Solar Science

A blog of solar physics

Posts Tagged ‘Sunspot

SC24: Sunspots appear in both hemispheres

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Just when I thought we’d get to watch a single sunspot make its weary way across the surface of the Sun, a new sunspot group appears in the Northern Hemisphere. We haven’t seen a sight like this in a long time

Of course the Sun has surprised us before – one swallow not making a summer and all of that jazz – but I remain cautiously optimistic. It will be interesting to see if the new Northern Hemisphere spots last for at least a few days.

Boy, am I a glutton for punishment.

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Written by John A

September 23, 2009 at 10:27 am

Posted in Uncategorized

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NASA on the disappearing sunspots

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This just in from NASA:

September 3, 2009: The sun is in the pits of the deepest solar minimum in nearly a century. Weeks and sometimes whole months go by without even a single tiny sunspot. The quiet has dragged out for more than two years, prompting some observers to wonder, are sunspots disappearing?

“Personally, I’m betting that sunspots are coming back,” says researcher Matt Penn of the National Solar Observatory (NSO) in Tucson, Arizona. But, he allows, “there is some evidence that they won’t.”

Penn’s colleague Bill Livingston of the NSO has been measuring the magnetic fields of sunspots for the past 17 years, and he has found a remarkable trend. Sunspot magnetism is on the decline:

Above: Sunspot magnetic fields measured by Livingston and Penn from 1992 – Feb. 2009 using an infrared Zeeman splitting technique.

“Sunspot magnetic fields are dropping by about 50 gauss per year,” says Penn. “If we extrapolate this trend into the future, sunspots could completely vanish around the year 2015.”

Hmmm, yes they could. But the solar magnetic field could simply be in a cyclical downturn of which this is a part. We need an expert!

“This work has caused a sensation in the field of solar physics,” comments NASA sunspot expert David Hathaway, who is not directly involved in the research. “It’s controversial stuff.”

The controversy is not about the data. “We know Livingston and Penn are excellent observers,” says Hathaway. “The trend that they have discovered appears to be real.” The part colleagues have trouble believing is the extrapolation. Hathaway notes that most of their data were taken after the maximum of Solar Cycle 23 (2000-2002) when sunspot activity naturally began to decline. “The drop in magnetic fields could be a normal aspect of the solar cycle and not a sign that sunspots are permanently vanishing.”

Yes, what he said.

Penn himself wonders about these points. “Our technique is relatively new and the data stretches back in time only 17 years. We could be observing a temporary downturn that will reverse itself.”

The technique they’re using was pioneered by Livingston at the NASA-supported McMath-Pierce solar telescope near Tucson. He looks at a spectral line emitted by iron atoms in the sun’s atmosphere. Sunspot magnetic fields cause the line to split in two—an effect called “Zeeman splitting” after Dutch physicist Pieter Zeeman who discovered the phenomenon in the 19th century. The size of the split reveals the intensity of the magnetism

If the solar magnetism continues to decline what could this mean for the Earth?

If sunspots do go away, it wouldn’t be the first time. In the 17th century, the sun plunged into a 70-year period of spotlessness known as the Maunder Minimum that still baffles scientists. The sunspot drought began in 1645 and lasted until 1715; during that time, some of the best astronomers in history (e.g., Cassini) monitored the sun and failed to count more than a few dozen sunspots per year, compared to the usual thousands.

Note that of course, they don’t mention that this coincided with the coldest part of the Little Ice Age. But that would be politically incorrect, wouldn’t it?

“Whether [the current downturn] is an omen of long-term sunspot decline, analogous to the Maunder Minimum, remains to be seen,” Livingston and Penn caution in a recent issue of EOS. “Other indications of solar activity suggest that sunspots must return in earnest within the next year.”

I’d love to know what those other indications are, because the prognostications of future solar activity have been startlingly poor from practically everybody.

I leave the last words to David Hathaway, who dares to speak the truth to solar science:

Whatever happens, notes Hathaway, “the sun is behaving in an interesting way and I believe we’re about to learn something new.”

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Written by John A

September 3, 2009 at 10:13 am

Testing the "Watts Effect"

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On Anthony Watts’ blog, he’s testing his apparent paranormal power to cause the Sun to break out into sunspots by writing about how blank the Sun is.

On this blog, I don’t believe in the paranormal, and it looks like the Sun is still slumbering, with no end in sight.

Here is the stereo view looking behind the Sun to the surface that has yet to come into view:

Stereo image of solar farside 29-08-2009

Stereo image of solar farside 29-08-2009

Nothing to report other than a coronal hole. Looks like Anthony’s got no more powers than I have.

Here’s the solar cycle progression to July 2009.

ISES Solar Cycle Progression Jul 2009

ISES Solar Cycle Progression Jul 2009

With August 2009 expected to be zero, that red line prediction is looking more and more optimistic.

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Written by John A

August 28, 2009 at 7:20 pm

Posted in Solar Cycle 24

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What comes around

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Following on from my previous post noting the rotating back into view of the region formerly known as Sunspot 1024, we now have a clearer picture:

Sunspot 1024 is over, man

Sunspot 1024 is over, man

Its just a plage, the end game of a sunspot.

The Sun remains quiet.

