Posted on 03/07/2006 2:30:00 AM PST by S0122017
Solar Minimum has Arrived
03.06.2006
March 6, 2006: Every year in February, the students of Mrs. Phillips's 5th grade class in Bishop, California, celebrate Galileo's birthday (Feb. 15th) by repeating one of his discoveries. They prove that the sun spins.
It's simple. Step 1: Look at the sun. Galileo did this using a primitive telescope; Mrs. Phillips's students use the internet. Step 2: Sketch the sunspots. Step 3: Repeat daily. After only a few days, it's obvious that the sunspots are moving and sun is spinning, performing one complete turn every 27 days.
This procedure worked fine in 1610. But in 2006, "we had a problem," says young Jonathan Garcia. "No sunspots," explains his science fair partner Dakota Winkler.
Right: A picture of the sun taken Feb. 10, 2006, by the Solar and Heliospheric Observatory (SOHO). [Larger image]
For almost the entire month of February 2006 the sun was utterly blank. If Galileo had looked at the sun on his 442nd birthday, he would have been disappointed—no sunspots, no spin, no discovery.
What's going on? NASA solar physicist David Hathaway explains: "Solar minimum has arrived."
Sunspots come and go with an 11-year rhythm called the sunspot cycle. At the cycle's peak, solar maximum, the sun is continually peppered with spots, some as big as the planet Jupiter. But for every peak there is a valley, and during solar minimum months can go by without a single sunspot.
"That's where we are now—at minimum," says Hathaway.
Actually, we're at the beginning of the minimum. February 2006 was the first month in almost ten years with mostly no sunspots. For 21 of February's 28 days, the sun was blank. Hathaway expects this situation to continue for the rest of 2006.
Below: Sunspot counts from the time of Galileo through the end of 2005. In recent centuries, counts have gone up and down with an 11-year period. [More] 
No sunspots means low solar activity. Sunspots are sources of solar flares and coronal mass ejections that can disrupt radio communications and even cause power outages on Earth during severe magnetic storms. These problems should subside during the year ahead. Auroras, a beautiful side-effect of magnetic storms, should subside, too. "Too bad," says Hathaway, who enjoys Northern Lights.
Galileo was lucky. The year 1610 was close to a maximum of the sunspot cycle, so when he projected an image of the sun through his spyglass, he immediately saw enormous spots. The spots themselves did not surprise him. Chinese astronomers looking at the sun naked-eye through clouds and mist had reported seeing sunspots as early as 28 BC. The reality of sunspots was uncontroversial, but the nature of sunspots was a mystery. Were they satellites of the sun? Dark clouds in the sun's atmosphere? Or something else? Galileo's daily sketches showed plainly that the sun was spinning and that sunspots were close to the surface of the spinning orb. Personally, Galileo thought sunspots might be clouds.
Now we know what they really are: great islands of magnetism. Sunspots appear when magnetic force-fields generated by the sun's inner dynamo poke through the surface. These fields block the flow of heat from below, cooling the sun in their vicinity. If you stuck a thermometer in a sunspot, it would register "only" a few thousand degrees Celsius. This makes it look dark compared to the surrounding inferno.
Sunspots are in a state of non-stop upheaval. Tangled lines of magnetism twist and stretch until the tension becomes too great and an explosion occurs—a flare. This link between flares and spots is why solar minimum is so quiet.
"But not absolutely quiet," adds Hathaway. "During solar minimum we can have occasional sunspots and solar flares." Indeed there was at least one monster spot and one X-class solar flare (the most powerful kind) during each of the last three minima in 1976, 1986 and 1996.
2006 will probably be the same—long stretches of quiet with occasional episodes of spots and flares. How long will this last? Stay tuned for the answer in our next story: "Solar Storm Warning."
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Author: Dr. Tony Phillips | Production Editor: Dr. Tony Phillips | Credit: Science@NASA
I went to the link, and tried to bump it.
I guess it's too old!
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"I went to the link, and tried to bump it.
I guess it's too old!
Like us!"
Add me to the list.
BTW, I've had some odd interference on my Sat. TV (dish network) for the last week or two. I thought it was solar, but if we're at the minimum, that seems unlikely.
I saw that.
And you had an article in Canadian Astronomy about dark skies?
Cool!
Welcome to the list!
We'll be able to answer that in about a month.
It all sounds very grand, but the newsletter was hand-typed and then xeroxed, and they were hungry for fillers. However, it was more than could be said for my late, first brother-in-law's works. Despite attending college for virtually all his life ( I called him a Professional Student... ) studying writing and ancillary fields, he never got a thing into print. Too busy writing "the next Great American Novel," he viewed such yeomanly work as magazine articles or ad copy as being beneath him.
Each thing I had published was like unto coals of fire, heaped on his head.
LOL!
"Twenty-two year cycle"
I have noticed that when there is a particularly severe drought, the whether people are likely to talk about "the worst in 22 years", and sometimes about the sun spot cycles.
When I took Astronomy in 1959, there was also talk of a larger 88 year cycle. Now let's see, 1929 plus 88 equals 2017. We are having major droughts in the west and Texas. Perhaps this is a warmup for what will happen in 11 years; another Dust Bowl??
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