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Post by csspider57 on Oct 18, 2010 2:22:04 GMT
The shape of the current sheet in March 2000 as calculated by the Blue Horizon supercomputer.
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Post by csspider57 on Oct 18, 2010 2:43:02 GMT
This next article is way too to let slide by us here whilst we are this subject and Leif got a good wobbler pic for you later too.. ok A Star with two North PolesSometimes the Sun's magnetic field goes haywire, and the effects are felt throughout the solar system
Normally, our star, like Earth itself, has a north and a south magnetic pole. But for nearly a month beginning in March 2000, the Sun's south magnetic pole faded, and a north pole emerged to take its place. The Sun had two north poles.
"It sounds impossible, but it's true," says space physicist Pete Riley of Science Applications International Corporation (SAIC) in San Diego. "In fact, it's a fairly normal side-effect of the solar cycle.. .."The south pole never really vanished," notes Riley. It migrated north and, for a while, became a band of south magnetic flux smeared around the Sun's equator. By May 2000 the south pole had returned.. ..Ordinarily, the current sheet circles the Sun's equator like a wavy skirt around a ballerina's waist. But during the double north pole event of March 2000, the current sheet was radically altered: The waviness increased. Irregularities appeared. Its topology "morphed" from a ballerina's skirt to a giant seashell.. Interesting to a solar physicist, perhaps...
...but ordinary people should care about this, too. First because of energetic cosmic rays: The current sheet acts as a barrier to cosmic rays traveling through the heliosphere. Cosmic rays can't cross the sheet; instead they flow along it. The shape of the current sheet therefore determines how many cosmic rays strike Earth. ..The episode of the double north pole provided a key test of their software. "We calculated the shape of the current sheet for a Sun with two north poles," recalls Riley. "The result looked like a conch shell ... more than a billion kilometers wide."
But how could he check his results?
NASA's Ulysses spacecraft provided the crucial data. In early 2000, Ulysses was about 600 million km from the Sun--perfect for testing the conch model. As the spacecraft cruised through space at 10 km/s it crossed the current sheet twice, once in March and again in April 2000. Onboard magnetometers recorded the crossings, which were in good agreement with Riley's predictions.
Using only measurements of the Sun's surface magnetic field, his software had successfully predicted magnetic fields in interplanetary space 600 million km away. Impressive.
Ulysses observations of the Sun's magnetic field in March 2000 overlaid on Riley's magnetohydrodynamic (MHD) calculations. science.nasa.gov/science-news/science-at-nasa/2003/22apr_currentsheet/
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Post by lsvalgaard on Oct 18, 2010 3:11:47 GMT
This next article is way too to let slide by us here whilst we are this subject and Leif got a good wobbler pic for you later too.. ok A Star with two North PolesSometimes the Sun's magnetic field goes haywire, and the effects are felt throughout the solar system
Normally, our star, like Earth itself, has a north and a south magnetic pole. But for nearly a month beginning in March 2000, the Sun's south magnetic pole faded, and a north pole emerged to take its place. The Sun had two north poles.
"It sounds impossible, but it's true," says space physicist Pete Riley of Science Applications International Corporation (SAIC) in San Diego. "In fact, it's a fairly normal side-effect of the solar cycle.. .."The south pole never really vanished," notes Riley. It migrated north and, for a while, became a band of south magnetic flux smeared around the Sun's equator. By May 2000 the south pole had returned.. ..Ordinarily, the current sheet circles the Sun's equator like a wavy skirt around a ballerina's waist. But during the double north pole event of March 2000, the current sheet was radically altered: The waviness increased. Irregularities appeared. Its topology "morphed" from a ballerina's skirt to a giant seashell.. Interesting to a solar physicist, perhaps...
...but ordinary people should care about this, too. First because of energetic cosmic rays: The current sheet acts as a barrier to cosmic rays traveling through the heliosphere. Cosmic rays can't cross the sheet; instead they flow along it. The shape of the current sheet therefore determines how many cosmic rays strike Earth. ..The episode of the double north pole provided a key test of their software. "We calculated the shape of the current sheet for a Sun with two north poles," recalls Riley. "The result looked like a conch shell ... more than a billion kilometers wide." But how could he check his results?
NASA's Ulysses spacecraft provided the crucial data. In early 2000, Ulysses was about 600 million km from the Sun--perfect for testing the conch model. As the spacecraft cruised through space at 10 km/s it crossed the current sheet twice, once in March and again in April 2000. Onboard magnetometers recorded the crossings, which were in good agreement with Riley's predictions.