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Written by John A

July 27, 2009 at 2:14 pm

Posted in Solar Cycle

Tagged with ,

What goes around…

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It looks as though the active region formerly known as Sunspot 1024 is still active and will be rotating back into view in the next few days.

Here’s the region as pictured by the Stereo satellites which give a view of some of the solar farside. The active region is the bright area at about 7.30 on this image:

behind_euvi_195_260709

and here is the SOHO view which is close to what is almost the terrestrial view of the Sun. The active region is the bright area on the lower left edge of the photosphere.

eit_284_260709

Apart from this one region, there’s nothing else to report. I’m going to be checking the solar flux to see whether there is any change, but I’m not optimistic.

Meanwhile Dr David Hathaway has popped up in the New York Times saying that contrary to his previous forecasts, a Dalton Minimum-like weak sunspot cycle (ramping up to only 50-70)

For example, in 2006, Dr. Hathaway looked at disturbances in the Earth’s magnetic field that are caused by the Sun, and they were strong. During past cycles, strong disturbances at minimum indicated strong fields all over the Sun at maximum and a bounty of sunspots. Because the previous cycles had been shorter than average, Dr. Hathaway thought the next one would be shorter and thus solar minimum was imminent. He predicted the new solar cycle would be a ferocious one, consistent with a short cycle.

Instead, the new cycle did not arrive as quickly as Dr. Hathaway anticipated, and the disturbances weakened. His revised prediction is for a smaller-than-average maximum. Last November, it looked like the new cycle was finally getting started, with the new cycle sunspots in the middle latitudes outnumbering the old sunspots of the dying cycle that are closer to the equator.

After a minimum, solar activity usually takes off quickly, but instead the Sun returned to slumber. “There was a long lull of several months of virtually no activity, which had me worried,” Dr. Hathaway said.

Worried? Why? Because your previous forecasts were flat out wrong?

Nobody’s perfect.

Not even me.

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Written by John A

July 25, 2009 at 3:39 pm

Posted in Solar Cycle 24

Tagged with ,

This Quiet Sun

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The Sun has gone back to blank after having had just one sunspot group that caused otherwise rational people to go off their heads…

Here’s the magnetogram of the Sun showing precisely nothing that presages any sunspot formation:

Magnetogram of the Sun 16/07/2009

Magnetogram of the Sun 16/07/2009

As a comparison, here is the sun image from the Extreme ultraviolet Imaging Telescope at 304 ångstroms for today and near solar maximum in 2000 by way of comparison

Sun at 17/07/2009 (left) and near solar maximum 31/05/2000

Sun at 17/07/2009 (left) and near solar maximum 31/05/2000 (right)

Now its easy to see how quiet the Sun really is at the moment. The prominences are weak, the coronal holes are very small, the corona (the solar atmosphere) shrunken.

All of this can be seen to be normal behaviour for the Sun, except that this hiatus between Solar Cycle 23 finally winding down and the next cycle is unprecedented in nearly a hundred years. (By the way, the overuse of “unprecedented” by climate alarmists has me wincing at using it as a cliché)

Eventually the solar cycle must return. The question is whether solar scientists gain insight into the behaviour of the Sun by understanding why their models failed (see below). The result can only be better science.

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Written by John A

July 17, 2009 at 5:21 pm

Ken Tapping: Still no sign of the next cycle

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Previously on this blog, I’d mentioned my skepticism that one decent sunspot marked the end of the hiatus in the solar cycle we’ve seen for nearly two years. It might be my nature, but everybody has been wrong before.

As part of my public duty to actually ask real scientists monitoring the Sun, I wrote to Dr Ken Tapping of Canada’s National Research Council at the Herzberg Institute of Astrophysics in British Columbia:

Dear Dr Tapping

For the first time in a very long time, the Sun has managed to produce a sunspot (1024) which has lasted more than a few hours.

Is there any sign of an upswing in radio emissions indicating an end to the hiatus?

Best regards

John

and Dr Tapping replied (with my emphasis):

Hi John,

Last weekend I saw a really nice sunspot group on the Sun, which could have been part of the new cycle. The solar radio flux went up a little while it was there. However now the flux has slumped back to low values again.

Some theorists have suggested the new cycle is currently under way, but that for some unknown reason we are not getting the spots to go with it. I’m not sure what that really means, so I am making no suggestion as to what is going on.

Being very conservative, according to the measurements being made under our Solar Radio Monitoring Programme, we have yet to see signs the next cycle is really under way.

Regards,

Ken

Now this is what I’d thought, that the nice sunspot (1024) we’d seen did not presage a change in the behavior of the Sun: the solar wind speed remained subdued, coronal holes remained very small, there were no prominences to speak of.

It also baffles me how “some theorists have suggested the new cycle is currently under way, but that for some unknown reason we are not getting the spots to go with it”. If there are very few sunspots and the radio flux remains extremely subdued, on what basis are these theorists making their statements?

It could be that this is the first “radio quiet” solar cycle … anyone believe that?

So for solar physicists, it remains “interesting times” and probably a time to clear out some old theories and start again.

My thanks to Dr Tapping for the correspondence.

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Written by John A

July 10, 2009 at 8:53 am