Massive
holes in the Sun’s corona spotted by NASA telescopes
NASA's
Solar and Heliospheric Observatory (SOHO) captured images of a
massive hole in the Sun's corona a few weeks ago. Numerous cameras
and telescopes trained on the Sun have been recording similar holes
ever since.
29
July, 2013
The
hole showed up in early July and crossed the side of the Sun that was
facing Earth around the middle of the month. It was so large that it
covered nearly a quarter of the Sun's visible disk.
These
holes open up in the corona due to changes in the Sun's magnetic
field and they allow streams of fast-moving solar particles to escape
into the solar wind. Coronal holes are nothing unusual. They happen
most often towards the minimum of the sun's 11-year cycle and
decrease in number towards the cycle's maximum (predicted for later
this year).
The
reason why the hole shows up as a dark region (when the Sun is always
so bright) is because it's much cooler than the surrounding material.
The image shows temperatures right around two million degrees Kelvin,
with hotter temperatures showing up very bright (like in the active
regions scattered about), and cooler temperatures showing up darker.
Of course, you still wouldn't want to touch those darker regions. As
with everything, temperatures on the Sun are all relative, and
temperatures in those darker regions are still up in the hundreds of
thousands of degrees, and possibly up to a million degrees or more.
NASA's
Solar Dynamics Observatory (SDO) was watching too, and it recorded
these images, which were strung together into a time-lapse video:
This
wasn't the only coronal hole going on at the time, either. As this
large hole tracked its way towards the other side of the Sun, SDO saw
a smaller hole open up at the Sun's equator:
The
reason why these coronal holes open up is still a mystery. However,
with missions like SOHO, SDO and NASA's new Interface Region Imaging
Spectrograph (IRIS), that launched in late June, multiple eyes are
always trained on the Sun. With more of these amazing images beaming
back to us here on Earth, and IRIS providing even higher resolution
than we've seen so far, we can't be too far from figuring out the the
answers to these stellar riddles
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