How Low Can It Go? Sun Plunges into the Quietest Solar Minimum in a Century

April 1, 2009

The Michelson Doppler Imager on SOHO captured this white light continuum image of the spotless sun on March 31, 2009. Credit: SOHO, NASA/ESA.
( -- The sunspot cycle is behaving a little like the stock market. Just when you think it has hit bottom, it goes even lower.

2008 was a bear. There were no sunspots observed on 266 of the year's 366 days (73 percent). To find a year with more blank suns, you have to go all the way back to 1913, which had 311 spotless days. Prompted by these numbers, some observers suggested that the solar cycle had hit bottom in 2008.

Maybe not. Sunspot counts for 2009 have dropped even lower. As of March 31st, there were no sunspots on 78 of the year's 90 days (87 percent).

It adds up to one inescapable conclusion: "We're experiencing a very deep ," says solar physicist Dean Pesnell of NASA’s Goddard Space Flight Center in Greenbelt, Md.

"This is the quietest sun we've seen in almost a century," agrees forecaster David Hathaway of NASA’s Marshall Space Flight Center in Huntsville, Ala.

Quiet suns come along every 11 years or so. It's a natural part of the sunspot cycle, discovered by German astronomer Heinrich Schwabe in the mid-1800s. Sunspots are planet-sized islands of magnetism on the surface of the sun, and they are sources of solar flares, coronal mass ejections, and intense UV radiation. Plotting sunspot counts, Schwabe saw that peaks of solar activity were always followed by valleys of relative calm—a clockwork pattern that has held true for more than 200 years.

The current solar minimum is part of that pattern. In fact, it's right on time. But is it supposed to be this quiet?

Measurements by the Ulysses spacecraft reveal a 20 percent drop in solar wind pressure since the mid-1990s—the lowest point since such measurements began in the 1960s. The solar wind helps keep galactic cosmic rays out of the inner solar system. With the solar wind flagging, more cosmic rays penetrate the solar system, resulting in increased health hazards for astronauts. Weaker solar wind also means fewer geomagnetic storms and auroras on Earth.

Careful measurements by several NASA spacecraft have also shown that the sun's brightness has dimmed by 0.02 percent at visible wavelengths and a whopping 6 percent at extreme UV wavelengths since the solar minimum of 1996. These changes are not enough to reverse global warming, but there are some other, noticeable side-effects.

Earth's upper atmosphere is heated less by the sun and it is therefore less "puffed up." Satellites in Earth orbit experience less atmospheric drag, extending their operational lifetimes. That’s the good news. Unfortunately, space junk also remains in orbit longer, posing an increased threat to useful satellites.

Finally, radio telescopes are recording the dimmest "radio sun" since 1955. After World War II, astronomers began keeping records of the sun's brightness at radio wavelengths, particularly 10.7 cm. Some researchers believe that the lessening of radio emissions during this solar minimum is an indication of weakness in the sun's global magnetic field. No one is certain, however, because the source of these long-monitored radio emissions is not fully understood.

The sunspot cycle from 1995 to the present. The jagged curve traces actual sunspot counts. Smooth curves are fits to the data and one forecaster's predictions of future activity. Credit: David Hathaway, NASA/MSFC

All these lows have sparked a debate about whether the ongoing minimum is extreme or just an overdue market correction following a string of unusually intense solar maxima.

"Since the Space Age began in the 1950s, solar activity has been generally high," notes Hathaway. "Five of the ten most intense solar cycles on record have occurred in the last 50 years. We're just not used to this kind of deep calm."

Deep calm was fairly common a hundred years ago. The solar minima of 1901 and 1913, for instance, were even longer than what we're experiencing now. To match those minima in depth and longevity, the current minimum will have to last at least another year.

In a way, the calm is exciting, says Pesnell. "For the first time in history, we're getting to observe a deep solar minimum." A fleet of spacecraft — including the Solar and Heliospheric Observatory (SOHO), the twin probes of the Solar Terrestrial Relations Observatory (STEREO), and several other satellites — are all studying the sun and its effects on Earth. Using technology that didn't exist 100 years ago, scientists are measuring solar winds, cosmic rays, irradiance and magnetic fields and finding that solar minimum is much more interesting than anyone expected.

Modern technology cannot, however, predict what comes next. Competing models by dozens of solar physicists disagree, sometimes sharply, on when this solar minimum will end and how big the next solar maximum will be. The great uncertainty stems from one simple fact: No one fully understands the underlying physics of the sunspot cycle.

Pesnell believes sunspot counts should pick up again soon, "possibly by the end of the year," to be followed by a solar maximum of below-average intensity in 2012 or 2013.

But like other forecasters, he knows he could be wrong. Bull or bear? Stay tuned for updates.

Provided by Tony Phillips, PhD, NASA

Explore further: Spotless Sun: Blankest Year of the Space Age

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3.5 / 5 (14) Apr 01, 2009
"Careful measurements by several NASA spacecraft have also shown that the sun's brightness has dimmed by 0.02 percent at visible wavelengths and a whopping 6 percent at extreme UV wavelengths since the solar minimum of 1996. ..."

