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greeting all
Over the last 2 weeks I have noted the first sunspots of the new solar cycle 25.
How do I know they are spots of the new cycle ?
Because they are higher latitude and opposite magnetic polarity.
Before I show an image, a little history and science. Over the many observed solar cycles, a
feature of the sunspots and the 11 year cycle, is that the spots migrate from higher latitudes
down to the equatorial region of the sun as the cycle progresses. This process produces what is
known as the "butterfly pattern"...
Courtesy NASA
The graph shows approx. 120 years from cycle 12 to cycle 23
The top part of the diagram shows the butterfly pattern and below it, the peaks in each cycle can
be seen in relation to the percentage of the sun's surface covered in sunspots. Basically an
indication of sunspot numbers and the peaks in the numbers.
Now for the spots themselves. Spots and spot groups have magnetic polarities and these
polarities are opposite in the northern and southern hemispheres of the sun. And those polarities
reverse with each new solar cycle. This is known as Hale's sunspot polarity law ...
https://www2.hao.ucar.edu/Education/Sun/hales-sunspot-polarity-law
The left side of the diagram shows a magnetogram from cycle 21 and you can see with the magnetic
polarities that in the northern hemisphere the white areas lead the black areas and that is opposite
in the southern hemisphere.
The right side shows a magnetogram from cycle 22 and you can now see that the polarities in each
hemisphere have swapped. So now we have the big clue for detecting the start of a new solar cycle.
We are looking for high latitude spots in either hemisphere that have opposite magnetic polarities
compared to spots at lower latitudes in the same hemisphere.
OK, let's look at the current cycle 24 polarities. Daily, I download a number of the solar images
from https://umbra.nascom.nasa.gov/images/latest.html . The green and blue Fe ( ionised iron)
the red He, the magnetogram and the intensitygram ( visible light -- shows the actual sunspots)
Below is a magnetogram from the 11 Sept 2018. The left active region is just below the equator
and the right region is just above the equator. Note the magnetic polarities for the different
hemispheres. Southern hemisphere, white is leading the black and the opposite for the region to
the right that in in the northern hemisphere. This is the arrangement for cycle 24.
Come forward a couple of months to this last week and we see that there is now a higher
latitude ( northern hemisphere) active region that has an opposite polarity ...
The large region to the right, altho right on the equator, is part of the northern hemisphere set.
This can be confirmed when it is followed back in time and compared to other regions that are
definitely just on the south side of the equator, as in the previous image.
As the next months and years go by, more high latitude active regions, in both the northern and
southern hemispheres will be seen as the sun moves towards the next solar max in approximately
5 years time.Dave
EDIT: fixed a couple of typos
Over the last 2 weeks I have noted the first sunspots of the new solar cycle 25.
How do I know they are spots of the new cycle ?
Because they are higher latitude and opposite magnetic polarity.
Before I show an image, a little history and science. Over the many observed solar cycles, a
feature of the sunspots and the 11 year cycle, is that the spots migrate from higher latitudes
down to the equatorial region of the sun as the cycle progresses. This process produces what is
known as the "butterfly pattern"...
Courtesy NASA
The graph shows approx. 120 years from cycle 12 to cycle 23
The top part of the diagram shows the butterfly pattern and below it, the peaks in each cycle can
be seen in relation to the percentage of the sun's surface covered in sunspots. Basically an
indication of sunspot numbers and the peaks in the numbers.
Now for the spots themselves. Spots and spot groups have magnetic polarities and these
polarities are opposite in the northern and southern hemispheres of the sun. And those polarities
reverse with each new solar cycle. This is known as Hale's sunspot polarity law ...
https://www2.hao.ucar.edu/Education/Sun/hales-sunspot-polarity-law
The left side of the diagram shows a magnetogram from cycle 21 and you can see with the magnetic
polarities that in the northern hemisphere the white areas lead the black areas and that is opposite
in the southern hemisphere.
The right side shows a magnetogram from cycle 22 and you can now see that the polarities in each
hemisphere have swapped. So now we have the big clue for detecting the start of a new solar cycle.
We are looking for high latitude spots in either hemisphere that have opposite magnetic polarities
compared to spots at lower latitudes in the same hemisphere.
OK, let's look at the current cycle 24 polarities. Daily, I download a number of the solar images
from https://umbra.nascom.nasa.gov/images/latest.html . The green and blue Fe ( ionised iron)
the red He, the magnetogram and the intensitygram ( visible light -- shows the actual sunspots)
Below is a magnetogram from the 11 Sept 2018. The left active region is just below the equator
and the right region is just above the equator. Note the magnetic polarities for the different
hemispheres. Southern hemisphere, white is leading the black and the opposite for the region to
the right that in in the northern hemisphere. This is the arrangement for cycle 24.
latitude ( northern hemisphere) active region that has an opposite polarity ...
This can be confirmed when it is followed back in time and compared to other regions that are
definitely just on the south side of the equator, as in the previous image.
As the next months and years go by, more high latitude active regions, in both the northern and
southern hemispheres will be seen as the sun moves towards the next solar max in approximately
5 years time.Dave
EDIT: fixed a couple of typos
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