  had any answers to your question, and it seems that the mechanism is not understood, even under "normal" conditions.
From Coronal Holes Wikipedia

Their size and population vary based on the solar cycle. It is known that every 11 years coronal holes reach their maximum.During a solar maximum, the number of coronal holes actually decreases because the magnetic fields are about to reverse in the Sun’s core. New coronal holes appear at the opposite magnetic alignment. They appear and expand over the pole and continue to do so even when the sun moves to solar minimum again. Coronal holes are linked to unipolar concentrations of open magnetic field lines. During solar minimum, coronal holes are mainly found at the Sun's polar regions, but they can be located anywhere on the sun during solar maximum. 

So it does appear, like sunspots, to be a cyclical event and  it may be that only time will tell when the minimum part of the cycle begins. The north and south poles feature  permanent coronal holes, so even during the solar minimum there are still coronal holes.
A: Oh boy, I think I figured it out.  I really thought the SDO satellite was above the N. Pole, but it's actually over the Equator doing figure eights, so it's a very good possibility (like 99.9999%) that the dark swaths across the Sun are the Earth obscuring the SDO's view.  I feel rediculous!  Thank you for you help with this "great mystery" of mine, haha. ♡♡  -PD
