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Featured Stargazing Solar Cycle #25 is upon us

  1. Nov 17, 2018 #1


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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 ....



    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, lets 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.


    EDIT: fixed a couple of typos
    Last edited: Nov 17, 2018
  2. jcsd
  3. Nov 19, 2018 #2


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    This is awesome. Perhaps you could make your post into an insights article for @Greg Bernhardt and get a $25 gift card(?) I think that was his offer for this November. Me, I'm holding out for the Xmas offer ;-).

    Back to your post:

    How does acoustics play into the sunspot activity? I remember a NOVA show where they mentioned that there were acoustical waves wafting across the Sun's surface and wondered if they played a role in these sunspot cycles.

    Here's a link to the NOVA program (@ the 11:24 min mark they mention sound waves):

    Here's a reference to Helioseismology:

    Last edited: Nov 19, 2018
  4. Nov 20, 2018 #3
    What is this expected to mean in terms of weather and communications?
  5. Nov 20, 2018 #4


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    Wow, great post @davenn , How do they measure those magnetic polarities?
  6. Nov 20, 2018 #5


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    I need to dig a bit deeper to see what I can find out

    I hadn't seen that particular doco before, tho am aware of most of what was presented ....
    a great video for anyone who wants a good introduction into the workings of the sun and space weather :wink:

    It has it's good and bad effects on communications ... a general improvement of long haul (worldwide) HF communications but intense
    solar maximums and large flares also cause HF propagation blackouts. With the increased energy input to the Earths atmosphere,
    it heats the atmosphere causing expansion and increasing drag on satellites .... Skylab was lost partly for that reason.
    more sunspots equals more energy output from the sun which generally relates to a warming of the Earth. Long periods of / deep solar minimums,
    eg. the Maunder Minimum is recognised to have produced a mini ice age in the northern hemisphere.
  7. Nov 20, 2018 #6

    Vanadium 50

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    Polarization of atomic spectral lines.
  8. Nov 20, 2018 #7

    Vanadium 50

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    Is that true? They were certainly coincident, but was it cause and effect?
  9. Nov 20, 2018 #8


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    well I did recently see an argument against the Maunder Minimum being the main cause including the wiki quote below ....

    from Wiki

    Maybe they are right ? and the Maunder Minimum just intensified that cooling period ?

    On the other hand there was little telescopic observations of the sun prior to them MM period .... The telescope had only been around for
    ~ 40 years at that time, so maybe the minimum or at least lower activity stretched back even further and can still be directly linked ?
    I see graphs showing a maxima of spots prior to the MM period, yet other text states what I said in the first sentence of this paragraph
    So who isn't telling the truth ??

    Many others still aim in the other direction



    for anyone with access to Researchgate ( I don't)

    The big problem is that there is so much sensationalising by various sources




    a good one.....

  10. Nov 20, 2018 #9


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  11. Nov 27, 2018 #10

    jim hardy

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    last night i stumbled across Professor Valentina Zharkova's interesting lecture.

    EDIT i see it's picked up by too many "sensationalists" for me to trust.

    An amateur's mistake

    i apologize

    old jim

    She has developed a math curve fit for sunspot activity that appears to pretty well match past data as far back as it goes.

    What startled me was when she added Rhodes Fairbridge's planetary influence to what she'd calculated with 'dynamo theory' ,
    her match got a lot better. (i dont pretend to be well versed in either)

    Her presentation is a full hour

    and i wouldn't ask you to invest that much time in my amateur question
    so if you've not heard of her just dismiss this whole post.

    i guess the best way to phrase my question is:
    as a layman
    i'm curious
    Is Ms Zharkova an esteemed solar phycisist ?
    Is her premise
    of two very stable circulations inside the sun
    whose beat frequency,
    modulated by solar tides from the planets' gravitational pull,
    and manifesting as sunspots and solar system's magnetic field
    considered by you folks who've actually studied the sun,
    likely ?

    My total exposure to solar astronomy is i read Clark's "The Sun Kings" , a history of solar observations and observers ..
    So as i said it's an amateur question and an off the cuff response will satisfy me.

    We'll see anyway in just a couple years whether she was on to something.

    thanks for reading

    old jim
    Last edited: Nov 28, 2018
  12. Nov 27, 2018 #11


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    Thanks Jim

    I will watch and read through and comment when I get home from work :smile:

  13. Nov 27, 2018 #12

    jim hardy

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    dave that's a whole hour presentation and i wouldn't ask you to invest that sort of time .

    if you do watch it i'd value your take on it.

    I read some of Fairbridge's papers about ten years ago and remember thinking he was on to part of a bigger picture
    This i thought might be one more piece
    but if it's a wild goose chase , well for me it was an interesting one and no harm done.

    It is an honest question with no intent to hijack your thread..

    old jim
  14. Nov 28, 2018 #13


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    Brilliant thread, thanks for kicking it off.
    The other good news is that you will have a chance to use your new kit in anger and not just in hope!!
  15. Nov 28, 2018 #14


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    thanks :smile:

    for sure .... I think it's been at least a month since my last imaging session :frown:
  16. Nov 28, 2018 #15


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    Hey Jim

    no problems ... :smile:
    I only got to see a little bit of it last nite ( had end of month invoicing to do) and I tend to agree with your comments

  17. Dec 3, 2018 #16
  18. Dec 3, 2018 #17

    I was curious to get your opinion on the next solar grand minimum. This paper suggests they happen on average every ~400 years and the last one was at the end of the 16th century, so another may occur soon if the proxy methods are strong.

    The origin of grand minima in the sunspot cycle
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