Solar Science

A blog of solar physics

The Sun is in a deep minimum

with 4 comments

Yesterday I pulled this magnetogram picture from the SOHO website


Ignoring the phage in the Southern Hemisphere (which is SC23 polarized, natch) there is no magnetic activity at all to speak of.

Throw in the result announced by NASA in the last few days:

“The sun’s million mile-per-hour solar wind inflates a protective bubble, or heliosphere, around the solar system. It influences how things work here on Earth and even out at the boundary of our solar system where it meets the galaxy,” said Dave McComas, Ulysses’ solar wind instrument principal investigator and senior executive director at the Southwest Research Institute in San Antonio, Texas. “Ulysses data indicate the solar wind’s global pressure is the lowest we have seen since the beginning of the space age.”


In 2007, Ulysses made its third rapid scan of the solar wind and magnetic field from the sun’s south to north pole. When the results were compared with observations from the previous solar cycle, the strength of the solar wind pressure and the magnetic field embedded in the solar wind were found to have decreased by 20 percent. The field strength near the spacecraft has decreased by 36 percent.

“The sun cycles between periods of great activity and lesser activity,” Smith said. “Right now, we are in a period of minimal activity that has stretched on longer than anyone anticipated.”

Its clear that the Sun has entered a phase that we might never have seen before with anything like modern instrumentation.

The spots on the Sun have become so evanescent and small that we now have the ludicrous arguments over whether a darkened spot that lasts a few hours is counted as a spot or a speck. Anthony Watts refers to this as “Speckwatch” and furthermore even these specks have been SC23 not SC24 polarized.

What is clear is that these spots or specks are way below the range at which our scientific ancestors from the 18th and 19th Centuries could ever have detected.


Written by John A

October 6, 2008 at 1:54 pm

Posted in News and Views

Tagged with ,

4 Responses

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  1. From what little I understand about solar observations I can say that few, if any of the recent “sunspots” would have been detectable with the instruments available 100 or 200 years ago. That makes the current minimum that much more anomalous. I’ve plotted the recent pattern of “zero days” and it looks more like the minimum of ~1912 than anything else


    October 9, 2008 at 4:27 am

  2. How does the current minimum compare to the one before SC19, can you plot those? That would be an interesting comparison.


    October 12, 2008 at 6:33 am

  3. Actually on Warwick Hughes blog, David Archibald has done an interesting exercise which could indicate how weak SC24 might actually be.

    John A

    October 13, 2008 at 8:21 am

    I find it interesting that in December 2006, this paper projected what appears to be our current Solar Minimum.
    Now, I can’t validate all the research – but pardon the pun – it appeard to be “Spot On” regarding the sunspot activity this month.


    October 27, 2008 at 1:01 am

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