Solar Science

A blog of solar physics

Posts Tagged ‘minimum

It comes from the Far Side..?

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After being starved of any significant solar activity for so long, any detection of a sunspot very nearly becomes headline news. Therefore when a significant spot is detected on the solar farside, people start writing furiously.

So what to do? The first detection of a potential (and substantial) sunspot in more than a month came from GONG

But will it survive to the nearside?

There’s something that might be a spot on the far eastern limb of the latest STEREO image

But GONG now shows nothing at all

GONG data as of 16th September 2009

GONG data as of 16th September 2009

So what to believe? The next few days should show whether we’re looking at a spot or a plage. I confess that the sensitivity of the seismic results interpreted by GONG are often less accurate as to whether we are seeing a solar disturbance (like a coronal hole or a prominence) or a real sunspot.

I suspect that this is continuation of a pattern we have been seeing for many months, a single sunspot or very small group with SC24 polarity passes in front of us, but nothing else happens and the Sun’s activity quickly falls back to very low levels.

Because of this phenomenon, the most likely response from the solar science community is likely to be muted, after so many false dawns.

Solarcycle24.com has produced a graph showing the remarkable difference between the spotless days between solar cycles 22 and 23 and between 23 and 24.

There’s no end in sight for this minimum.

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Written by John A

September 16, 2009 at 9:15 pm

Posted in Solar Cycle 24

Tagged with , ,

The Sun is in a deep minimum

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Yesterday I pulled this magnetogram picture from the SOHO website

20081006_0141_mdimag_512.jpg

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.”

and

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

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