Using only measurements of the Sun's surface magnetic field, his software had successfully predicted magnetic fields in interplanetary space 600 million km away. Impressive. Ulysses observations of the Sun's magnetic field in March 2000 overlaid on Riley's magnetohydrodynamic (MHD) calculations. science.nasa.gov/science-news/science-at-nasa/2003/22apr_currentsheet/This happens EVERY eleven year as the polar field reversal is a rather random process. The two poles NEVER reverse at precisely the same time., simply because there is not one huge dipole inside the Sun that flips over. Rather, the field consists of thousands of little strands that live rather independent lives, being eaten up by surrounding dead sunspots.
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Post by karlox on Oct 18, 2010 8:06:42 GMT
Not done yet Karlox check this out. Right: An artist's concept of the heliospheric current sheet. The rotating Sun is located in the center. Credit: Brian Grimm Thanks! some more music for the background... www.youtube.com/watch?v=KBalSWs5ngY
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Post by csspider57 on Oct 18, 2010 12:10:48 GMT
Yes, Dr. S., every eleven years solar polar reversal. Except the last one was somewhat exceptional in overall length. But .. good graphics on helio current sheet and how it sometimes responds.
Who used to say, "We now return control of your tv back to you?" whatever
Back to the Sunspot Magnetism---Livingston & Penn discussion.
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Post by lsvalgaard on Oct 18, 2010 13:34:51 GMT
Yes, Dr. S., every eleven years solar polar reversal. Except the last one was somewhat exceptional in overall length. But .. good graphics on helio current sheet and how it sometimes responds. Who used to say, "We now return control of your tv back to you?" whatever Back to the Sunspot Magnetism---Livingston & Penn discussion. No, not somewhat exceptional. Same thing happened in cycle 19 and in cycle 20. E.g. adsabs.harvard.edu/abs/1959ApJ...130..364B
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Post by lsvalgaard on Oct 19, 2010 8:56:02 GMT
update:
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Post by Bob k6tr on Oct 19, 2010 10:00:10 GMT
update: Tnx Leif I notice that Bill doesn't mark off a Blue Mean Dot with every update. Are they designated at a certain number of measurements ?
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Post by af4ex on Oct 19, 2010 10:48:29 GMT
> update: Leif, what is the latest estimate for the 'spots vanish' date?
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Post by af4ex on Oct 19, 2010 12:06:32 GMT
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Post by skypilot on Oct 19, 2010 15:30:42 GMT
"We now return control of your tv back to you?"
The Outer Limits
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Post by csspider57 on Oct 19, 2010 20:03:01 GMT
Yes, Dr. S., every eleven years solar polar reversal. Except the last one was somewhat exceptional in overall length. But .. good graphics on helio current sheet and how it sometimes responds. Who used to say, "We now return control of your tv back to you?" whatever Back to the Sunspot Magnetism---Livingston & Penn discussion. No, not somewhat exceptional. Same thing happened in cycle 19 and in cycle 20. E.g. adsabs.harvard.edu/abs/1959ApJ...130..364BGee thanks Leif. Perhaps should have said, "a slower than average polar reversal."Solar Polar Fields During Cycles 21 — 23: Correlation with Meridional Flows P. Janardhan1 K.B. Susanta1 S. Gosain1,2 Need to bring up from the depths that solar cycle anomalies thread. Thanks Skypilot, Rod Sterling.
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Post by lsvalgaard on Oct 19, 2010 22:31:19 GMT
> update: Leif, what is the latest estimate for the 'spots vanish' date? look for yourself... Let me say 2022, but with a wide margin.
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Post by lsvalgaard on Oct 19, 2010 22:33:10 GMT
Gee thanks Leif. Perhaps should have said, "a slower than average polar reversal."Solar Polar Fields During Cycles 21 — 23: Correlation with Meridional Flows P. Janardhan1 K.B. Susanta1 S. Gosain1,2 Need to bring up from the depths that solar cycle anomalies thread. Thanks Skypilot, Rod Sterling. I don't think it was 'slower than average'. We have only observed reversals in 1958, 1968, 1980, 1990, 2001, so 'average' is not well defined. 1958 was slow too. And 1968.
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Post by af4ex on Oct 19, 2010 23:05:20 GMT
> look for yourself... > Let me say 2022, but with a wide margin.
That's the intercept that I plotted too, with a straight line through the quadratic curve and Y=1500.
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