Interesting that NASA says they measure a change of 0.02% in the visible whereas here: http://www.physor...575.html they say they are unable to measure changes that small, what gives? Both releases can't be correct. Perhaps neither is. Looks like another example of double talk from never a straight answer.

In addition the increase in cosmic rays have been shown (by the Danes) to increase nucleation and the formation of clouds. More clouds means greater reflection of solar energy. Much more than the reduction in solar output. Thus cooling of the earth's atmosphere - just like the Maunder minimum/little ices age. So, ignore the man behind the green curtain... telling you that: "These changes are not enough to reverse global warming,..." The cooling has already begun.
1.4 / 5 (11) Apr 01, 2009
More clouds means greater reflection of solar energy. Much more than the reduction in solar output.

To claim that the impact of cloud cover exceeds the impact of solar changes is a pretty weak claim. It doesn't take much to exceed the relatively small impact of solar changes on our climate. Can you make (and provide references for) the much stronger claim that the cloud cover changes would dominate over changes in C02 concentration?

The cooling has already begun.

Um... how do you figure? The overall temperature trend in recent decades is very strongly upward. Or are you talking about the downtick which has occurred in the past few years? A few years' worth of data is meaningless on the time scales we're talking about. It's like trying to gauge the direction of the economy based on a few days' worth of Dow history. You can see at http://en.wikiped...cord.png that the most recent downtick is actually pretty minimal compared to much larger downticks that occurred in 1992 and 1999. There are lots of downticks in the graph, even as the general trend is strongly upward. This is called "noise".
1.6 / 5 (7) Apr 01, 2009

"Apr. 4, 2008 - New research has dealt a blow to the skeptics who argue that climate change is all due to cosmic rays rather than to man-made greenhouse gases. The new evidence shows no reliable connection between the cosmic ray intensity and cloud cover."
2.8 / 5 (9) Apr 02, 2009
It was predicted that due to the solar cycle, the global temp would be the lower than normal. Guess what, global temp was below normal. Putting the temperature changes over the last century it matches the solar cycle.
3 / 5 (5) Apr 02, 2009
In 2005, I found that the peak intensity of solar sunspot cycles over the last 350 year, depends critically on whether the alignments of Jupiter, Saturn and the Sun (known as syzygies) occured before or after solar maximum. The details of this
predictive method is published in the peer reviewed journal PASA (Publications of the Astronomical Society of Australia). The predictive model is based upon the presence of a spin-orbit coupling mechanism transfering angular momentum between the orbits of the Jovian planets and the spin angular momentum of the Sun:


The next alignment of Jupiter and Saturn occurs in 2011.2. This means that the expected solar sunspot cycle maximum (for cycle 24) in 2012 - 2013 will occur after syzygy and the peak sunspot number will be less than 80.

The model also predicts that solar cycles 25 and 26 will also be very weak.
1 / 5 (1) Apr 02, 2009
Sorry, here is the correct URL for the paper

1 / 5 (1) Apr 02, 2009
It works if you join the following two lines together on the same line:

3.6 / 5 (14) Apr 02, 2009
global warming is a huge lie, watch as the warmies dance ever more frantically trying to twist the real world into fitting their expectations. the warmies haven't been able to predict anything correctly. never once. the only thing that they get correct is that you need to give them money.
2.2 / 5 (6) Apr 02, 2009
100 years is nothing for our Sun, to have a representative sample we need to have at least a million years worth of records.
2.4 / 5 (8) Apr 02, 2009

"Apr. 4, 2008 - New research has dealt a blow to the skeptics who argue that climate change is all due to cosmic rays rather than to man-made greenhouse gases. The new evidence shows no reliable connection between the cosmic ray intensity and cloud cover."

Read the paper; http://www.iop.or...668b2d4b - Well done! It is about low level clouds. See; http://esa-spacew...nsen.pdf pg 12. Article (2001) still has Mann's phoney hockey stick graph with no evidence of Maunder Minimum/"little ice age".

Now read: http://wattsupwit...climate/ and, if you have the desire to seek the facts, as opposed to protecting the AGW religious dogma, search for beryllium 10 and climate for much more info.
4.3 / 5 (4) Apr 02, 2009
Somehow I have the feeling that the solar activity that moves charged particles along the iron core of the earth, magnetizes the earth core and defines the strength of the earth magnetic field. As you may have read, the earth magnetic field is lowering, and some theories suspect that the polarity might invert in the near future. I wonder if the reversal has much to do with the solar wind and with the polarity vector of a coming strong solar storm. Maybe the north south orientation simply charges up again.
2.4 / 5 (9) Apr 02, 2009
lengould100, if you look at who gave who to whom, then then the stock manuipulators were democrats as they gave most of their donation to the democratic party and candidates. not republicans. Its just like the global warmers, most of them are democrats
3.7 / 5 (3) Apr 03, 2009
As a former (amateur) solar observer I feel for current solar observers equipped with only neutral density filters. How many days do I see sunspot counts on at ZERO. I can recall seeing at least a few good sunspot complexes even during solar minimum in the 70's & 80's. I'm sure the sun is just being itself here, but a spotless sun gets boring to look at (unless you own a narrowband filter or like observing faculae).

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